1`
UNITED STATES
SECURITIES AND EXCHANGE COMMISSION
Washington, D.C. 20549
FORM
For the quarterly period ended
For the transition period from to
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Securities registered pursuant to Section 12(b) of the Act:
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Indicate by check mark whether the registrant (1) has filed all reports required to be filed by Section 13 or 15(d) of the Securities Exchange Act of 1934 during the preceding 12 months (or for such shorter period that the registrant was required to file such reports), and (2) has been subject to such filing requirements for the past 90 days.
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Emerging growth company | ||||
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As of November 9, 2026, there were
McEWEN INC.
FORM 10-Q
Index
2
PART I – FINANCIAL INFORMATION
Item 1. FINANCIAL STATEMENTS
McEWEN INC.
CONSOLIDATED STATEMENTS OF OPERATIONS AND COMPREHENSIVE INCOME (LOSS) (UNAUDITED)
(in thousands of U.S. dollars, except per share, and shares)
Three months ended September 30, | Nine months ended September 30, | ||||||||||
2026 | 2025 | | 2026 | | 2025 | ||||||
Revenue from gold and silver sales | $ | | $ | | $ | | $ | ||||
Production costs applicable to sales | ( | ( |
| ( |
| ( | |||||
Depreciation and depletion | ( | ( | ( | ( | |||||||
Gross profit | | | | | |||||||
OTHER OPERATING INCOME (EXPENSES): | |||||||||||
Advanced projects | ( | ( | ( | ( | |||||||
Exploration | ( | ( | ( | ( | |||||||
General and administrative (Note 19) | ( | ( |
| ( |
| ( | |||||
Income (loss) from equity method investments (Note 9) | ( | ( | | ( | |||||||
Depreciation | ( | ( |
| ( |
| ( | |||||
Reclamation and remediation | ( | ( |
| ( | ( | ||||||
( | ( | ( |
| ( | |||||||
Operating income (loss) | ( | ( |
| |
| ( | |||||
OTHER INCOME (EXPENSES): | |||||||||||
Interest and other finance income | | | | | |||||||
Interest and other finance expenses | ( | ( |
| ( |
| ( | |||||
Other income (expenses) (Note 3) | ( | |
| ( |
| | |||||
Total other income (expenses) | ( | |
| ( |
| | |||||
Income (loss) before income and mining taxes | ( | ( | | ( | |||||||
Income and mining tax recovery (expense) (Note 17) | ( | | ( | | |||||||
Net income (loss) after income and mining taxes | $ | ( | $ | ( | $ | | $ | ( | |||
Net income (loss) per share (Note 13): | |||||||||||
Basic | $ | ( | $ | ( | $ | | $ | ( | |||
Diluted | $ | ( | $ | ( | $ | | $ | ( | |||
Weighted average common shares outstanding (thousands) (Note 13): | |||||||||||
Basic | | | | | |||||||
Diluted | | | | | |||||||
OTHER COMPREHENSIVE INCOME: | |||||||||||
Change in foreign currency translation adjustments (Note 9) | $ | | $ | — | $ | | $ | — | |||
Comprehensive income (loss) | $ | ( | $ | ( | $ | | $ | ( | |||
The accompanying notes are an integral part of these consolidated financial statements.
3
McEWEN INC.
CONSOLIDATED BALANCE SHEETS (UNAUDITED)
(in thousands of U.S. dollars and shares)
As at | As at | |||||
September 30, | December 31, | |||||
2026 | 2025 | |||||
ASSETS | ||||||
Current assets: | ||||||
Cash and cash equivalents (Note 4) | $ | | $ | | ||
Marketable securities (Note 5) | | | ||||
Receivables, prepaids and other current assets (Note 6) | | | ||||
| | |||||
Due from McEwen Copper Inc. (Note 14) | | | ||||
Total current assets | | | ||||
Mineral property interests and plant and equipment, net (Note 8) | | | ||||
Equity method investments (Note 9) | | | ||||
| | |||||
Deferred tax assets | | | ||||
Inventories (Note 7) | | | ||||
Restricted cash (Note 4) | | | ||||
Other assets | — | | ||||
TOTAL ASSETS | $ | | $ | | ||
LIABILITIES AND SHAREHOLDERS’ EQUITY | ||||||
Current liabilities: | ||||||
Accounts payable and accrued liabilities | $ | | $ | | ||
Long-term debt, current portion (Note 10) | | — | ||||
Reclamation and remediation liabilities (Note 11) | | | ||||
Contract liability (Note 16) | | | ||||
Flow-through share premium (Note 12) | — | | ||||
Tax liabilities | | | ||||
Lease liabilities | | | ||||
Total current liabilities | | | ||||
Long-term debt, net of issuance costs (Note 10) | | | ||||
Reclamation and remediation liabilities (Note 11) | | | ||||
Deferred tax liabilities | | | ||||
Lease liabilities | | | ||||
Other liabilities | | | ||||
Total liabilities | $ | | $ | | ||
Shareholders’ equity: | ||||||
$ | | $ | | |||
Accumulated deficit | ( | ( | ||||
Accumulated other comprehensive income | | — | ||||
Total shareholders’ equity | | | ||||
TOTAL LIABILITIES AND SHAREHOLDERS’ EQUITY | $ | | $ | | ||
The accompanying notes are an integral part of these consolidated financial statements.
4
McEWEN INC.
CONSOLIDATED STATEMENTS OF CHANGES IN SHAREHOLDERS’ EQUITY (UNAUDITED)
(in thousands of U.S. dollars and shares)
Common Stock | Accumulated | ||||||||||||||||
and Additional | Common | Other | |||||||||||||||
Paid-in Capital | Stock | Accumulated | Comprehensive | ||||||||||||||
Three months ended September 30, 2025 and 2026 | | Shares | Amount | Issuable | Deficit | Income | Total | ||||||||||
Balance, June 30, 2025 |
| | $ | | $ | — | $ | ( | $ | — | $ | | |||||
Stock-based compensation |
| | | — | — | — | | ||||||||||
Exercise of warrants | | | — | — | — | | |||||||||||
Net loss | — | — | — | ( | — | ( | |||||||||||
Balance, September 30, 2025 |
| | $ | | $ | — | $ | ( | $ | — | $ | | |||||
Balance, June 30, 2026 |
| | $ | | $ | | $ | ( | $ | | $ | | |||||
Investment in Canadian Gold Corp. (Note 18) | | | ( | — | — | — | |||||||||||
Investment in Golden Lake Exploration Inc. (Note 18) | — | — | — | — | — | — | |||||||||||
Stock-based compensation |
| | | — | — | — | | ||||||||||
Exercise of warrants | | | — | — | — | | |||||||||||
Share issuance | | | | ||||||||||||||
Net loss | — | — | — | ( | — | ( | |||||||||||
Change in foreign currency translation adjustments (Note 9) | — | — | — | — | | | |||||||||||
Balance, September 30, 2026 |
| | $ | | $ | — | $ | ( | $ | | $ | | |||||
Common Stock | Accumulated | ||||||||||||||||
and Additional | Common | Other | |||||||||||||||
Paid-in Capital | Stock | Accumulated | Comprehensive | ||||||||||||||
Nine months ended September 30, 2025 and 2026 | Shares | Amount | Issuable | Deficit | Income | Total | |||||||||||
Balance, December 31, 2024 | | $ | | — | $ | ( | $ | — | $ | | |||||||
Stock-based compensation |
| | | — | — | — | | ||||||||||
Exercise of warrants | | | — | — | — | | |||||||||||
Investment in Goliath Resources Limited | | | — | — | — | | |||||||||||
Purchase of capped call options (Note 10) | — | ( | — | — | — | ( | |||||||||||
Shares issued for debt refinancing (Note 10) | | | — | — | — | | |||||||||||
Net loss |
| — | — | — | ( | — | ( | ||||||||||
Balance, September 30, 2025 |
| | $ | | — | $ | ( | $ | — | $ | | ||||||
Balance, December 31, 2025 |
| | $ | | — | $ | ( | $ | — | $ | | ||||||
Investment in Canadian Gold Corp. (Note 18) | | | — | — | — | | |||||||||||
Investment in Golden Lake Exploration Inc. (Note 18) | | | — | — | — | | |||||||||||
Sales of flow-through shares (Note 12) | | | — | — | — | | |||||||||||
Stock-based compensation |
| | | — | — | — | | ||||||||||
Exercise of warrants | | | — | — | — | | |||||||||||
Share issuance | | | | ||||||||||||||
Net income | — | — | — | | — | | |||||||||||
Change in foreign currency translation adjustments (Note 9) | — | — | — | — | | | |||||||||||
Balance, September 30, 2026 |
| | $ | | — | $ | ( | $ | | $ | | ||||||
The accompanying notes are an integral part of these consolidated financial statements.
5
McEWEN INC.
CONSOLIDATED STATEMENTS OF CASH FLOWS (UNAUDITED)
(in thousands of U.S. dollars)
Nine months ended September 30, | ||||||
2026 | 2025 | |||||
Cash flows from operating activities: | ||||||
Net income (loss) | $ | | $ | ( | ||
Adjustments to reconcile net income (loss) from operating activities: | ||||||
Loss (income) from equity method investments (Note 9) | ( | | ||||
Dividends received from Minera Santa Cruz S.A. (Note 9) | | — | ||||
Depreciation, amortization and depletion | | | ||||
Loss (gain) on marketable securities (Note 5) | | ( | ||||
Reclamation accretion and adjustments to estimate | | | ||||
Deferred income and mining tax expense (recovery) (Note 17) | | ( | ||||
Flow-through premium amortization (Note 12) | ( | ( | ||||
Loss on revaluation of consideration payable for Canadian Gold Corp. acquisition (Note 14) | | — | ||||
Other | | | ||||
Changes in non-cash working capital items: | ||||||
Change in inventories | ( | ( | ||||
Change in other assets related to operations | ( | ( | ||||
Change in accounts payable and accrued liabilities | ( | | ||||
Change in contract liability | | | ||||
Change in other liabilities related to operations | ( | ( | ||||
Cash provided by operating activities | $ | | $ | | ||
Cash flows from investing activities: | ||||||
Additions to mineral property interests and plant and equipment | $ | ( | $ | ( | ||
Loan receivable from McEwen Copper Inc. (Note 14) | ( | ( | ||||
Proceeds from relinquishment of loan receivable from McEwen Copper Inc. (Note 14) | | — | ||||
Other | | | ||||
Cash used in investing activities | $ | ( | $ | ( | ||
Cash flows from financing activities: | ||||||
Issuance of flow-through common shares, net of issuance costs (Note 12) | $ | | $ | — | ||
Proceeds from senior convertible notes (Note 10) | — | | ||||
Purchase of capped call options (Note 10) | — | ( | ||||
Convertible notes financing costs (Note 10) | — | ( | ||||
Principal repayment on long-term debt (Note 10) | — | ( | ||||
Proceeds from exercise of stock options and warrants | | | ||||
Payment of finance lease obligations | ( | ( | ||||
Cash provided by financing activities | $ | | $ | | ||
Effect of exchange rate change on cash and cash equivalents | | | ||||
Increase (decrease) in cash, cash equivalents and restricted cash | ( | | ||||
Cash, cash equivalents and restricted cash, beginning of period | | | ||||
Cash, cash equivalents and restricted cash, end of period | $ | | $ | | ||
Supplemental disclosure of cash flow information: | ||||||
Cash received (paid) during the period: | ||||||
Interest paid | $ | ( | $ | ( | ||
Interest received | $ | | $ | | ||
Taxes paid | $ | ( | $ | ( | ||
Non-cash investing activities: | ||||||
Additions to mineral property interests and plant and equipment included in accounts payable and accrued liabilities | $ | | $ | — | ||
The accompanying notes are an integral part of these consolidated financial statements.
6
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
NOTE 1 NATURE OF OPERATIONS AND BASIS OF PRESENTATION
McEwen Inc. (the “Company”), through its predecessor entity, US Gold Corporation, was organized under the laws of the State of Colorado on July 24, 1979. The Company is engaged in the production and sale of gold and silver, as well as the development and exploration of copper, gold and silver mineral properties across North and South America.
The Company owns a
The interim consolidated financial statements included herein have been prepared by the Company pursuant to the rules and regulations of the Securities and Exchange Commission (“SEC”) and are unaudited. While information and note disclosures normally included in annual financial statements and prepared in accordance with accounting principles generally accepted in the United States of America (“U.S. GAAP”) have been condensed or omitted pursuant to such rules and regulations, the Company believes that the information and disclosures included in the interim consolidated financial statements are adequate and not misleading. Therefore, these interim consolidated financial statements should be read in conjunction with the audited consolidated financial statements and notes thereto and the summary of significant accounting policies included in the Company’s Annual Report on Form 10-K for the year ended December 31, 2025, as amended. Except as noted below, there have been no material changes in the footnotes from those accompanying the audited consolidated financial statements contained in the Company’s Form 10-K for the year ended December 31, 2025.
In management’s opinion, the unaudited Consolidated Statements of Operations and Comprehensive Income (Loss) (“Statements of Operations”) for the three and nine months ended September 30, 2026 and 2025, the unaudited Consolidated Balance Sheet as at September 30, 2026 and December 31, 2025, the unaudited Consolidated Statements of Changes in Shareholders’ Equity for the three and nine months ended September 30, 2026 and 2025, and the unaudited Consolidated Statements of Cash Flows for the nine months ended September 30, 2026, and 2025, contained herein, reflect all adjustments, consisting solely of normal recurring items, which are necessary for the fair presentation of the Company’s financial position, results of operations and cash flows on a basis consistent with that of the Company’s prior audited consolidated financial statements. However, the results of operations for the interim periods may not be indicative of results to be expected for the full fiscal year. The consolidated financial statements include the accounts of the Company and its wholly owned subsidiaries. Intercompany accounts and transactions have been eliminated. Investments over which the Company exerts significant influence but does not control through majority ownership are accounted for using the equity method. Certain prior period amounts have been reclassified for consistency with the current period presentation in the unaudited Consolidated Statements of Cash Flows. The reclassifications had no impact on reported results.
References to “CAD” refers to Canadian Dollar, “USD” refers to United States Dollar, “MXN” refers to Mexican Peso, and “ARS” refers to Argentine Peso.
NOTE 2 OPERATING SEGMENT REPORTING
The chief operating decision-maker (“CODM”) is the executive leadership team of the Company. The CODM reviews operating results, assesses performance and makes decisions about allocation of resources to these segments at the major mine/project level for individual mines with similar economic characteristics, or by investee for investments that are considered reportable segments. As a result, these operating segments also represent the Company’s reportable segments.
7
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
The CODM reviews segment income or loss, defined as gold and silver sales, less production costs applicable to sales, depreciation and depletion, advanced projects, and exploration costs and an allocation of other segment items for all segments except for the McEwen Copper and MSC segments, which are evaluated based on the attributable equity income or loss pickup. The CODM uses segment gross profit (loss) and profit (loss) before taxes, or income (loss) from equity method investments, to allocate resources (including employees, property and financial or capital resources) for each segment. CODM predominantly considers such measures in the annual budget and forecasting process. The CODM considers budget-to-actual variances for operating segments on a quarterly basis to support resource allocation and performance evaluation.
Gold and silver sales and production costs applicable to sales for the reportable segments are reported net of intercompany transactions. Capital expenditures include costs capitalized in mineral property interests and plant and equipment in the respective periods.
Significant information relating to the Company’s
Gold Bar | Fox | Tartan | McEwen | ||||||||||||||||||
Three months ended September 30, 2026 | Mine Complex | Complex | Lake (7) | El Gallo | MSC | Copper | Total | ||||||||||||||
Revenue from gold and silver sales | $ | | $ | | $ | — | $ | | $ | — | $ | — | $ | | |||||||
Production costs applicable to sales (1) | ( | ( | — | ( | — | — | ( | ||||||||||||||
Depreciation and depletion (1) | ( | ( | — | — | — | — | ( | ||||||||||||||
Gross profit (loss) | | ( | — | | — | — | | ||||||||||||||
Advanced projects (1) | — | ( | — | ( | — | — | ( | ||||||||||||||
Exploration (1) | ( | ( | ( | — | — | — | ( | ||||||||||||||
Income (loss) from equity method investments (2) | — | — | — | — | | ( | ( | ||||||||||||||
Other segment items (3) | ( | ( | | ( | — | — | ( | ||||||||||||||
Segment profit (loss) | $ | ( | $ | ( | $ | ( | $ | ( | $ | | $ | ( | $ | ( | |||||||
Unallocated amounts: | |||||||||||||||||||||
Loss from equity method investment (4) | ( | ||||||||||||||||||||
General and administrative (5) | ( | ||||||||||||||||||||
Depreciation (6) | ( | ||||||||||||||||||||
Interest and other finance expense, net | ( | ||||||||||||||||||||
Other expense | ( | ||||||||||||||||||||
Loss before income and mining taxes | $ | ( | |||||||||||||||||||
Capital expenditures | $ | | $ | | $ | | $ | | $ | — | $ | — | $ | | |||||||
8
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
Gold Bar | Fox | Tartan | McEwen | ||||||||||||||||||
Nine months ended September 30, 2026 | Mine Complex | Complex | Lake (7) | El Gallo | MSC | Copper | Total | ||||||||||||||
Revenue from gold and silver sales | $ | | $ | | $ | — | $ | | $ | — | $ | — | $ | | |||||||
Production costs applicable to sales (1) | ( | ( | — | ( | — | — | ( | ||||||||||||||
Depreciation and depletion (1) | ( | ( | — | — | — | — | ( | ||||||||||||||
Gross profit | | | — | | — | — | | ||||||||||||||
Advanced projects (1) | — | ( | — | ( | — | — | ( | ||||||||||||||
Exploration (1) | ( | ( | ( | — | — | — | ( | ||||||||||||||
Income (loss) from equity method investments (2) | — | — | — | — | | ( | | ||||||||||||||
Other segment items (3) | ( | ( | | ( | — | — | ( | ||||||||||||||
Segment profit (loss) | $ | | $ | ( | $ | ( | $ | | $ | | $ | ( | | ||||||||
Unallocated amounts: | |||||||||||||||||||||
Loss from equity method investment (4) | ( | ||||||||||||||||||||
General and administrative (5) | ( | ||||||||||||||||||||
Depreciation (6) | ( | ||||||||||||||||||||
Interest and other finance expense, net | ( | ||||||||||||||||||||
Other expense | ( | ||||||||||||||||||||
Income before income and mining taxes | $ | | |||||||||||||||||||
Capital expenditures | $ | | $ | | $ | | $ | | $ | — | $ | — | $ | | |||||||
Gold Bar | Fox | McEwen | ||||||||||||||||
Three months ended September 30, 2025 | Mine Complex | Complex | El Gallo | MSC | Copper | Total | ||||||||||||
Revenue from gold and silver sales | $ | | $ | | $ | | $ | — | $ | — | $ | | ||||||
Production costs applicable to sales (1) | ( | ( | ( | — | — | ( | ||||||||||||
Depreciation and depletion (1) | ( | ( | — | — | — | ( | ||||||||||||
Gross profit | | | | — | — | | ||||||||||||
Advanced projects (1) | — | — | ( | — | — | ( | ||||||||||||
Exploration (1) | ( | ( | — | — | — | ( | ||||||||||||
Income (loss) from equity method investments (2) | — | — | — | | ( | ( | ||||||||||||
Other segment items (3) | ( | ( | ( | — | — | ( | ||||||||||||
Segment profit (loss) | $ | | $ | ( | $ | ( | $ | | $ | ( | $ | ( | ||||||
Unallocated amounts: | ||||||||||||||||||
General and administrative (5) | ( | |||||||||||||||||
Depreciation (6) | ( | |||||||||||||||||
Interest and other finance expense, net | ( | |||||||||||||||||
Other income | | |||||||||||||||||
Loss before income and mining taxes | $ | ( | ||||||||||||||||
Capital expenditures | $ | | $ | | $ | | $ | — | $ | — | $ | | ||||||
9
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
Gold Bar | Fox | McEwen | ||||||||||||||||
Nine months ended September 30, 2025 | | Mine Complex | Complex | El Gallo | MSC | Copper | Total | |||||||||||
Revenue from gold and silver sales | $ | | $ | | $ | | $ | — | $ | — | $ | | ||||||
Production costs applicable to sales (1) | ( | ( | ( | — | — | ( | ||||||||||||
Depreciation and depletion (1) | ( | ( | — | — | — | ( | ||||||||||||
Gross profit (loss) | | ( | | — | — | | ||||||||||||
Advanced projects (1) | — | — | ( | — | — | ( | ||||||||||||
Exploration (1) | ( | ( | — | — | — | ( | ||||||||||||
Income (loss) from equity method investments (2) | — | — | — | | ( | ( | ||||||||||||
Other segment items (3) | ( | ( | ( | — | — | ( | ||||||||||||
Segment profit (loss) | $ | | $ | ( | $ | ( | $ | | $ | ( | $ | ( | ||||||
Unallocated amounts: | ||||||||||||||||||
General and administrative (5) | ( | |||||||||||||||||
Depreciation (6) | ( | |||||||||||||||||
Interest and other finance expense, net | ( | |||||||||||||||||
Other income | | |||||||||||||||||
Loss before income and mining taxes | $ | ( | ||||||||||||||||
Capital expenditures | $ | | $ | | $ | | $ | — | $ | — | $ | | ||||||
| (1) | The significant expense categories and amounts align with the segment-level information that is regularly provided to CODM. |
| (2) | Operating results of McEwen Copper and MSC on a |
| (3) | Other segment items include: |
| a. | General and administrative expenses attributable to the segment |
| b. | Depreciation unrelated to production activities of the segment |
| c. | Reclamation and remediation |
| d. | Interest and other expenses (income) |
| e. | Foreign currency loss (gain) |
| (4) | Operating results of Paragon on a |
| (5) | General and administrative expenses comprise primarily of corporate expenses not attributable to any reporting segment. |
| (6) | Depreciation is attributable to the corporate assets and other non-productive assets. |
| (7) | Tartan Lake is a newly identified segment resulting from the acquisition of Canadian Gold Corp. (“Canadian Gold”), refer to Note 18 – Asset Acquisitions. |
10
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
Geographic information
Geographic information includes the long-lived asset balances and revenues presented for the Company’s operating segments, as follows:
Non-current Assets | Revenue (1) | Revenue (1) | ||||||||||||||||
September 30, | December 31, | Three months ended September 30, | Nine months ended September 30, | |||||||||||||||
2026 | 2025 | 2026 | 2025 | | 2026 | 2025 | ||||||||||||
USA | $ | | $ | | $ | | $ | | $ | | $ | | ||||||
Canada (2) | | | | | | | ||||||||||||
Mexico | | | | | | | ||||||||||||
Argentina (3)(4) | | | — | — | — | — | ||||||||||||
Total consolidated | $ | | $ | | $ | | $ | | $ | | $ | | ||||||
| (1) | Presented based on the location from which the precious metals originated. |
| (2) | Includes investment in Paragon of $ |
| (3) | Includes investment in MSC of $ |
| (4) | Revenue is not reported on a consolidated basis for equity method investments. For a breakdown of Argentina segment revenue, refer to Note 9 – Equity Method Investments. |
NOTE 3 OTHER INCOME (EXPENSES)
The following is a summary of other income (expenses) for the three and nine months ended September 30, 2026 and 2025:
Three months ended September 30, | Nine months ended September 30, | |||||||||||
2026 | 2025 | | 2026 | | 2025 | |||||||
Unrealized and realized gain (loss) on investments | $ | | $ | | $ | ( | $ | | ||||
Other income (expenses) | ( | | ( | | ||||||||
Total other income (expenses) | $ | ( | $ | | $ | ( | $ | | ||||
NOTE 4 CASH AND CASH EQUIVALENTS AND RESTRICTED CASH
The following table provides a breakdown of cash and cash equivalents and restricted cash reported in the Consolidated Balance Sheets:
September 30, 2026 | December 31, 2025 | |||||
Cash and cash equivalents | $ | | $ | | ||
Restricted cash in non-current assets | | | ||||
Total cash and cash equivalents and restricted cash | $ | | $ | | ||
11
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
NOTE 5 MARKETABLE SECURITIES
The following is a summary of the activity in marketable securities for the nine months ended September 30, 2026 and 2025:
As at | Additions/ | Disposals/ | Loss on | As at | |||||||||||
December 31, | transfers during | transfers during | securities | September 30, | |||||||||||
2025 | period | period | held | 2026 | |||||||||||
Equity securities | $ | | $ | — | $ | ( | $ | ( | $ | | |||||
Warrants | | | ( | ( | | ||||||||||
Total marketable securities | $ | | $ | | $ | ( | $ | ( | $ | | |||||
As at | Additions/ | Disposals/ | Gain on | As at | |||||||||||
December 31, | transfers during | transfers during | securities | September 30, | |||||||||||
2024 | period | period | held | 2025 | |||||||||||
Marketable securities | $ | | $ | | $ | ( | $ | | $ | | |||||
Warrants | | | ( | | | ||||||||||
Total marketable securities | $ | | | ( | | | |||||||||
Marketable securities consist of equity securities and warrants of publicly listed companies in the mining sector. Equity securities and warrants are measured at fair value with changes in fair value recognized in net income (loss). Refer to Note 15 - Fair Value Accounting, for the fair value hierarchy levels and valuation techniques.
NOTE 6 RECEIVABLES, PREPAIDS AND OTHER CURRENT ASSETS
The following is a breakdown of balances in receivables, prepaids and other current assets as at September 30, 2026 and December 31, 2025:
September 30, 2026 | December 31, 2025 | |||||
Government sales tax receivable | $ | | $ | | ||
Prepaids and other assets | | | ||||
Receivables, prepaids and other current assets | $ | | $ | | ||
Government sales tax receivables primarily consist of VAT recoverable from tax authorities in Canada, Mexico and Argentina. As at September 30, 2026, the Company has $
12
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
NOTE 7 INVENTORIES
Inventories as at September 30, 2026 and December 31, 2025 consisted of the following:
September 30, 2026 | December 31, 2025 | |||||
Material on leach pads | $ | | $ | | ||
In-process inventory | | | ||||
Stockpiles | | | ||||
Precious metals | | | ||||
Materials and supplies | | | ||||
$ | | $ | | |||
Less: long-term portion | ( | ( | ||||
Current portion | $ | | $ | | ||
During the nine months ended September 30, 2026, inventories at Fox Complex operations were written down by $
NOTE 8 MINERAL PROPERTY INTERESTS AND PLANT AND EQUIPMENT
The applicable definition of proven and probable reserves is set forth in the Regulation S-K 1300 requirements of the SEC. If proven and probable reserves or economically viable deposits exist at the Company’s properties, the relevant capitalized mineral property interests and asset retirement costs are charged to expense based on the units-of-production method upon commencement of production. The Company’s Gold Bar Mine Complex, San José, and Los Azules have proven and probable reserves estimated, and the Grey Fox deposit, within the Fox Complex, has probable reserves in accordance with Regulation S-K 1300.
The mineral properties associated with the Fox Complex include the Froome and Black Fox mines, the Grey Fox deposit, and the Stock property. With the exception of Grey Fox, which has probable reserves, the Fox Complex properties do not have proven and probable reserves that conform to Regulation S-K 1300 and are depleted and depreciated using the units-of-production method over the estimated production for the remaining life of the mine.
The Company reviews and evaluates its long-lived assets for impairment on a quarterly basis or when events or changes in circumstances indicate that the related carrying amounts may not be recoverable. Once it is determined that impairment exists, an impairment loss is measured as the amount by which the asset carrying value exceeds its estimated fair value.
During the nine months ended September 30, 2026, mineral property interests and plant and equipment increased by approximately $
During the nine months ended September 30, 2026,
13
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
NOTE 9 EQUITY METHOD INVESTMENTS
The Company accounts for investments over which it exerts significant influence, but does not control through majority ownership using the equity method of accounting. In applying the equity method of accounting to the Company’s investments in McEwen Copper, Paragon and MSC, the financial statements of Paragon and MSC, which are originally prepared in accordance with IFRS Accounting Standards as issued by the International Accounting Standards Board, have been adjusted to conform with U.S. GAAP.
A reconciliation of the Company’s equity method investments as at September 30, 2026 and December 31, 2025 is as follows:
As at | September 30, 2026 | December 31, 2025 | ||||
Investment in McEwen Copper Inc. | $ | | $ | | ||
Investment in Minera Santa Cruz S.A. | | | ||||
Investment in Paragon Advanced Labs Inc. | | | ||||
Total equity method investments | $ | | $ | | ||
Equity method investment in McEwen Copper
A summary of the operating results for McEwen Copper for the three and nine months ended September 30, 2026 and 2025 is as follows:
Three months ended September 30, | Nine months ended September 30, | |||||||||||
2026 | 2025 | 2026 | 2025 | |||||||||
McEwen Copper ( | ||||||||||||
Advanced projects | $ | — | $ | ( | $ | — | $ | ( | ||||
Other expenses | ( | ( | ( | ( | ||||||||
Foreign exchange loss | ( | ( | ( | ( | ||||||||
Interest and other income (expenses) (1) | ( | ( | ( | | ||||||||
Loss before tax | $ | ( | $ | ( | $ | ( | $ | ( | ||||
Income tax recovery (expense) | | — | ( | — | ||||||||
Net loss | $ | ( | $ | ( | $ | ( | $ | ( | ||||
Portion attributable to McEwen Inc. ( | ||||||||||||
Net loss | $ | ( | $ | ( | $ | ( | $ | ( | ||||
McEwen Inc.’s portion of interest capitalized | ( | — | ( | — | ||||||||
Loss from investment in McEwen Copper | $ | ( | $ | ( | $ | ( | $ | ( | ||||
(1) Interest and other income (expenses) include interest on term debt and finance-related income and expenses.
Changes in the Company’s investment in McEwen Copper for the nine months ended September 30, 2026, and for the year ended December 31, 2025, are as follows:
Nine months ended | Year ended | |||||
September 30, 2026 | December 31, 2025 | |||||
Investment, beginning of period | $ | | $ | | ||
Dilution gain | — | | ||||
Attributable net loss from McEwen Copper | ( | ( | ||||
Investment, end of period | $ | | $ | | ||
14
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
A summary of the key assets and liabilities of McEwen Copper as at September 30, 2026, and December 31, 2025, is as follows:
As at | September 30, 2026 | December 31, 2025 | ||||
Current assets | $ | | $ | | ||
Non-current assets | | | ||||
Total assets | $ | | $ | | ||
Current liabilities | $ | ( | $ | ( | ||
Non-current liabilities | ( | ( | ||||
Total liabilities | $ | ( | $ | ( | ||
As at September 30, 2026, the Company’s investment in McEwen Copper exceeded its proportionate share of the underlying net assets by $
Equity method investment in MSC
A summary of the operating results for MSC for the three and nine months ended September 30, 2026 and 2025 is as follows:
Three months ended September 30, | Nine months ended September 30, | |||||||||||
2026 | 2025 | 2026 | 2025 | |||||||||
Minera Santa Cruz S.A. ( | ||||||||||||
Revenue from gold and silver sales | $ | | $ | | $ | | $ | | ||||
Production costs applicable to sales | ( | ( | ( | ( | ||||||||
Depreciation and depletion | ( | ( | ( | ( | ||||||||
Gross profit | | | | | ||||||||
Exploration | ( | ( | ( | ( | ||||||||
Other expenses (1) | ( | ( | ( | ( | ||||||||
Income before tax | $ | | $ | | $ | | $ | | ||||
Current and deferred income tax expense | ( | ( | ( | ( | ||||||||
Net income | $ | | $ | | $ | | $ | | ||||
Portion attributable to McEwen Inc. ( | ||||||||||||
Net income | $ | | $ | | $ | | $ | | ||||
Amortization of fair value increments | ( | ( |
| ( |
| ( | ||||||
Income tax recovery | | | | | ||||||||
Income from investment in MSC, net of amortization | $ | | $ | | $ | | $ | | ||||
(1) Other expenses include foreign exchange gains and losses, accretion of asset retirement obligations, and other finance-related expense.
The income or loss from the investment in MSC attributable to the Company includes amortization of the fair value increments arising from the initial purchase price allocation and related income tax recovery. The income tax recovery reflects the impact of the devaluation of the Argentine peso against the U.S. dollar on the peso-denominated deferred tax liability recognized at the time of acquisition, as well as income tax rate changes over the periods.
15
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
Changes in the Company’s investment in MSC for the nine months ended September 30, 2026, and for the year ended December 31, 2025, are as follows:
Nine months ended | Year ended | |||||
September 30, 2026 | December 31, 2025 | |||||
Investment, beginning of period | $ | | $ | | ||
Attributable net income from MSC | | | ||||
Amortization of fair value increments | ( | ( | ||||
Income tax recovery | | | ||||
Dividend distribution received | ( | ( | ||||
Investment, end of period | $ | | $ | | ||
A summary of the key assets and liabilities of MSC as at September 30, 2026, and December 31, 2025, is as follows:
As at | September 30, 2026 | December 31, 2025 | ||||
Current assets | $ | | $ | | ||
Non-current assets | | | ||||
Total assets | $ | | $ | | ||
Current liabilities | $ | ( | $ | ( | ||
Non-current liabilities | ( | ( | ||||
Total liabilities | $ | ( | $ | ( | ||
As at September 30, 2026, the Company’s investment in MSC exceeded its proportionate share of the underlying net assets by $
Equity method investment in Paragon
On December 9, 2025, the Company completed the transaction to acquire
Subsequent to the acquisition, on December 15, 2025, an existing shareholder exercised
Due to the timing of the availability of financial information, the Company recognizes its share of the earnings of Paragon on a three-month lag basis. Accordingly, the Company recognized its share of Paragon’s net loss of $
16
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
A summary of the operating results for Paragon for the three months ended June 30, 2026, and for the period from December 5, 2025 to June 30, 2026, is as follows:
Three months ended June 30, | Period ended June 30, | |||||||||||
2026 | 2025 | 2026 | 2025 | |||||||||
Paragon ( | ||||||||||||
Revenue | $ | | $ | — | $ | | $ | — | ||||
Production costs applicable to sales | ( | — | ( | — | ||||||||
Gross profit (loss) | ( | — | | — | ||||||||
Operating expense | ( | — | ( | — | ||||||||
Other income | | — | | — | ||||||||
Net loss | ( | — | ( | — | ||||||||
Change in foreign currency translation adjustments | | — | | — | ||||||||
Net comprehensive loss for the period | $ | ( | $ | — | $ | ( | $ | — | ||||
Portion attributable to McEwen Inc. ( | ||||||||||||
Net loss | $ | ( | $ | — | $ | ( | $ | — | ||||
Attributable change in foreign currency translation adjustments | | — | | — | ||||||||
Comprehensive loss from investment in Paragon | $ | ( | $ | — | $ | ( | $ | — | ||||
Changes in the Company’s investment in Paragon for the nine months ended September 30, 2026, and December 31, 2025, are as follows:
Nine months ended | Year ended | |||||
September 30, 2026 | December 31, 2025 | |||||
Investment, beginning of period | $ | | $ | — | ||
Investment in Paragon | — | | ||||
Net loss attributable to McEwen Inc. | ( | — | ||||
Dilution loss | ( | — | ||||
Change in foreign currency translation adjustments | | — | ||||
Investment, end of period | $ | | $ | | ||
A summary of the key assets and liabilities of Paragon as at September 30, 2026, and December 31, 2025, is as follows:
As at | September 30, 2026 | December 31, 2025 | ||||
Current assets | $ | | $ | | ||
Non-current assets | | | ||||
Total assets | $ | | $ | | ||
Current liabilities | $ | ( | $ | ( | ||
Non-current liabilities | ( | ( | ||||
Total liabilities | $ | ( | $ | ( | ||
As at September 30, 2026, the Company’s investment in Paragon exceeded its proportionate share of the underlying net assets by $
17
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
NOTE 10 DEBT
A reconciliation of the Company’s long-term debt as at September 30, 2026, and December 31, 2025, is as follows:
September 30, 2026 | December 31, 2025 | |||||
Convertible senior unsecured notes due 2030 | $ | | $ | | ||
Term loan facility | | | ||||
Debt issuance costs | ( | ( | ||||
$ | | $ | | |||
Less: current portion of debt | | — | ||||
Long-term debt | $ | | $ | | ||
Term loan facility
On January 31, 2025, the Company amended its Third Amended and Restated Credit Agreement (“ARCA”). The amendments refinanced the outstanding $
| ● | Scheduled repayments of principal under the ARCA were extended by |
| ● | On May 6, 2025, the Company issued |
| ● | The Company was permitted to incur up to $ |
The consideration issued for the maintenance, continuation and extension of the maturity date of the loan was accounted for as debt issuance costs, which were capitalized as deferred financing costs within long-term debt. These costs are being amortized as interest expense over the term of the debt using the effective interest method.
Following the issuance of the Convertible Notes (as defined below), on February 21, 2025, the Company voluntarily repaid $
Total interest expense related to the term loan for the three and nine months ended September 30, 2026 was $
Convertible senior unsecured notes
On February 11, 2025, the Company issued $
18
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
The convertible notes will be convertible into cash, shares of the Company’s common stock or a combination thereof, at the Company’s election. The initial conversion rate is
The Convertible Notes may be converted at any time prior to May 15, 2030, only under the following circumstances:
| (1) | During any calendar quarter starting after March 31, 2025, if, for at least |
| (2) | During the business days following any |
| (3) | If the Company issues a notice of redemption for the notes, at any time before the close of business on the second trading day prior to the redemption date; or |
| (4) | Upon the occurrence of specified corporate events. |
On or after May 15, 2030, until the close of business on the second trading day before the maturity date, holders may convert their notes at any time, regardless of prior conditions.
The Convertible Notes will be redeemable, in whole or in part, at the Company’s option at any time from August 21, 2028, through the 46th trading day prior to maturity, provided that the Company’s common stock has traded at or above
If the Company undergoes a “fundamental change”, as defined in the Indenture, and subject to certain conditions and exceptions, holders may require the Company to repurchase all or a portion of their notes for cash at a price equal to
The Indenture contains other customary terms and covenants, including certain events of default. The Convertible Notes are accounted for as a single liability in its entirety. No portion of the proceeds was attributed to the conversion option, as the embedded feature did not require bifurcation. In connection with the above-noted transaction, the Company incurred approximately $
As at September 30, 2026, the Convertible Notes have a net carrying amount of $
19
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
Capped call transactions
In connection with the offering of the Convertible Notes, the Company used approximately $
As the Capped Call Transactions are freestanding instruments that are both indexed to the issuer’s own stock and classified in shareholders’ equity, the premiums paid in the Capped Call Transactions were classified as a reduction to the additional paid-in capital and will not be remeasured as long as they continue to meet the conditions for equity classification.
NOTE 11 RECLAMATION AND REMEDIATION LIABILITIES
The Company is responsible for the reclamation of certain past and future disturbances at its properties. As at September 30, 2026, the reclamation and remediation liability balances at the properties subject to these obligations were $
A reconciliation of the Company’s reclamation and remediation liabilities for the nine months ended September 30, 2026, and for the year ended December 31, 2025, is as follows:
September 30, 2026 | December 31, 2025 | |||||
Reclamation and remediation liabilities, beginning balance | $ | | $ | | ||
Acquisitions and divestitures | | — | ||||
Settlements | ( | ( | ||||
Accretion of liability | | | ||||
Revisions to estimates and discount rate | | ( | ||||
Foreign exchange revaluation | ( | | ||||
Reclamation and remediation liabilities, ending balance | $ | | $ | | ||
Less: current portion | | | ||||
Long-term portion | $ | | $ | | ||
\
NOTE 12 SHAREHOLDERS’ EQUITY
Flow-through shares issuance
Canadian Exploration Expenses (“CEE”)
On December 19, 2025, the Company issued
20
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
The Company is required to spend these flow-through share proceeds on flow-through eligible expenditures, as defined by subsection 66.1(5) and 66.1(6) of the Income Tax Act (Canada). As at September 30, 2026, the Company has fulfilled the CEE obligation arising from the December 19, 2025 financing.
Canadian Development Expenses (“CDE”)
On January 22, 2026, the Company issued
On January 28, 2026, the Company issued
The Company is required to spend these flow-through share proceeds on flow-through eligible expenditures, as defined by subsection 66.1(5) and 66.1(6) of the Income Tax Act (Canada). As at September 30, 2026, the Company has fulfilled the CDE obligation arising from the January 22, 2026 and January 28, 2026 financing.
Investments in Goliath Resources Limited
On March 10, 2025, the Company issued
Investments in Paragon Advanced Labs Inc.
On December 9, 2025, the Company issued
Investments in Canadian Gold Corp.
On January 5, 2026, the Company completed the acquisition of Canadian Gold by acquiring all issued and outstanding common shares. Pursuant to an Arrangement Agreement, the Company issued
21
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
Investments in Golden Lake Exploration Inc. (“Golden Lake”).
On April 30, 2026, the Company completed the acquisition of Golden Lake by acquiring all of its issued and outstanding common shares. Pursuant to an Arrangement Agreement, the Company issued
NOTE 13 NET INCOME (LOSS) PER SHARE
Basic net income (loss) per share is computed by dividing the net income (loss) by the weighted average number of common shares outstanding during the period. Diluted net income (loss) per share is calculated using the treasury stock method for options and warrants and the if-converted method for the convertible senior unsecured notes. Under the if-converted method, interest expense, net of tax, is added back to net income (loss) and the weighted average shares outstanding are increased by the shares issuable upon conversion of the notes. In applying the treasury stock method, instruments with an exercise price greater than the average quoted market price of the common shares for the period are not included in the calculation, as the impact would be anti-dilutive.
For periods in which the Company has reported a net loss, diluted net loss per share is computed in the same manner as basic net loss per share because potentially dilutive instruments, including the conversion option embedded in the convertible senior unsecured notes, are generally anti-dilutive during such periods.
Below is a reconciliation of the basic and diluted weighted average number of common shares and the computations for basic and diluted net income (loss) per share for the three and nine months ended September 30, 2026 and 2025:
Three months ended September 30, | Nine months ended September 30, | ||||||||||
2026 | | 2025 | | 2026 | | 2025 | |||||
(amounts in thousands, unless otherwise noted) | |||||||||||
Basic earnings per share | |||||||||||
Net income (loss) available to common stockholders – Basic earnings per share | $ | ( | $ | ( | $ | | $ | ( | |||
Weighted average basic shares | | | | | |||||||
Basic net income (loss) per share | $ | ( | $ | ( | $ | | $ | ( | |||
Diluted earnings per share | |||||||||||
Net income (loss) available to common stockholders – Diluted earnings per share | $ | ( | $ | ( | $ | | $ | ( | |||
Weighted average basic shares |
| |
| | | | |||||
Dilutive effect of stock options, restricted stock units and warrants | — | — | | — | |||||||
Weighted average diluted shares | | | | | |||||||
Diluted net income (loss) per share | $ | ( | $ | ( | $ | | $ | ( | |||
Diluted Earnings per Share
For the three months ended September 30, 2026, all
22
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
For the nine months ended September 30, 2026, the weighted average number of common shares outstanding was increased by
For the three and nine months ended September 30, 2025, all
NOTE 14 RELATED PARTY TRANSACTIONS
Due to related parties
The Company recorded the following expenses in respect to the related parties outlined below during the periods presented:
Three months ended September 30, | | Nine months ended September 30, | ||||||||||
2026 | 2025 | 2026 | | 2025 | ||||||||
REVlaw | $ | | $ | | $ | | $ | | ||||
Paragon Advanced Labs Inc. | | — | | — | ||||||||
Total expenses | $ | | $ | | $ | | $ | | ||||
The Company has the following outstanding accounts payable balances in respect to the related parties outlined below:
September 30, 2026 | December 31, 2025 | |||||
Paragon Advanced Labs Inc. | $ | | $ | | ||
REVlaw | — | | ||||
Total due to related parties | $ | | $ | |
On January 5, 2026, the Company completed the acquisition of Canadian Gold by acquiring all issued and outstanding common shares of Canadian Gold in exchange for shares of the Company’s common stock. All Canadian Gold shares, other than those held by Robert R. McEwen, Chairman and Chief Executive Officer of the Company, were exchanged for
REVlaw is a company owned by Carmen Diges, General Counsel and Secretary of the Company. The legal services of Ms. Diges as General Counsel and Secretary and other support staff, as needed, are provided by REVlaw in the normal course of business and have been recorded at their exchange amount.
Paragon is a related party of the Company, in which the Company holds a
23
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
An affiliate of Robert R. McEwen, Evanachan Limited, acted as a lender in the restructured $
Due from related parties
Current receivables
As at September 30, 2026, current receivables of $
McEwen Copper loan
On February 6, 2026, the Company entered into a loan agreement with McEwen Copper in the amount of $
Subsequently, on August 26, 2026, the Company transferred its $
Andes Corporación Minera S.A. (“ACMSA”) loan
On February 6, 2026, Minera Andes S.A., an Argentinian subsidiary of the Company, entered into a loan agreement with ACMSA, an Argentinian subsidiary of McEwen Copper, in respect of $
Investments in related parties
On March 27, 2025, the Company participated in a private placement offering of units issued by Canadian Gold, an affiliate of Robert R. McEwen, who owned approximately
On April 28, 2025, the Company exercised
24
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
NOTE 15 FAIR VALUE ACCOUNTING
The hierarchy of fair value measurements assigns a level to fair value measurements based on the inputs used in the respective valuation techniques. The levels of the hierarchy, as defined below, give the highest priority to unadjusted quoted prices in active markets for identical assets or liabilities and the lowest priority to unobservable inputs.
● Level 1 is defined as observable inputs such as quoted prices in active markets for identical assets. The Company’s Level 1 assets include investments in equity securities, which are exchange-traded and are valued using quoted market prices in active markets.
● Level 2 is defined as observable inputs other than Level 1 prices. These include quoted prices for similar assets or liabilities in an active market, quoted prices for identical assets and liabilities in markets that are not active, or other inputs that are observable or can be corroborated by observable market data for substantially the full term of the assets or liabilities. The Company’s Level 2 assets include investments in share purchase warrants with fair value determined using the option pricing model and inputs from observable market data, including historic volatility.
● Level 3 is defined as unobservable inputs in which little or no market data exists, therefore requiring an entity to develop its own assumptions. The Company’s Level 3 financial instruments reported as of June 30, 2026 related to the McEwen Copper warrants. These warrants were derecognized during Q3/26 and accordingly, the Company has no financial instruments classified within Level 3 of the fair value hierarchy as at September 30, 2026.
The following table presents the Company’s financial assets that are recorded at fair value in the accompanying Consolidated Balance Sheets:
Fair value as at September 30, 2026 | ||||||||||||
Level 1 | Level 2 | Level 3 | Total | |||||||||
Assets: | ||||||||||||
Marketable securities | $ | | $ | | $ | — | $ | | ||||
Fair value as at December 31, 2025 | ||||||||||||
Level 1 | Level 2 | Level 3 | Total | |||||||||
Assets: | ||||||||||||
Marketable securities | $ | | $ | | $ | — | $ | | ||||
The fair value measurement of the Company’s convertible senior unsecured notes is presented in Note 10 – Debt and is not included in the table above. The carrying value of the term loan approximates its fair value based on its recent refinancing.
The fair values of other financial assets and liabilities were assumed to approximate their carrying values due to their short-term nature and historically negligible credit losses.
NOTE 16 COMMITMENTS AND CONTINGENCIES
Reclamation obligations
As part of its ongoing business and operations, the Company is required to provide bonding for its environmental reclamation obligations. As at September 30, 2026, the Company has surety facilities in place to cover its bonding obligations, which include $
25
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
The terms of the facilities carry an average annual financing fee of
Flow-through eligible expenses
On December 19, 2025, the Company completed a flow-through share issuance for gross proceeds of $
On January 22, 2026 and January 28, 2026, the Company completed flow-through share issuances for gross proceeds of $
Prepayment agreement
On February 10, 2026, the Company extended the existing precious metals purchase agreement with Auramet International LLC. Key terms of the agreement remained unchanged. Under this agreement, the Company may sell the gold and silver contained in doré bars produced at the Gold Bar Mine Complex, Fox Complex and El Gallo prior to the completion of refining on a Spot Basis, on a Forward Basis, on an In-Process Basis and Prepayment Basis i.e., the gold is priced and paid for while the gold is:
| (i) | at a mine for a maximum of |
| (ii) | in transit to a refinery; or |
| (iii) | while being refined at a refinery. |
During the three and nine months ended September 30, 2026, the Company received net proceeds of $
Other potential contingencies
The Company’s mining and exploration activities are subject to various laws and regulations governing the protection of the environment. These laws and regulations are continually changing and generally becoming more restrictive. The Company conducts its operations so as to protect public health and the environment, and believes its operations are materially in compliance with all applicable laws and regulations. The Company has made, and expects to make in the future, expenditures to comply with such laws and regulations.
26
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
The Company and its predecessors have transferred their interest in several mining properties to third parties throughout its history. The Company could remain potentially liable for environmental enforcement actions related to its prior ownership of such properties. However, the Company has no reasonable belief that any violation of relevant environmental laws or regulations has occurred regarding these transferred properties.
NOTE 17 INCOME AND MINING TAXES
The Company’s income and mining tax expense (recovery) for the three and nine months ended September 30, 2026 and 2025 consisted of the following:
Three months ended September 30, | Nine months ended September 30, | |||||||||||
| 2026 | | 2025 | | 2026 | | 2025 | |||||
Domestic | $ | | $ | | $ | | $ | ( | ||||
Foreign | | | | | ||||||||
Current tax expense | $ | | $ | | $ | | $ | | ||||
Domestic | $ | | $ | — | $ | | $ | — | ||||
Foreign | | ( | | ( | ||||||||
Deferred tax expense (recovery) | $ | | $ | ( | $ | | $ | ( | ||||
Total income and mining tax expense (recovery) | $ | | $ | ( | $ | | $ | ( | ||||
The income and mining tax expense (recovery) for the three and nine months ended September 30, 2026 and 2025 varies from the amounts that would have resulted from applying the statutory tax rates to pre-tax income or loss, primarily due to the impact of taxation in foreign jurisdictions and the non-recognition of deferred tax assets.
For the three and nine months ended September 30, 2026 and 2025, the Company used the annual effective tax rate method to calculate its tax provision. The current income and mining tax expense of $
NOTE 18 ASSET ACQUISITIONS
Canadian Gold Corp. acquisition
On January 5, 2026, the Company completed the acquisition of Canadian Gold, an exploration mine that has a
The Company accounted for the acquisition of Canadian Gold as an asset acquisition, in accordance with Accounting Standards Codification (“ASC”) 805 – Business Combinations.
Consideration transferred to acquire Canadian Gold was measured at fair value. Pursuant to the Arrangement Agreement, the Company issued
27
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
Upon receipt of shareholder approval on June 4, 2026, the consideration payable was remeasured at fair value of $
The following tables summarize the purchase price and the estimated fair value of assets acquired and liabilities assumed on January 5, 2026:
Fair value | |||
January 5, 2026 | |||
Purchase price: | |||
Common shares | $ | | |
Subscription receipts (Note 14) |
| | |
Previously held equity interest |
| | |
$ | | ||
Fair value | |||
January 5, 2026 | |||
Purchase price: | |||
Cash and cash equivalents | $ | | |
Accounts receivable | | ||
Prepaid and other current assets | | ||
Property, plant and equipment | | ||
Mineral property interests | | ||
Accounts payable and accrued liabilities | ( | ||
Deferred income tax liability | ( | ||
$ | | ||
Golden Lake Exploration Inc. acquisition
On April 30, 2026, the Company completed the acquisition of Golden Lake, a mineral exploration company that has an option to purchase a
The Company accounted for the acquisition of Golden Lake as an asset acquisition, in accordance with ASC 805 – Business Combinations.
Consideration transferred to acquire Golden Lake was measured at fair value. Pursuant to the Arrangement Agreement, the Company issued
28
McEWEN INC.
NOTES TO CONSOLIDATED FINANCIAL STATEMENTS (UNAUDITED)
September 30, 2026
(tabular amounts are in thousands of U.S. dollars, unless otherwise noted)
The following tables summarize the purchase price and the estimated fair value of assets acquired and liabilities assumed on April 30, 2026:
Fair value | |||
April 30, 2026 | |||
Purchase price: | |||
Common shares | $ | | |
Options |
| | |
$ | | ||
Fair value | |||
April 30, 2026 | |||
Purchase price: | |||
Cash and cash equivalents | $ | | |
Restricted cash | | ||
Accounts receivable | | ||
Mineral property interests | | ||
Reclamation and remediation liabilities | ( | ||
Accounts payable and accrued liabilities | ( | ||
Deferred income tax liability | ( | ||
$ | | ||
NOTE 19 GENERAL AND ADMINISTRATIVE EXPENSES
The Company’s general and administrative expenses for the three and nine months ended September 30, 2026 and 2025 consisted of the following:
Three months ended September 30, | Nine months ended September 30, | |||||||||||
2026 | 2025 | 2026 | 2025 | |||||||||
Professional services | $ | | $ | | $ | | $ | | ||||
Salaries and benefits | | | | | ||||||||
Acquisition and financing costs | | | | | ||||||||
Legal fees | | | | | ||||||||
Other | | | | | ||||||||
$ | | $ | | $ | | $ | | |||||
Less: debt issuance costs in general and administrative | — | — | — | ( | ||||||||
Total general and administrative expenses | $ | | $ | | $ | | $ | | ||||
NOTE 20 SUBSEQUENT EVENT
On October 8, 2026, the Company and its wholly owned subsidiaries, Lexam VG Gold Inc. and VG Holdings Inc., entered into an agreement with Dome Mine Ltd., a wholly owned subsidiary of Discovery Mining Ltd., to sell certain mineral and surface interests associated with the Fuller and Paymaster properties located in Timmins, Ontario, for total consideration of $
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Item 2. MANAGEMENT’S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF OPERATIONS
In the following discussion, “McEwen”, the “Company,” “we,” “our,” and “us” refer to McEwen Inc. and, as the context requires, its consolidated subsidiaries.
The discussion also analyzes our results of operations for the three and nine months ended September 30, 2026, and compares those to the results for the three and nine months ended September 30, 2025. Regarding properties or projects that are not in production, we provide some details of our plan of operation. We suggest that you read this discussion in conjunction with Management’s Discussion and Analysis of Financial Condition and Results of Operations and our audited consolidated financial statements contained in our Annual Report on Form 10-K for the year ended December 31, 2025 (as amended, the “Annual Report”).
The discussion contains financial performance measures that are not prepared in accordance with United States Generally Accepted Accounting Principles (“US GAAP” or “GAAP”). Each of the following is a non-GAAP measure: cash costs, cash costs per ounce, all-in sustaining costs (“AISC”), all-in sustaining cost per ounce, adjusted earnings before interest, taxes, depreciation, and amortization (“Adjusted EBITDA”), and average realized price per ounce. These non-GAAP measures are used by management in running the business and we believe they provide useful information that can be used by investors to evaluate our performance and our ability to generate cash flows. These measures do not have standardized definitions and should not be relied upon in isolation or as a substitute for measures prepared in accordance with GAAP.
For a reconciliation of these non-GAAP measures to the most directly comparable GAAP measure included in our Consolidated Statements of Operations and Comprehensive Income (Loss) for the three and nine months ended September 30, 2026, and 2025 and to our Consolidated Balance Sheets as of September 30, 2026, and December 31, 2025, and certain limitations inherent in such measures, see discussion under “Non-GAAP Financial Performance Measures,” beginning on page 47.
This discussion also includes references to “advanced-stage properties,” which are defined as properties for which advanced studies and reports have been completed indicating the presence of measured, indicated, and inferred resources or proven and probable reserves, or that have obtained or are in the process of obtaining the required permitting. Our designation of certain properties as “advanced-stage properties” should not suggest that we have or ever will have proven or probable reserves at those properties as defined by S-K 1300. This section provides information up to the date of the filing of this report.
Throughout this Management’s Discussion and Analysis (“MDA”), the reporting periods for the three months ended September 30, 2026, and 2025 are abbreviated as Q3/26 and Q3/25, respectively and the reporting periods for the nine months ended September 30, 2026, and 2025 are abbreviated as 9M/26 and 9M/25, respectively. Disclosed gold equivalent ounces (“GEO”) includes gold and silver ounces calculated based on a gold to silver ratio of 68:1 for Q3/26 and 88:1 for Q3/25, based on the average per ounce price of gold and silver during each period.
In this report, “Au” represents gold; “Ag” represents silver; “oz” represents troy ounce; “t” represents metric tonne; “g/t” represents grams per metric tonne; “ft” represents feet; “m” represents meter; “sq” represents square; and CAD refers to Canadian dollars. All of our financial information is reported in United States (U.S.) dollars unless otherwise noted.
OVERVIEW
The Company was organized under the laws of the State of Colorado on July 24, 1979, and is engaged in the production and sale of gold and silver, as well as the development and exploration of copper, gold, and silver mineral properties across North and South America.
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The Company owns 100% of the Froome mine and Stock mill in Ontario, Canada; 100% of the Tartan Mine Project in Manitoba, Canada; 100% of the Gold Bar Mine Complex in Nevada; 100% of the Jewel Ridge Project in Nevada; 100% of El Gallo (previously known as the Fenix Project) in Sinaloa, Mexico; a 46.3% interest in McEwen Copper Inc., the owner of the Los Azules copper project (“Los Azules”) in San Juan, Argentina; a 49% interest in MSC, the owner and operator of the San José mine in Santa Cruz, Argentina and 26.7% interest in Paragon Advanced Labs Inc. (“Paragon”), a provider of advanced analytical services to the mining industry. In addition to the above, we hold interests in advanced-stage and exploration-stage projects in the United States, Canada, Mexico, and Argentina.
Index to Management’s Discussion and Analysis:
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Q3/26 OPERATING AND FINANCIAL HIGHLIGHTS
Highlights for Q3/26 are summarized below and discussed further under “Consolidated Performance”:
Corporate Developments
| ● | On August 26, 2026, the Company sold and assigned its entire interest in the McEwen Copper Inc. loan receivable, together with the associated warrants, to unrelated third parties for cash proceeds of $13.6 million. Following the transaction, the Company retained no rights, interests, or continuing involvement in the transferred loan or warrants. |
| ● | McEwen Copper Inc. ("MCI"), in which the Company holds a 46.3% ownership interest, closed a $240.0 million senior secured term loan facility on August 27, 2026. The financing, provided by a syndicate of lenders, will support the continued advancement of the Los Azules copper project in San Juan, Argentina, as well as general corporate purposes. The facility enhances MCI's liquidity as it advances engineering and early works activities toward a final investment decision anticipated in mid-2027 and continues preparations for a potential initial public offering. |
Subsequent Events
| ● | On October 8, 2026, the Company entered into an agreement to sell its interests in the Fuller and Paymaster properties and certain related surface rights for total consideration of $55.0 million, consisting of $5.0 million in cash and $50.0 million in common shares of Discovery Mining Ltd. The transaction is expected to provide additional capital to support the Company’s operations and development projects and remains subject to customary closing conditions. The sale was subsequently completed on October 21, 2026. |
Financial Highlights
| ● | Q3/26 revenues of $43.6 million were recognized from the sale of 10,689 GEOs from our 100% owned operations at an average realized price(2) of $4,151 per GEO. This compares to Q3/25 revenues of $50.5 million from the sale of 14,968 GEOs at an average realized price of $3,477 per GEO. |
| ● | We reported gross profit of $4.0 million in Q3/26 compared to $7.8 million in Q3/25. The change was primarily driven by a 14% decrease in revenues as a result of a 29% decrease in GEOs sold, offset by a 19% increase in average realized price during the quarter. |
| ● | Net loss for Q3/26 was $36.7 million, or $0.60 per share, compared to a net loss of $0.5 million, or $0.01 per share, in Q3/25. The higher net loss primarily reflected a 49% decrease in gross profit and a $12.9 million increase in other operating expenses, driven by increased exploration and advanced project expenditures, including drilling at Grey Fox and exploration and resource conversion and expansion activities at Windfall and Lookout Mountain within the Eureka Project. The increase in net loss also reflects a $9.0 million increase in other expense, primarily due to higher unrealized losses on marketable securities of $7.3 million and a $13.0 million income tax expense for Q3/26. |
| ● | Adjusted EBITDA (loss) (2) for Q3/26 was a loss of $10.9 million, compared to Q3/25 adjusted EBITDA of $11.8 million. Adjusted EBITDA excludes the impact of McEwen Copper and Paragon’s results and reflects the earnings of our operating properties, including the San José mine(1). |
| ● | Fox Complex unit costs: Cash costs(2) and AISC(2) per GEO sold in Q3/26 were $2,911 and $3,725 respectively as compared to annual guidance ranges of $2,200 to $2,400 and $2,650 to $2,850, respectively. Q3/26 unit costs were above annual guidance primarily due to lower production and GEOs sold as operations transitioned from Froome to Stock. The Company expects to remain on track to end the year within its annual guidance ranges, including costs associated with the additional production expected from Froome West in Q4/26. |
| ● | Gold Bar Mine Complex unit costs: Cash costs(2) and AISC(2) per GEO sold in Q3/26 were $3,248 and $3,520, respectively, as compared to annual guidance of $2,650 to $2,950 and $2,900 to $3,200 respectively. Q3/26 unit costs were higher than annual guidance primarily due to lower quarterly GEO production. |
| ● | San José unit costs: Cash costs(2) and AISC(2) per GEO sold in Q3/26 were $2,916 and $3,414, respectively, as compared to full year guidance of $2,000 to $2,200 and $2,300 to $2,500, respectively. Higher unit costs were primarily the result of 23% higher production costs due to relative strength in the Argentine peso compared to the US Dollar, as well as Argentine inflation. These trends are expected to continue through the remainder of 2026. |
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Exploration Highlights
| ● | We completed 25,886 feet (7,884 meters) of drilling at our Grey Fox deposit, incurring $2.7 million of exploration expenditures during Q3/26. During July 2026, an updated reserve and resource estimate was released supporting the results of the prefeasibility study announced in June 2026. The study outlines a 15-year mine life extending production at the Fox Complex through 2041, supported by probable mineral reserves of 980,300 ounces of gold, and demonstrates robust project economics, including a post-tax NPV (5%) of $282 million and an IRR of 24.8% at a gold price of $3,000 per ounce. |
| ● | We incurred $5.5 million in exploration expenses at the Gold Bar Mine Complex during Q3/26, primarily to advance exploration and resource development activities across the Eureka Project, including the Windfall and Lookout Mountain deposits. The July 2026 reserve and resource estimate reported combined Indicated Mineral Resources of 629,800 ounces of gold and Inferred Mineral Resources of 262,000 ounces of gold, with most of the mineralization considered potentially amenable to heap-leach processing. Exploration drilling continued during the quarter to support resource conversion, expansion and potential resource growth. |
| ● | We incurred $3.1 million in exploration expenses at the Tartan Mine Project during Q3/26. The exploration expense was primarily incurred on drilling aiming to upgrade and expand both the high-grade portion of the Main Zone and the current mineral resources that were published in a supporting Technical Report Summary in May. The mineral resource estimate incorporates drill hole data compiled from both historical and recent exploration programs, supporting an estimated 308,900 ounces of indicated gold resources and 302,700 ounces of inferred gold resources. |
(1) At our 49% attributable interest.
(2) This is a Non-GAAP financial performance measure. See “Non-GAAP Financial Performance Measures” beginning on page 47.
Operational Highlights
| ● | Q3/26 consolidated production was 22,852 GEOs (9M/26 – 84,195 GEOs), compared to 29,662 GEOs in Q3/25 (9M/25 – 81,346 GEOs). Production includes 11,786 GEOs in Q3/26 for our attributable interest in the San José mine(1) (Q3/25 – 14,986) and 43,388 attributable GEOs in 9M/26 (9M/25 – 39,628 GEOs). Due to forecasted changes in our operations, we have revised our 2026 consolidated guidance to 109,000 to 120,000 GEOs. |
| ● | Q3/26 consolidated sales of 20,268 GEOs (9M/26 – 81,467 GEOs), compared to 26,134 GEOs sold in Q3/25 (9M/25 – 77,988 GEOs). Total sales include 9,579 attributable GEOs from the San José mine(1) in Q3/26 (Q3/25 – 11,166 GEOs) and 41,078 attributable GEOs during 9M/26 (9M/25 – 35,425 GEOs). |
| ● | At the Fox Complex, we invested approximately $12.2 million in the Stock project during Q3/26, advancing underground development and completing key ventilation, heating, electrical and other infrastructure as the project progresses toward commercial production. Development activities continued at Stock East and West, while personnel and equipment began transitioning from Froome to Stock to support ongoing mine development. At Froome, we produced 4,427 GEOs during Q3/26 (9M/26 – 17,212 GEOs), representing a 31% decrease from 6,386 GEOs in Q3/25 (9M/25 – 17,334 GEOs), primarily reflecting lower processed grades and tonnage as operations continued the transition from Froome to Stock. Production at Froome is expected to continue until Q1/27. |
| ● | At the Gold Bar Mine Complex, we produced 6,215 GEOs during Q3/26 (9M/26 – 19,941 GEOs), representing a 24% decrease from the 8,191 GEOs produced in Q3/25 (9M/25 – 24,285 GEOs). Lower Q3/26 production primarily reflected fewer ounces recovered during the quarter despite higher tonnes stacked and average mined grades, as ounces reflected higher carbonaceous materials encountered in certain mining zones. The year-to-date decrease also reflected operational challenges experienced during Q2/26, including the temporary shutdown of the mine assay laboratory and complex mining zones containing higher carbonaceous material that did not reconcile with the mine model. |
| ● | San José’s Q3/26 production decreased by 21%, with 24,054 GEOs produced in Q3/26 (9M/26 – 88,546 GEOs), compared to 30,583 GEOs in Q3/25 (9M/25 – 80,874 GEOs). The decrease primarily reflected an 8% reduction in processed mineralized material and lower recoveries due to operational challenges experienced during the winter season. San José remains on track to meet its annual production guidance of 59,000 to 64,000 GEOs. |
| ● | We continued to meet safety expectations at our 100% owned operations. During Q3/26, we did not have any lost-time incidents at the Fox Complex, the Gold Bar Mine Complex, or El Gallo. The Nevada Mining Association recently recognized the Gold Bar Mine Complex as the recipient of its 2026 Mine Operator and Safety Award that recognizes companies that demonstrate exceptional safety performance. |
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SELECTED CONSOLIDATED FINANCIAL AND OPERATING RESULTS
The following tables present consolidated selected financial and operating results of the Company for the three and nine months ended September 30, 2026, and 2025:
Three months ended September 30, | Nine months ended September 30, | ||||||||||||
2026 | | 2025 | | 2026 | | 2025 | | ||||||
(in thousands, except per share) | |||||||||||||
Revenue from gold and silver sales (1) | $ | 43,640 | $ | 50,534 | $ | 176,923 | $ | 132,930 | |||||
Production costs applicable to sales (1) | $ | (32,797) | $ | (35,233) | $ | (99,586) | $ | (82,571) | |||||
Gross profit (1) | $ | 3,954 | $ | 7,816 | $ | 55,529 | $ | 30,167 | |||||
Net (loss) income | $ | (36,655) | $ | (462) | $ | 6,330 | $ | (3,692) | |||||
Net income (loss) per share | $ | (0.60) | $ | (0.01) | $ | 0.11 | $ | (0.07) | |||||
Adjusted EBITDA (2) | $ | (10,850) | $ | 11,815 | $ | 53,989 | $ | 38,007 | |||||
Cash from (used in) operating activities | $ | (29,862) | $ | 5,215 | $ | 28,462 | $ | 3,761 | |||||
Additions to mineral property interests and plant and equipment | $ | 17,586 | $ | 25,363 | $ | 57,435 | $ | 35,012 | |||||
| (1) | Excludes results from the San José mine, which is accounted for under the equity method. |
| (2) | This is a Non-GAAP financial performance measure. See “Non-GAAP Financial Performance Measures” beginning on page 47. |
September 30, 2026 | December 31, 2025 | |||||
(in thousands, unless otherwise indicated) | ||||||
Cash and cash equivalents | $ | 49,116 | $ | 51,015 | ||
Current assets | $ | 101,450 | $ | 107,886 | ||
Current liabilities | $ | 75,865 | $ | 63,809 | ||
Long-term debt | $ | 117,783 | $ | 126,168 | ||
Three months ended September 30, | Nine months ended September 30, | ||||||||||||
2026 | | 2025 | | 2026 | | 2025 | | ||||||
GEOs produced (1) | 22,852 | 29,662 | 84,195 | 81,346 | |||||||||
100% owned operations | 11,066 | 14,676 | 40,807 | 41,718 | |||||||||
San José mine (49% attributable) | 11,786 | 14,986 | 43,388 | 39,628 | |||||||||
GEOs sold (1) | 20,268 | 26,134 | 81,467 | 77,988 | |||||||||
100% owned operations | 10,689 | 14,968 | 40,389 | 42,563 | |||||||||
San José mine (49% attributable) | 9,579 | 11,166 | 41,078 | 35,425 | |||||||||
Average realized price ($/GEO) (2)(3) | $ | 4,151 | $ | 3,477 | $ | 4,514 | $ | 3,218 | |||||
P.M. Fix Gold ($/oz) | $ | 4,262 | $ | 3,457 | $ | 4,545 | $ | 3,201 | |||||
Cash costs per ounce ($/GEO sold) (2) | |||||||||||||
100% owned operations | $ | 3,107 | $ | 2,366 | $ | 2,579 | $ | 1,943 | |||||
San José mine (49% attributable) | $ | 2,916 | $ | 2,196 | $ | 2,525 | $ | 2,355 | |||||
AISC per ounce ($/GEO sold) (2) | |||||||||||||
100% owned operations | $ | 3,606 | $ | 2,639 | $ | 3,035 | $ | 2,364 | |||||
San José mine (49% attributable) | $ | 3,414 | $ | 2,771 | $ | 2,946 | $ | 2,881 | |||||
Gold : Silver ratio (1) | 68 : 1 | 88 : 1 | 62 : 1 | 92 : 1 | |||||||||
| (1) | Silver production is presented as a gold equivalent with a gold : silver ratio of 68 : 1 for Q3/26, and 88 : 1 for Q3/25 |
| (2) | This is a Non-GAAP financial performance measure. See “Non-GAAP Financial Performance Measures” beginning on page 47. |
| (3) | On sales from 100% owned operations only, excluding sales from our streaming arrangement at the Fox Complex. |
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CONSOLIDATED OPERATIONS REVIEW
Revenue from gold and silver sales: During 9M/26, revenue from our 100%-owned operations increased by 33% to $176.9 million, from $132.9 million in 9M/25, primarily reflecting a higher average realized price of $4,514 per GEO compared to $3,218 per GEO in 9M/25. During Q3/26, revenue decreased by 14% to $43.6 million, from $50.5 million in Q3/25, as a 29% decrease in GEOs sold more than offset the 19% increase in the average realized price to $4,151 per GEO from $3,477 per GEO.
Production costs applicable to sales: For 9M/26, production costs applicable to sales increased to $99.6 million from $82.6 million in 9M/25, reflecting higher costs at Gold Bar and Fox. At Gold Bar, the increase reflected higher fuel and assay costs, including temporary building and generator rental costs associated with the laboratory shutdown earlier in the year, while higher costs at Fox reflected increased mining and processing activities as operations progressed through the transition from Froome to Stock. For Q3/26, production costs decreased to $32.8 million from $35.2 million in Q3/25, primarily due to lower labour, materials and contractor costs at Fox associated with the timing of operating development at Stock.
Advanced project costs were $5.3 million in Q3/26, a $3.7 million increase compared to $1.7 million in Q3/25. For 9M/26, advanced project costs were $13.5 million as compared to $4.2 million in 9M/25. This increase was primarily attributable to study costs associated with the Grey Fox project and a $2.2 million increase in costs incurred at El Gallo related to additional crushing activities and metallurgical testing undertaken to optimize cyanide destruction.
Exploration costs were $28.0 million in 9M/26, compared to $15.9 million in 9M/25. For Q3/26, exploration costs were $11.2 million, compared to $6.8 million in Q3/25. The increases primarily reflected expanded drilling and exploration activities across the Company’s development assets. At the Fox Complex, $2.7 million was incurred as drilling continued at Grey Fox, including the Gibson and Whiskey Jack zones, supporting resource growth and the potential extension of mine life. At the Gold Bar Mine Complex, exploration activities focused on the Eureka Project, including Windfall and Lookout Mountain, with drilling directed toward resource conversion, expansion and opportunities for additional resource growth.
Income from equity method investments: During 9M/26, we recorded an income of $40.9 million from our equity method investments compared to a loss of $12.3 million in 9M/25. During 9M/26, we reported an income of $54.6 million from Minera Santa Cruz S.A., a loss of $12.1 million from McEwen Copper and a $1.6 million loss from Paragon. In Q3/26, we recorded a loss of $0.7 million from our equity method investments, compared to a loss of $0.8 million in Q3/25. This amount represents the Company’s proportionate share of the results of MSC, McEwen Copper, and Paragon. Details of operating results of the Company’s equity method investees are presented in the “Operations Review” section of this MDA and Note 9 to the Consolidated Financial Statements.
General and administrative expenses: General and administrative costs of $24.6 million for 9M/26 increased by $10.1 million compared to 9M/25. In Q3/26, we incurred $7.2 million in general and administrative expenses compared to $6.1 million in Q3/25. The increase was primarily attributable to a $2.0 million increase for Q3/26 and an $8.6 million increase for 9M/26 related to fees paid for professional services.
Interest and other finance expenses, net: Interest and other finance expenses totaled $2.6 million for 9M/26, a $2.1 million decrease compared with $4.7 million for 9M/25. The decrease was primarily attributable to $2.4 million of interest income earned on short-term investments and $0.9 million of interest income earned on a loan receivable from a related party, partially offset by $1.3 million of interest expense associated with the Company’s convertible notes.
Other income (expense): Other expense of $9.7 million for 9M/26 decreased from an income of $16.9 million for 9M/25. The changes in other income for 9M/26, were primarily driven by an unrealized loss in marketable securities of $5.1 million, a $19.6 million decrease from an unrealized gain of $14.5 million in 9M/25. Other factors include a $4.8 million increase in foreign currency loss and a $1.1 million increase in loss from the fair value revaluation on the contingent shares owed to a related party in connection with the Canadian Gold Corp. acquisition.
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Income and mining tax recovery: Income and mining tax expense was $9.0 million for the nine months ended September 30, 2026, compared with a recovery of $3.5 million in the prior-year period. The increase in tax expense was primarily attributable to $3.0 million of dividend withholding tax in Argentina, a $5.4 million deferred tax expense related to the reversal of a previously recognized deferred tax asset, and a $4.0 million net deferred tax expense primarily related to the recognition of an outside basis difference on the Company’s investment in Minera Santa Cruz. These amounts were partially offset by $3.4 million of tax recoveries, primarily related to the amortization of the flow-through share premium and deferred tax recoveries at Canadian Gold Corp., as well as other current and deferred tax amounts recognized across the Company’s operating jurisdictions.
LIQUIDITY AND CAPITAL RESOURCES
Our cash, cash equivalents and restricted cash balance decreased by $4.0 million during 9M/26, from $55.3 million as at December 31, 2025, to $51.3 million as at September 30, 2026.
Cash provided by operating activities of $28.5 million during 9M/26 reflects the net income of $6.3 million for the period and $58.3 million in dividends received from MSC, adjusted for non-cash impacts, including net income from equity method investments of $40.9 million, depreciation, amortization, and depletion of $22.3 million, unrealized loss on marketable securities of $5.0 million, flow-through premium amortization of $2.1 million, loss on consideration payable of $2.4 million, a deferred income and mining tax expense of $7.3 million, and $31.8 million in other and changes in non-cash working capital. Further details are provided in the Consolidated Statements of Cash Flows.
Cash used in investing activities of $49.7 million during 9M/26 primarily consisted of payments made to acquiring mineral property interests, plant and equipment of $57.4 million, net cash inflow of $6.1 million from loan activity, including a $7.5 million advance and a $13.6 million of proceeds from relinquishment, and cash provided by other investing activities of $1.7 million.
Cash provided by financing activities of $17.0 million during 9M/26 consisted of $14.8 million proceeds from issuance of flow through common shares and $3.0 million proceeds from exercise of stock options and warrants, partially offset by a $0.9 million repayment of finance lease obligations.
Working capital as at September 30, 2026, was $25.6 million, a $18.5 million decrease from $44.1 million as at December 31, 2025. The decrease in working capital was primarily driven by a $1.9 million decrease in cash and cash equivalents, a $10.7 million decrease in marketable securities, a $9.0 million increase in current-portion of long term debt, a $3.8 million increase in accounts payable and accrued liabilities, partially offset by a $2.5 million increase in inventories, a $2.8 million increase in receivables and a $1.1 million decrease in tax liabilities.
As of September 30, 2026, our material cash requirements consisted primarily of reclamation, lease, and property holding obligations of approximately $8.1 million over the next twelve months. We expect to fund these cash requirements through a combination of cash and cash equivalents on hand, cash generated from operating activities, and, if necessary, available borrowings under existing financing arrangements. The primary purposes of these expenditures and commitments are to support ongoing operations, fund growth initiatives, satisfy contractual obligations, and meet general working capital requirements.
The Company believes that it has sufficient liquidity along with funds generated from ongoing operations to fund anticipated cash requirements for operations, capital expenditures and working capital purposes for the next 12 months and beyond. See Note 10, Debt, Note 11, Reclamation and Remediation Liabilities, and Note 16, Commitments and Contingencies, to the consolidated financial statements included elsewhere in this report for further details regarding our material cash requirements from known contractual and other obligations.
36
OPERATIONS REVIEW
United States Segment
The United States segment is comprised of the Gold Bar Mine Complex, consisting of the operating Gold Bar mine, and the Tonkin, Jewel Ridge, Windfall and Lookout Mountain exploration projects; as well as other exploration properties in the State of Nevada.
Gold Bar Mine Complex
The following table summarizes the operating and financial results for the Gold Bar Mine for the three and nine months ended September 30, 2026, and 2025:
Three months ended September 30, | Nine months ended September 30, | |||||||||||
| 2026 | | 2025 | | 2026 | | 2025 | |||||
Operating Results | ||||||||||||
Mined mineralized material (kt) |
| 490 |
| 442 |
| 1,441 |
| 1,280 | ||||
Average grade (g/t Au) |
| 0.50 |
| 0.47 |
| 0.64 |
| 0.76 | ||||
Stacked mineralized material (kt) |
| 465 |
| 430 |
| 1,424 |
| 1,299 | ||||
Average grade (g/t Au) |
| 0.49 |
| 0.44 |
| 0.73 |
| 0.74 | ||||
Gold ounces: | ||||||||||||
Produced |
| 6,213 |
| 8,190 |
| 19,935 |
| 24,281 | ||||
Sold |
| 5,965 |
| 8,538 |
| 19,708 |
| 24,823 | ||||
Silver ounces: | ||||||||||||
Produced |
| 125 |
| 80 |
| 358 |
| 353 | ||||
Sold |
| 236 |
| 472 |
| 306 |
| 472 | ||||
GEOs: | ||||||||||||
Produced |
| 6,215 |
| 8,191 |
| 19,941 |
| 24,285 | ||||
Sold |
| 5,969 |
| 8,543 |
| 19,713 |
| 24,828 | ||||
Revenue from gold and silver sales ($000s) | $ | 24,977 | $ | 29,427 | $ | 88,709 | $ | 79,340 | ||||
Cash costs (1) ($000s) | $ | 19,387 | $ | 21,701 | $ | 54,637 | $ | 44,815 | ||||
Cash costs per ounce ($/GEO sold) (1) | $ | 3,248 | $ | 2,540 | $ | 2,772 | $ | 1,805 | ||||
All‑in sustaining costs (1) ($000s) | $ | 21,012 | $ | 24,363 | $ | 58,645 | $ | 56,749 | ||||
AISC per ounce ($/GEO sold) (1) | $ | 3,520 | $ | 2,852 | $ | 2,975 | $ | 2,286 | ||||
Gold : Silver ratio |
| 68 : 1 |
| 88 : 1 |
| 62 : 1 |
| 92 : 1 | ||||
| (1) | This is a Non-GAAP financial performance measure. See “Non-GAAP Financial Performance Measures” beginning on page 47. |
2026 compared to 2025
The Gold Bar Mine produced 6,215 GEOs in Q3/26, primarily from the Pick III deposit, representing a 24% decrease from the 8,191 GEOs produced in Q3/25 (9M/26 and 9M/25 – 19,941 GEOs and 24,285 GEOs, respectively). The decrease in Q3/26 production primarily reflected lower recoveries due to higher carbonaceous material, despite an 8% increase in tonnes stacked as compared to Q3/25. For 9M/26, the decrease in production compared to 9M/25 also reflected operational challenges experienced during Q2/26, including a one-month shutdown of the internal laboratory, which constrained ore mining rates and resulted in a greater focus on waste stripping activities. Production was also impacted by complex mining zones containing higher carbonaceous material that did not reconcile with the mine model.
Revenue from gold and silver sales was $25.0 million in Q3/26, a 15% decrease from $29.4 million in Q3/25, primarily due to a 30% decrease in GEOs sold as a result of a 24% lower production during the quarter. Revenue for 9M/26 was $88.7 million, compared to $79.3 million for 9M/25, with the increase primarily attributable to a higher average realized price of $4,514 per GEO, compared to $3,218 per GEO in 9M/25.
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Production costs applicable to sales were $19.4 million in Q3/26, a decrease of $2.3 million from $21.7 million in Q3/25. The decrease was primarily attributable to lower contractor costs due to shorter haul distances and lower processing costs resulting from fewer tonnes processed during the quarter, partially offset by higher fuel consumption and related costs, increased ore control drilling costs, and an unfavorable inventory movement resulting from the timing of finished goods sales. For 9M/26, production costs applicable to sales were $54.6 million, an increase of $9.8 million compared to $44.8 million in 9M/25. In addition to the factors impacting Q3/26, the year-to-date increase reflected higher assay costs and temporary building and generator rental expenses incurred in connection with the laboratory shutdown during the prior quarter.
Cash costs and AISC per GEO sold in Q3/26 were $3,248 and $3,520 respectively, compared to $2,540 and $2,852 in Q3/25, respectively. The increase in cash costs, and the corresponding increase in AISC, was primarily attributable to a 24% decrease in GEOs produced and fewer GEOs sold, resulting in costs being allocated over fewer ounces, partially offset by a favorable build in heap leach inventory.
Exploration Activities
During Q3 2026, exploration activities at the Eureka Project focused on the Windfall and Lookout Mountain deposits in Nevada, including ongoing land management and claim survey programs to further define property boundaries. In July 2026, the Company filed an updated reserve and resource estimate for both deposits, effective May 4, 2026. The estimate reported indicated mineral resources of 629,800 oz of gold and inferred mineral resources of 262,000 oz of gold. At Lookout Mountain, indicated resources totaled 402,300 oz of gold (19.6 million tonnes grading 0.64 g/t Au) and inferred resources totaled 134,200 oz of gold (7.29 million tonnes grading 0.57 g/t Au). At Windfall, indicated resources totaled 227,500 oz of gold (9.4 million tonnes grading 0.75 g/t Au) and inferred resources totaled 127,800 oz of gold (2.6 million tonnes grading 1.53 g/t Au). Approximately 89% of Lookout Mountain's contained gold ounces and 100% of Windfall's contained gold ounces occur within oxide mineralization, which is considered potentially amenable to heap-leach processing.
Exploration drilling continued to support the potential for resource growth across the Eureka Project. During the quarter, two rigs advanced the Pick infill program, and drilling returned to Eureka in late September to continue resource conversion and expansion drilling. Exploration activities are expected to increasingly focus on targets outside of known resources within the Eureka Project area to evaluate opportunities for additional resource growth. Updated seismic results were also received for Twin Peaks at north Tonkin.
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Canada Segment
The Canada segment is comprised of the Fox Complex, which currently includes our Froome underground gold mine (including the Froome West deposit); the Stock Mine (consisting of the West, East and Main zones); the Stock mill; the Grey Fox exploration project; and a number of exploration and other properties located near the city of Timmins, Ontario. The Canada segment also comprises of the Tartan Mine Project located in Flin Flon, Manitoba which is an exploration project within the Flin Flon Greenstone belt.
Fox Complex
The following table summarizes the operating and financial results for the Fox Complex for the three and nine months ended September 30, 2026, and 2025:
Three months ended September 30, | Nine months ended September 30, | |||||||||||
| 2026 | | 2025 | | 2026 | | 2025 | |||||
Operating Results | ||||||||||||
Mined mineralized material (kt) |
| 66 |
| 86 |
| 190 |
| 223 | ||||
Average grade (g/t Au) |
| 2.65 |
| 2.72 |
| 3.75 |
| 2.82 | ||||
Processed mineralized material (kt) |
| 72 |
| 80 |
| 205 |
| 221 | ||||
Average grade (g/t Au) |
| 2.62 |
| 2.75 |
| 3.78 |
| 2.83 | ||||
Gold ounces: | ||||||||||||
Produced |
| 4,413 |
| 6,377 |
| 17,152 |
| 17,311 | ||||
Sold, excluding stream | 4,000 | 5,800 | 15,605 | 16,250 | ||||||||
Sold, stream |
| 290 |
| 525 |
| 1,389 |
| 1,387 | ||||
Sold, including stream | 4,290 | 6,325 | 16,994 | 17,636 | ||||||||
Silver ounces: | ||||||||||||
Produced |
| 958 |
| 826 |
| 3,708 |
| 2,113 | ||||
Sold |
| 637 |
| — |
| 3,780 |
| 46 | ||||
GEOs: | ||||||||||||
Produced |
| 4,427 |
| 6,386 |
| 17,212 |
| 17,334 | ||||
Sold, excluding stream | 4,009 | 5,800 | 15,667 | 16,250 | ||||||||
Sold | 4,299 | 6,325 | 17,056 | 17,636 | ||||||||
Revenue from gold and silver sales ($000s) | $ | 16,939 | $ | 20,780 | $ | 71,122 | $ | 53,263 | ||||
Cash costs (1) ($000s) | $ | 12,513 | $ | 13,485 | $ | 41,456 | $ | 37,709 | ||||
Cash costs per ounce ($/GEO sold) (1) | $ | 2,911 | $ | 2,132 | $ | 2,349 | $ | 2,138 | ||||
All‑in sustaining costs (1) ($000s) | $ | 16,016 | $ | 14,879 | $ | 51,247 | $ | 43,615 | ||||
AISC per ounce ($/GEO sold) (1) | $ | 3,725 | $ | 2,352 | $ | 3,107 | $ | 2,473 | ||||
Gold : Silver ratio |
| 68 : 1 |
| 88 : 1 |
| 62 : 1 |
| 92 : 1 | ||||
| (1) | This is a Non-GAAP financial performance measure. See “Non-GAAP Financial Performance Measures” beginning on page 47. |
Stock Project
During Q3/26, the Company invested $12.2 million in the Stock project with $35.2 million invested for 9M/26. Development during the quarter included the completion of key ventilation, heating, electrical and other underground infrastructure, while development of the Stock East and West areas, dewatering activities and the transition of personnel from Froome to Stock continued. For 9M/26, investment primarily reflected the continued advancement of underground mine development and supporting infrastructure as the Stock project progresses toward commercial production by mid-2027.
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2026 compared to 2025
Fox Complex produced 4,427 GEOs from the Froome Mine in Q3/26, representing a 31% decrease from the 6,386 GEOs produced in Q3/25 (9M/26 and 9M/25: 17,212 GEOs and 17,334 GEOs, respectively). The decrease was primarily attributable to a 5% decrease in processed grades and a 10% decrease in processed tonnage during the quarter, as operations continued the transition from Froome to Stock. During Q3/26, planned development at Froome was substantially completed and personnel and equipment began transitioning to Stock to support ongoing mine development. Production at Froome is expected to continue during the transition period.
Revenue from gold sales was $16.9 million in Q3/26, compared to $20.8 million in Q3/25, with the decrease primarily attributable to a 32% decrease in GEOs sold, partially offset by higher realized gold prices during the quarter. Revenue for 9M/26 was $71.1 million, compared to $53.3 million for 9M/25, with the increase primarily attributable to a higher average realized price of $4,514 per GEO, compared to $3,218 per GEO in 9M/25, partially offsetting the decrease in GEOs sold.
Production costs applicable to sales were $12.5 million in Q3/26, compared to $13.5 million in Q3/25. The decrease primarily reflected lower mining costs, including lower labour, materials and contractor costs associated with the timing of operating development at Stock, partially offset by higher processing costs associated with increased mill throughput and maintenance activities. For 9M/26, production costs applicable to sales were $41.5 million, an increase of $3.7 million compared to 9M/25, reflecting higher production costs incurred throughout the year as mining and processing activities progressed.
Cash costs and AISC per GEO sold were $2,911 and $3,725 in Q3/26, respectively, compared to $2,132 and $2,352 in Q3/25. The 37% increase in cash costs per GEO sold was primarily attributable to a 32% decrease in GEOs sold during the quarter, resulting in production costs being absorbed over fewer ounces. The increase in AISC per GEO sold was further impacted by higher sustaining capital expenditures, including a $3.3 million increase in sustaining mine development costs at Froome West.
Exploration Activities
In June 2026, a PFS for the Grey Fox Project was released which demonstrates the potential to extend the Fox Complex mine life by approximately 15 years to 2041. The study indicates Grey Fox contributing average annual production of approximately 43,000 gold ounces from 2028 to 2035 and becoming the sole source of production from 2035 to 2040, averaging approximately 87,000 gold ounces per year. Initial capital expenditures are estimated at $181 million and are expected to be primarily funded through existing treasury balances and operating cash flow, with expenditures phased between 2026 and 2029. The assessment also indicates additional mine life extension potential, as current mine reserves represent approximately 40% of the existing resource base and significant exploration upside remains.
During Q3/26, the Company incurred $2.7 million in exploration expenditures as drilling activities continued across the Fox Complex. Four drill rigs were active during Q3/26, with Major Drilling and Black Diamond Drilling advancing the various exploration programs. Further, during Q3/26, 25,886 feet (7,884 meters) had been drilled, with exploration activities continuing through the remainder of the year. The exploration programs remain focused on advancing high-priority drilling targets at Grey Fox including at the Gibson and Whiskey Jack zones.
Tartan Mine Project
The Tartan Mine Project is located in Flin Flon, Manitoba and was acquired as part of our Canadian Gold acquisition completed on January 5, 2026.
During Q3/26, a total of $3.1 million (9M/26 - $6.3 million) was incurred at the Tartan Mine Project to advance drilling, permitting, and metallurgical testing to optimize both process plant designs and underground mine plans, and engineering studies. The same factors which contributed to the 9M/26 expenditures are expected to continue for the remainder of the year. Further, a technical report summary was published in Q2/26 highlighting an estimated 308,900 ounces of indicated gold resources and 302,700 ounces of inferred gold resources.
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As per the technical report, a second diamond drill was added to support exploration and infill drilling aimed at expanding the resource and upgrading inferred resources to indicated, for mine planning purposes. Results included significant assays from the deepest holes drilled to date in the West and South Zones, demonstrating mineralization at depth as well as the discovery of the Central zone. Infill drilling and expansion of the main high-grade shoot also increased resource confidence and highlighted further growth potential. It is expected that an updated Mineral Resource Estimate be produced with the year 2026 results in Q1 2027.
Mexico Segment
The Mexico segment consists of El Gallo, located in Sinaloa state.
El Gallo HLM
We have reached a construction decision for the Phase 1 heap leach material reprocessing project contemplated in our Feasibility Study (previously described as the Fenix project). In December 2025, the Company was granted the extension of its Environmental Impact Assessment (Manifestación de Impacto Ambiental) from the Mexican government. The Company is currently proceeding with the final detailed engineering plan for the mill, which has been purchased and is onsite. The earth works at the mill began in September 2026 and we anticipate beginning construction late-2026, with production commencing late-2027.
Phase 1 is expected to produce for 10 years, producing approximately 20,000 GEOs annually once commercial production is achieved. Production will come from the reprocessing of the material currently on the leach pad, through a ball mill with an operating plan optimized for cash flow and recovery. Remaining capital costs to complete construction are estimated at $35 million. Since the material that will be processed has been previously leached, there will be no significant development or exploration costs anticipated.
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Minera Santa Cruz Segment, Argentina
The Minera Santa Cruz Segment consists of a 49% interest in the San José mine, located in Santa Cruz, Argentina. Hochschild is the majority owner and operator of the San José mine.
The following table sets out certain operating results for the San José mine for the three and nine months ended September 30, 2026 and 2025 on a 100% basis:
Three months ended September 30, | Nine months ended September 30, | ||||||||||||
| 2026 | | 2025 | | 2026 | | 2025 |
| |||||
Operating Results | |||||||||||||
San José Mine—100% basis | |||||||||||||
Mined mineralized material (kt) |
| 173 |
| 173 |
| 549 |
| 490 |
| ||||
Average grade mined (g/t) | |||||||||||||
Gold |
| 2.58 |
| 2.40 |
| 3.09 |
| 3.70 |
| ||||
Silver |
| 86 |
| 129 |
| 145 |
| 191 |
| ||||
Processed mineralized material (kt) |
| 169 |
| 184 |
| 536 |
| 519 |
| ||||
Average grade processed (g/t) | |||||||||||||
Gold |
| 3.4 |
| 3.9 |
| 3.7 |
| 3.7 |
| ||||
Silver |
| 123 |
| 191 |
| 145 |
| 185 |
| ||||
Average recovery (%): | |||||||||||||
Gold |
| 85.9 |
| 85.0 |
| 86.1 |
| 82.2 |
| ||||
Silver |
| 82.5 |
| 84.4 |
| 83.8 |
| 83.1 |
| ||||
Gold ounces: | |||||||||||||
Produced |
| 15,980 |
| 19,681 |
| 54,546 |
| 52,484 |
| ||||
Sold |
| 13,018 |
| 14,601 |
| 51,201 |
| 46,776 |
| ||||
Silver ounces: | |||||||||||||
Produced |
| 549,027 |
| 958,672 |
| 2,106,850 |
| 2,615,807 |
| ||||
Sold |
| 444,081 |
| 717,038 |
| 2,010,045 |
| 2,341,539 |
| ||||
GEOs: | |||||||||||||
Produced |
| 24,054 |
| 30,583 |
| 88,546 |
| 80,874 |
| ||||
Sold |
| 19,549 |
| 22,788 |
| 83,833 |
| 72,295 |
| ||||
Revenue from gold and silver sales ($000s) | $ | 89,355 | $ | 91,723 | 408,577 | $ | 258,511 | ||||||
Average realized price(1): | |||||||||||||
Gold ($/Au oz) | $ | 4,354 | $ | 3,806 | $ | 4,657 | $ | 3,411 | |||||
Silver ($/Ag oz) | $ | 64.04 | $ | 43.28 | $ | 75.69 | $ | 37.00 | |||||
Cash costs (1) ($000s) | $ | 57,003 | $ | 50,053 | $ | 211,694 | $ | 170,244 | |||||
Cash costs per ounce sold ($/GEO) (1) | $ | 2,916 | $ | 2,196 | $ | 2,525 | $ | 2,355 | |||||
All‑in sustaining costs (1) ($000s) | $ | 66,735 | $ | 63,146 | $ | 246,996 | $ | 208,296 | |||||
AISC per ounce sold ($/GEO) (1) | $ | 3,414 | $ | 2,771 | $ | 2,946 | $ | 2,881 | |||||
Gold : Silver ratio | 68 : 1 |
| 88 : 1 |
| 62 : 1 |
| 92 : 1 | ||||||
(1) This is a Non-GAAP financial performance measure. See “Non-GAAP Financial Performance Measures” beginning on page 47.
The analysis below compares the operating and financial results of MSC on a 100% basis.
Q3/26 compared to Q3/25
On a 100% basis, the San José mine produced 24,054 GEOs in Q3/26, compared to 30,583 GEOs in Q3/25. The 21% decrease in Q3/26 primarily reflected an 8% decrease in processed mineralized material and lower recoveries due to operational challenges experienced during the winter season, including difficulties processing high-clay ore.
Revenue from gold and silver sales was $89.4 million in Q3/26, compared to $91.7 million in Q3/25. The 3% decrease was primarily attributable to a 21% decrease in GEOs produced and 14% decrease in GEOs sold, partially offset by higher realized metal prices, with average realized gold and silver prices increasing by 20% and 55%, respectively.
42
Production costs applicable to sales were $57.0 million in Q3/26, compared to $50.1 million in Q3/25. The increase primarily reflected inflationary pressures and the relative strength of the Argentine peso against the U.S. dollar, together with higher operating costs associated with challenging winter conditions and lower operating efficiencies during the quarter.
Cash costs and AISC per GEO sold increased to $2,916 and $3,414 in Q3/26, respectively, from $2,196 and $2,771 in Q3/25. The increase primarily reflected 23% higher production costs driven by Argentine inflation and the relative strength of the peso against the U.S. dollar, as well as a 21% decrease in GEO production reflecting lower throughput and recoveries due to challenging winter conditions, high moisture levels and difficulties processing high-clay ore.
Investment in MSC
Our 49% attributable share of operations from our investment in MSC in Q3/26 resulted in income of $4.5 million, compared to income of $3.5 million in Q3/25. Despite the challenging macroeconomic environment, favorable metal prices continued to support MSC's financial performance and liquidity. As at September 30, 2026, MSC reported working capital of $181.4 million, remaining comparable to $182.8 million as at December 31, 2025.
MSC Dividend Distribution (49%)
We received $58.3 million in dividends from MSC in 9M/26, compared to $2.2 million in 9M/25.
43
McEwen Copper Inc.
We own a 46.3% interest in McEwen Copper, which owns a 100% interest in the Los Azules copper project in San Juan, Argentina, and the Elder Creek exploration project in Nevada, USA. We have invested over $426 million in exploration expenditures to develop Los Azules into a world-class copper deposit, including amounts spent by Minera Andes Inc. before 2012 and directly by McEwen Inc. prior to 2021.
Los Azules, San Juan, Argentina
As of September 30, 2026, we owned a 46.3% interest in McEwen Copper Inc. (“McEwen Copper”), which owns the Los Azules copper project in San Juan, Argentina and the Elder Creek exploration project in Nevada, USA. As of September 30, 2026 our investment in McEwen Copper was $262.1 million.
During the fourth quarter of 2025, McEwen Copper completed the Los Azules Feasibility Study and announced the project’s first mineral reserve estimate. Proven and Probable Mineral Reserves contain 10.2 billion pounds of copper, based on a copper price assumption of $4.25 per pound, supporting a 21-year mine life (22-year production life) and positioning Los Azules among the largest copper development projects in the Americas.
Following completion of the Feasibility Study, McEwen Copper continued a work program designed to advance Los Azules toward a Final Investment Decision (“FID”) and a potential full project development release. The program includes ongoing engineering, infrastructure planning and development, execution planning, site investigations, stakeholder engagement and financing activities.
Quarterly Progress
As of September 30, 2026, approximately 78% of planned design and development deliverables for the FID work program had been completed, compared with approximately 27% at June 30, 2026. Engineering for FID continues to progress as planned; the change in the expected completion of the FID work program described below reflects site access conditions and the project financing timeline.
McEwen Copper previously expected to complete the FID work program in Q4/26 and now expects completion in H1/27, reflecting delays to site activities from the heavy snow season and alignment with the project financing process, for which Société Générale is acting as sole financial advisor. A final investment decision and completion of project financing remain targeted for H1/27, subject to completion of the FID work program, securing project financing and customary approvals. Construction is expected to commence following a final investment decision, with commercial copper cathode production targeted for 2030. In the interim, McEwen Copper continues to advance engineering and early works, including the access road and camp, funded by its term loan.
44
Key project advancement activities during the period included:
| ● | Engineering and mine planning: McEwen Copper continued to advance FID engineering, including an updated mine plan incorporating revised geotechnical design criteria and costs. Advanced engineering progressed on key process packages, including SX/EW, the sulfuric acid plant and crushing systems, while detailed engineering for the Phase 1 leach pad and site water management facilities was completed. |
| ● | Contracting and power: Evaluation of mining fleet, maintenance and EPCM tenders progressed, together with assessment of power supply alternatives. Power supply proposals are expected in Q4/26 and will incorporate the requirements of Argentina’s new Extra-Trend Demand Regime (XDEM). |
| ● | Access road and early works: Development of the permanent access road continued, including tendering and permitting activities for Sections 1 and 2 and preparatory work for Section 3. Main works on Section 2 are expected to begin in December 2026, with Section 3 targeted to commence in Q2/27. |
| ● | Permitting: Permitting activities advanced, including approvals related to camp operations, access road works and the Los Patos bridge, as well as environmental approval for the electrical interconnection route contemplated in the 2025 Feasibility Study |
Technical and Field Work
The project experienced one of the heaviest snow seasons in more than two decades, affecting the site and much of the current access road. Reopening of the roads and camps is expected to delay site activities by up to four months compared with a normal season that would typically start in November. Snowmelt and rain in the fourth quarter of 2026 may cause further disruption.
The 2025-2026 field campaign was completed in H1/26, comprising 5,643 meters of geotechnical, condemnation and hydrogeological drilling. Geotechnical results supported further optimization of the open pit design, while condemnation drilling confirmed the planned location of the North-East rock storage facility. Planning was completed for more than 8,000 meters of drilling and field work for the 2026-2027 campaign, which is now expected to commence in Q1/27. The program will focus on additional condemnation, infill and geotechnical drilling to support resource conversion, project infrastructure planning and detailed engineering.
Growth Potential and District Exploration
Mineralization at Los Azules remains open in several areas around the pit and at depth beyond the current mine design. Geotechnical holes drilled to support the mine design were also sampled and assayed. Those assays will be included in a future resource update.
| ● | Mapping and chip sampling continued at Porfido Norte, Tango and Mercedes to evaluate exploration targets outside the current design pit. |
| ● | At La Ballena, the western corridor hosts an open mineralized trend extending more than 700 meters. Historical drilling included 618.5 meters grading 0.51% copper, while recent geotechnical drilling returned 116 meters grading 0.366% copper, including 18 meters at 0.689% copper, supporting the resource block model. Along the eastern corridor, drilling also identified copper mineralization below the current design pit floor, including 28 meters grading 0.403% copper. |
| ● | At the Franca target, immediately north of the deposit, previously reported drilling intersected 1,052 meters grading 0.29% copper, including 480 meters at 0.42% copper, supporting continuity of the mineralized system toward the northeast. |
| ● | At the southern pit extension target, drilling intersected 70 meters grading 0.31% copper, while the Austral target continues to show geophysical responses comparable to La Ballena along the same structural corridor. |
45
These results highlight the potential to expand the current pit and add resources adjacent to the existing deposit. Any expansion would require additional drilling and study; the completed Feasibility Study remains the basis for the project’s development. Drill intercepts have been reported as-drilled lengths; true widths have not been determined. Additional exploration work is planned to continue to investigate and develop additional targets within or adjacent to the Los Azules property.
While not included in the Feasibility Study base case, the application of Nuton® leaching technology, or construction of a conventional concentrator, could potentially be used to process the project’s primary sulfide mineralization and extend the mine life. The technical report summary includes only a preliminary economic evaluation of the concentrator alternative, which includes Inferred Mineral Resources, and describes Nuton® technology as an opportunity. There is no certainty that either alternative will be economically viable. Metallurgical testing and mine planning have started in anticipation of a pre-feasibility study expected to begin in 2027 for the expansion case beyond the Feasibility Study. Combined with potential future exploration success, these opportunities could extend the operating life of Los Azules; however, there can be no assurance that this potential will be realized.
Stakeholder Engagement and Financing
McEwen Copper continued engagement with local communities, government stakeholders, suppliers, and industry participants in connection with project readiness and its social licence to operate. Activities included community education initiatives, regional supplier engagement, and participation in mining sector forums.
Financing activities continued during the period, with Société Générale appointed as the exclusive financial advisor for the project’s debt financing process and preparations initiated for a potential initial public offering.
RIGI Approval and Outlook
On September 26, 2025, McEwen Copper received approval under Argentina’s Regime of Incentive for Large Investments (“RIGI”), which provides Los Azules with certain fiscal and regulatory benefits, including reduced corporate income tax, construction-phase VAT relief, elimination of export duties, foreign exchange relief, 30-year fiscal stability, and access to international arbitration. McEwen Copper is in compliance with all RIGI requirements.
Management is focused on completing the FID work program, evaluating financing alternatives, and advancing Los Azules as a large-scale, long-life copper development project in Argentina, while unlocking the district-scale exploration potential of its surrounding land package.
Liquidity Update
As at September 30, 2026, McEwen Copper had $157.8 million in cash and cash equivalents and a working capital of $138.9 million.
In February 2026, MCI entered into a $59.6 million loan facility with various lenders, bearing interest at 12% per annum and maturing in February 2030. In connection with the financing, lenders received warrants to acquire MCI common shares. The facility was subsequently amended in April and August 2026 to include additional lenders and the total commitments increased to $240.0 million. The additional borrowings under the April and August amendments mature in April 2030 and August 2030, respectively. In connection with the loan facility, the Company issued one warrant for each $1,000 advanced. Each warrant entitles the holder to purchase 15 common shares at an exercise price of $40.00 per share, for a period of five years from the date of issuance. The warrants are separate from the loan and remain outstanding regardless of repayment of the loan. As of September 30, 2026, a total of 3.6 million warrants had been issued and outstanding in connection with the facility.
46
NON-GAAP FINANCIAL PERFORMANCE MEASURES
We have included in this report certain non-GAAP performance measures as detailed below. In the gold mining industry, these are common performance measures but do not have any standardized meaning and are considered non-GAAP measures. We use these measures to evaluate our business on an ongoing basis and believe that, in addition to conventional measures prepared in accordance with GAAP, certain investors use such non-GAAP measures to evaluate our performance and ability to generate cash flow. We also report these measures to provide investors and analysts with useful information about our underlying costs of operations and clarity over our ability to finance operations. Accordingly, they are intended to provide additional information and should not be considered in isolation or as a substitute for the most directly comparable measures of performance prepared in accordance with GAAP. There are limitations associated with the use of such non-GAAP measures. We compensate for these limitations by relying primarily on our US GAAP results and using the non-GAAP measures supplementally.
The non-GAAP measures are presented for our wholly owned mines and our interest in the San José mine. The GAAP information used for the reconciliation to the non-GAAP measures for our minority interest in the San José mine may be found in Item 8. Financial Statements and Supplementary Data, Note 9, Equity Method Investments. We do not control the interest in or operations of MSC and the presentations of assets and liabilities and revenues and expenses of MSC do not represent our legal claim to such items. The amount of cash we receive is based upon specific provisions of the Option and Joint Venture Agreement (“OJVA”) and varies depending on factors including the profitability of the operations.
The presentation of these measures, including the minority interest in the San José mine, has limitations as an analytical tool. Some of these limitations include:
| ● | The amounts shown on the individual line items were derived by applying our overall economic ownership interest percentage determined when applying the equity method of accounting and do not represent our legal claim to the assets and liabilities, or the revenues and expenses; and |
| ● | Other companies in our industry may calculate their cash costs, cash cost per ounce, all-in sustaining costs, all-in sustaining cost per ounce, adjusted EBITDA and average realized price per ounce differently than we do, limiting the usefulness as a comparative measure. |
Cash Costs and All-In Sustaining Costs
The terms cash costs, cash cost per ounce, all-in sustaining costs (“AISC”), and all-in sustaining cost per ounce used in this report are non-GAAP financial measures. We report these measures to provide additional information regarding operational efficiencies on an individual mine basis, and believe these measures used by the mining industry provide investors and analysts with useful information about our underlying costs of operations.
Cash costs consist of mining, processing, onsite general and administrative expenses, community and permitting costs related to current operations, royalty costs, refining and treatment charges (for both doré and concentrate products), sales costs, export taxes and operational stripping costs, but exclude depreciation and amortization (non-cash items). The sum of these costs is divided by the corresponding gold equivalent ounces sold to determine a per ounce amount.
All-in sustaining costs consist of cash costs (as described above), plus accretion of retirement obligations and amortization of the asset retirement costs related to operating sites, environmental rehabilitation costs for mines with no reserves, sustaining exploration and development costs, sustaining capital expenditures and sustaining lease payments. Our all-in sustaining costs exclude the allocation of corporate general and administrative costs.
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The following is additional information regarding our all-in sustaining costs:
| ● | Sustaining operating costs represent expenditures incurred at current operations that are considered necessary to maintain current annual production at the mine site and include mine development costs and ongoing replacement of mine equipment and other capital facilities. Sustaining capital costs do not include the costs of expanding the project that would result in improved productivity of the existing asset, increased existing capacity or extended useful life. |
| ● | Sustaining exploration and development costs include expenditures incurred to sustain current operations and to replace reserves and/or resources extracted as part of the ongoing production. Exploration activities performed near-mine (brownfield) or new exploration projects (greenfield) are classified as non-sustaining. |
The sum of all-in sustaining costs is divided by the corresponding gold equivalent ounces sold to determine a per ounce amount.
Costs excluded from cash costs and all-in sustaining costs, in addition to depreciation and depletion, are income and mining tax expense, all corporate financing charges, costs related to business combinations, asset acquisitions and asset disposals, impairment charges and any items that are deducted for the purpose of normalizing items.
The following tables reconcile these non-GAAP measures to the most directly comparable GAAP measure, production costs applicable to sales:
Three months ended September 30, 2026 | Nine months ended September 30, 2026 | |||||||||||||||||
Gold Bar | Fox Complex | Total | Gold Bar | Fox Complex | Total | |||||||||||||
(in thousands, except per ounce) | (in thousands, except per ounce) | |||||||||||||||||
Production costs applicable to sales (100% owned) - cash costs |
| $ | 19,387 | $ | 12,513 | $ | 31,900 | $ | 54,637 | $ | 41,456 | $ | 96,093 | |||||
Less: costs of externally sourced material processed | — | — | — | — | (2,722) | (2,722) | ||||||||||||
Production costs applicable to sales (100% owned) | 19,387 | 12,513 | 31,900 | 54,637 | 38,734 | 93,371 | ||||||||||||
In‑mine exploration | 432 | — | 432 | 563 | — | 563 | ||||||||||||
Capitalized mine development (sustaining) | — | 3,360 | 3,360 | — | 12,300 | 12,300 | ||||||||||||
Capital expenditures on plant and equipment (sustaining) | 1,193 | — | 1,193 | 3,445 | — | 3,445 | ||||||||||||
Sustaining leases | — | 143 | 143 | — | 214 | 214 | ||||||||||||
All‑in sustaining costs | $ | 21,012 | $ | 16,016 | $ | 37,028 | $ | 58,645 | $ | 51,247 | $ | 109,893 | ||||||
Ounces sold, including stream (GEO) | 5,969 | 4,299 | 10,268 | 19,713 | 17,056 | 36,769 | ||||||||||||
Less: ounces from externally sourced material processed (GEO) | — | — | — | — | (564) | (564) | ||||||||||||
Ounces sold from own production, including stream (GEO) | 5,969 | 4,299 | 10,268 | 19,713 | 16,492 | 36,205 | ||||||||||||
Cash cost per ounce sold ($/GEO) | $ | 3,248 | $ | 2,911 | $ | 3,107 | $ | 2,772 | $ | 2,349 | $ | 2,579 | ||||||
AISC per ounce sold ($/GEO) | $ | 3,520 | $ | 3,725 | $ | 3,606 | $ | 2,975 | $ | 3,107 | $ | 3,035 | ||||||
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Three months ended September 30, 2025 | Nine months ended September 30, 2025 | |||||||||||||||||
Gold Bar | Fox Complex | Total | Gold Bar | Fox Complex | Total | |||||||||||||
(in thousands, except per ounce) | (in thousands, except per ounce) | |||||||||||||||||
Production costs applicable to sales (100% owned) - cash costs | $ | 21,701 | $ | 13,485 | $ | 35,186 | $ | 44,815 | $ | 37,709 | $ | 82,524 | ||||||
In‑mine exploration | 94 | — | 94 | 212 | — | 212 | ||||||||||||
Capitalized underground mine development (sustaining) | — | 1,248 | 1,248 | 7,597 | 5,725 | 13,322 | ||||||||||||
Capital expenditures on plant and equipment (sustaining) | 2,557 | — | 2,557 | 4,092 | — | 4,092 | ||||||||||||
Sustaining leases | 11 | 146 | 157 | 33 | 181 | 214 | ||||||||||||
All‑in sustaining costs | $ | 24,363 | $ | 14,879 | $ | 39,242 | $ | 56,749 | $ | 43,615 | $ | 100,364 | ||||||
Ounces sold, including stream (GEO) | 8,543 | 6,325 | 14,869 | 24,828 | 17,636 | 42,464 | ||||||||||||
Cash cost per ounce sold ($/GEO) | $ | 2,540 | $ | 2,132 | $ | 2,366 | $ | 1,805 | $ | 2,138 | $ | 1,943 | ||||||
AISC per ounce sold ($/GEO) | $ | 2,852 | $ | 2,352 | $ | 2,639 | $ | 2,286 | $ | 2,473 | $ | 2,364 | ||||||
Three months ended September 30, | Nine months ended September 30, | |||||||||||
| 2026 | | 2025 | | 2026 | | 2025 | |||||
San José mine cash costs (100% basis) | (in thousands, except per ounce) | |||||||||||
Production costs applicable to sales - cash costs | $ | 57,003 | $ | 50,053 | $ | 211,694 | $ | 170,244 | ||||
Site exploration expenses |
| 3,599 | 1,922 | 13,657 | 5,213 | |||||||
Capitalized underground mine development (sustaining) |
| 5,106 | 8,186 | 16,180 | 26,033 | |||||||
Less: Depreciation | (530) | (638) | (570) | (1,991) | ||||||||
Capital expenditures (sustaining) |
| 1,557 | 3,623 | 6,035 | 8,797 | |||||||
All‑in sustaining costs | $ | 66,735 | $ | 63,146 | $ | 246,996 | $ | 208,296 | ||||
Ounces sold (GEO) | 19,549 | 22,788 | 83,833 | 72,295 | ||||||||
Cash cost per ounce sold ($/GEO) | $ | 2,916 | $ | 2,196 | $ | 2,525 | $ | 2,355 | ||||
AISC per ounce sold ($/GEO) | $ | 3,414 | $ | 2,771 | $ | 2,946 | $ | 2,881 | ||||
Adjusted EBITDA
Adjusted earnings before interest expense, taxes, depreciation, and amortization (“Adjusted EBITDA”) is a non-GAAP financial measure and does not have any standardized meaning. We use adjusted EBITDA to evaluate our operating performance and ability to generate cash flow from our gold operations in production, including the San José mine; we believe this measure provides valuable assistance to investors and analysts in evaluating our ability to finance our gold operations and capital activities separately from our other operations and investments. The most directly comparable measure prepared in accordance with GAAP is net income (loss).
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The following tables present a reconciliation of Adjusted EBITDA:
Three months ended September 30, | Nine months ended September 30, | ||||||||||||
2026 | | 2025 | 2026 | | 2025 | ||||||||
(in thousands) | (in thousands) | ||||||||||||
Net income (loss) | $ | (36,655) | $ | (462) | $ | 6,330 | $ | (3,692) | |||||
Less: | |||||||||||||
Depreciation and depletion | 7,066 | 7,643 | 22,330 | 20,667 | |||||||||
Loss from investment in Paragon Advanced Labs Inc. (Note 9) | 650 | — | 1,710 | — | |||||||||
Loss from investment in McEwen Copper Inc. (Note 9) | 4,550 | 4,275 | 12,058 | 19,831 | |||||||||
Interest (income) expense | 574 | 1,628 | 2,585 | 4,660 | |||||||||
Income and mining tax (expense) recovery | 12,965 | (1,269) | 8,975 | (3,459) | |||||||||
Adjusted EBITDA | $ | (10,850) | $ | 11,815 | $ | 53,989 | $ | 38,007 | |||||
Average realized price per ounce
The term average realized price per ounce used in this report is also a non-GAAP financial measure. We prepare this measure to evaluate our performance against the market (London P.M. Fix). The average realized price for our 100% owned properties is calculated as gross sales of gold and silver, less streaming revenue, divided by the number of net ounces sold in the period, less ounces sold under streaming agreements.
The following tables reconcile average realized prices to the most directly comparable U.S. GAAP measure, which is revenue from gold and silver sales.
Three months ended September 30, | Nine months ended September 30, | |||||||||||
2026 | | 2025 | | 2026 | | 2025 | ||||||
Average realized price - 100% owned | (in thousands, except per ounce) | |||||||||||
Revenue from gold and silver sales | $ | 43,640 | $ | 50,534 | $ | 176,923 | $ | 132,930 | ||||
Less: revenue from gold sales, stream | 473 | 322 | 865 | 525 | ||||||||
Revenue from gold and silver sales, excluding stream | $ | 43,167 | $ | 50,212 | $ | 176,058 | $ | 132,405 | ||||
GEOs sold | 10,689 | 14,968 | 40,389 | 42,563 | ||||||||
Less: gold ounces sold, stream | 290 | 525 | 1,389 | 1,422 | ||||||||
GEOs sold, excluding stream | 10,399 | 14,443 | 39,000 | 41,141 | ||||||||
Average realized price per GEO sold, excluding stream | $ | 4,151 | $ | 3,477 | $ | 4,514 | $ | 3,218 | ||||
Three months ended September 30, | Nine months ended September 30, | |||||||||||
| 2026 | | 2025 | | 2026 | | 2025 | |||||
Average realized price - San José mine (100% basis) | (in thousands, except per ounce) | |||||||||||
Gold sales | $ | 59,509 | $ | 58,856 | $ | 249,461 | $ | 167,795 | ||||
Silver sales | 29,846 |
| 32,867 | 159,116 |
| 90,716 | ||||||
Gold and silver sales | $ | 89,355 | $ | 91,723 | $ | 408,577 | $ | 258,511 | ||||
Less: commercial discounts | (4,216) | (5,120) | (17,971) | (12,757) | ||||||||
Revenue from gold and silver sales, excluding commercial discounts | 85,139 | 86,603 | 390,606 | 245,754 | ||||||||
Gold ounces sold |
| 13,018 |
| 14,601 | 51,201 |
| 46,776 | |||||
Silver ounces sold |
| 444,081 |
| 717,038 | 2,010,045 |
| 2,341,539 | |||||
GEOs sold |
| 19,549 |
| 22,788 | 83,833 |
| 72,295 | |||||
Average realized price per gold ounce sold | $ | 4,354 | $ | 3,806 | $ | 4,657 | $ | 3,411 | ||||
Average realized price per silver ounce sold | $ | 64.04 | $ | 43.28 | $ | 75.69 | $ | 37.00 | ||||
Average realized price per GEO sold | $ | 4,354 | $ | 3,800 | $ | 4,659 | $ | 3,399 | ||||
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CRITICAL ACCOUNTING POLICIES AND ESTIMATES
Critical accounting policies and estimates used to prepare our financial statements are discussed with our Audit Committee as they are implemented on an annual basis.
There have been no material changes in our critical accounting policies or estimates since the filing of our Annual Report. For further details on the Company’s accounting policies and estimates, refer to the Form 10-K for the year ended December 31, 2025.
FORWARD-LOOKING STATEMENTS
This report contains or incorporates by reference “forward-looking statements”, as that term is used in federal securities laws, about our financial condition, results of operations and business. These statements include, among others:
| ● | statements about our anticipated exploration results, costs and feasibility of production, production estimates, receipt of permits or other regulatory or governmental approvals and plans for the development of our properties; |
| ● | statements regarding strategic alternatives that we are, or may in the future, evaluate in connection with our business; |
| ● | statements concerning the benefits or outcomes that we expect will result from our business activities and certain transactions that we contemplate or have completed, such as receipt of proceeds, increased revenues, decreased expenses and avoided expenses and expenditures; |
| ● | statements of our expectations, beliefs, future plans and strategies, anticipated developments and other matters that are not historical facts. |
These statements may be made expressly in this document or may be incorporated by reference to other documents that we will file with the SEC. Many of these statements can be found by looking for words such as “believes”, “expects”, “anticipates”, “estimates” or the negative of these terms or similar expressions used in this report or incorporated by reference in this report, but the absence of these terms does not mean that a statement is not forward-looking.
Forward-looking statements and information are based upon a number of estimates and assumptions that, while considered reasonable by management, are inherently subject to significant business, economic and competitive uncertainties, risks and contingencies, and there can be no assurance that such statements and information will prove to be accurate. Therefore, actual results and future events could differ materially from those anticipated in such statements and information.
Included among the forward-looking statements and information that we may provide is production guidance. From time to time the Company provides guidance on operations, based on stand-alone budgets for each operating mine. In developing the mine production portion of the budget, we evaluate a number of factors and assumptions, which include, but are not limited to:
| ● | gold and silver price forecasts; |
| ● | average gold and silver grade mined, using a resource model; |
| ● | average grade processed by the crushing facility (Gold Bar Mine Complex) or milling facility (San José mine and Fox Complex); |
| ● | expected tonnes moved and strip ratios; |
| ● | available stockpile material (grades, tonnes, and accessibility); |
| ● | estimates of in process inventory (either on the leach pad or plant for Gold Bar Mine Complex, or in the mill facility for the San José mine and the Fox Complex); |
| ● | estimated leach recovery rates and leach cycle times (Gold Bar Mine Complex); |
| ● | estimated mill recovery rates (San José mine and Fox Complex); |
| ● | dilution of material processed; |
| ● | internal and contractor equipment and labor availability; and |
| ● | seasonal weather patterns. |
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Actual production results are sensitive to variances in any of the key factors and assumptions noted above. As a result, we frequently evaluate and reconcile actual results to budgeted results to determine if key assumptions and estimates require modification. Any changes will, in turn, influence production guidance.
We caution you not to put undue reliance on these forward-looking statements, which speak only as of the date of this report. Further, the forward-looking information contained in this document or incorporated herein by reference is a statement of our present intention and is based on present facts and assumptions, and may change at any time and without notice, based on changes in such facts or assumptions. Readers should not place undue reliance on forward-looking statements.
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RISK FACTORS IMPACTING FORWARD-LOOKING STATEMENTS
Important factors that could prevent us from achieving our stated goals and objectives include, but are not limited to, those set forth in the “Risk Factors” section in our report on Form 10-K for the year ended December 31, 2025 and other reports filed with the SEC, and the following:
| ● | our ability to raise funds required for the execution of our business strategy. |
| ● | our acquisitions may not achieve their intended results. Our ability to secure permits or other regulatory and government approvals needed to operate, develop or explore our mineral properties and projects. |
| ● | our ability to maintain an ongoing listing of our common stock on the New York Stock Exchange or another national securities exchange in the United States. |
| ● | decisions of foreign countries, banks, and courts within those countries. |
| ● | national and international geopolitical events and conflicts, and unexpected changes in business, economic, and political conditions. |
| ● | operating results of MSC and McEwen Copper. |
| ● | fluctuations in interest rates, inflation rates, currency exchange rates, or commodity prices. |
| ● | timing and amount of mine production. |
| ● | our ability to retain and attract key personnel. |
| ● | technological changes in the mining industry. |
| ● | changes in operating, exploration or overhead costs. |
| ● | access and availability of materials, equipment, supplies, labor and supervision, power and water. |
| ● | results of current and future exploration activities. |
| ● | results of pending and future feasibility studies or the expansion or commencement of mining operations without feasibility studies having been completed. |
| ● | changes in our business strategy. |
| ● | interpretation of drill hole results and the geology, grade and continuity of mineralization. |
| ● | the uncertainty of reserve estimates and timing of development expenditures. |
| ● | litigation or regulatory investigations and procedures affecting us. |
| ● | changes in federal, state, provincial and local laws and regulations. |
| ● | local, indigenous and community impacts and issues including criminal activity and violent crimes. |
| ● | accidents, public health issues, and labor disputes. |
| ● | uncertainty relating to title to mineral properties. |
| ● | changes in relationships with the local communities in the areas in which we operate; and |
| ● | decisions by third parties over which we have no control. |
We undertake no responsibility or obligation to update publicly these forward-looking statements, except as required by law and may update these statements in the future in written or oral statements. Investors should take note of any future statements made by or on our behalf.
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Item 3. QUANTITATIVE AND QUALITATIVE DISCLOSURES ABOUT MARKET RISK
Our exposure to market risks includes, but is not limited to, the following risks: changes in foreign currency exchange rates, equity price risks, commodity price fluctuations, credit risk, interest rate risk and inflationary risk. We do not use derivative financial instruments as part of an overall strategy to manage market risk.
Further, our participation in the joint venture with Hochschild for the 49.0% interest held at MSC and our 46.3% ownership in McEwen Copper as of September 30, 2026, creates additional risks because, among other things, we do not exercise decision-making power over the day-to-day activities at MSC or McEwen Copper; however, implications from our partner’s decisions may result in us having to provide additional funding to MSC or McEwen Copper, or result in a further decrease in our percentage of ownership.
Foreign Currency Risk
The Company is exposed to foreign currency risks directly through exposure to the Mexican peso and Canadian dollar, and indirectly through exposure to the Argentine peso through our investments in MSC and McEwen Copper.
During the three months ended September 30, 2026, the Mexican peso and Argentine peso depreciated by 3.4% and 2.3%, respectively, while the Canadian dollar appreciated by 0.1% against the U.S. dollar. In the same period of 2025, the Mexican peso appreciated by 2.4%, while the Canadian dollar and Argentine peso depreciated by 1.9% and 13.5% respectively.
The value of cash and cash equivalents denominated in foreign currencies also fluctuates with changes in currency exchange rates. Appreciation of non-U.S. dollar currencies results in a foreign currency gain on such investments and a depreciation in non-U.S. dollar currencies results in a loss. We hold portions of our cash reserves in non-U.S. dollar currencies.
Our Canadian dollar and Mexican peso cash balances were $1.0 million (CAD $1.4 million) and $0.8 million (MXN $13.9 million), respectively, as at September 30, 2026. The effect that a 1.0% change in these respective currencies would result in gains/losses that are immaterial for disclosure. We have not utilized material market risk-sensitive instruments to manage our exposure to the Canadian dollar and Mexican peso exchange rates but may do so in the future.
Equity Price Risk
We have invested and may continue to invest in shares of common stock of other entities in the mining sector. Some of our investments may be highly volatile and lack liquidity caused by lower trading volumes. As a result, we are inherently exposed to fluctuations in the fair value of our investments, which may result in gains or losses upon their valuation. Based on the marketable securities balance of $10.4 million as at September 30, 2026, a 1.0% change in fair value would result in a gain or loss of approximately $0.1 million.
We have in the past sought and will likely in the future seek to acquire additional funding from the sale of common stock or other equity securities. Movements in the price of our investments have been volatile in the past and may also be volatile in the future. As a result, there is a risk that we may not be able to sell equity securities at an acceptable price to meet future funding requirements.
In February 2025, we raised gross proceeds of $110.0 million through the issuance of Convertible Senior Notes due August 15, 2030, as further described in Note 10 to the consolidated financial statements. In connection with the offering, we entered into separate Capped Call Transactions intended to offset potential dilution upon conversion of the Convertible Notes. These transactions, which are subject to customary anti-dilution adjustments, cover the aggregate number of shares of common stock initially underlying the Convertible Notes.
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Commodity Price Risk
We produce and sell gold and silver. Changes in the market price of gold and silver have and will in the future significantly affect the results of our operations and cash flows. Changes in the price of gold and silver could materially affect our revenues. Based on our revenues from gold and silver sales of $43.6 million for the three months ended September 30, 2026, a 10% change in the price of gold and silver would have had an impact of approximately $4.4 million on our revenues. Changes in the price of gold and silver can also affect the provisionally priced sales that we make under sales agreements. At September 30, 2026, we had no gold or silver sales subject to provisional pricing at our 100% owned operations.
We have in the past and may in the future hold a portion of our treasury in gold and silver bullion, where the value is recorded at the lower of cost or market. Gold and silver prices will affect the value of any bullion that we hold in treasury.
We do not hedge any of our sales and are therefore subject to all changes in commodity prices.
Credit Risk
We may be exposed to credit loss through our precious metals and doré sales agreements with financial institutions and refineries if these customers are unable to make payment in accordance with the terms of the agreements. However, based on the history and the financial condition of our counterparties, we do not anticipate that any of our customers will default on their obligations. As of September 30, 2026, we do not believe we have any significant credit exposure associated with precious metals and our doré sales agreements.
In Nevada and Ontario, Canada we are required to provide security to cover our projected reclamation costs. As at September 30, 2026, we have surety bonds of $51.8 million in place to satisfy bonding requirements for this purpose. The bonds have an annual fee of 2.2% of their value and require a deposit of 2.2% of the amount of the bond. Although we do not believe we have any significant credit exposure associated with these bonds or the deposit, we are exposed to the risk that the surety may default in returning our deposit or that the surety bonds may no longer be accepted by the governmental agencies as satisfactory reclamation coverage, in which case we would be required to replace the surety bonding with cash.
Interest Rate Risk
Our outstanding debt consists of the $110.0 million Convertible Notes due 2030, the $20.0 million term loan facility, and various equipment leases. As the Convertible Notes and term loan have fixed coupons, we do not have any significant exposure to interest rate risks.
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Item 4. CONTROLS AND PROCEDURES
Overview
We maintain a system of controls and procedures designed to ensure that information required to be disclosed by us in reports that we file or submit under the Securities Exchange Act of 1934, as amended (“Exchange Act”), is recorded, processed, summarized and reported, within time periods specified in the SEC’s rules and forms and to ensure that information required to be disclosed by us in the reports that we file or submit under the Exchange Act is accumulated and communicated to our management, including our Chief Executive Officer and Chief Financial Officer, as appropriate to allow timely decisions regarding required disclosure.
Evaluation of Disclosure Controls and Procedures
During the fiscal period covered by this report, our management, with the participation of the Chief Executive Officer and Chief Financial Officer, carried out an evaluation of the effectiveness of the design and operation of our disclosure controls and procedures (as defined in Rules 13a-15(e) and 15d-15(e) under the Exchange Act). Based on such evaluation, our Chief Executive Officer and Chief Financial Officer have concluded that, as of September 30, 2026, our disclosure controls and procedures were effective.
Changes in Internal Control Over Financial Reporting
There were no changes in our internal control over financial reporting during the quarter ended September 30, 2026 that materially affected or are reasonably likely to materially affect our internal controls over financial reporting.
Limitations on Controls and Procedures
All disclosure controls and procedures and internal control over financial reporting processes and systems, no matter how well designed, have inherent limitations. Processes and systems deemed to be effective at any time can provide only reasonable assurance with respect to financial statement preparation and presentation. Also, projections of any evaluation of effectiveness for future periods are subject to the risk that controls may become inadequate due to changes in conditions, or that the degree of compliance with the policies or procedures may deteriorate. The Company conducts periodic evaluations of its internal controls to enhance, where deemed appropriate, its procedures and controls.
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PART II OTHER INFORMATION
Item 1. LEGAL PROCEEDINGS
We are not currently subject to any material legal proceedings. To the best of our knowledge, no such proceeding is threatened, the results of which would have a material impact on our properties, results of operations, or financial condition. Nor, to the best of our knowledge, are any of our officers or directors involved in any legal proceedings in which we are an adverse party.
Item 1A. RISK FACTORS.
There were no material changes from the risk factors set forth under Part I, Item 1A, Risk Factors of our Annual Report. The risks described in our Annual Report, herein and other reports we have filed with the SEC are not the only risks facing us. Additional risks and uncertainties not currently known to us or that we currently deem to be immaterial may also materially adversely affect our business, financial condition, cash flows and/or future results.
Item 2. UNREGISTERED SALES OF EQUITY SECURITIES, USE OF PROCEEDS, AND ISSUER PURCHASES OF EQUITY SECURITIES
All unregistered sales of equity securities effected by the Company or a subsidiary thereof during the quarter ended September 30, 2026, and through the date of filing of this report were previously reported in reports the Company has filed with the SEC.
Item 3. DEFAULTS UPON SENIOR SECURITIES.
None.
Item 4. MINE SAFETY DISCLOSURES
At McEwen Inc., safety is a core value, and we strive for superior performance. Our health and safety management system, which includes detailed standards and procedures for safe operations, addresses topics such as employee training, risk management, workplace inspection, emergency response, accident investigation and program auditing. Based on strong leadership and involvement from all levels of the organization, these programs and procedures form the cornerstone of safety at McEwen Inc., ensuring that employees are provided a safe and healthy environment and are intended to reduce workplace accidents, incidents and losses, comply with all mining-related regulations and provide support for both regulators and the industry to improve mine safety.
The operations of our Gold Bar Mine Complex are subject to regulation by the Federal Mine Safety and Health Administration (“MSHA”) under the Federal Mine Safety and Health Act of 1977 (the “Mine Act”). MSHA inspects our projects and mine on a regular basis and may issue citations and orders when it believes a violation has occurred under the Mine Act. While we assign most of the mining operations at the Gold Bar mine to an independent contractor, we may be considered an “operator” for purposes of the Mine Act and may be issued notices or citations if MSHA believes that we are responsible for violations.
We are required to report certain mine safety violations or other regulatory matters required by Section 1503(a) of the Dodd-Frank Wall Street Reform and Consumer Protection Act and Item 104 of Regulation S-K, and that required information is included in Exhibit 95 filed with this report.
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Item 5. OTHER INFORMATION
| (a) | During the quarter ended September 30, 2026, there was no information required to be disclosed on Form 8-K that was not previously reported. |
| (b) | During the quarter ended September 30, 2026, there were no material changes to the procedures by which stockholders may recommend nominees to the Company’s board of directors. |
| (c) | During the quarter ended September 30, 2026, none of the Company’s directors or executive officers |
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Item 6. EXHIBITS
The following exhibits are filed or incorporated by reference with this report:
3.1.1 | ||
3.1.2 | ||
3.1.3 | ||
3.1.4 | ||
3.1.5 | ||
3.1.6* | ||
3.2* | ||
23.1* | ||
23.2* | ||
23.3* | ||
23.4* | ||
23.5* | ||
23.6* | ||
23.7* | ||
23.8* | ||
23.9* | ||
23.10* | ||
31.1* | ||
31.2* | ||
32* | Section 1350 Certifications of Chief Executive Officer and Chief Financial Officer. | |
95* | ||
99* | ||
99.1* | ||
101.SCH | Inline XBRL Taxonomy Extension Schema Document. | |
101.CAL | Inline XBRL Taxonomy Extension Calculation Linkbase Document. | |
101.DEF | Inline XBRL Taxonomy Extension Definition Linkbase Document. | |
101.LAB | Inline XBRL Taxonomy Extension Label Linkbase Document. | |
101.PRE | Inline XBRL Taxonomy Extension Presentation Linkbase Document. | |
104 | Cover Page Interactive Data File (embedded within the Inline XBRL document). | |
*Furnished herewith. | ||
59
SIGNATURES
Pursuant to the requirements of the Securities Exchange Act of 1934, the registrant has duly caused this report to be signed on its behalf by the undersigned thereunto duly authorized.
MCEWEN INC. | |
/s/ Robert R. McEwen | |
Date: November 9, 2026 | By: Robert R. McEwen, |
Chairman and Chief Executive Officer | |
/s/ Perry Ing | |
Date: November 9, 2026 | By: Perry Ing, |
Interim Chief Financial Officer |
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Exhibit 3.1.6
ARTICLES OF AMENDMENT
TO THE
SECOND AMENDED AND RESTATED ARTICLES OF INCORPORATION
OF
MCEWEN MINING INC.
Pursuant to Section 7-110-103 of the Colorado Business Corporation Act, McEwen Mining Inc., a Colorado corporation (the “Corporation”), adopts the following Articles of Amendment to its Second Amended and Restated Articles of Incorporation and hereby certifies as follows:
1. | The name of the Corporation is MCEWEN MINING INC. |
2. | The board of directors of the Corporation duly approved the following amendment to the Second Amended and Restated Articles of Incorporation and recommended it for approval by the shareholders of the Corporation on April 21, 2025 and the shareholders of the Corporation duly approved said amendment on June 19, 2025. |
3. | The Second Amended and Restated Articles of Incorporation of the Corporation is hereby amended as follows: |
a. | The title thereof is hereby amended and restated in its entirety as follows: |
“SECOND AMENDED AND RESTATED
ARTICLES OF INCORPORATION
OF
MCEWEN INC.”
b. | Article I thereof is hereby amended and restated in its entirety as follows: |
ARTICLE I
NAME
The name of the Corporation is McEwen Inc. (the “Corporation”).
4. | The remainder of the Second Amended and Restated Articles of Incorporation, as previously amended, shall remain unchanged and in full force and effect. |
5. | The effective date of these Articles of Amendment shall be July 7, 2025. |
[Signature Page Follows]
IN WITNESS WHEREOF, the undersigned has executed these Articles of Amendment this 26th day of June 2025.
| MCEWEN MINING INC. | |
| | |
| | |
| By: | /s/ Carmen Diges |
| Name: Carmen Diges | |
| Title: General Counsel and Secretary | |
SIGNATURE PAGE TO ARTICLES OF AMENDMENT
Exhibit 3.2

AMENDED AND RESTATED
BYLAWS OF
MCEWEN INC.
AMENDED AND RESTATED BYLAWS OF
MCEWEN INC.
DESCRIPTION | PAGE |
|---|---|
ARTICLE I – Principal Office and Corporate Seal | 1 |
Section 1.1 – Business Offices | 1 |
Section 1.2 – Corporate Seal | 1 |
ARTICLE II – Shares and Transfer Thereof | 1 |
Section 2.1 – Stock Certificates | 1 |
Section 2.2 – Payment for Shares | 1 |
Section 2.3 – New Certificates | 1 |
Section 2.4 – Lost Certificates | 1 |
Section 2.5 – Transfer of Shares | 1 |
Section 2.6 – Transfer Agents, Registrars and Paying Agents | 2 |
ARTICLE III – Shareholders and Meetings Thereof | 2 |
Section 3.1 – Holders of Record | 2 |
Section 3.2 – Place of Meetings | 2 |
Section 3.3 – Annual Meetings | 2 |
Section 3.4 – Special Meetings | 2 |
Section 3.5 – Notice of Shareholder Business and Nominations | 2 |
Section 3.6 – Fixing Record Dates | 5 |
Section 3.7 – Notice of Meetings | 6 |
Section 3.8 – Stock List | 6 |
Section 3.9 – Proxies | 7 |
Section 3.10 – Quorum and Required Vote | 7 |
Section 3.11 – Conduct of Meetings | 7 |
Section 3.12 – Remote Communications | 7 |
ARTICLE IV – DIRECTORS, POWERS AND MEETINGS | 8 |
Section 4.1 – General Powers | 8 |
Section 4.2 – Number, Tenure and Qualifications | 8 |
Section 4.3 – Nomination of Directors | 8 |
Section 4.4 – Chairman | 8 |
Section 4.5 – Regular Meetings | 8 |
Section 4.6 – Special Meetings | 8 |
Section 4.7 – Participation in Meetings by the Telephone | 9 |
Section 4.8 – Quorum and Voting | 9 |
Section 4.9 – Resignations | 9 |
Section 4.10 – Vacancies | 9 |
Section 4.11 – Compensation | 9 |
Section 4.12 – Committees | 9 |
Section 4.13 – Removal of Directors | 10 |
ARTICLE V – OFFICERS | 10 |
Section 5.1 – General | 10 |
Section 5.2 – Other Officers | 10 |
Section 5.3 – Officer Positions | 10 |
Section 5.4 – Compensation | 11 |
Section 5.5 – Delegation of Powers | 11 |
Section 5.6 – Removal | 11 |
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DESCRIPTION | PAGE |
Section 5.7 – Vacancies | 11 |
Section 5.8 – Surety Bonds | 11 |
ARTICLE VI - FINANCE | 11 |
Section 6.1 – Funds | 11 |
Section 6.2 – Deposits and Checks | 11 |
Section 6.3 – Fiscal Year | 12 |
ARTICLE VII - WAIVER OF NOTICE | 12 |
ARTICLE VIII - ACTION WITHOUT A MEETING | 12 |
Section 8.1 – Action Without a Meeting | 12 |
Section 8.2 – Effect of Action Without a Meeting | 12 |
ARTICLE IX - INDEMNIFICATION OF DIRECTORS, OFFICERS AND OTHERS | 12 |
Section 9.1 – General Scope | 12 |
Section 9.2 – Exclusions | 13 |
Section 9.3 – Expenses | 13 |
Section 9.4 – Approval | 13 |
Section 9.5 – Advance Expenses | 13 |
Section 9.6 – Insurance | 13 |
Section 9.7 – Non-Duplication | 13 |
Section 9.8 – Non-Contravention and Non-Exclusivity | 14 |
Section 9.9 – Continuation of Rights | 14 |
ARTICLE X - AMENDMENTS | 14 |
Section 10.1 – Amendment of Bylaws | 14 |
ARTICLE XI – MISCELLANEOUS | 14 |
Section 11.1 – Gender | 14 |
Section 11.2 – Voting of Securities by the Corporation | 14 |
Section 11.3 – Facsimile Signatures | 14 |
Section 11.4 – Reliance Upon Books, Reports and Records | 14 |
Section 11.5 – Time periods | 14 |
Section 11.6 – Subject to Law and Articles of Incorporation | 14 |
Section 11.7 – Presumption of Assent | 15 |
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ARTICLE I
Principal Office and Corporate Seal
Section 1.1Business Offices. The principal office of McEwen Inc. (the “Corporation”) shall be at Toronto, Canada or such other place as determined from time to time by resolution of the Board of Directors of the Corporation (the “Board”). Other offices and places of business may be established both within and without the state of Colorado from time to time by resolution of the Board or as the business of the Corporation may require.
Section 1.2Corporate Seal. The seal of the Corporation shall have inscribed thereon the name of the Corporation and shall be in such form as may be approved by the Board, which shall have power to alter the same at pleasure. The Corporation may use the seal by causing it, or a facsimile thereof, to be impressed or affixed or in any other manner reproduced.
ARTICLE II
Shares and Transfer Thereof
Section 2.1Stock Certificates. The shares of stock of the Corporation may be represented by certificates, or may be uncertificated shares that may be evidenced by a book entry system maintained by the registrar of such stock, or a combination of both. To the extent that the shares are represented by certificates, such certificates shall be in the form authorized by the Board and signed, either manually or in facsimile, by any two of the following: the chair or vice chair of the Board, the chief executive officer and president or a vice president, the treasurer or an assistant treasurer, the secretary or an assistant secretary or by such other officer or officers as may be designated by the Board, and may be sealed with the seal of the Corporation or a facsimile thereof. In case any officer who has signed a certificate shall have ceased to be such officer before such certificate is issued, it may be issued by the Corporation with the same effect as if he were such officer at the date of its issue.
Section 2.2Payment for Shares. Shares shall be issued for such consideration as shall be determined from time to time by the Board. Treasury shares shall be disposed of for such consideration as may be determined from time to time by the Board. Such consideration shall be paid in such form and in such manner as the Board shall determine. In the absence of actual fraud in the transaction, the judgment of the Board as to the value of such consideration shall be conclusive. The capital stock issued by the Corporation shall be deemed to be fully paid and non-assessable stock if: (a) the entire amount of the consideration has been received by the Corporation in the form of cash, services rendered, personal property, real property, leases of real property or a combination thereof; or (b) not less than the amount of the consideration determined to be capital pursuant to statute has been received by the Corporation in such form and the Corporation has received a binding obligation of the subscriber or purchaser to pay the balance of the subscription or purchase price; provided, however, nothing contained herein shall prevent the Board from issuing partly paid shares pursuant to statute.
Section 2.3New Certificates. To the extent that shares are represented by certificates, no new certificates evidencing shares shall be issued unless and until the old certificate or certificates, in lieu of which the new certificate is issued, shall be surrendered for cancellation, except as provided in Section 2.4.
Section 2.4Lost Certificates. In case of a certificate of stock of the Corporation alleged to have been lost, stolen or destroyed, another certificate may be issued, at the discretion of the Board, in its place upon satisfactory proof of such loss or destruction and, at the discretion of the Board, upon giving to the Corporation a satisfactory bond of indemnity issued by a corporate surety in an amount and for a period satisfactory of the Board.
Section 2.5Transfer of Shares. Transfers of shares of stock of the Corporation shall be made only on the books of the Corporation upon authorization of the registered holder thereof, or by such holder’s attorney thereunto authorized by a power of attorney duly executed and filed with the Corporation’s secretary or a transfer agent for such stock, if any, and if such shares are represented by a certificate or certificates, upon surrender of the certificate or certificates for such shares properly endorsed or accompanied by a duly executed stock transfer power (or by proper evidence of succession, assignment or authority to transfer) and the payment of any taxes thereon; provided, however, that the Corporation shall be entitled to recognize and enforce any lawful restriction on transfer. The person in whose name shares are registered on the books of the Corporation shall be deemed the owner thereof for all purposes as
1
regards the Corporation; provided, however, that whenever any transfer of shares shall be made for collateral security and not absolutely, and written notice thereof shall be given to the Corporation’s secretary or to such transfer agent, such fact shall be stated in the entry of transfer. No transfer of shares shall be valid against the Corporation, or its shareholders and creditors, for any purpose until it shall have been entered in the stock records of the Corporation by an entry showing from whom and to whom transferred.
Section 2.6Transfer Agents, Registrars and Paying Agents. The Board may, at its discretion, appoint one or more transfer agents, registrars and agents for making payment upon any class of stock, bond, debenture or other security of the Corporation. Such agents and registrars may be located either within or outside the State of Colorado. They shall have such rights and duties and shall be entitled to such compensation as may be agreed between the Corporation and such agents.
ARTICLE III
Shareholders and Meetings Thereof
Section 3.1Holders of Record. Only shareholders of record on the books of the Corporation shall be entitled to be treated by the Corporation as holders in fact of the shares standing in their respective names, and the Corporation shall not be bound to recognize any equitable or other claim to, or interest in, any shares on the part of any other person, firm or corporation, whether or not it shall have express or other notice thereof, except as expressly provided by the laws of Colorado.
Section 3.2Place of Meetings. Meetings of shareholders shall be held at the principal office of the Corporation, or at such other place, either within or outside the State of Colorado, as may be designated in the notice of meeting given by or at the direction of the Board.
Section 3.3Annual Meetings. An annual meeting of shareholders of the Corporation for the election of directors, and for the transaction of such other business as may properly come before the meeting, shall be held within the six (6) months following the Corporation’s fiscal year-end on such other date and time as may be determined from time to time by the Board. Failure to hold an annual meeting as required by these Bylaws shall not invalidate any action taken by the Board or officers of the Corporation.
Section 3.4Special Meetings. Special meetings of shareholders may be called only by (i) the president, (ii) the chairman of the Board, (iii) the Board or (iv) the holders of not less than one-tenth of all the shares entitled to vote at the meeting. Any request to call a special meeting shall state the purpose or purposes of the proposed meeting. Business conducted at any special meeting of the shareholders shall be limited to matters properly brought before the meeting and specified in the notice of such special meeting.
Section 3.5Notice of Shareholder Business and Nominations.
(a)The proposal of business to be considered by the shareholders and nominations of persons for election to the Board at an annual or special meeting of the shareholders may be made only (a) pursuant to the Corporation’s notice of meeting (or any supplement thereto), (b) by or at the direction of the Board, or (c) by any shareholder of the Corporation (i) who was a shareholder of record (and, with respect to any beneficial owner, if different, on whose behalf such business is proposed or such nomination or nominations are made, only if such beneficial owner was the beneficial owner of shares of the Corporation) both at the time of giving of notice provided for in this Section 3.5 and on the record date for the determination of shareholders entitled to vote at the meeting, (ii) who is entitled to vote at the meeting upon such election of directors or such business, as the case may be, and (iii) who complies with the notice procedures set forth in Section 3.5(b). As to proposals sought to be included in any proxy statement of the Corporation, shareholders shall comply with Rule 14a-8 under the Securities Exchange Act of 1934, as amended (the “Exchange Act”). As to matters not sought to be included in any proxy statement of the Corporation, Section 3.5(b) shall be the exclusive means for shareholders to make nominations or submit business to be brought before an annual or special meeting of the shareholders. In addition, for business (other than the nomination of persons for election to the Board) to be properly brought before an annual or special meeting by a shareholder, such business must be a proper matter for shareholder action pursuant to the Articles of Incorporation of the Corporation (the “Articles of Incorporation”), these Bylaws and applicable law.
2
(b)For nominations or other business to be properly brought before an annual or special meeting by a shareholder, other than a special meeting called by such shareholder, pursuant to this Section 3.5, the shareholder (a) must have given timely notice thereof in writing and in proper form to the secretary of the Corporation at the principal executive offices of the Corporation, and (b) must provide any updates or supplements to such notice at such times and in the forms required by this Section 3.5. To be timely, a shareholder’s notice relating to an annual meeting shall be received by the secretary at the principal executive offices of the Corporation, in the case of an annual meeting, not less than ninety (90) nor more than one hundred twenty (120) calendar days prior to the first anniversary of the preceding year’s annual meeting (provided, however, that if the date of the annual meeting is more than thirty (30) days before or more than thirty (30) days after such anniversary date, notice by the shareholder must be so delivered, or mailed and received, not less than ninety (90) nor more than one hundred twenty (120) calendar days before such annual meeting, or not more than ten (10) calendar days following the day on which public announcement (as defined below) of the date of such meeting is first made by the Corporation). To be timely, a shareholder’s notice relating to a special meeting shall be received by the secretary at the principal executive offices of the Corporation not more than one hundred twenty (120) calendar days before such special meeting nor less than the later of (i) ninety (90) calendar days prior to such meeting or (ii) if a public announcement is first made of the date of the special meeting less than one hundred (100) calendar days prior to such meeting, ten (10) calendar days following such public announcement. In no event shall the public announcement of an adjournment or postponement of a meeting of shareholders commence a new time period (or extend any time period) for the giving of a shareholder’s notice as described above. To be in proper form for purposes of this Section 3.5(b), such notice shall set forth the information required by Section 3.5(c).
(c)To be in proper form for purposes of this Section 3.5, such shareholder’s notice (as specified in Section 3.5(b)) shall set forth:
(1)as to each person whom the shareholder proposes to nominate for election or re-election as a director, (i) all information relating to such person that is required to be disclosed in solicitations of proxies for election of directors in an election contest, or is otherwise required, in each case, pursuant to Regulation 14A under the Exchange Act, including such person’s written consent to being named in the proxy statement as a nominee and to serving as a director if elected, (ii) a description of all Derivative Interests (as defined below) that have been entered into, as of the date of the notice, by or on behalf of such proposed nominee or any affiliate or associate thereof, such description to include (1) the class, series, and actual or notional number, principal amount or dollar amount of all securities of the Corporation underlying or subject to such Derivative Interests, (2) the material economic terms of such Derivative Interests, and (3) the contractual counterparty for such Derivative Interests, and (iii) a description of all direct and indirect compensation and other material monetary or other business agreements, arrangements and understandings during the past three (3) years, and any other material relationships, between or among such shareholder and beneficial owner, if any, on whose behalf the nomination is being made, and their respective affiliates and associates, or others acting in concert therewith, on the one hand, and each proposed nominee, and his or her respective affiliates and associates, or others acting in concert therewith, on the other hand, including, without limitation, all information that would be required to be disclosed pursuant to Rule 404 promulgated under Regulation S−K if the shareholder making the nomination and any beneficial owner on whose behalf the nomination is made, if any, or any affiliate or associate thereof or person acting in concert therewith, were the “registrant” for purposes of such rule and the nominee were a director or executive officer of such registrant;
(2)as to any other business that the shareholder proposes to bring before the meeting, (i) a brief description of the business desired to be brought before the meeting, the reasons for conducting such business at the meeting and the text of the proposal or business (including the text of any resolutions proposed for consideration and, if such business includes a proposal to amend these Bylaws, the text of the proposed amendment), (ii) any material interest in such business of such shareholder and the beneficial owner, if any, or any affiliate or associate thereof, on whose behalf the proposal is made, (iii) a description of all arrangements or understandings between the shareholder, or any affiliate or associate thereof, on the one hand, and any other person or persons (naming such person or persons), on the other hand, regarding the proposal, and (iv) all other information relating to the proposal and the shareholder or any affiliate or associate thereof that would be required to be disclosed in filings with the Securities and Exchange Commission (the “SEC”) in connection with the solicitation of proxies by the shareholder pursuant to Section 14 of the Exchange Act and the rules and regulations promulgated thereunder;
(3)as to the shareholder giving the notice and the beneficial owner, if any, or any affiliate or associate thereof, on whose behalf the nomination or proposal is made, (i) the name and address of such shareholder, as they
3
appear on the Corporation’s books, and of such beneficial owner, if any, and any affiliate thereof, (ii) the class and number of shares of the Corporation which are, directly or indirectly, owned beneficially and of record by such shareholder and such beneficial owner, if any, and any affiliate thereof, (iii) any proxy, contract, arrangement, understanding, or relationship pursuant to which such shareholder or beneficial owner, if any, or any affiliate thereof, has a right to vote any shares of any security of the Corporation, (iv) a description of all Derivative Interests that have been entered into as of the date of the notice by, or on behalf of, such shareholder or beneficial owner, if any, or by any affiliate or associate thereof, such description to include (1) the class, series, and actual or notional number, principal amount or dollar amount of all securities of the Corporation underlying or subject to such Derivative Interests, (2) the material economic terms of such Derivative Interests, and (3) the contractual counterparty for such Derivative Interests, and (v) any other information relating to such shareholder and beneficial owner, if any, or any affiliate thereof, that would be required to be disclosed in a proxy statement or other filings required to be made in connection with solicitations of proxies for, as applicable, the proposal and/or for the election of directors in a contested election pursuant to Section 14 of the Exchange Act and the rules and regulations promulgated thereunder;
(4)a description of all agreements, arrangements and understandings between such shareholder and beneficial owner, if any, or any affiliate thereof, and any other person or persons (including their names) in connection with the proposal of such business or nominations by the shareholder;
(5)a representation that the shareholder is a holder of record of stock of the Corporation, entitled to vote at such meeting, and intends to appear in person or by proxy at the meeting to propose such business or nominations; and
(6)a representation as to whether the shareholder or the beneficial owner, if any, or any affiliate or associate thereof, is or intends to be part of a group that intends (i) to deliver a proxy statement and/or form of proxy to holders of at least the percentage of the Corporation’s outstanding capital stock required to approve or adopt the proposal and/or (ii) otherwise to solicit proxies from shareholders in support of such proposal.
For purposes of these Bylaws, “public announcement” shall mean disclosure in a press release or in a document publicly filed or furnished by the Corporation with the SEC pursuant to Section 13, 14 or 15(b) of the Exchange Act, and the meaning of the term “group” shall be within the meaning ascribed to such term under Section 13(d)(3) of the Exchange Act.
For purposes of these Bylaws, “Derivative Interests” shall mean (i) any option, warrant, convertible security, appreciation right or similar right with an exercise, conversion or exchange privilege, or a settlement payment or mechanism, related to any security of the Corporation, or any similar instrument with a value derived in whole or in part from the value of any security of the Corporation, in any such case whether or not it is subject to settlement in any security of the Corporation or otherwise and (ii) any arrangement, agreement or understanding (including any short position or any borrowing or lending of any securities) which includes an opportunity for the shareholder, or any affiliate or associate thereof, or any proposed nominee, or any affiliate or associate thereof, directly or indirectly, to profit or share in any profit derived from any increase or decrease in the value of any security of the Corporation, to mitigate any loss or manage any risk associated with any increase or decrease in the value of any security of the Corporation or to increase or decrease the number of securities of the Corporation which such person is or will be entitled to vote or direct the vote, in any case whether or not it is subject to settlement in any security of the Corporation or otherwise; provided, however, that Derivative Interests shall not include: (a) rights of a pledgee under a bona fide pledge of any security of the Corporation unless such pledge has voting rights with respect to such security; (b) rights applicable to all holders of a class or series of securities of the Corporation to receive securities of the Corporation pro rata, or obligations to dispose of securities of the Corporation, as a result of a merger, exchange offer or consolidation involving the Corporation; (c) rights or obligations to surrender any number or principal amount of securities of the Corporation, or have any number or principal amount of securities of the Corporation withheld, upon the receipt or exercise of a derivative security issued pursuant to an employee benefit plan of the Corporation or the receipt or vesting of any securities issued pursuant to an employee benefit plan of the Corporation, in order to satisfy the exercise price or the tax withholding consequences of receipt, exercise, or vesting; (d) interests in broad-based index options, broad-based index futures, and broad-based publicly traded market baskets of stocks approved for trading by the appropriate federal governmental authority; (e) interests or rights to participate in employee benefit plans of the Corporation held by current or former directors, employees, consultants or agents of the Corporation; or (f) options granted to an underwriter in a registered public offering for the purpose of satisfying over-allotments in such offering.
4
(d)Notwithstanding anything in Section 3.5(b) to the contrary, if the number of directors to be elected to the Board at an annual meeting is increased and there is no public announcement by the Corporation specifying the size of the increased Board at least one hundred (100) days before the first anniversary of the preceding year’s annual meeting, a shareholder’s notice required by this Section 3.5 shall also be considered timely, but only with respect to nominees for any new positions created by such increase, if it shall be received by the secretary at the principal executive offices of the Corporation not more than ten (10) calendar days following the day on which such public announcement is first made by the Corporation.
(e)Notwithstanding anything in these Bylaws to the contrary, no business shall be conducted at a meeting of the shareholders and no person shall be eligible for election as a director by means of shareholder nomination except in accordance with the procedures set forth in this Section 3.5 or pursuant to a special meeting called by such shareholders in accordance with Sections 3.4 and 3.10. The chairman of the Board or other person presiding at a meeting shall, if the facts warrant, determine that any business or nomination was not properly brought before the meeting in accordance with the provisions of this Section 3.5 and, if such person should so determine, he or she shall so declare to the meeting, any such business not properly brought before the meeting shall not be transacted, and any nomination not properly brought before the meeting shall be disregarded.
(f)A shareholder providing notice of nominations of persons for election to the Board at or of business proposed to be brought before an annual or special meeting of shareholders shall further update and supplement such notice so that the information provided or required to be provided in such notice pursuant to Section 3.5(a) through Section 3.5(e) shall be true and correct both as of the record date for the determination of shareholders entitled to notice of the meeting and as of the date that is ten (10) business days before the meeting or the rescheduled date of the meeting following any adjournment or postponement thereof, and such updated and supplemental information shall be received by the secretary at the principal executive offices of the Corporation (a) in the case of information that is required to be updated and supplemented to be true and correct as of the record date for the determination of shareholders entitled to notice of the meeting, not later than the later of five (5) business days after such record date or five (5) business days after the public announcement of such record date, and (b) in the case of information that is required to be updated and supplemented to be true and correct as of ten (10) business days before the meeting or the rescheduled date of the meeting following any adjournment or postponement thereof, not later than eight (8) business days before the meeting or the rescheduled date of the meeting following any adjournment or postponement thereof (or if not practicable to provide such updated and supplemental information not later than eight (8) business days before the rescheduled date of the meeting following any adjournment or postponement, on the first practicable date before the date of such rescheduled meeting).
(g)Notwithstanding the foregoing provisions of this Section 3.5, unless otherwise required by law, if the shareholder (or a qualified representative of the shareholder) does not appear at the annual or special meeting of shareholders of the Corporation to present a nomination or proposed business, such nomination shall be disregarded and such proposed business shall not be transacted, notwithstanding that proxies in respect of such vote may have been received by the Corporation. For purposes of this Section 3.5, to be considered a qualified representative of the shareholder, a person must be authorized by a writing executed by such shareholder or an electronic transmission delivered by such shareholder to act for such shareholder as proxy at the meeting of shareholders and such person must produce such writing or electronic transmission, or a reliable reproduction of the writing or electronic transmission, at the meeting of shareholders.
Section 3.6Fixing Record Dates. For the purpose of determining shareholders entitled to notice of or to vote at any meeting of shareholders, or any adjournment thereof, or entitled to receive payment of any dividend or other distribution or allotment of any rights, or entitled to exercise any rights in respect of any change, conversion or exchange of stock or for any other lawful action, or in order to make a determination of shareholders for any other proper purpose, the Board may fix in advance a record date for any such determination of shareholders, which date in any case shall not be more than seventy (70) days and, in case of a meeting of shareholders or for payment of a dividend, not less than ten (10) days prior to the date on which the particular action requiring such determination of shareholders is to be taken or the date on which the dividend is declared. If the Board so fixes a record date for purposes of determining shareholders entitled to notice of a meeting of shareholders, such date shall also be the record date for determining the shareholders entitled to vote at such meeting unless the Board determines, at the time it fixes such record date, that a later date on or before the date of the meeting shall be the date for making such determination. If the Board does not fix in advance a record date, as above provided, then the record date shall be thirty (30) days prior
5
to the date on which the particular action requiring such determination of shareholders is to be taken. A determination of shareholders of record entitled to notice of or to vote at a meeting of shareholders shall apply to any adjournment of the meeting; provided, however, that the Board may fix a new record date for the adjourned meeting.
Section 3.7Notice of Meetings. Written notice of any annual or special meeting of the shareholders shall be delivered by the person or persons calling such meeting. Notice of meetings of shareholders shall state the place (if any), day and hour of the meeting, the record date for determining shareholders entitled to vote at such meetings (if such record date is different from the record date for determining shareholders entitled to receive notice of such meetings), the means of remote communication (if any) by which shareholders and proxyholders may be deemed to be present in person and vote at such meeting and, in case of a special meeting, the purpose or purposes for which the meeting is called. Notices of meetings of shareholders shall be delivered, unless otherwise provided by law, not less than ten (10) days nor more than sixty (60) days before the date of the meeting, either personally or by mail to each shareholder of record entitled to notice of and to vote at such meeting; except to the extent that such notice is waived or is not required as provided in the Business Corporation Act of the State of Colorado, as amended from time to time (the “CBCA”), the Articles of Incorporation or these Bylaws. However, if the authorized shares of the Corporation are to be increased, at least thirty (30) days’ notice shall be given. Notice to shareholders of record, if mailed, shall be deemed given as to any shareholder of record, when deposited in the United States mail, addressed to the shareholder at his address as it appears on the stock transfer books of the Corporation, with postage thereon prepaid, but if three successive letters mailed to the last-known address of any shareholder of record are returned as undeliverable, no further notices to such shareholder shall be necessary, until another address for such shareholder is made known to the Corporation. Without limiting the foregoing, any notice to shareholders given by the Corporation pursuant to these Bylaws shall be effective if given by a form of electronic transmission consented to by the shareholder to whom the notice is given.
When a meeting is adjourned to another time or place, notice need not be given of the adjourned meeting if the time, place and the means of remote communication, if any, by which shareholders and proxyholders may be deemed to be present in person and vote at such adjourned meeting are announced at the meeting at which the adjournment is taken. At the adjourned meeting the Corporation may transact any business which might have been transacted at the original meeting. If the adjournment is for more than thirty (30) days, or if after the adjournment a new record date is fixed for the adjourned meeting, a notice of the adjourned meeting shall be given to each shareholder of record entitled to vote at the meeting.
Section 3.8Stock List. The officer or agent having charge of the stock transfer books for shares of the Corporation shall prepare and make available for inspection, a complete list of the shareholders entitled to vote at a meeting of the shareholders or any adjournment thereof, arranged in alphabetical order, with the address of and the number of shares held of record by each such shareholder, beginning the earlier of ten (10) days before the meeting for which the list was prepared or two (2) business days after notice of the meeting is given and continuing through the meeting. Such list shall be subject to inspection by any shareholder for any purpose germane to the meeting at any time during usual business hours at the principal office of the Corporation, whether within or outside Colorado, or at a place identified in the notice of the meeting in the city on which the meeting will be held; provided, however, if the record date for determining the shareholders entitled to vote is less than ten (10) days before the meeting date, the list shall reflect the shareholders entitled to vote as of the tenth (10th) day before the meeting date. If the meeting is to be held at a designated place, such list shall also be produced and kept open at the time and place of the meeting and shall be subject to the inspection of any shareholder for any purpose germane to the meeting during the whole time of the meeting. If the meeting is to be held solely by means of remote communication, then such list shall also be subject to the inspection of any shareholder for any purpose germane to the meeting during the whole time of the meeting on a reasonably accessible electronic network, and the information required to access such list shall be provided with the notice of the meeting. The original stock transfer books shall be prima facie evidence as to who are the shareholders entitled to examine such record or transfer books or to vote at any meeting of shareholders.
Section 3.9Proxies. Each shareholder entitled to vote at a meeting of shareholders or to express consent or dissent to corporate action in writing without a meeting may vote, consent or dissent either in person or by proxy executed in writing by the shareholder or by his duly authorized attorney in fact. No proxy shall be valid after eleven months from the date of its execution, unless otherwise provided in the proxy.
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Section 3.10Quorum and Required Vote. Except as otherwise provided by statute or by the Articles of Incorporation, the presence in person or by proxy of one-third of the voting power of the outstanding shares of the Corporation entitled to vote shall constitute a quorum at a meeting of shareholders. If less than one-third of voting power of the outstanding shares are represented at a meeting, either the presiding officer of the meeting or a majority of the voting power of the shares so represented may adjourn the meeting from time to time in accordance with Section 3.7, until a quorum shall be present or represented. A quorum, once established, shall not be broken by the withdrawal of enough outstanding shares of the Corporation entitled to vote that leaves less than a quorum.
If a quorum is present at a meeting of shareholders, action on a matter is approved if the votes favoring the action exceed the votes opposing the action, unless a greater number of affirmative votes, or voting by voting groups, is required by law, the Articles of Incorporation or these Bylaws (if authorized by the Articles of Incorporation). Notwithstanding the foregoing and unless the Articles of Incorporation provide otherwise, in the election of directors each shareholder entitled to vote at such election shall have the right to vote the number of shares owned by such shareholder for as many persons as there are directors to be elected, and for whose election the shareholder has the right to vote. Those candidates receiving the highest number of votes cast in their favor (equal to the number of directors to be elected) are elected to the board of directors. Cumulative voting shall not be allowed.
Section 3.11Conduct of Meetings. At each meeting of shareholders, the president of the Corporation or such other person as the president or the Board designates shall act as the presiding officer of the meeting and shall fix and announce the date and time of the opening and the closing of the polls for each matter upon which the shareholders will vote at the meeting and shall determine the order of business and all other matters of procedure. The Board may adopt by resolution such rules, regulations, and procedures for the conduct of the meeting of shareholders as it shall deem appropriate. Except to the extent inconsistent with any such rules and regulations adopted by the Board, the presiding officer of the meeting shall have the right and authority to convene and to adjourn the meeting and to establish rules, regulations, and procedures, which need not be in writing, for the conduct of the meeting and to maintain order and safety. Without limiting the foregoing, he or she may:
(a)restrict attendance at any time to bona fide shareholders of record and their proxies and other persons in attendance at the invitation of the presiding officer or the Board;
(b)place restrictions on entry to the meeting after the time fixed for the commencement thereof;
(c)restrict dissemination of solicitation materials and use of audio or visual recording devices at the meeting;
(d)adjourn the meeting without a vote of the shareholders, whether or not there is a quorum present; and
(e)make rules governing speeches and debate, including time limits and access to microphones.
The presiding officer of the meeting shall act in his or her absolute discretion, and his or her rulings shall not be subject to appeal.
Section 3.12Remote Communications. For the purposes of these Bylaws, if authorized by the Board in its sole discretion, and subject to such guidelines and procedures as the Board may adopt, shareholders and proxyholders not physically at a meeting of shareholders may, by means of remote communication:
(a)participate in a meeting of shareholders; and
(b)be deemed present in person and vote at a meeting of shareholders whether such meeting is to be held at a designated place or solely by means of remote communication, provided that (i) the Corporation shall implement reasonable measures to verify that each person deemed present and permitted to vote at the meeting by means of remote communication is a shareholder or proxyholder, (ii) the Corporation shall implement reasonable measures to provide such shareholders and proxyholders a reasonable opportunity to participate in the meeting and to vote on matters submitted to the shareholders, including an opportunity to read or hear the proceedings of the meeting substantially concurrently with such proceedings, and (iii) if any shareholder or proxyholder votes or takes other action
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at the meeting by means of remote communication, a record of such vote or other action shall be maintained by the Corporation.
ARTICLE IV
Directors, Powers and Meetings
Section 4.1General Powers. The business and affairs of the Corporation shall be managed by or under the direction of its Board. In addition to the powers and authorities expressly conferred upon the Board by these Bylaws, the Board may exercise all such powers of the Corporation and do all such lawful acts and things as are not by statute or by the Articles of Incorporation or by these Bylaws directed or required to be exercised or done by the shareholders or officers.
Section 4.2Number, Tenure and Qualifications. The Board shall consist of such number of directors as may be determined from time to time by the Board, but such number shall not be less than three (3) nor more than twelve (12) and shall initially be set at eleven (11). Directors need not be shareholders of the Corporation or residents of the State of Colorado. Each director shall hold office until his or her successors shall have been elected and qualified or until his or her earlier death, resignation or removal.
Section 4.3Nomination of Directors. Nominations of candidates for election as directors at any annual meeting of shareholders at which directors will be elected may be made (i) by the Board, or (ii) by any shareholder entitled to vote at any such meeting only in accordance with the procedures established in Section 3.5.
Section 4.4Chairman. The Board may elect a chairman, and any such chairman shall (when present) preside at meetings of the Board and lead the Board in fulfilling its responsibilities. In the absence of the chairman, a member of the Board selected by the members present shall preside at meetings of the Board. The Board may delegate such other authority and assign such additional duties to the chairman as it may from time to time determine.
Section 4.5Regular Meetings. A regular meeting of the Board shall be held as soon as practicable after the annual meeting of shareholders at the time and place, either within or without the State of Colorado, determined by the Board for the purpose of electing officers and the transaction of such other business as may come before the meeting, and no notice shall be required in connection therewith. Additional regular meetings of the Board may be held without notice at the time and place, either within or without the State of Colorado, as determined by resolution adopted by the Board.
Section 4.6Special Meetings. Special meetings of the Board or any committee designated by said Board may be called at any time by or at the request of the chairman of the Board, the president, or any director, and may be held within or outside the State of Colorado at such time and place as the notice or waiver thereof may specify. Notice of the date, time and place of each such special meeting shall be given to each director who has not waived notice. Such notice shall be properly and timely given if it is (a) deposited in the United States mail not later than the fifth (5th) calendar day preceding the date of the meeting, or (b) personally delivered, telegraphed, sent by either facsimile transmission, electronic mail (effective when directed to an electronic mail address of the director), or other form of electronic transmission, or communicated by telephone or in person at least forty-eight (48) hours prior to the date or time fixed for the meeting. Special meetings of the Board may be held at any time that all directors are present in person, and presence of any director at a meeting shall constitute waiver of notice of such meeting except as otherwise provided by law. Unless specifically required by law, the Articles of Incorporation or these Bylaws, neither the business to be transacted at, nor the purpose of, any meeting of the Board or any committee designated by said Board need be specified in the notice or waiver of notice of such meeting.
Section 4.7Participation in Meetings by Telephone. Members of the Board or any committee designated by such Board may participate in a meeting of the Board or committee by means of conference telephone, webcast or other communications equipment by which all persons participating in the meeting can hear each other. Such participation shall constitute presence in person at the meeting.
Section 4.8Quorum and Voting. A quorum at all meetings of the Board shall consist of the presence in person of a majority of the total number of directors then holding office. If less than a quorum is present at a meeting, a majority of the directors present may adjourn the meeting from time to time without further notice, until a quorum
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shall be present. The vote of the majority of the directors present at a meeting at which a quorum is present shall be the act of the Board, unless the vote of a greater number is required by the laws of the State of Colorado or by the Articles of Incorporation or these Bylaws. No director may vote or act by proxy at any meeting of the Board.
Section 4.9Resignations.
(a)Any director may resign at any time by giving written notice to the Corporation. A director’s resignation shall take effect at the time specified therein or, if no time is specified, upon receipt thereof by the Corporation. Unless otherwise specified therein, the acceptance of such resignation shall not be necessary to make it effective.
(b)Any director who is an employee of the Corporation shall be deemed to have tendered his/her resignation as a director to the Board upon termination of his/her employment with the Corporation. The Board shall determine whether to accept such resignation or whether the director shall finish his/her term as a director. Until and unless the Board formally accepts, by majority vote, such resignation or if the Board does not accept, by majority vote, the resignation, the director shall continue to serve on the Board and have full authority, power and privileges of a member of the Board until the end of such director’s term.
Section 4.10Vacancies. Unless otherwise provided in the Articles of Incorporation, any vacancy occurring in the Board may be filled by the affirmative vote of a majority of the remaining directors though less than a quorum of the Board. Any directorship to be filled by reason of an increase in the number of directors shall be filled by the affirmative vote of a majority of the directors then in office or by an election at an annual meeting, or at a special meeting of shareholders called for that purpose. A director elected pursuant to this Section 4.10 shall hold such office until the next annual meeting of shareholders and until his or her successor is duly elected and qualified, unless sooner displaced.
Section 4.11Compensation. Directors, as such, may receive such compensation as may be established by resolution of the Board for their services as directors, and in addition thereto, shall be paid for their reasonable traveling expenses, if any, for attendance at meetings of the Board. No such payment shall preclude any director from serving the Corporation in any other capacity and receiving compensation therefore. Members of any committee of the Board may be allowed compensation for attending committee meetings and service on such committee.
Section 4.12Committees.
(a)The Board, by resolution, may designate from among its members an executive committee, and one or more other committees each of which, to the extent provided in the resolution shall have all of the authority of the Board; but no such committee shall have the authority of the Board in reference to amending the Articles of Incorporation, adopting a plan of merger or consolidation, recommending to the shareholders the sale, lease, exchange or other disposition of all or substantially all of the property and assets of the Corporation otherwise than in the usual and regular course of its business, recommending to the shareholders a voluntary dissolution of the Corporation or a revocation thereof, or amending these Bylaws. The Board may also designate one (1) or more directors as alternate members of any committee, who may replace any absent or disqualified member at any meeting of the committee. In the absence or disqualification of a member of a committee, the member or members thereof present at any meeting and not disqualified from voting, whether or not they constitute a quorum, may unanimously appoint another member of the Board to act at the meeting in the place of any such absent or disqualified member.
(b)Each committee may determine the procedural rules for meeting and conducting its business and shall act in accordance therewith, except as otherwise provided herein or required by law. Adequate provision shall be made for notice to members of all meetings; one-third of the members shall constitute a quorum unless the committee shall consist of one or two members, in which event one member shall constitute a quorum; and all matters shall be determined by a majority vote of the members present. Each committee shall keep regular minutes of its meetings and report the same to the Board when required.
(c)The designation of such committees and the delegation thereto of authority shall not operate to relieve the Board, or any member thereof, of any responsibility imposed by law.
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Section 4.13Removal of Directors. The shareholders may, at a meeting called for the express purpose of removing directors, by a majority vote of the shares entitled to vote at an election of directors, remove the entire Board or any lesser number, with or without cause.
ARTICLE V
Officers
Section 5.1General. The officers of the Corporation shall consist of at least a president, a corporate secretary and a chief financial officer each of whom shall be eighteen years or older and who shall be elected by the Board at its first meeting after the annual meeting of shareholders. Unless removed in accordance with procedures established by law and these Bylaws, the said officers shall serve until the next succeeding annual meeting of the Board and until their respective successors are elected and qualified or until their earlier death, resignation or removal. Any two offices, but not more than two, may be held by the same person at the same time, except that one person may not simultaneously hold the offices of president and secretary.
Section 5.2Other Officers. The Board may elect or appoint such other officers, assistant officers and agents as it may deem advisable, who shall hold office during the pleasure of the Board.
Section 5.3Officer Positions. The officers of the Corporation shall exercise and perform the respective powers, duties and functions as are stated below, and as may be assigned to them by the Board.
(a)The president shall be the chief executive of the Corporation and shall, subject to the control of the Board, have general supervision, direction and control of the business and officers of the Corporation. He, or his designate, shall preside at all meetings of the shareholders and of the Board, in the absence of the chairman of the Board. The president or a vice president may sign and execute, to the fullest extent permitted by law, in the name of the Corporation, all authorized stock certificates, bonds, deeds, mortgages, leases, contracts and other instruments of the Corporation, except in cases in which the signing and execution thereof shall have been expressly delegated to some other officer or agent of the Corporation. The president shall have such powers customarily and usually associated with the position of president and shall perform all the duties commonly incident to this office and such other duties as the Board shall designate.
(b)In the absence or disability of the president, the vice president or vice presidents, if any, in order of their rank as fixed by the Board, and if not ranked, the vice presidents in the order designated by the Board, shall perform all the duties of the president, and when so acting shall have all the powers of, and be subject to all the restrictions on, the president. Each vice president shall have such other powers and perform such other duties as may from time to time be assigned to him by the president.
(c)The secretary shall keep accurate minutes of all meetings of the shareholders and the Board. The secretary shall keep, or cause to be kept a record of the shareholders of the Corporation and shall be responsible for the giving of notice of meetings of the shareholders and of the Board. The secretary shall be custodian of the records and of the seal of the Corporation and shall attest the affixing of the seal of the Corporation when so authorized. The secretary shall have such powers and perform all duties commonly incident to his office and such other powers and duties as may from time to time be assigned to him by the president.
(d)An assistant secretary may, at the request of the secretary, or in the absence or disability of the secretary, perform all of the duties of the secretary. He shall perform such other duties as may be assigned to him by the president or by the secretary.
(e)The chief financial officer, subject to the order of the Board, shall have the care and custody of the money, funds, valuable papers and documents of the Corporation. He shall keep accurate books of accounts of the Corporation’s transactions, which shall be the property of the Corporation, and shall render financial reports and statements of condition of the Corporation when so requested by the Board or president. The chief financial officer shall perform all duties commonly incident to his office and such other duties as may from time to time be assigned to him by the president. In the absence or disability of the president and vice president or vice presidents, the chief financial officer shall perform the duties of the president.
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(f)An assistant chief financial officer or individual serving in a similar capacity may, at the request of the chief financial officer, or in the absence or disability of the treasurer, perform all of the duties of the chief financial officer. He shall perform such other duties as may be assigned to him by the president or by the treasurer.
Section 5.4Compensation. All officers of the Corporation may receive salaries or other compensation if so ordered and fixed by the Board. The Board shall have authority to fix salaries in advance for stated periods or render the same retroactive as the Board may deem advisable. No officer shall be prevented from receiving a salary by reason of the fact that he or she is also a director of the Corporation.
Section 5.5Delegation of Powers. Notwithstanding any provisions of these Bylaws, the Board may from time to time delegate the powers or duties of any officer to any other officers or agents, including in the event of the absence or inability of any officer to act.
Section 5.6Removal. Any officer or agent of the Corporation may be removed at any time, with or without cause, by the Board or by the president, if any, whenever in its judgment the best interest of the Corporation will be served thereby, but such removal shall be without prejudice to the contract rights, if any, of the person so removed. Election or appointment of an officer or agent shall not, of itself, create contract rights.
Section 5.7Vacancies. Any officer or agent may resign at any time, subject to any rights or obligations under any existing contracts between such officer or agent and the Corporation, by giving written notice to the Corporation. An officer’s or agent’s resignation shall take effect at the time specified therein or, if no time is specified, upon receipt thereof by the Corporation. Unless otherwise specified therein, the acceptance of such resignation shall not be necessary to make it effective. Any vacancy occurring in any office by death, resignation, removal or otherwise shall be appointed by the Board for the unexpired portion of the term and until a successor shall have been duly chosen and qualified.
Section 5.8Surety Bonds. The Board may require any officer or agent of the Corporation to execute to the Corporation a bond in such sums and with such sureties as shall be satisfactory to the Board, conditioned upon the faithful performance of his or her duties and for the restoration to the Corporation of all books, papers, vouchers, money and other property of whatever kind in his or her possession or under his or her control belonging to the Corporation.
ARTICLE VI
Finance
Section 6.1Funds. The Board, in its uncontrolled discretion, may set aside from time to time, out of the net profits or earned surplus of the Corporation, such sum or sums as it deems expedient as a reserve fund to meet contingencies, for equalizing dividends, for maintaining any property of the Corporation, and for any other purpose.
Section 6.2Deposits and Checks. The moneys of the Corporation shall be deposited in the name of the Corporation in such bank or banks or trust company or trust companies, as the Board shall designate, and may be drawn out only on checks or other transfers signed or authorized in the name of the Corporation by such person or persons as the Board by appropriate resolution may direct. Notes and commercial paper, when authorized by the Board, shall be signed in the name of the Corporation by such officer or officers or agent or agents as shall thereunto be authorized from time to time.
Section 6.3Fiscal Year. The fiscal year of the Corporation shall be determined by resolution of the Board.
ARTICLE VII
Waiver of Notice
With any notices required by law, the Articles of Incorporation or these Bylaws to be given to any shareholder or director of the Corporation, a waiver thereof in writing signed by the person entitled to such notice, whether before, at, or after the time stated therein shall be the equivalent to the giving of such notice. Attendance of a person at a meeting or (in the case of a shareholder) by proxy shall constitute a waiver of notice of such meeting, except when the person attends a meeting for the express purpose of objecting, at the beginning of the meeting, to the transaction
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of any business because the meeting was not lawfully called or convened. Neither the business to be transacted at, nor the purpose of, any regular or special meeting of the shareholders, directors, or members of a committee of directors need be specified in any written waiver of notice unless so required by the Articles of Incorporation or these Bylaws.
ARTICLE VIII
Action Without a Meeting
Section 8.1Action Without a Meeting. Any action required or permitted to be taken at a meeting of the directors, executive committee, or other committee of the directors, or shareholders of the Corporation, may be taken without a meeting if a consent in writing, setting forth the action so taken shall be signed by all of the directors, executive or other committee members or shareholders, as the case may be, entitled to vote with respect to the subject matter thereof. Any such consent may be submitted to the Corporation by facsimile transmission, electronic mail or other form of wire or wireless communication that provides the Corporation with a complete copy of such consent, including a copy of the signature thereto.
Section 8.2Effect of Action Without a Meeting. Such consent shall have the same force and effect as a unanimous vote of the directors, executive committee or other committee members or shareholders, as the case may be and may be stated as such in any articles or document filed with the Secretary of State of Colorado.
ARTICLE IX
Indemnification of Directors, Officers and Others
Section 9.1General Scope.
(a)The Corporation shall indemnify and hold harmless, to the fullest extent permitted by the CBCA, any person who was or is a party or was or is threatened to be made a party to any threatened, pending or completed action, suit or proceeding, whether civil, criminal, administrative or investigative (a “proceeding”) by reason of the fact that he or she, or a person of whom he or she is the legal representative, is or was a director, officer, employee or agent of the Corporation, or is or was serving at the request of the Corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise, against all expenses (including attorneys’ fees) , liability, losses, judgments, fines and amounts paid in settlement actually and reasonably incurred by such person in connection with such proceeding if such person acted in good faith and in a manner he or she reasonably believed (i) to be in, or not opposed to, the best interests of the Corporation in the case of conduct in an official capacity with the corporation or (ii) was at least not opposed to the best interests of the Corporation in all other cases, and, with respect to any criminal action or proceeding, had no reasonable cause to believe his or her conduct was unlawful.
(b)The termination of any action, suit or proceeding by judgment, order, settlement, or conviction, or upon a plea of nolo contendere or its equivalent, shall not of itself create a presumption that the person did not meet the standard of conduct described in Section 9.1(a).
(c)The Corporation will indemnify a director, officer, employee or agent who is or was a party to a proceeding and failed to meet the standard of conduct set forth in the CBCA and in Section 9.1(a) only to the extent that the court in which such proceeding was brought or another court of competent jurisdiction determines upon application that, despite the failure of the director to meet the applicable standard of conduct but in view of all circumstances of the case, such person is fairly and reasonably entitled to indemnification for such expenses which such court shall deem proper.
Section 9.2Exclusions. The Corporation shall not indemnify nor hold harmless any person who is adjudged liable (a) to the Corporation in connection with a proceeding by or in the right of the Corporation, or (b) is adjudged liable on the basis that he or she derived an improper personal benefit in connection with any proceeding charging that the director derived an improper personal benefit, whether or not involving action in an official capacity; unless and only to the extent that the court in which such proceeding was brought or another court of competent jurisdiction determines upon application that, despite the adjudication of liability but in view of all circumstances of the case, such person is fairly and reasonably entitled to indemnification for such reasonable expenses which such court shall deem proper.
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Section 9.3Expenses. To the extent that a director, officer, employee or agent of the Corporation has been successful on the merits in defense of any action, suit or proceeding referred to in Section 9.1, or in defense of any claim, issue or matter therein, he shall be indemnified against expenses (including attorneys’ fees) actually and reasonably incurred by him in connection therewith.
Section 9.4Approval. Any indemnification under Section 9.1 (unless ordered by a court) shall be made by the Corporation only as authorized in the specific case upon a determination that indemnification of the officer, director, employee or agent is proper in the circumstances because he or she has met the applicable standard of conduct set forth in the CBCA and in Sections 9.1 and 9.2. Such determination shall be made by either (a) the Board by a majority vote of the directors present at a meeting at which a quorum is present with only those directors not parties to the proceeding being counted in satisfying the quorum; (b) if a quorum cannot be obtained, by a majority vote of a committee of the Board designated by the Board, which consists of two or more directors not parties to the proceeding (except that directors who are parties to the proceeding may participate in the designation of directors for the committee); (c) independent legal counsel appointed in accordance with the CBCA; or (d) the shareholders of the Corporation.
Section 9.5Advance Expenses. Expenses incurred (including attorneys’ fees) in defending a proceeding may be paid by the Corporation in advance of the final disposition of such proceeding as authorized by the Board as provided in Section 9.4 upon (a) receipt of a written affirmation of the director’s, officer’s, employee’s or agent’s good faith belief that he or she has met the applicable standard of conduct set forth in the CBCA and Sections 9.1 and 9.2, (b) receipt of a written undertaking, executed personally or on behalf of the director, officer, employee or agent, to repay such amount if it is ultimately determined that he or she did not meet the applicable standard of conduct; and (c) a determination that the facts then known would not preclude indemnification under the CBCA or this Article IX.
Section 9.6Insurance. The Board may exercise the Corporation’s power to purchase and maintain insurance on behalf of itself and any person who is or was a director, officer, employee or agent of the Corporation, or is or was serving at the request of the Corporation as a director, officer, employee or agent of another corporation, partnership, joint venture, trust or other enterprise against any expense, liability or loss, whether or not the Corporation would have the power to indemnify such person against such expense, liability or loss hereunder or otherwise.
Section 9.7Non-Duplication. The Corporation’s obligation, if any, to indemnify any person who was or is serving at its request as a director, officer, employee or agent of another corporation, partnership, joint venture, trust, or other enterprise shall not be interpreted so as to duplicate any amount such person may collect as indemnification from such other corporation, partnership, joint venture, trust or other enterprise.
Section 9.8Non-Contravention and Non-Exclusivity. The rights conferred on any person by this Article IX shall not contravene the provisions of any applicable laws and such rights shall not be exclusive of any other rights that such person may be entitled under any provisions of the Articles of Incorporation, these Bylaws, agreement, vote of shareholders or disinterested directors, the CBCA, or otherwise.
Section 9.9Continuation of Rights. The rights conferred on any person by this Article IX shall continue as to a person who has ceased to be a director, officer, employee or agent and shall inure to the benefit of the heirs, executors, administrators and personal representatives of such a person. Subject to any applicable laws, all rights provided by or granted pursuant to this Article IX shall be deemed to be a contract between the Corporation and each director, officer, employee or agent of the Corporation who serves or served in such capacity at any time while this Article IX is in effect. Any repeal or modification of this Article IX shall not in any way diminish any rights to indemnification of such directors, officers, employees or agents, or the obligations of the Corporation arising hereunder.
ARTICLE X
Amendments
Section 10.1Amendment of Bylaws. The Board may amend these Bylaws at any time to add, change or delete a provision unless otherwise prohibited by law. The shareholders may amend the Bylaws even though the Bylaws may also be amended by the Board.
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ARTICLE XI
Miscellaneous
Section 11.1Gender. Whenever in these Bylaws the masculine gender is used, it shall be deemed to include the feminine gender.
Section 11.2Voting of Securities by the Corporation. Unless otherwise ordered by the Board, the president, chief financial officer, each vice president, and the corporate secretary shall have full power and authority on behalf of the Corporation: (a) to attend and to vote at any meeting of security holders of other corporations entities in which the Corporation may hold securities; (b) to execute any proxy for such meeting on behalf of the Corporation; or (c) to execute a written action in
Section 11.3 lieu of a meeting of such other corporation entity on behalf of the Corporation. At such meeting, by such proxy or by such writing in lieu of meeting, the president and each vice president shall possess and may exercise any and all rights and powers incident to the ownership of such securities that the Corporation might have possessed and exercised if it had been present. The Board may, from time to time, confer like powers upon any other person or persons.
Section 11.4Facsimile Signatures. In addition to the provisions for use of facsimile signatures elsewhere specifically authorized in these Bylaws, facsimile signatures of any officer or officers of the Corporation may be used whenever and as authorized by the Board or a committee thereof.
Section 11.5Reliance Upon Books, Reports and Records. Each director, each member of any committee designated by the Board, and each officer of the Corporation shall, in the performance of his or her duties, be fully protected in relying in good faith upon the books of account or other records of the Corporation, including reports made to the Corporation by any of its officers, by an independent certified public accountant, or by an appraiser selected with reasonable care.
Section 11.6Time Periods. In applying any provision of these Bylaws which require that an act be done or not done a specified number of days prior to an event or that an act be done during a period of a specified number of days prior to an event, calendar days shall be used, the day of the doing of the act shall be excluded, and the day of the event shall be included.
Section 11.7Subject to Law and Articles of Incorporation. All powers, duties and responsibilities provided for in these Bylaws, whether or not explicitly so qualified, are qualified by the Articles of Incorporation and applicable law.
Section 11.8Presumption of Assent. A director or shareholder of the Corporation who is present at a meeting of the Board or shareholders at which action on any corporate matter is taken shall be presumed to have assented to the action taken unless his or her dissent shall be entered in the minutes of the meeting or unless he or she shall file a written dissent of such action with the person acting as the secretary of the meeting before the adjournment thereof or shall forward such dissent by registered mail to the secretary of the Corporation immediately after the adjournment of the meeting. Such right to dissent shall not apply to a director or shareholder who voted in favor of such action.
14
Exhibit 23.1
CONSENT OF QUALIFIED PERSON
To: McEwen Inc. (the "Company")
Re: Quarterly Report on Form 10-Q for the Quarterly Period Ended September 30, 2026
I, Michael C. Baumann, AIPG-CPG10674, SME-RM# 185920, hereby consent to:
| 1. | The filing and use by the Company of the technical report summary titled "S-K 1300 Initial Assessment Technical Report Summary for the Lookout Mountain and Windfall Deposits, Eureka, Nevada, USA" with an effective date of November 9, 2026 (the "Technical Report Summary"), as Exhibit 99 to the Company’s Quarterly Report on Form 10-Q for the Quarterly Period ended September 30, 2026 (the "Form 10-Q"), and any amendments thereto. |
| 2. | The use of my name as an expert and as a "qualified person" (as defined in Item 1300 of Regulation S-K) in connection with the Form 10-Q and any disclosure of the mineral resource, exploration results, or other technical information contained or incorporated by reference therein. |
| 3. | The quotation or summarization of disclosures from, and the incorporation by reference of, the Technical Report Summary into the Form 10-Q. |
I further confirm that I have read the disclosures in the Form 10-Q that are derived from or based upon the Technical Report Summary, and that such disclosures fairly and accurately represent the information in the Technical Report Summary for which I am responsible under Item 1302 of Regulation S-K.
Dated: November 9, 2026 | |
| /s/ Michael C. Baumann, AIPG-CPG10674, SME-RM# 185920 |
| Michael C. Baumann, Senior Resource Geologist, McEwen Mining Nevada Inc. |
Exhibit 23.2
CONSENT OF QUALIFIED PERSON
To: McEwen Inc. (the "Company")
Re: Quarterly Report on Form 10-Q for the Quarterly Period Ended September 30, 2026
I, Barry L Carlson, P.E., P.Eng, SME-RM, hereby consent to:
| 1. | The filing and use by the Company of the technical report summary titled "S-K 1300 Initial Assessment Technical Report Summary for the Lookout Mountain and Windfall Deposits, Eureka, Nevada, USA" with an effective date of November 9, 2026 (the "Technical Report Summary"), as Exhibit 99 to the Company’s Quarterly Report on Form 10-Q for the Quarterly Period ended September 30, 2026 (the "Form 10-Q"), and any amendments thereto. |
| 2. | The use of my name as an expert and as a "qualified person" (as defined in Item 1300 of Regulation S-K) in connection with the Form 10-Q and any disclosure of the mineral resource, exploration results, or other technical information contained or incorporated by reference therein. |
| 3. | The quotation or summarization of disclosures from, and the incorporation by reference of, the Technical Report Summary into the Form 10-Q. |
I further confirm that I have read the disclosures in the Form 10-Q that are derived from or based upon the Technical Report Summary, and that such disclosures fairly and accurately represent the information in the Technical Report Summary for which I am responsible under Item 1302 of Regulation S-K.
Dated: November 9, 2026 | |
| /s/ Barry L. Carlson, P.E., P.Eng, SME-RM |
| Barry L. Carlson, Senior Advisor Process / Metallurgical Engineer Consultant, SLR International Corporation |
Exhibit 23.3
CONSENT OF QUALIFIED PERSON
To: McEwen Inc. (the "Company")
Re: Quarterly Report on Form 10-Q for the Quarterly Period Ended September 30, 2026
I, Gary Edmondo, CPG (AIPG# 11089), hereby consent to:
| 1. | The filing and use by the Company of the technical report summary titled "S-K 1300 Initial Assessment Technical Report Summary for the Lookout Mountain and Windfall Deposits, Eureka, Nevada, USA" with an effective date of November 9, 2026 (the "Technical Report Summary"), as Exhibit 99 to the Company’s Quarterly Report on Form 10-Q for the Quarterly Period ended September 30, 2026 (the "Form 10-Q"), and any amendments thereto. |
| 2. | The use of my name as an expert and as a "qualified person" (as defined in Item 1300 of Regulation S-K) in connection with the Form 10-Q and any disclosure of the mineral resource, exploration results, or other technical information contained or incorporated by reference therein. |
| 3. | The quotation or summarization of disclosures from, and the incorporation by reference of, the Technical Report Summary into the Form 10-Q. |
I further confirm that I have read the disclosures in the Form 10-Q that are derived from or based upon the Technical Report Summary, and that such disclosures fairly and accurately represent the information in the Technical Report Summary for which I am responsible under Item 1302 of Regulation S-K.
Dated: November 9, 2026 | |
| /s/ Gary Edmondo, CPG (AIPG #11089) |
| Gary Edmondo, Senior Exploration Geologist, McEwen Mining Nevada Inc. |
Exhibit 23.4
CONSENT OF QUALIFIED PERSON
To: McEwen Inc. (the "Company")
Re: Quarterly Report on Form 10-Q for the Quarterly Period Ended September 30, 2026
I, Robert L. Kastelic, CPG, hereby consent to:
| 1. | The filing and use by the Company of the technical report summary titled "S-K 1300 Initial Assessment Technical Report Summary for the Lookout Mountain and Windfall Deposits, Eureka, Nevada, USA" with an effective date of November 9, 2026 (the "Technical Report Summary"), as Exhibit 99 to the Company’s Quarterly Report on Form 10-Q for the Quarterly Period ended September 30, 2026 (the "Form 10-Q"), and any amendments thereto. |
| 2. | The use of my name as an expert and as a "qualified person" (as defined in Item 1300 of Regulation S-K) in connection with the Form 10-Q and any disclosure of the mineral resource, exploration results, or other technical information contained or incorporated by reference therein. |
| 3. | The quotation or summarization of disclosures from, and the incorporation by reference of, the Technical Report Summary into the Form 10-Q. |
I further confirm that I have read the disclosures in the Form 10-Q that are derived from or based upon the Technical Report Summary, and that such disclosures fairly and accurately represent the information in the Technical Report Summary for which I am responsible under Item 1302 of Regulation S-K.
Dated: November 9, 2026 | |
| /s/ Robert L. Kastelic, CPG |
| Robert L. Kastelic, Exploration Manager, McEwen Mining Nevada Inc. |
Exhibit 23.5
CONSENT OF QUALIFIED PERSON
I, Carson Cybolsky, consent to the disclosure of the information in Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary that is dated November 9th, 2026, and consent to any extracts from, or a summary of, the technical report in the news release entitled “Pre-Feasibility Study for Grey Fox at Fox Complex” dated 08 June 2026 (the “news release”) and confirm that the information for which I am responsible is based on, and fairly and accurately reflects, in the form and context in which it appears, the information in my supporting documentation relating to the Mineral Resource Estimates, as well as drilling, data verification and production history.
| |
Dated: November 9, 2026 | /s/ Carson Cybolsky, P. Geo |
Exhibit 23.6
CONSENT OF QUALIFIED PERSON
I, Daniel Morrison, consent to the disclosure of the information in Grey Fox Project Prefeasibility Study SK 1300 Technical Report Summary that is dated November 9th, 2026, and consent to any extracts from, or a summary of, the technical report in the news release entitled “Pre-Feasibility Study for Grey Fox at Fox Complex” dated 08 June 2026 (the “news release”) and confirm that the information for which I am responsible is based on, and fairly and accurately reflects, in the form and context in which it appears, the information in my supporting documentation relating to the mineral processing and related cost estimates.
| |
Dated: November 9, 2026 | /s/ Daniel Weich Morrison, P. Eng. |
Exhibit 23.7
CONSENT OF QUALIFIED PERSON
I, Gerd M. Wiatzka, consent to the disclosure of the information in Grey Fox Project Prefeasibility Study SK 1300 Technical Report Summary that is dated November 9th, 2026, and consent to any extracts from, or a summary of, the technical report in the news release entitled “Pre-Feasibility Study for Grey Fox at Fox Complex” dated 08 June 2026 (the “news release”) and confirm that the information for which I am responsible is based on, and fairly and accurately reflects, in the form and context in which it appears, the information in my supporting documentation relating to: Geochemical and Water Analysis; Tailings Storage and Facilities; Site Wide Water Balance; and Water Treatment Plant Infrastructure.
| |
Dated: November 9, 2026 | /s/ Gerd M. Wiatzka, P. Eng. |
Exhibit 23.8
CONSENT OF QUALIFIED PERSON
I, Mark Hatton, consent to the disclosure of the information in Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary that is dated November 9th, 2026, and consent to any extracts from, or a summary of, the technical report in the news release entitled “Pre-Feasibility Study for Grey Fox at Fox Complex” dated 08 June 2026 (the “news release”) and confirm that the information for which I am responsible is based on, and fairly and accurately reflects, in the form and context in which it appears, the information in my supporting documentation relating to the underground mine design, related surface infrastructure and cost estimates and economic modelling.
| |
Dated: November 9, 2026 | /s/ Mark Hatton, P. Eng. |
Exhibit 23.9
CONSENT OF QUALIFIED PERSON
I, Sean Bradley Farrell, consent to the disclosure of the information in Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary that is dated November 9th 2026, and consent to any extracts from, or a summary of, the technical report in the news release entitled “Pre-Feasibility Study for Grey Fox at Fox Complex” dated 08 June 2026 (the “news release”) and confirm that the information for which I am responsible is based on, and fairly and accurately reflects, in the form and context in which it appears, the information in my supporting documentation relating to the Geology and Exploration.
| |
Dated: November 9, 2026 | /s/ Sean Bradley Farrell, P. Geo. |
Exhibit 23.10
CONSENT OF QUALIFIED PERSON
I, William Luke Willis, consent to the disclosure of the information in Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary that is dated November 9th, 2026, and consent to any extracts from, or a summary of, the technical report in the news release entitled “Pre-Feasibility Study for Grey Fox at Fox Complex” dated 08 June 2026 (the “news release”) and confirm that the information for which I am responsible is based on, and fairly and accurately reflects, in the form and context in which it appears, the information in my supporting documentation relating to the Davidson Tisdale resource estimate.
| |
Dated: November 9, 2026 | /s/ William Luke Willis, P. Geo. |
Exhibit 31.1
CERTIFICATION
Pursuant to Section 302 of the
Sarbanes-Oxley Act of 2002
I, ROBERT R. MCEWEN, certify that:
1. | I have reviewed this Quarterly Report on Form 10-Q of McEwen Inc.; |
2. | Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report; |
3. | Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report; |
4. | The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have: |
a. | Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared; |
b. | Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles; |
c. | Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and |
d. | Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and |
5. | The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions): |
a. | All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and |
b. | Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting. |
Dated: November 9, 2026 | |
| /s/ Robert R. McEwen |
| Robert R. McEwen, Chairman and Chief Executive Officer |
| |
Exhibit 31.2
CERTIFICATION
Pursuant to Section 302 of the
Sarbanes-Oxley Act of 2002
I, PERRY ING, certify that:
1. | I have reviewed this Quarterly Report on Form 10-Q of McEwen Inc.; |
2. | Based on my knowledge, this report does not contain any untrue statement of a material fact or omit to state a material fact necessary to make the statements made, in light of the circumstances under which such statements were made, not misleading with respect to the period covered by this report; |
3. | Based on my knowledge, the financial statements, and other financial information included in this report, fairly present in all material respects the financial condition, results of operations and cash flows of the registrant as of, and for, the periods presented in this report; |
4. | The registrant’s other certifying officer(s) and I are responsible for establishing and maintaining disclosure controls and procedures (as defined in Exchange Act Rules 13a-15(e) and 15d-15(e)) and internal control over financial reporting (as defined in Exchange Act Rules 13a-15(f) and 15d-15(f)) for the registrant and have: |
a. | Designed such disclosure controls and procedures, or caused such disclosure controls and procedures to be designed under our supervision, to ensure that material information relating to the registrant, including its consolidated subsidiaries, is made known to us by others within those entities, particularly during the period in which this report is being prepared; |
b. | Designed such internal control over financial reporting, or caused such internal control over financial reporting to be designed under our supervision, to provide reasonable assurance regarding the reliability of financial reporting and the preparation of financial statements for external purposes in accordance with generally accepted accounting principles; |
c. | Evaluated the effectiveness of the registrant’s disclosure controls and procedures and presented in this report our conclusions about the effectiveness of the disclosure controls and procedures, as of the end of the period covered by this report based on such evaluation; and |
d. | Disclosed in this report any change in the registrant’s internal control over financial reporting that occurred during the registrant’s most recent fiscal quarter (the registrant’s fourth fiscal quarter in the case of an annual report) that has materially affected, or is reasonably likely to materially affect, the registrant’s internal control over financial reporting; and |
5. | The registrant’s other certifying officer(s) and I have disclosed, based on our most recent evaluation of internal control over financial reporting, to the registrant’s auditors and the audit committee of the registrant’s board of directors (or persons performing the equivalent functions): |
a. | All significant deficiencies and material weaknesses in the design or operation of internal control over financial reporting which are reasonably likely to adversely affect the registrant’s ability to record, process, summarize and report financial information; and |
b. | Any fraud, whether or not material, that involves management or other employees who have a significant role in the registrant’s internal control over financial reporting. |
Dated: November 9, 2026 | |
| /s/ Perry Ing |
| Perry Ing, Interim Chief Financial Officer |
Exhibit 32
CERTIFICATION
Pursuant to Section 906 of the
Sarbanes-Oxley Act of 2002
In connection with the Quarterly Report on Form 10-Q of McEwen Inc., a Colorado corporation (the “Company”) for the quarter ended September 30, 2026, as filed with the Securities and Exchange Commission (the “Report”), each of the undersigned officers of the Company does hereby certify pursuant to Section 906 of the Sarbanes-Oxley Act of 2002 that to the best of our knowledge:
1. | The Report fully complies with the requirements of Section 13(a) or 15(d) of the Securities Exchange Act of 1934; and |
2. | The information contained in the Report fairly presents, in all material respects, the financial condition and results of operations of the Company. |
Dated: November 9, 2026 | |
| /s/ Robert R. McEwen |
| Robert R. McEwen, Chairman and Chief |
| Executive Officer |
| |
| /s/ Perry Ing |
| Perry Ing, Interim Chief Financial Officer |
| |
Exhibit 95
Mine Safety Disclosure
The following disclosures are provided pursuant to the Dodd-Frank Wall Street Reform and Consumer Protection Act (the “Act”) and Item 104 of Regulation S-K, which require certain disclosures by companies required to file periodic reports under the Securities Exchange Act of 1934, as amended, that operate mines regulated under the Federal Mine Safety and Health Act of 1977 (the “Mine Act”). The disclosures reflect our U.S. mining operations at the Gold Bar mine only, as the requirements of the Act and Item 104 of Regulation S-K do not apply to our mines operated outside the United States.
Whenever the Federal Mine Safety and Health Administration (“MSHA”) believes a violation of the Mine Act, any health or safety standard or any regulation has occurred, it may issue a citation which describes the alleged violation and fixes a time within which the mining operator must abate the alleged violation. The citation may include a civil penalty or fine.
The table below reflects citations and orders issued to our subsidiary, McEwen Mining Nevada Inc., which may be considered an operator under the Mine Act, by MSHA during the quarter ended September 30, 2026. The proposed assessments for the quarter ended September 30, 2026, were taken from the MSHA data retrieval system.
|
| |
|
| |
| Mine or Operation (1) | |
| Gold Bar Mine | |
| MSHA ID #26-02818 | |
Total # of "Significant and Substantial" Violations Under §104(a) |
| 0 |
Total # of Orders Issued Under §104(b) |
| 0 |
Total # of Citations and Orders Issued Under §104(d) |
| 0 |
Total # of Flagrant Violations Under §110(b) |
| 0 |
Total # of Imminent Danger Orders Under §107(a) |
| 0 |
Total Amount of Proposed Assessments from MSHA under the Mine Act | $ | 0 |
Total # of Mining-Related Fatalities |
| 0 |
Received Notice of Pattern of Violations under Section 104(e) |
| No |
Received Notice of Potential to have Patterns under Section 104(e) |
| No |
Pending Legal Actions |
| 0 |
Legal Actions Instituted |
| 0 |
Legal Actions Resolved |
| 0 |
_______________________________
Additional information about the Act and MSHA references used in the table are as follows:
| ◾ | Section 104(a) S&S Citations: Citations received from MSHA under section 104(a) of the Mine Act for violations of mandatory health or safety standards that could significantly and substantially contribute to the cause and effect of a mine safety or health hazard. |
| ◾ | Section 104(b) Orders: Orders issued by MSHA under section 104(b) of the Mine Act, which represents a failure to abate a citation under section 104(a) within the period of time prescribed by MSHA. This results in an order of immediate withdrawal from the area of the mine affected by the condition until MSHA determines that the violation has been abated. |
| ◾ | Section 104(d) S&S Citations and Orders: Citations and orders issued by MSHA under section 104(d) of the Mine Act for unwarrantable failure to comply with mandatory, significant and substantial health or safety standards. |
| ◾ | Section 110(b)(2) Violations: Flagrant violations issued by MSHA under section 110(b)(2) of the Mine Act. |
| ◾ | Section 107(a) Orders: Orders issued by MSHA under section 107(a) of the Mine Act for situations in which MSHA determined an “imminent danger” (as defined by MSHA) existed. |
Exhibit 99

Prepared By: | Prepared By: |
| |
McEwen Inc. | Mr. Michael Baumann SME-RM, CPG Senior Resource Modeler, McEwen Mining Nevada. |
| |
| Mr. Barry Carlson, P.E., P.Eng., SME-RM, Senior Metallurgical Engineer, SLR International Corp. |
Report Date: | |
| Mr. Gary Edmondo CPG,. Senior Exploration Geologist, McEwen Mining Nevada. |
November 9, 2026 | |
| Mr. Robert Kastelic, MSc, CPG, Exploration Manager, McEwen Mining Nevada. |
Dates and Signatures
Report Title: | | S-K 1300 Initial Assessment Technical Report Summary for the Lookout Mountain and Windfall Deposits, Eureka, Nevada. |
| | |
Property: | | Eureka Property |
| | |
Location: | | Eureka, Nevada, USA |
| | |
Date of Report: | | November 9, 2026 |
| | |
Qualified Persons: | | |
“Signed and sealed” | | 9 November 2026 |
Michael C Baumann, SME-RM, CPG, | | |
McEwen Mining Nevada | | |
| | |
“Signed and sealed” | | 9 November 2026 |
Barry Carlson, P.E., P.Eng., SME-RM | | |
SLR International Corp. | | |
| | |
| | |
“Signed and sealed” | | 9 November 2026 |
Gary Edmondo, CPG | | |
McEwen Mining Nevada | | |
| | |
| | |
“Signed and sealed” | | 9 November 2026 |
Robert Kastelic MSc, CPG | | |
McEwen Mining Nevada | | |
See Table 2-1 for each Qualified Person’s area of responsibility within this TRS.
McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
TABLE OF CONTENTS
TABLE OF CONTENTS | I | |||
1. | EXECUTIVE SUMMARY | 1 | ||
| 1.1. | Location and Ownership | 1 | |
| 1.2. | Exploration and Mining History | 3 | |
| 1.3. | Geology and Mineralization | 4 | |
| 1.4. | Drilling and Sampling | 7 | |
| 1.5. | Metallurgy | 9 | |
| 1.6. | Mineral Resource Estimates | 10 | |
| 1.7. | Conclusions and Recommendations | 11 | |
2. | INTRODUCTION | 14 | ||
| 2.1. | Project Scope and Terms of Reference | 14 | |
| 2.2. | Qualified Persons, Site Visits and Scope of Personal Inspection | 14 | |
| 2.3. | Effective Dates | 15 | |
| 2.4. | Definitions and frequently used acronyms and abbreviations | 15 | |
| 2.5. | Sources of information | 17 | |
3. | PROPERTY DESCRIPTION AND LOCATION | 18 | ||
| 3.1. | Property Location | 18 | |
| 3.2. | Land Area | 21 | |
| 3.3. | Agreements and Encumbrances | 23 | |
| | 3.3.1. | Agreement between Staccato and Rocky Canyon Mining Company | 24 |
| | 3.3.2. | Acquisition of Timberline Resources Corp by McEwen | 24 |
| | 3.3.3. | Royalties on the Lookout Mountain Claim Group | 24 |
| | 3.3.4. | Agreements on the Windfall Claims | 25 |
| | 3.3.5. | Royalties on the Windfall Project | 25 |
| 3.4. | Environmental Permits and Licenses | 25 | |
| 3.5. | Environmental Liabilities | 26 | |
| 3.6. | Environmental Studies | 27 | |
| | 3.6.1. | Baseline Biological Resources | 27 |
| | 3.6.2. | Archaeological Surveys | 27 |
| | 3.6.3. | Baseline Hydrology | 28 |
| | 3.6.4. | Waste Rock Geochemical Characterization | 31 |
4. | ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY | 32 | ||
| 4.1. | Access to Property | 32 | |
| 4.2. | Climate | 34 | |
| 4.3. | Physiography | 34 | |
| 4.4. | Local Resources and Infrastructure | 34 | |
| 4.5. | Facilities Design | 34 | |
i
McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
5. | HISTORY | 36 | ||
| 5.1. | Exploration History | 36 | |
| | 5.1.1. | Windfall Exploration Programs | 37 |
| | 5.1.2. | Lookout Mountain Exploration Programs | 38 |
| 5.2. | Past Production | 45 | |
6. | GEOLOGIC SETTING AND MINERALIZATION | 46 | ||
| 6.1. | Geologic Setting | 46 | |
| | 6.1.1. | Regional Geology | 46 |
| | 6.1.2. | Local Geology | 47 |
| | 6.1.3. | Project Geology | 49 |
| 6.2. | Alteration and Mineralization | 58 | |
| | 6.2.1. | Lookout Mountain | 58 |
| | 6.2.2. | Windfall | 59 |
| | 6.2.3. | Gold Resource Areas | 61 |
| | 6.2.4. | Other Gold Occurrences in the Eureka Property | 64 |
| 6.3. | Deposit Type | 72 | |
| 6.4. | Gold Deposit Paragenesis | 72 | |
7. | EXPLORATION AND DRILLING | 74 | ||
| 7.1. | Introduction | 74 | |
| 7.2. | Geologic Mapping | 74 | |
| 7.3. | Geophysical Exploration | 74 | |
| 7.4. | Geochemical Exploration | 74 | |
| 7.5. | Drilling | 77 | |
| | 7.5.1. | Historical drilling at Lookout Mountain | 80 |
| | 7.5.2. | Historical Drilling at Windfall | 81 |
| 7.6. | Newmont Mining Corp. | 82 | |
| 7.7. | Windfall Ventures/Idaho Mining | 82 | |
| 7.8. | Amselco Exploration Inc. | 83 | |
| 7.9. | Norse Windfall Mines | 84 | |
| 7.10. | EFL | 84 | |
| 7.11. | Barrick | 84 | |
| 7.12. | Echo Bay | 84 | |
| 7.13. | Staccato | 85 | |
| 7.14. | Timberline | 86 | |
| | 7.14.1. | Drilling from 2010 to 2011 | 86 |
| | 7.14.2. | Drilling from 2012 | 87 |
| | 7.14.3. | Drilling from 2014 to 2015 | 87 |
| | 7.14.4. | Drilling from 2020 to 2022 | 87 |
| | 7.14.5. | RC and Core Processing | 88 |
| 7.15. | McEwen Nevada. | 89 | |
| | 7.15.1. | 2024 Drilling | 89 |
ii
McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
| | 7.15.2. | 2025 Drilling | 89 |
| 7.16. | Collar Surveys, Down-Hole Surveys, and Project Coordinates | 91 | |
| 7.17. | Rotary and Reverse-Circulation Drillhole Sample Quality | 94 | |
8. | SAMPLE PREPARATION | 100 | ||
| 8.1. | Amselco | 101 | |
| 8.2. | Norse Windfall Mines and Windfall Ventures | 103 | |
| 8.3. | EFL | 108 | |
| 8.4. | Barrick | 108 | |
| 8.5. | Echo Bay | 109 | |
| 8.6. | Pathfinder Exploration | 109 | |
| 8.7. | Cambior USA Inc | 109 | |
| 8.8. | Staccato | 109 | |
| 8.9. | Timberline | 110 | |
| 8.10. | McEwen Nevada | 112 | |
| 8.11. | Laboratory Accreditation | 112 | |
| 8.12. | Quality Assurance / Quality Control | 113 | |
9. | DATA VERIFICATION | 114 | ||
| 9.1. | Metallurgical Data | 114 | |
| 9.2. | Drillhole Database | 114 | |
| 9.3. | Quality Assurance/Quality Control Data | 115 | |
| | 9.3.1. | McEwen Nevada 2024-2025 Program | 116 |
| 9.4. | Site and Field Office Inspections | 123 | |
| 9.5. | Additional Data Verification | 124 | |
10. | MINERAL PROCESSING AND METALLURGICAL TESTING | 125 | ||
| 10.1. | Introduction | 127 | |
| 10.2. | Metallurgical Laboratories | 128 | |
| 10.3. | Metallurgical Testing by Historical Operators | 130 | |
| 10.4. | Metallurgical Testing By Timberline | 134 | |
| | 10.4.1. | 2010 Bulk Samples | 135 |
| | 10.4.2. | 2010 Core Samples | 140 |
| | 10.4.3. | 2012 Core Samples | 143 |
| 10.5. | Preliminary HPGR Crushing Test | 146 | |
| 10.6. | Historical Mine Recovery | 148 | |
| 10.7. | Discussion of Metallurgical Results | 148 | |
11. | MINERAL RESOURCE ESTIMATES | 150 | ||
| 11.1. | Introduction | 150 | |
| 11.2. | Lookout Mountain Resource Modeling | 152 | |
| | 11.2.1. | Mineral resource database | 152 |
| | 11.2.2. | Geological modelling | 153 |
| | 11.2.3. | Mineralization | 153 |
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McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
| | 11.2.4. | Oxide and non-oxide modeling | 154 |
| | 11.2.5. | Composites and grade populations | 154 |
| | 11.2.6. | Domaining | 155 |
| | 11.2.7. | Density Modeling | 156 |
| | 11.2.8. | Capping | 157 |
| | 11.2.9. | Variography | 157 |
| | 11.2.10. | Block Model Parameters, Coding and Estimation | 158 |
| | 11.2.11. | Model Validation | 159 |
| | 11.2.12. | Classification | 162 |
| | 11.2.13. | Reasonable Prospects for Eventual Economic Extraction | 162 |
| | 11.2.14. | Mineral Resource Statement | 163 |
| | 11.2.15. | Factors that could affect Mineral Resource Estimate | 164 |
| 11.3. | Windfall Resource Modeling | 165 | |
| | 11.3.1. | Mineral resource database | 165 |
| | 11.3.2. | Geological modelling | 167 |
| | 11.3.3. | Mineralization | 169 |
| | 11.3.4. | Oxide Modeling | 170 |
| | 11.3.5. | Composites | 170 |
| | 11.3.6. | Domaining | 170 |
| | 11.3.7. | Density | 174 |
| | 11.3.8. | Capping | 174 |
| | 11.3.9. | Variography | 174 |
| | 11.3.10. | Block Model Parameters, Coding and Estimation | 177 |
| | 11.3.11. | Model Validation | 179 |
| | 11.3.12. | Classification | 182 |
| | 11.3.13. | Reasonable Prospects for Eventual Economic Extraction | 184 |
| | 11.3.14. | Mineral Resource Statement | 186 |
| | 11.3.15. | Factors that could affect Mineral Resource Estimate | 187 |
12. | MINERAL RESERVE ESTIMATES | 189 | ||
20. | ADJACENT PROPERTIES | 190 | ||
21. | OTHER RELEVANT DATA AND INFORMATION | 192 | ||
22. | INTERPRETATION AND CONCLUSIONS | 193 | ||
| 22.1. | Lookout Mountain | 193 | |
| 22.2. | Windfall | 194 | |
23. | RECOMMENDATIONS | 196 | ||
| 23.1. | Lookout Mountain | 196 | |
| 23.2. | Windfall | 197 | |
24. | REFERENCES | 199 | ||
25. | RELIANCE ON INFORMATION PROVIDED BY THE REGISTRANT | 204 | ||
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McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
Figure 1-1 | Location of the Lookout Mountain and Windfall Projects | 2 |
Figure 3-1 | Location of the Lookout Mountain and Windfall Projects | 19 |
Figure 3-2 | Eureka Property Map | 20 |
Figure 3-3 | Lookout Mountain Plan of Operations (“PoO”) Showing current Resource Outline | 22 |
Figure 3-4 | Windfall Trend Showing Resource outline | 23 |
Figure 3-5 | Lookout Mountain Spring and Groundwater Monitoring Well Location Map | 30 |
Figure 4-1 | Location and access | 33 |
Figure 5-1 | Ground RTP Magnetics map showing IP and CSAMT Lines at Lookout Mountain and Windfall | 44 |
Figure 6-1 | District Geology with Jackson-Lawton Fault system and the Ratto Ridge – Dugout fault system | 50 |
Figure 6-2 | Stratigraphic Column of the Eureka District | 51 |
Figure 6-3 | Geologic Map of the Eureka Property | 52 |
Figure 6-4 | Section through the Lookout Mountain Pit | 54 |
Figure 6-5 | Geologic Map of Lookout Mountain | 55 |
Figure 6-6 | Geologic Map of the Windfall Trend | 56 |
Figure 6-7 | Section Through the Lookout Mountain Pit | 63 |
Figure 6-8 | Exploration Targets | 68 |
Figure 6-9 | West-East Cross Section Paroni | 69 |
Figure 6-10 | West-East Cross Section South Windfall Area | 70 |
Figure 6-11 | West-East Cross Section Rustler Pit | 71 |
Figure 7-1 | Gold in Surface Rock Samples in Lookout Mountain Project Area | 76 |
Figure 7-2 | Location Map of All Lookout Mountain Drill Holes | 79 |
Figure 7-3 | Location Map of All Windfall Drill Holes | 80 |
Figure 7-4 | Amselco Rotary – Rotary Twin-Hole Comparison | 96 |
Figure 7-5 | Amselco Core – Rotary Twin-Hole Comparison | 97 |
Figure 7-6 | Amselco Core – RC Twin-Hole Comparison | 97 |
Figure 7-7 | Staccato Core – Amselco RC Twin-Hole Comparison | 98 |
Figure 7-8 | Staccato Core – Barrick RC Twin-Hole Comparison | 98 |
Figure 8-1 | Amselco RC – RC Twin-Hole Comparison | 102 |
Figure 8-2 | Norse Windfall RC (LM-15) – Amselco RC (RTR-56) Twin-Hole Comparison | 104 |
Figure 8-3 | Norse Windfall RC (LM-5) – Amselco Core Twin-Hole (RTC-201) Comparison | 104 |
Figure 8-4 | Q-Q Plots of Fire assay vs Cyanide assay results for Windfall Venture R-series holes | 106 |
Figure 8-5 | Q-Q Plots of Fire assay vs Cyanide assay results for Windfall Venture W-series holes | 107 |
Figure 8-6 | Hole and assay depth showing cyanide vs fire assay pairs for Windfall Venture R series drill holes | 108 |
Figure 9-1 | Fire Assay Normalized CRM Control Chart | 117 |
Figure 9-2 | Photon Assay Normalized CRM Control Chart | 118 |
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McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
Figure 9-3 | Blanks | 119 |
Figure 9-4 | Fire Assay Log QQ Plot – Original vs Duplicate | 120 |
Figure 9-5 | Photon Assay Log QQ Plot – Original vs Duplicate | 121 |
Figure 9-6 | Fire Assay Log QQ Plot – Original vs Check | 122 |
Figure 9-7 | Photon Assay Log QQ Plot – Original vs Check | 123 |
Figure 10-1 | Lookout Mountain Metallurgical Testing Sample Areas and Composite Column Test Locations | 129 |
Figure 10-2 | Historical Lookout Mountain Pit Area Metallurgical Drillhole and Bulk Sample Locations | 130 |
Figure 10-3 | Timberline 2010 KCA Cumulative Gold Extraction Curves for Bulk-Sample Column Tests, LMB-1-4 | 140 |
Figure 10-4 | KCA Column Test Gold Recoveries | 141 |
Figure 10-5 | McClelland Re-Analyses vs. Original KCA Bottle-Roll Results | 146 |
Figure 11-1 | Geologic model with mineralization and block model | 153 |
Figure 11-2 | Log Probability plot of the Lookout Mountain total data set 10 ft composites | 154 |
Figure 11-3 | Lookout Mountain Cross Section 14314100 Showing Gold Mineral Domain LM_005 | 156 |
Figure 11-4 | Variogram of Lookout Mountain Domain LM_005 Composites | 158 |
Figure 11-5 | Swath plot of the low-grade domain through the resource model | 161 |
Figure 11-6 | Resource model visual check compared to drill intercepts section 14312600N | 161 |
Figure 11-7 | All drill holes in the Windfall project are shown (plan view) | 167 |
Figure 11-8 | Geologic Map of the Windfall project | 168 |
Figure 11-9 | 3D Geological model of the Windfall deposit | 169 |
Figure 11-10 | Cross section showing the geology and mineral zone | 170 |
Figure 11-11 | Plan Map of Geological interpretation of Windfall North and South domains | 171 |
Figure 11-12 | Log Probability plot of the Windfall total data set 10 ft composites | 171 |
Figure 11-13 | Log Histogram of gold grades in the low-grade south domain (LG_South) | 172 |
Figure 11-14 | Log Histogram of gold grades in the high-grade south domain (HG_South) | 172 |
Figure 11-15 | Log Histogram of gold grades in the low-grade north domain (LG_North) | 173 |
Figure 11-16 | Log Histogram of gold grades in the high-grade north domain (HG_North) | 173 |
Figure 11-17 | Search ellipse for Domain LG_South | 175 |
Figure 11-18 | Search ellipse for Domain HG_South | 176 |
Figure 11-19 | Search ellipse for Domain LG_North | 176 |
Figure 11-20 | Search ellipse for Domain HG_North | 177 |
Figure 11-21 | N-S Long section looking East showing the Interpolated block model with gold grades in opt | 178 |
Figure 11-22 | E-W Cross-section 14330250N looking north with Resource pit outline in black | 180 |
Figure 11-23 | E-W section 14330200N looking north with resource model and exploration drill holes | 181 |
Figure 11-24 | Swath plot (Northings) for South domain | 182 |
Figure 11-25 | Windfall block model long section showing indicated mineral blocks and grade in opt | 183 |
Figure 11-26 | Windfall block model long section showing inferred blocks and grade in opt | 184 |
Figure 11-27 | Oblique plan view of the Windfall pit shell with block model | 185 |
Figure 20-1 | McEwen’s Eureka Project, Greater Eureka Property, and Adjacent Gold and CRD Occurrences | 191 |
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McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
Table 2-1 | Details of QPs and Site Visits | 15 |
Table 6-1 | Significant Drillhole Intercepts in the Water Well Zone (2014 - 2021) | 66 |
Table 7-1 | Lookout Mountain and Windfall Project Drillhole Summary | 77 |
Table 8-1 | Compilation of Analytical Laboratories and Assay Methods | 100 |
Table 9-1 | Fire Assay Normalized CRM Control Chart Table | 117 |
Table 9-2 | Photon Assay Normalized CRM Control Chart Table | 118 |
Table 9-3 | Blanks | 120 |
Table 10-1 | Summary of Lookout Mountain Metallurgical Testing | 126 |
Table 10-2 | Amselco 1985 Hazen Bottle-Roll Test Results on RC Cutting Composites | 131 |
Table 10-3 | Amselco 1986 Hazen Preliminary Column-Leach Results on RTC-201 Core Composites | 132 |
Table 10-4 | Tenneco 1986 Heinen-Lindstrom Bottle-Roll Results on RC Drill-Cutting Composites | 132 |
Table 10-5 | Norse Windfall 1987 KCA Column-Leach Results on Historical Pit Bulk Sample Material | 133 |
Table 10-6 | Alta Gold 1997 McClelland Bottle-Roll Results on Historical Pit Bulk Samples | 134 |
Table 10-7 | Timberline 2010 Historical Pit Bulk Sample Descriptions | 135 |
Table 10-8 | Timberline 2010 KCA Fine Bottle-Roll Results on Bulk Samples, P80 200 Mesh | 136 |
Table 10-9 | Timberline 2010 KCA Coarse Bottle-Roll Results on Bulk Samples, P80 10 Mesh | 137 |
Table 10-10 | Timberline 2010 KCA Column-Leach Results on Historical Pit Bulk Samples | 138 |
Table 10-11 | Timberline 2010 KCA Summary of Bulk-Sample Bottle-Roll and Column-Leach Results | 139 |
Table 10-12 | Timberline 2010 KCA Bottle-Roll Results on Sulfide Core Intervals BHSE-029C-094 and 029C-108 | 142 |
Table 10-13 | Timberline 2010 KCA Composite Bottle-Roll Results on Core-Composited Oxide Material | 142 |
Table 10-14 | Timberline 2010 KCA Column-Leach Results on Core Composites 47030, 47032, and 47034 | 143 |
Table 10-15 | Timberline 2012–2014 Comparison of Jasperoid Bottle-Roll Results from KCA and McClelland | 145 |
Table 10-16 | Comparison of Bottle-Roll Test Gold Recovery in Jasperoid by HPGR Crush Product, Area, and Conventional Crush Where Available | 147 |
Table 10-17 | Summary Results for Bottle-Roll Test Gold Recovery in Jasperoid by HPGR Crush vs. Conv. Crush | 148 |
Table 11-1 | Drill hole data compilation | 152 |
Table 11-2 | Drill hole Footage by Company | 152 |
Table 11-3 | Descriptive Statistics of Lookout Mountain Coded Gold Assays and top cut | 157 |
Table 11-4 | Summary of Lookout Mountain Estimation Parameters | 159 |
Table 11-5 | Global Bias check of Mineral Resource | 160 |
Table 11-6 | Lookout Mountain Classification Parameters | 162 |
Table 11-7 | Pit Optimization Parameters | 163 |
Table 11-8 | Lookout Mountain Project Gold Resources | 163 |
Table 11-9 | Sensitivity table for Mineral Inventory at Lookout Mountain | 164 |
Table 11-10 | Drill hole data compilation | 166 |
Table 11-11 | Drill Footage by Company | 166 |
Table 11-12 | Global database for Windfall | 166 |
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McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
Table 11-13 | Descriptive Statistics of Windfall Domain Coded Gold Composites and Capping levels | 174 |
Table 11-14 | Block model parameters | 178 |
Table 11-15 | Global Bias check on interpolation methods | 182 |
Table 11-16 | Pit Optimization Parameters | 185 |
Table 11-17 | Windfall Mineral Resource Estimate | 186 |
Table 11-18 | Sensitivity table for Mineral Inventory at Windfall | 187 |
Table 23-1 | Recommended Phase II Lookout Mountain Work Program | 197 |
Table 23-2 | Recommended Phase II Windfall Work Program | 198 |
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McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
1. EXECUTIVE SUMMARY
The Lookout Mountain and Windfall projects represent advanced exploration-stage gold assets located in a proven mining district with excellent regional infrastructure and access. Historical exploration and production demonstrate the presence of significant gold mineralization in both oxide and sulfide systems. Existing infrastructure corridors, favorable climate, and established local support provide a strong foundation for continued exploration and potential future development, subject to further technical, economic, and permitting studies.
This Technical Report Summary (TRS or Report) provides supporting technical information for the mineral resource estimations of the Lookout Mountain and Windfall deposits. The Report has been prepared in accordance with the disclosure requirements of the United States Securities and Exchange Commission (SEC) under Sub-part 229.1300 of Regulation S-K.
The date of this report is November 9, 2026.
1.1.Location and Ownership
The Eureka Property, located in the Eureka Mining District of north-central Nevada, comprises approximately 20,500 acres (32 square miles) along the southeastern end of the Battle Mountain– Eureka (Cortez) mineralized trend (Figure 1-1). The property includes multiple claim blocks, of which the Lookout Mountain (Rocky Canyon) and Windfall-Hoosac projects are the focus of this report.
Lookout Mountain is situated approximately 8 miles south of Eureka, Nevada, while Windfall lies approximately 3.3 miles to the northeast along the eastern flank of Prospect Mountain. Both projects are accessible via established infrastructure within a historically active mining district.
Land Tenure and Ownership
McEwen Inc. (“McEwen”) acquired the Eureka Property through its 2024 acquisition of Timberline Resources Corp. (“Timberline”), consolidating ownership of the project area.
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McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
Figure 1-1 Location of the Lookout Mountain and Windfall Projects
(McEwen, 2026 modified from Gustin, 2023)

The Property consists of a combination of unpatented claims administered under United States Bureau of Land Management and the State of Nevada and patented mining claims.
· | Lookout Mountain comprises 378 unpatented lode mining claims totaling approximately 6,520 acres, of which McEwen controls 373 through lease agreements, and owns five fractional claims. |
· | Windfall consists of 179 unpatented claims (~3,700 acres) and 13 patented claims that host the current mineral resource and are wholly owned by McEwen. |
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McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
Unpatented claims confer the right to explore and mine subject to the U.S. Mining Law of 1872 and Bureau of Land Management (BLM) regulations, with annual maintenance fees required to maintain ownership.
Permitting and Regulatory Status
Exploration activities at Lookout Mountain are conducted under an approved BLM Plan of Operations (“PoO”), originally authorized in 2010, which allows for controlled surface disturbance and exploration activities including drilling, trenching, and groundwater monitoring.
At Windfall, exploration is conducted under Nevada state permits on patented lands, supplemented by BLM notice-level permits approved in 2026 for adjacent federal lands.
Extractive mining is not currently permitted on the property; future development would require expanded environmental baseline studies and new permits.
Environmental Liabilities and Baseline Studies
Historic mining at Lookout Mountain resulted in legacy disturbance, including an open pit and waste dumps. Current operators are not liable for reclamation of these disturbances provided they are not reactivated.
Extensive environmental baseline work has been completed and is ongoing to support future permitting, including:
· | Biological, cultural, and hydrological studies |
· | Groundwater monitoring and characterization |
· | Waste rock geochemical testing |
· | Geotechnical and engineering assessments |
Additional work, including expanded monitoring networks and geochemical testing, will be required to support any future mine development and regulatory approvals.
1.2.Exploration and Mining History
History
The Eureka mining district has a long history of mineral production dating back to the 1860s, with significant output of gold, silver, lead, and zinc. Total gold production from the district is estimated at approximately 1.65 million ounces.
The Windfall area was initially developed as an underground gold mine in the early 1900s, followed by extensive exploration and open-pit mining from the 1970s through the 1980s. Reported production from open pits totals up to approximately 2.8 million tons of ore at average grades near 0.04 oz/ton gold.
Lookout Mountain was discovered in the late 1970s through systematic exploration and began production in 1987–1988, during which approximately 180,000 tons of ore averaging 0.12 oz/ton gold were mined and processed at Windfall, yielding approximately 17,700 ounces of gold.
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McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
Subsequent exploration by multiple operators, including major mining companies, has identified widespread disseminated gold mineralization associated with Carlin-type systems, with both oxide and sulfide potential recognized at depth. Exploration activity has continued intermittently into modern times, culminating in acquisition by McEwen in 2024 with renewed drilling and evaluation programs undertaken by McEwen Mining Nevada (“McEwen Nevada”).
Exploration
Exploration activities in 2024-2025 focused on resource expansion, confirmation drilling, and target generation at both Windfall and Lookout Mountain. A total of approximately 47,953 feet were drilled at Windfall across 86 core and RC drill holes, while 20,770.9 feet were completed at Lookout Mountain. Drilling programs included infill, step-out, and metallurgical holes designed to refine structural controls and extend higher-grade mineralization, particularly south of the existing Lookout Mountain pit.
Complementary exploration programs included geologic mapping, geophysics, and geochemical analysis. Mapping extended known mineralized trends and supported target development in adjacent areas such as Rocky Canyon and Oswego. Geophysical datasets are being integrated into 3D models to delineate structures, alteration zones, and subsurface controls on mineralization. Geochemical datasets comprising thousands of surface rock samples and updated four-acid digestion analyses with mercury are being used to refine Carlin-style signatures and identify new exploration targets across the district.
1.3.Geology and Mineralization
Deposit Type
The Eureka Property hosts Carlin-type, sediment-hosted gold mineralization, characterized by disseminated gold primarily within carbonaceous silty limestones and calcareous sedimentary rocks. Mineralization is associated with classic Carlin pathfinder geochemistry, and is accompanied by pyrite and arsenian pyrite with subordinate realgar and orpiment. Alteration assemblages are dominated by decalcification, argillization, and silicification, reflecting hydrothermal fluid interaction with carbonate host rocks. Structural controls are significant, with mineralization localized along northwest-, northeast-, and north-trending fault and fracture systems within favorable Cambrian to Devonian stratigraphy.
Geologic Setting and Mineralization
The Lookout Mountain and Windfall projects are located within the Eureka Mining District of central Nevada, at the southern end of the Battle Mountain–Eureka (Cortez) trend, a prolific metallogenic belt hosting numerous world-class sediment-hosted gold deposits and carbonate replacement deposits. Mineralization formed through a multi-stage hydrothermal process consistent with Carlin-type systems.
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McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
Geologic Setting
The district is underlain by a thick sequence of Cambrian to Devonian carbonate and siliciclastic rocks deposited on a passive continental margin, subsequently overlain by Mississippian to Permian overlap sequences and Cretaceous non-marine clastic rocks.
Regional deformation is dominated by compressional tectonics associated with the Antler and Sevier orogenies, producing thrust faulting, folding, and structural stacking of lower Paleozoic units. These features were later overprinted by Cretaceous intrusion-related hydrothermal activity and Tertiary extensional tectonics, which generated high-angle normal faults and facilitated mineralizing fluid flow.
Intrusive activity is spatially and temporally associated with both carbonate replacement (CRD) and Carlin-type gold systems within the district.
Structural Controls
The Eureka District exhibits complex structural architecture characterized by:
· | Multiple thrust sheets placing older rocks over younger strata |
· | North-striking folds and major fault systems |
· | Overprinting by extensional normal faults and cross structures |
At Lookout Mountain, mineralization is strongly controlled by the north-trending Ratto Ridge fault system and associated cross faults, forming an extensive structural corridor exceeding 3.5 miles in strike length.
At Windfall, mineralization is localized within the Windfall Fault Zone, comprising two parallel north-striking structures with significant cross-faulting, interpreted as a potential southern continuation of the Jackson fault system.
These fault networks create favorable structural traps, particularly at intersections with stratigraphic contacts.
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McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
Host Stratigraphy and Deposit Controls
Gold mineralization in both project areas is primarily hosted within favorable stratigraphic horizons, notably:
· | Hamburg Dolomite (primary host) |
· | Dunderberg Shale (particularly at the contact zone) |
· | Secondary hosts include Pogonip Group, Bartine Limestone, and other carbonate units |
The most significant mineralization occurs at or near the Hamburg Dolomite–Dunderberg Shale contact, where dissolution, karst development, and collapse brecciation have enhanced permeability and fluid flow.
At Lookout Mountain, extensive collapse and solution breccias (“Lookout Mountain breccia”) form the principal host to mineralization, often localized beneath structural panels and along ramp-related fault zones.
At Windfall, mineralization is more tightly structurally controlled within decalcified and brecciated
Hamburg Dolomite along steeply dipping fault zones, with less development of large jasperoid bodies than at Lookout Mountain.
Mineralization Characteristics
Gold mineralization at both Lookout Mountain and Windfall is characteristic of Carlin-type systems, with gold occurring as submicron particles in arsenian pyrite and its oxidation products.
Key features include:
· | Strong association with arsenic, antimony, mercury, and thallium |
· | High-grade zones typically hosted in sulfidic collapse breccia or structurally controlled zones |
· | Lower-grade mineralization broadly distributed in oxidized and decalcified rocks |
At Windfall, mineralization locally exhibits elevated Pb-Zn-Ag values, indicating potential overprinting of Carlin-type gold mineralization on earlier carbonate replacement (CRD) systems.
Exploration Implications
The integration of favorable stratigraphy, extensive structural preparation, and hydrothermal alteration has created multiple mineralization styles and targets across the property. Key exploration controls include:
· | Structural corridors defined by north-trending faults and cross structures |
· | Stratigraphic contacts, especially the Hamburg Dolomite–Dunderberg Shale interface |
· | Collapse breccia zones and karst-enhanced porosity |
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McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
| ● | Potential for stacked mineralized horizons and deeper feeder systems |
Additional exploration upside exists in underexplored stratigraphic units, deeper extensions of known systems (e.g., Water Well Zone), and areas where Carlin-type mineralization may have overprinted CRD mineralization.
1.4.Drilling and Sampling
Drilling at the Lookout Mountain and Windfall projects comprises a substantial historical and modern database that supports mineral resource estimation. As of the effective date of this report, a total of 2,526 drill holes totaling approximately 898,800 feet have been completed across both properties.
Drilling has been conducted by multiple operators since the 1960s, resulting in a diverse dataset consisting of conventional rotary, reverse circulation (RC), and diamond core drilling.
The drilling database for Lookout Mountain and Windfall is extensive, multi-phase, and compiled from numerous operators over several decades. While early drilling methods present inherent limitations, these have been mitigated through validation, selective exclusion of suspect data, and the incorporation of higher-quality modern drilling.
Drill Methods and Data Quality
Historical drilling was dominated by vertical conventional rotary and RC drilling, particularly at Windfall, reflecting equipment availability and industry practices at the time. Later programs employed angled RC and core drilling, improving the ability to accurately intersect mineralized structures and better define their geometry.
At Lookout Mountain, drilling orientations include both vertical and angled holes, generally intersecting mineralized zones at appropriate angles for resource modeling. Sampling intervals are typically 5 feet, with some historical 10-foot intervals, which are considered appropriate relative to the thickness of mineralized zones.
Sampling and analytical procedures evolved over time, with modern programs implementing industry-standard QA/QC protocols, including systematic sample logging, splitting, and insertion of blanks and standards.
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McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
Drilling Programs (Modern Era)
Recent drilling by Timberline (2010–2022) and McEwen (2024–2025) has focused on resource definition, expansion, metallurgical testing, and hydrogeologic characterization. These programs include a combination of RC, core, and hybrid holes, with improved surveying, sampling, and database management practices.
McEwen Inc. has drilled over 104,000 feet since 2024, including RC and core drilling targeting extensions of known mineralization and improving confidence in higher-grade zones.
Survey Control and Database Integrity
Drill collar locations and downhole surveys have evolved from local mine grids and conventional survey methods to modern GPS-based systems with sub-meter accuracy. Historical datasets have undergone coordinate transformation and validation to align with current coordinate systems.
Modern survey methods use high-accuracy GPS and gyroscopic downhole tools, with rigorous data verification and integration into a centralized digital database, supporting confidence in spatial accuracy.
Sampling Quality and Limitations
Potential limitations associated with historical rotary and RC drilling, including downhole contamination and sample representativity, have been identified. Evidence of such issues includes cyclic grade patterns and anomalous mineralized intervals inconsistent with geological context.
To address these concerns, suspect intervals have been identified and excluded from mineral resource modeling, minimizing bias in the estimation process. Modern drilling programs incorporate improved protocols designed to reduce contamination and enhance sample representativity.
Data Verification
The QP concludes that:
· | The project database, including historical and recent drilling, has undergone sufficient verification and correction to support mineral resource estimation. |
· | Metallurgical, geological, and analytical datasets are of acceptable quality and consistent with industry standards. |
· | QA/QC programs, particularly in recent drilling campaigns, demonstrate high levels of accuracy, precision, and reliability. |
· | No material limitations or data issues have been identified that would adversely affect the resource estimates. |
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McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
1.5.Metallurgy
Metallurgical test work demonstrates that mineralization at the Lookout Mountain Project is generally amenable to cyanide heap-leach processing, particularly for oxidized material, while unoxidized (sulfide) material exhibits refractory characteristics requiring alternative processing routes.
A comprehensive metallurgical database has been developed from testing programs completed by several independent, industry-recognized laboratories conducted between 1985 and 2015, including approximately 8,600 cyanide-soluble gold assays, ~450 bottle-roll tests (BRTs), and 21 column-leach tests (CLTs) on a combination of bulk samples, drill core, and composites.
Test results consistently show that oxidized mineralization achieves moderate to high gold recoveries, typically in the range of approximately 70% to >90% depending on lithology, crush size, and test conditions. Column-leach tests on bulk samples simulating run-of-mine heap-leach conditions yielded recoveries of approximately 74% to 79% for oxide materials, indicating favorable performance under coarse-crush conditions and supporting a heap-leach development strategy. Historical production data further corroborates this, with an estimated 81% recovery achieved from heap leaching of oxidized ore in 1987.
Metallurgical performance is strongly influenced by lithology and oxidation state. Oxide collapse breccia and claystone materials generally demonstrate good leachability with relatively low reagent consumption, while jasperoid mineralization shows more variable recoveries due to silica-related gold encapsulation. Column and bottle-roll tests indicate improved recoveries with finer crushing for jasperoid, suggesting that liberation is a key factor controlling recovery.
In contrast, unoxidized (sulfide) mineralization exhibits poor cyanide leach performance, with recoveries commonly less than 20% in bottle-roll testing and locally as low as 1–3%, reflecting refractory behavior.
Test work also demonstrates that gold extraction is generally rapid, with a significant proportion of recoverable gold leached within the first few days of testing, supporting the suitability of heap-leach kinetics. However, some materials, particularly reactive sulfide-bearing zones, show high cyanide and lime consumption, indicating the need for further optimization and variability assessment.
Overall, the metallurgical program indicates that:
· | Oxidized Lookout Mountain mineralization is amenable to heap leaching with moderate to high recoveries. |
· | Gold recovery is controlled by lithology, oxidation state, and particle size, particularly in silica-rich units. |
· | Jasperoid mineralization may require finer crushing or enhanced comminution techniques to mitigate encapsulation effects. |
· | Sulfide mineralization is refractory and may require alternative processing approaches. |
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McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
· | The Windfall metallurgical database is currently limited relative to Lookout Mountain, with available information consisting primarily of historical cyanide shake data, current ICP analytical data, and selected samples identified for future recovery test work. |
· | Additional testing will be completed to support future recovery assumptions, evaluate metallurgical variability, and confirm whether Windfall material behaves similarly to or differently from the tested Lookout Mountain material. |
1.6.Mineral Resource Estimates
Mineral Resource estimates for the Lookout Mountain and Windfall gold deposits are reported using Item 1300 of Regulation S-K. The estimates were completed under the supervision of Michael Baumann, SME-RM, CPG, who is the Qualified Person for the Mineral Resource estimates. Mineral Reserves have not been established for either deposit; Mineral Resources do not have demonstrated economic viability.
The resource estimates were based on integrated historical and recent drilling databases, updated geological and oxidation models, grade-population analysis, mineral-domain interpretation, 10-foot compositing, high-grade capping, density assignment, variography, block modeling, grade interpolation, model validation, and resource classification. Lookout Mountain incorporates 860 drill holes totaling approximately 470,193 feet of drilling, while Windfall incorporates 1,507 drill holes totaling approximately 352,866 feet and 43,236 assay samples. Block models were constructed using 20-foot by 20-foot by 20-foot parent blocks, with Windfall using sub-cells to improve resolution of the mineralized zones.
Reasonable prospects for eventual economic extraction were demonstrated by constraining the reported Mineral Resources within optimized open pit shells using current economic assumptions. Both deposits were evaluated as potentially amenable to open pit mining, with heap-leach processing of oxide material. Lookout Mountain also considers potential toll milling of unoxidized material. The selected reporting cut-off grades are 0.005 oz Au/ton for oxide material at both projects and 0.050 oz Au/ton for Lookout Mountain sulfide material. Mineral Resources are reported at an in-situ reference point.
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The optimized-pit-constrained Mineral Resource estimates are summarized below:
Deposit | Classification | Tonnes (000s) | Au Grade (g/t) | Contained Au (oz) |
Lookout Mountain | Indicated | 19,570.0 | 0.64 | 402,300 |
Inferred | 7,292.0 | 0.57 | 134,200 | |
Windfall | Indicated | 9,402.8 | 0.75 | 227,500 |
Inferred | 2,596.4 | 1.53 | 127,800 |
Mineral Resources are reported by deposit and classification category, and figures may not sum due to rounding.
Model validation included visual checks, comparison of block model and domain volumes, nearest-neighbor and alternative interpolation checks, global bias comparisons, and swath plot reviews. The validation work did not identify unexpected relationships between the selected interpolation models and check estimates, and the global bias checks were within acceptable tolerances for the resource models described in the chapter.
Key factors that could affect the Mineral Resource estimates include changes in geological interpretation, mineralization continuity, grade continuity, high-grade capping assumptions, interpolation parameters, classification criteria, density assumptions, metallurgical recoveries, metal prices, operating cost assumptions, open pit design constraints, permitting, title, site access, and social license considerations. No other environmental, permitting, legal, title, taxation, socioeconomic, marketing, political, or other relevant factors are identified by the QP in the chapter as materially affecting the Mineral Resource estimates beyond those discussed.
1.7.Conclusions and Recommendations
Phase II work programs are recommended for the Lookout Mountain and Windfall projects to advance both assets toward Initial Assessment with Economic Analysis and then to Prefeasibility level studies. The primary objectives are to increase confidence in existing mineral resource estimates, upgrade resource classifications (particularly from inferred to higher categories), and collect the technical data required to support economic evaluation.
The recommended Phase II programs for both projects are designed to systematically reduce geological, metallurgical, engineering, and permitting uncertainties. Successful completion of these programs is expected to support resource upgrades and provide the technical foundation required to eventually advance Lookout Mountain and Windfall to Prefeasibility level studies, representing the next critical milestone in project development.
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Lookout Mountain
The proposed Phase II program at Lookout Mountain focuses on resource expansion, technical de-risking, and baseline studies required for project development. Approximately 10,000 feet of infill drilling is recommended to improve resource confidence, alongside comprehensive metallurgical testing to better define processing characteristics and recovery potential.
Key program components include:
·Drilling (~45,000 feet total): infill, exploration, metallurgical, hydrologic, geotechnical, and condemnation drilling to support both resource upgrading and engineering studies.
·Metallurgical testing: expanded bottle-roll, column, and mineralogical studies to refine processing parameters.
· | Geologic modeling: updated 3D geological and alteration models to support future economic evaluations. |
· | Geotechnical and hydrologic programs: pit slope stability analysis, hydrogeochemical characterization, and water resource studies. |
· | Environmental baseline and permitting: biological, cultural, and regulatory baseline work required for a Plan of Operations. |
· | Preliminary infrastructure design: early-stage facilities-planning including site layout considerations. |
The estimated cost of the Lookout Mountain Phase II program is $6.66 million, excluding landholding, personnel, permitting, and other indirect costs.
Windfall
The Windfall Phase II program is similarly designed to upgrade resource confidence and provide the data necessary to advance to the next stage. The program includes approximately 10,000 feet of infill drilling and expanded metallurgical testing, along with updated geologic modeling.
Key components include:
·Drilling (~35,000 feet total): infill, exploration, metallurgical, hydrologic, geotechnical, and condemnation drilling.
· | Continuation of metallurgical studies: building on Phase I results to refine recovery assumptions. |
· | Geologic modeling and resource estimation: updated models to support economic analysis. |
· | Geotechnical, hydrologic, and environmental programs: similar in scope to Lookout Mountain to support engineering and permitting requirements. |
· | Economic Assessment: completion of a study based on updated technical inputs. |
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The total estimated cost for the Windfall Phase II program is $4.5 million, excluding indirect and sustaining costs.
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2. INTRODUCTION
Lookout Mountain and Windfall are two of several deposit areas included within what McEwen refers to as the Eureka property. The focus of this report is on both the Lookout Mountain and Windfall portions of the property.
The Report has been prepared by McEwen in accordance with the disclosure requirements of the United States Securities and Exchange Commission (SEC) under Sub-part 229.1300 of Regulation S-K.
2.1.Project Scope and Terms of Reference
The purpose of this report is to provide supporting technical information on the mineral resource estimates for the Lookout Mountain and Windfall deposits. The first technical reports for the project were prepared for Staccato Gold Resources Ltd. (“Staccato”) by Russell (2005, 2007) under NI43-101 standards and guidelines. Mineral resource estimates for the Lookout Mountain (including the smaller South Adit deposit immediately to the south) were first reported in three subsequent technical reports prepared by Mine Development Associates, which was later acquired by RESPEC (Gustin, 2011, 2012, and 2013). These prior resource estimates did not include the application of pit optimizations to constrain the resources. In 2023, RESPEC consultants reported (for the first time under S-K 1300) mineral resources for Lookout Mountain and South Adit constrained by pit optimizations (Gustin, 2023). All of these mineral resource estimates are now considered historical and should not be relied upon, being replaced by the current mineral resources reported herein. This is the first time that resources are reported for Windfall.
This report, including the mineral resources estimation, has been prepared under the supervision of McEwen Nevada employees. Contributing authors from McEwen Nevada are Qualified Persons (QPs) and are not considered independent of the Company. One contributing QP author (Carlson) is independent of the Company. Mineral resources reported herein for the Lookout Mountain and Windfall deposits are estimated in accordance with the standards and requirements under Sub-part 229.1300 of Regulation S-K.
McEwen acquired all the assets and property from the previous operator Timberline in 2024. Based out of project offices in the nearby town of Eureka and McEwen Nevada’s operating mine at Gold Bar approximately 30 miles (49km) to the Northwest, McEwen Nevada employees have quickly ramped up exploration activities on the property and are currently engaged in prospecting, mapping, sampling and drilling activities on the site.
2.2.Qualified Persons, Site Visits and Scope of Personal Inspection
By virtue of their education, experience, and professional qualifications, the authors of this Technical Report Summary are QPs in their respective disciplines, including resource estimation, mining, geology, and metallurgy.
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Table 2-1 lists the individual QPs responsible for preparation of this Report, their titles, areas of responsibility, and the dates of their site visits.
Table 2-1 Details of QPs and Site Visits
Qualified Person | | Title | | Report Area of Responsibility | | Site Visit |
Michael C Baumann | | Senior Resource Modeler | | Sections 1.6 and 11 | | March 16, 2026 |
Barry Carlson | | Senior Advisor Process / | | Sections 1.5, 9.1 and 10. | | N/A* |
Gary P Edmondo | | Senior Exploration Geologist | | Sections 1.1, 1.3, 1.4, 3 to 6, 7.5 to 7.17, 8 | | Actively Works On-Site |
Robert Kastelic | | Exploration Manager Nevada | | Sections 1.2, 1.7, 2, 7.1 to 7.4, 9 (except 9.1), 12, 20-25, | | Actively Works On-Site |
*Barry Carlson did not conduct a separate site visit. The QP relied upon sampling, testing and verifications performed by the Geology QPs during their inspections, which was deemed sufficient for the recovery data. A physical visit would yield no additional verifiable technical data beyond the information provided in the model.
2.3.Effective Dates
Mineral Resources in the Report have the following effective dates:
· | Mineral Resource estimate (Lookout Mountain) – March 16, 2026 |
· | Mineral Resource estimate (Windfall) – February 11, 2026 |
· | The overall Report Date is November 9, 2026. |
2.4.Definitions and frequently used acronyms and abbreviations
Due in part to a local Imperial unit coordinate grid used by early explorers of the property, and as reported in previous technical reports, measurements are generally reported in Imperial units in this report, except tabulations of the reported mineral resource estimates. Where information was originally reported in metric units, conversions may have been made according to the formulas shown below; discrepancies may result in slight variations from the original data in some cases.
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Frequently used acronyms, abbreviations, and unit conversions | |
AA | atomic absorption spectrometry |
Ag | silver |
Au | gold |
BX NX NQ | core barrel sizes |
BLM | United States Department of the Interior, Bureau of Land Management |
CaO | Calcium Oxide |
CSAMT | Controlled Source Audio-Frequency Magneto-Telluric geophysical survey |
cm | centimeter; 1 cm = 0.3937 inch |
°F | degrees Fahrenheit |
ft | foot or feet; 1 ft = 0.3048 m |
g/t | grams per tonne; 1 g Au/t = 1 ppm Au = 0.02917 oz/ton |
ha | hectare; 1 ha = 2.471 acres |
ICP | inductively coupled plasma |
in. | inch or inches |
IP | induced polarization geophysical survey |
kg | kilogram; 1 kg = 2.205 pounds |
km | kilometer; 1 km = 0.6214 mile |
l | liter; 1 l = 1.057 US quarts |
Ma | million years old |
m | meter; 1 m = 3.2808 feet |
mm | millimeter; 1 mm = 0.001 m = 0.003281 ft |
NaCN | Sodium Cyanide |
NEPA | National Environmental Policy Act |
NSR | Net Smelter Return |
opt | troy ounces per short ton |
oz | troy ounce; 12 troy oz = 1 troy pound; 1 oz Au/ton = 34.2857 g Au/T |
PoO | Plan of Operations |
ppm | parts per million |
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ppb | parts per billion |
R | range |
RC | reverse-circulation drilling method |
SEM | scanning electron microscope |
TSX | Toronto Stock Exchange |
t, tonne | metric tonne = 1.1023 short tons |
T | imperial ton |
Currency: Unless otherwise indicated, all references to dollars ($) in this report refer to currency of the United States.
2.5.Sources of information
Information for this report comes from data collected by McEwen since the acquisition of the Eureka property in 2024. Data include drill hole assays, geochemistry, geological drill logs, geologic maps, surface samples, and 3-D modeling of mineralization. Other sources of information include extensive historical data produced by predecessor companies and property owners over several decades. Documents referenced in Section 24 also contributed to the information library.
The Lookout Mountain project has been previously described in four technical reports prepared for Timberline by Mine Development Associates (subsequently acquired by RESPEC) (Gustin, 2011, 2012, 2013, 2023) and in two earlier technical reports prepared for Staccato Gold Resources Ltd. (Russell, 2005, 2007). This is the first time the Windfall project has been described in a technical report.
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3. PROPERTY DESCRIPTION AND LOCATION
3.1.Property Location
Lookout Mountain and Windfall are two of several projects located on what McEwen calls its Eureka property, which covers an area of about 20,500 acres or approximately 32 square miles. The Eureka property lies within the Eureka mining district at the southeastern end of the Battle Mountain-Eureka (Cortez) mineralized trend of gold and base-metal deposits in north-central Nevada (Figure 3-1). The Eureka property consists of nine large claim blocks: Lookout Mountain (also known as Rocky Canyon), Windfall-Hoosac, North Amselco, Hiero-Syracuse, South Ratto, Q-claims, Trail, and New York Canyon (Figure 3-2). McEwen also recently acquired Golden Lake Exploration (Press Release April 30, 2026) as a strategic acquisition since the Southern border of the Golden Lake ground borders the North end of the Windfall resource area. The Eureka property is located in the southern part of the Eureka mining district in Eureka County, Nevada, about eight miles south of the town of Eureka, the Eureka County seat. The property lies at the junction of the south end of the Diamond Mountains with the east-central portion of the Fish Creek range.
The focus of this report is on the Lookout Mountain project in the Rocky Canyon Claim block, and the Windfall Project within the Windfall-Hoosac claim block.
The Lookout Mountain project claim block covers Lookout Mountain and Ratto Ridge in the northern part of surveyed Township 17 North, Range 53 East and in much of unsurveyed Township 18 North, Range 53 East, Mount Diablo Base and Meridian. The approximate center of the project is located at 39°24’ 16” N, 115°58’ 56” W. The Lookout Mountain project is covered by the United States Geological Survey 7.5-minute Pinto Summit and Spring Valley Summit topographic quadrangle maps.
The Windfall project is situated approximately 3.3 miles (5.3 km) to the North-Northeast of Lookout Mountain along the East flank of Prospect Mountain. The resource is located entirely within 13 patented claims, known as the Windfall Patents, that are wholly owned by McEwen Inc. The patented claims are surrounded by un-patented claims largely controlled by McEwen Inc, with 9 unpatented claims at the south end controlled by a third party. Patented and un-patented claims at Windfall lie within the north-east portion of un-surveyed Township 18N, Range 53E., Mount Diablo Baseline and Meridian. The approximate center of the Windfall project is located at 39°27’ 06” N, 115°58’ 35” W. The property is covered by the United States Geological Survey 7.5-minute Pinto Summit topographic quadrangle map
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Figure 3-1 Location of the Lookout Mountain and Windfall Projects
(McEwen, 2026 modified from Gustin, 2023)

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Figure 3-2 Eureka Property Map
(McEwen, 2026)

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3.2.Land Area
The Eureka Property is located in Townships 17, 18, and 19 North, Ranges 53 and 54 East, Mount Diablo Baseline and Meridian, in Eureka County, Nevada. Land title reviews were completed in 2008 (G.I.S. Land Services, 2008), which were updated by the law firm of Harris & Thompson in 2011 (Thompson, 2011).
The Rocky Canyon claim group (Figure 3-3) consists of 378 contiguous unpatented lode mining claims situated in portions of Sections 2, 3, 4, 9, and 10, Township 17 North, Range 53 East and Sections 8, 9, 10, 15, 16, 17, 20, 21, 22, 26, 27, 28, and 33, 34, 35, Township 18 North, Range 53 East, Mount Diablo Base and Meridian. The claims total approximately 6,520 acres (approximately 10.2 square miles). At Lookout Mountain, McEwen controls 373 of the 378 claims through a lease described in Section 3.3 and owns the remaining five internal fractional claims as described in Section 3.3.
The Windfall-Hoosac claim block consists of 179 unpatented claims, four of which are held under a lease agreement. The Windfall-Hoosac claim group is situated in Sections 1, 2, 11-14, Township 18N, Range 53E, Mount Diablo Base and Meridian (Figure 3-4). The claims total approximately 3,700 acres (approximately 5.8 square miles). McEwen acquired 13 patented claims referred to as the Windfall Patents from the acquisition of Timberline. The Claims are located in Township 18N, Range 53E, Sections 2 and 11. These claims host the resource discussed in this report.
Ownership of unpatented mining claims is in the name of the holder (locator), subject to the paramount title of the United States of America, under the administration of the U.S. Bureau of Land Management (BLM). Under the Mining Law of 1872, which governs the location of unpatented mining claims on federal lands, the locator has the right to explore, develop, and mine minerals on unpatented mining claims without payments of production royalties to the U.S. government, subject to the surface management regulation of the BLM. It should also be noted that in recent years there have been efforts in the U.S. Congress to change the Mining Law of 1872 to include, among other items, a provision of production royalties to the U.S. government. Currently, annual claim maintenance fees are the only federal payments related to unpatented mining claims. Nevada BLM records of mining claims can be searched on-line.
Certificates of Location for each claim of the Lookout Mountain claim block and Windfall-Hoosac claim block were properly filed with Eureka County and the BLM. It should be noted that, apart from the five internal fractional claims, the Lookout Mountain claim block has not been modified since the title review reports by G.I.S. Land Services in 2008 and Thompson (2011). The Windfall-Hoosac claim block remains unchanged since 2008 except for the addition of 28 contiguous claims staked to the east by Timberline in 2020.
As of September 1, 2025, the claims have been properly maintained, based on the Annual Notice of Intent to Hold documents filed in Eureka County and on the Annual Maintenance Fee documents filed with the BLM for the 2025-2026 assessment year. McEwen reports that the annual fee of $200 per claim was paid to the BLM, along with the annual recording fee of $12.00 per claim and $12.00 document fee for a Notice of Intent to Hold Mining Claims due to Eureka County for the 2025-2026 assessment year. The total cost for the 378 claims at Lookout Mountain in 2025-2026 is $80,148. For the Windfall claims the total is $20,576.
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Yearly holding costs for the entire property, including BLM and County fees for unpatented claims, and property taxes for patented claims total $358,848, including the advanced royalty payments to Rocky Canyon Mining Company.
Figure 3-3 Lookout Mountain Plan of Operations (“PoO”) Showing current Resource Outline
(McEwen, 2026)

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Figure 3-4 Windfall Trend Showing Resource outline (McEwen, 2026)

3.3.Agreements and Encumbrances
The 378 claims at Lookout Mountain were located by various owners, and after a series of transactions, a total of 373 of the 378 claims (the RAT and SELRAT claim groups and the DAVE #1 and TREVOR #1 claims) were consolidated under the single ownership of Rocky Canyon Mining Company (G.I.S. Land Services, 2008). Through an Assignment of Lease executed April 14, 2008, Staccato Gold Resources, Ltd. (“Staccato”) acquired leasehold title for the mineral rights of the claims from Century Gold LLC, who had previously leased the property from Rocky Canyon Mining Company (G.I.S. Land Services, 2008). As described in Section 3.3.2, Timberline acquired Staccato
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and BH Minerals in 2010. Section 5.1 describes the history of the property in more detail. In September 2011, Timberline staked an additional five fractional claims (TLRrat 1 through TLRrat 5) within the eastern portion of the original 373 claims that comprise the property (Timberline, written communication, April 2, 2012).
Staccato acquired the Windfall properties from Century Gold LLC in a stock purchase agreement in 2008. Other assets purchased consist of all the unpatented claims including the Hiero Syracuse group in Secret Canyon and the Claims formerly held by Windfall Ventures. The purchase included a lease-option between Century Gold and the Vining Family Trust for the Windfall Patents. The Windfall patents, and several other patented claims formerly held by Windfall Ventures, were purchased by Timberline in 2011. In 2020 Timberline augmented the original Windfall claim block to the east by staking an additional 28 claims.
McEwen acquired all the Eureka Property assets in 2024 through acquisition of Timberline.
3.3.1. Agreement between Staccato and Rocky Canyon Mining Company
Staccato Gold Resources Ltd acquired all assets from Century Gold LLC, who leased the Lookout Mountain claim block from Rocky Canyon Mining Company. The term of the lease is 20 years, commencing on June 1, 2008 and expires May 31, 2028. The lessee must pay an annual advanced royalty payment of $72,000 in addition to the BLM and Eureka County fees described in Section 3.2. The royalties included in this agreement are described in Section 3.3.3.
3.3.2. Acquisition of Timberline Resources Corp by McEwen
On June 2, 2010 Timberline acquired Staccato and Staccato’s Eureka property through a plan of arrangement whereby Timberline acquired all of the issued and outstanding common shares of Staccato by means of a share exchange.
McEwen acquired all the Eureka Property assets in 2024 through the acquisition of Timberline.
3.3.3. Royalties on the Lookout Mountain Claim Group
The Lookout Mountain claim group, excluding the five claims staked by Timberline in 2011, is subject to the following royalties as summarized from the 2008 title report (G.I.S. Land Services, 2008):
· | 1.5% Gross Value Royalty payable to Geneve and Mary Bisoni on production from the Rat and Selrat claim groups (the Trevor and Dave claims are not included). This royalty is capped at $1,500,000. |
· | 3.5% Gross Value Royalty payable to Rocky Canyon Mining Company on production from the Rat and Selrat claim groups and the Dave and Trevor claims. McEwen is required to pay advanced royalty payments of $6000/month to maintain the lease in good standing. |
The updated title review by Harris & Thompson (Thompson, 2011) found no transfers of these royalties of record, so they remain vested as described above.
All of the Lookout Mountain resources discussed herein are subject to both royalties listed above.
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3.3.4. Agreements on the Windfall Claims
The unpatented claims at Windfall, excepting four, are owned by McEwen through the acquisition of Timberline. Timberline acquired the claims from Century Gold as discussed in section 3.2 above. The claims are encumbered by Royalties as discussed below.
3.3.5. Royalties on the Windfall Project
The Windfall-Hoosac claim group is subject to royalties as summarized from multiple deeds including several amendments between 1979 and 2004 as registered with Eureka County. The royalties include:
· | Idaho Royalty: 2% Gross Value Royalty |
· | Windfall Royalty: 1.2% Gross Value Royalty |
· | R.G. Wilson Royalty: 0.8% Gross Value Royalty |
· | Silverado Royalty: 1% Net Smelter Royalty |
The Idaho and Windfall Royalties totaling 3.2% are payable upon mine production from the 13 Windfall patented claims and from production on any unpatented claims in the Hoosac claim block. The Idaho and Windfall Royalties are payable to Royal Gold Inc. associated parties. The R.G. Wilson Royalty is payable to the R.G. Wilson Trust as grantee. The Silverado Royalty is payable to Silver International for production from any of 4 claims within the Hoosac claim block under lease to McEwen.
3.4.Environmental Permits and Licenses
Non-mining exploration activities at Lookout Mountain are completed under a Plan of Operations (“PoO”) originally submitted to the BLM Mount Lewis Field Office by Staccato in March 2009 that outlines an area of approximately 3,000 acres (Figure 3-3). The BLM completed an environmental assessment (“EA”) to meet their requirements under NEPA and approved the Plan of Operations (NVN-086574) in September 2010.
Exploration PoO NVN-086574 authorized up to 266.4 acres of exploration-related surface disturbance within the project PoO area. The Nevada Division of Environmental Protection (“NDEP”), Bureau of Mining Regulation and Reclamation (“BMRR”) approved a Nevada Reclamation Permit (No. 0307) for the project and calculated an initial Reclamation Cost Estimate (“RCE”).
Timberline provided the State and the BLM with annual work plans for 2011 through 2014, 2016, and 2019 through 2022. A total of 64.4 acres is currently approved and bonded ($451,295 total in state-wide bond) with 42 acres of disturbance created since 2010. The RCE is reviewed and updated for escalation of reclamation costs on a three-year basis. Timberline last completed this RCE update in June 2023. The PoO allows for additional disturbance to be permitted above the 64 acres with an amendment to the plan.
Exploration activities covered by the PoO consist of drilling from constructed sites that would be accessed by existing roads and new road construction, construction of trenches or bulk sampling,
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and the installation of groundwater monitoring wells. Disturbance tracking is required and McEwen must provide both the BLM and NDEP with a map showing existing disturbance, new disturbance created during the reporting year, and any reclamation completed. A work plan can be submitted yearly with a letter and map showing proposed activity changes. If there are no changes to a prior year work plan activity, creating new disturbance is allowable although the activity must be based on the prior year’s work map, or the activity can utilize existing as-built disturbance from any prior year.
Extractive mining and ore processing activities are not allowed under the existing PoO. Such potential activities will require additional baseline-related studies (see Section 3.6).
Exploration activity on patented lands at the Windfall Project are completed under a state of Nevada reclamation permit from the Bureau of Mining Regulation and Reclamation (BMRR). The current Reclamation permit was obtained in 2024. The permit allows for up to 20 acres of disturbance and is bonded for reclamation activities. The state interim permit (# NRP#0433) cannot be increased in acreage with additional bonding. For additional acres, a full state exploration permit must be acquired. Yearly disturbance accounting is mandated with submission of a map showing the location of disturbed ground and a form that provides for a running summary of total disturbance from year to year.
The BLM approved two Notice level permits (NVNV106800852 and NVNV106800850) in May of 2026 for work on BLM ground adjacent to the patented claims. Notice-level permits have a maximum limit of five acres with yearly work plans and additional bonding required if new proposed disturbance will exceed the RCE bonded for disturbance. The notice level permits will allow for exploration to expand off the patented claims.
3.5.Environmental Liabilities
The Lookout Mountain property was previously mined in the 1980s for gold. This mining operation resulted in the development of an open pit, a waste rock dump, a haul road, and exploration drill roads. It appears that all processing of the ore occurred off-site. A certain amount of reclamation had historically been completed on the mining-related surface disturbance; however, that reclamation is not consistent with the current reclamation standards. Previously, Timberline were not held responsible for re-contouring or reclaiming the existing open pit and waste dump at Lookout Mountain. It is reasonable to expect that as long as McEwen does not reactivate the disturbance associated with the waste rock dump or the open pit, McEwen will continue to not be liable for any additional reclamation. Any Exploration work on the waste rock dump is subject to reclamation requirements
Work on patented claims (private land) is overseen by the State of Nevada Department of Environmental Protection. The disturbance caused by historic mining at Windfall, which is on both private and public lands, follows the same expectations as at Lookout Mountain regarding disturbance and reclamation.
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3.6.Environmental Studies
Additional environmental and engineering studies would be required to support permitting of a mine at the Eureka properties. These include expanded baseline studies in preparation for possible submission of a mine Plan of Operations to the BLM.
Baseline data studies would allow for the completion of the environmental permit applications and for NEPA compliance. These studies would include, but are not limited to biology, culture/archaeology, spring/riparian, groundwater characterization, and waste rock and ore characterization. In addition, geotechnical data would be necessary for completion of engineering design work required for mine permit applications.
Starting in late 2011 and continuing into 2013, and with additional work in 2022-2023, Timberline completed certain initial baseline studies in preparation for pre-feasibility work and submission of a mine Plan of Operations to the BLM. McEwen continued these studies in 2026; these studies included:
· | Baseline biological resources: threatened and endangered species and other biological surveys; |
· | Archaeological surveys in areas not completed previously for the exploration PoO; |
· | Baseline hydrologic characterization work; |
· | Acid generation/acid-base accounting (WAG/ABA) waste rock characterization; |
· | Facilities design; and |
· | Pit slope stability studies. |
3.6.1. Baseline Biological Resources
An updated survey of vegetation and wildlife resources is in process and ongoing, including consideration of spring/summer flowering and faunal breeding seasonal requirements for mine permitting.
3.6.2. Archaeological Surveys
To support expanded exploration and potential mine permitting requirements at Lookout Mountain, Timberline’s environmental consultant, Westland Engineering and Environmental Services, Inc. (“Westland”), advanced an update of the exploration PoO with an additional cultural resources survey of the project area. Field work for the updated survey was completed in 2021 and 2022, with follow-up analysis continuing through the second quarter of calendar year 2023. Westland submitted a final report to the BLM in July 2023. This report was under agency-review and not finalized. As with earlier reviews, multiple cultural avoidance areas were identified and will require additional site screening and potential mitigation prior to completion of field work, such as drilling or construction activities. McEwen does not consider the avoidance areas to be a significant impediment to planned exploration or mine development activities as they are typically small areas around which drill sites and access roads can be re-positioned and / or reasonable mitigation measures can be made.
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Kautz Environmental Consulting, Inc (“Kautz”) continued additional cultural resource surveys of the exploration plan boundary in 2024 and 2025. These surveys included the original surveys from Westland. Kautz submitted their final report to BLM in 2025. Kautz began cultural resource surveys for the mine plan boundary and completed the field work in 2025. These reports are under review.
3.6.3. Baseline Hydrology
Between 2011 and 2013, Schlumberger Water Services (SWS) completed preliminary surface and groundwater characterization studies to support permitting of a previously proposed mining operation at Lookout Mountain. The project site is located within the northern portion of the Little Smoky Valley Hydrographic Basin, Northern Part (Basin 155A) where surface water drains from the project area southward into the northern part of Fish Creek Valley.
The SWS surface water survey identified actively flowing springs and seeps, and initiated monitoring for NDEP Profile I parameters. Eleven sites were accessed and sampled by SWS, including two immediately east of the current Lookout Mountain project mineral resources (Figure 3-3).
Spring-water samples were collected in laboratory-supplied bottles, stored on ice, and transferred to WETLAB in Reno, Nevada under chain of custody protocol. The samples were analyzed for NDEP Profile I parameters and are generally classified as calcium-magnesium bicarbonate type waters with slightly high pH and concentrations of Profile I constituents below Nevada Reference Values (“NRVs”) in Murray and Secret Canyon Springs in the Windfall Project area. Sierra and Ratto Springs, located within the Lookout Mountain project boundary, produced water that exceeded maximum contaminant levels for aluminum and arsenic, respectively. Quarterly monitoring of the springs continued in 2012 and 2013 and further documents the surface water quality baseline.
SWS also initiated groundwater studies in the Lookout Mountain project area in 2012 with completion of eight RC groundwater pilot test holes, four of which were dry. The four successful holes were completed as monitoring wells located north, east, and southeast of the project’s mineral resource areas (Figure 3-5). The wells were completed with 4-in diameter steel blank casing and mill-slotted screen with silica sand gravel packs, developed and air-lift tested, and equipped with industry standard Geokon electronic data logger pressure transducers. In addition to completion of four monitoring wells, an RC drillhole located within the central portion of the Lookout Mountain resource area was completed for measurement of groundwater levels with a vibrating wire piezometer within a back-filled cement bentonite mix.
The monitoring wells were installed to depths of approximately 500 to 900 feet with static water levels of approximately 54 to 470 feet below ground surface level (approximate elevations of 6,976 to 7,474 feet above mean sea level). Water quality samples were collected in each monitoring well after construction and well development and quarterly thereafter for one year in one well that had a dedicated bladder pump installed. Water samples were collected, stored, and analyzed at WETLAB under the same protocols as surface samples. The groundwater quality is characterized as a calcium-sodium bicarbonate type with neutral to slightly high pH and concentrations of Profile I constituents below NRVs in all wells except BHMW-001. The groundwater quality from well BHMW-001 periodically exceeded NRVs for aluminum, arsenic, iron, and manganese, and the pH also exceeded the NRV for the first sampling event.
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Based on the hydrologic characterization completed in 2013, additional surface water sampling and water quality analysis would be required to meet current regulatory standards for mine permitting. Up to four additional monitoring wells are anticipated to be required that would be fitted with pressure transducers for water level data. Installations would be sited at the potential open pit, rock-waste storage facility, heap-leach pad, and other facilities. All sites, including previously installed monitoring wells, would be surveyed to allow determination of existing groundwater elevations, hydraulic gradients, aquifer parameters, and advancement of a conceptual hydrologic model for the site.
In addition to installation of additional monitoring wells, investigations would be undertaken to identify potential water supply well source(s), installation, and test-pumping of production test well(s), and to provide data adequate for water rights permitting. Permitting for additional monitoring wells is in progress.
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Figure 3-5 Lookout Mountain Spring and Groundwater Monitoring Well Location Map (McEwen 2026)

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3.6.4. Waste Rock Geochemical Characterization
BLM and Nevada mine permitting regulations require geochemical characterization of waste rock and ore materials to establish a defensible geochemical database suitable for permitting under NEPA, and to define preliminary operational and closure strategies. Data collected would need to be appropriate for predictive work on pit wall runoff or seepage chemistry from mine and processing facilities where waste and ore rocks may be exposed to the environment. Testing would also be required to include static and kinetic methods to determine short- and long-term geochemical characterization of mined materials.
Previously, Timberline developed and initiated a baseline geochemical characterization plan in 2012 for the project with samples selected from drill core. Characterization work in 2012-2013 included six humidity cell kinetic tests (HCTs), five of which reported Non-PAG (non-potential acid generating) material and one reported PAG (potential acid generating) material. Six MWMP (meteoric water mobility procedure) static tests were completed with non-deleterious results.
With changes in the regulatory requirements since 2013, additional HCTs are anticipated to be required and may need to run for up to 50 weeks in duration. Additional samples are expected to be required for ABA/NAG pH, and for MWMP testing.
Cultural, biological, geochemical, and hydrological baseline environmental studies are ongoing at Windfall.
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4. | ACCESSIBILITY, CLIMATE, LOCAL RESOURCES, INFRASTRUCTURE AND PHYSIOGRAPHY |
4.1.Access to Property
Access to the property is via U.S. Highway 50 which passes to the North and East of the project area (Figure 4-1). Access off Highway 50 is via Windfall Canyon Road, a county-maintained gravel road, approximately 2 miles (3.2km) south of the town of Eureka. The northern part of the project area is accessed by the county-maintained Windfall Canyon Road and its westward extension, the former haul road for the historical Lookout Mountain mine, also a county-maintained gravel road. The southern Lookout Mountain and Windfall project areas are accessible by traveling approximately eight miles south of Eureka on U.S. 50 to South Gate, then approximately one mile south-southwest on the Fish Creek Valley Road (NV-379) to a turnoff to the north and northwest on the Secret Canyon Road for Windfall project and another one mile south-southwest on the Fish Creek Valley Road (NV-379) to a turnoff to the West and Northwest on the Ratto Canyon Road for the Lookout Mountain Project.
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Figure 4-1 Location and access.
Many dirt tracks within the property provide access to various localities at the project (McEwen, 2026)

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4.2.Climate
The Lookout Mountain and Windfall area is characterized by the high-desert climate of the Great Basin. The climate is semi-arid with moderate winter snowfalls, and occasional thunderstorms that can include heavy rains from time to time during otherwise hot and dry summers. November snow commonly lingers until April in the higher elevations, and several feet of snow often accumulate on the property during the winter months. Unpaved county roads are not maintained during winter.
Temperatures range from as cold as -10ºF in winter to occasional days near 100ºF in summer. Summer temperatures usually consist of many consecutive days of over 90º F. Winter temperatures are usually in the 20º to 35ºF range. Precipitation amounts vary from year to year, averaging about 10.0 inches annually for the area.
At Eureka, located eight miles north of the property, the average temperature is 44°F, with an average high of 61.9°F and an average low of 26.7°F. Average annual precipitation is 10.1 inches.
Mining can be conducted year-round, but heavy snow may impede exploration during the winter.
4.3.Physiography
The Lookout Mountain and Windfall projects are located in the Basin and Range physiographic province, characterized by generally north-trending fault-bounded ranges separated by alluvial valleys. The terrain on the property is rugged, with high ridges, steep canyons, and narrow valleys. Elevations range from 6,600 to 9,500 feet. Ridges show abundant bedrock exposures; slopes and valleys are typically covered by soil and alluvium. Sagebrush abounds in lower-elevation areas, while juniper, pinion and mountain mahogany cover the higher elevations. Grasses and shrubs are plentiful around springs and soil covered slopes at all elevations.
4.4.Local Resources and Infrastructure
The Lookout Mountain and Windfall projects are situated in central Nevada in an area with established mining infrastructure. Transmission power lines serve Eureka from the north; no power exists at the project sites. Essential services such as food and lodging are available in Eureka, including dockage for shipments of heavy equipment. Eureka’s estimated 2024 population was 279. A small airport at Eureka is available for private air transport, and regularly scheduled air service is available in Elko, Nevada, about a two-hour drive north of the property. US Highway 50 that crosses Nevada in an east-west direction lies to the north and east of the property. The Union Pacific Railroad runs parallel to Interstate 80 about 85 miles north of the property.
Skilled miners and mining professionals are available at Eureka and 100 miles to the north at Carlin, Elko, and Spring Creek. Mining supplies and services are available at Carlin and Elko.
4.5.Facilities Design
The northern access road to the former Lookout Mountain mine was utilized in the early 1980’s as a haul road to transport ore to the Windfall Mine for processing (Russell, 2005). The road remains as a facility in use for access to the property.
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Potential development of the Lookout Mountain and Windfall resources is envisioned as open pit oxide heap-leach operations with a load-out facility for direct shipment of high-grade refractory unoxidized materials. Previously, NewFields (2012), a geotechnical engineering services consultancy, completed a scoping-level facilities-location study for Lookout Mountain in 2012 and identified prospective sites for a rock storage area, leach pad, ponds, and a process facility envisioned to be located west of a north-south-trending, conceptual open pit. This study is no longer valid, is historical in nature and should not be relied upon. Further development planning will be undertaken by McEwen as the project moves forward.
Potential Windfall facilities at this stage have not been modeled. Historical production from open pit mining in the 1970’s and 1980’s was placed on a leach pad in the drainage area and waste dumps placed adjacent to the open pits. Development planning will be undertaken by McEwen as the project moves forward.
No power exists at the project sites. Power would likely either be supplied from i) grid sources to the north near Eureka, ii) from on-site generation, or iii) from new power lines brought in from Newark Valley, East of the project area. Past operations at Windfall were supplied power from the grid in Eureka. Poles and lines exist up the Windfall Canyon Road to the Property, but the lines are not currently active and require repair.
At present, both projects do not control any water rights. Such rights could potentially be purchased or leased from an existing user(s) within the appropriate hydrographic basin. Windfall is in hydrographic Basin 153 and Lookout Mountain is in Basin 155A. Based on monitoring wells currently in place at Lookout Mountain, it is anticipated that water supply production wells could be sited down-gradient of the current resource area, with water pumped to the process facility and leach pads. Windfall water access could also be from production wells pumping water to the facilities
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5. HISTORY
5.1.Exploration History
The following information is taken from Russell (2005, 2007), Morris (2007), Edmondo (2008a, 2008b), Nolan (1962), Shawe and Nolan (1989), and Emmons (1995, 1996), with additional references as cited.
Exploration in the Eureka area began around 1860, and the Eureka mining district was discovered in 1864. Production of lead-silver-zinc-gold mineralization from small bonanza mines dates from 1865. Early production from the district was from oxidized, gold-rich, chimney-like replacement deposits in Paleozoic carbonate rocks along faults within favorable host rock. Cretaceous stocks and small dikes occur near several of the early mines. In addition to gold, the Eureka deposits produced substantial amounts of lead and silver. Incomplete production records prior to the 1950s suggest that production of gold, silver, copper, lead, and zinc from the Eureka district may have totaled $122 million (in 1962 dollars) (Nolan, 1962). About 1.65 million ounces of gold were produced from the Eureka district, mostly during the period from 1870 to 1890 (Shawe and Nolan, 1989).
The initial discovery of mineralization at Eureka was in New York Canyon, about 1¾ of a mile North of the Windfall project. Several small lead-silver-gold mines were discovered in the southern part of the Eureka district (also known as the Secret Canyon district) about one mile east of Lookout Mountain/Ratto Ridge, during this same time period.
The historic Windfall open pits are at the southern end of a series of small to moderate sized lead-zinc-silver mines. A series of small lead-silver mines also occurs 1 mile southeast of the Windfall Pit on top of Hoosac Mountain. Production of lead-silver ores from the Secret Canyon portion of the Eureka District is unknown but considered small.
Mineralization that contained gold with no base metals and only minor, if any, silver was present in three mines within the district. The largest gold-only mine was discovered in 1904 at Windfall Canyon, about 3.5 miles northeast of Lookout Mountain. The Windfall Mine had early gold production from 1904 until 1908 and 1909 to 1912 (Vanderburg, 1938) from underground operations. The mineralization mined from underground at Windfall was largely oxidized and siliceous. Windfall’s mineralization differs from the other mineralized bodies in the Eureka district in that the Windfall is characterized by high-grade gold shoots with indistinct assay walls grading into low grade mineralization. Gangue minerals, iron, lead, silver, and zinc are generally absent from the Windfall mineralization. Windfall’s gold mineralization occurs in altered Hamburg Dolomite. Individual mineralized shoots show both structural and stratigraphic control, localized by the intersection of northeast-striking fissures with the uppermost beds of the Hamburg Dolomite (Nolan, 1962). Most of the old stopes terminated above the 200-foot level, and none extended below the 300-foot level (Nolan, 1962).
Gold-only mineralization was also found at the Lost Jewel Mine, located in New York Canyon, 3/4-mile Northwest of Windfall Canyon, and at the Oswego Mine, on the West Flank of Secret Canyon
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Ridge, 1 mile East of Lookout Mountain. Both had minor production. All three mines were explored and operated in the early 1900’s (Nolan, 1962). In the 1960’s, due to interest in the invisible gold discoveries at Carlin and Cortez, exploration was initiated at the old Windfall mine by Idaho Mining, and at Lookout Mountain by Cordero Mining.
Exploration activities for disseminated gold deposits elsewhere in the district began in earnest in the late 1960’s and early 1970’s at Windfall, Lookout Mountain, the Lost Jewel mine in New York Canyon, and at the Old Ruby Hill workings. Homestake Mining began exploring the Eureka District in 1991, eventually signing a lease with Sharon Steel to acquire the patented and unpatented claims at the North end of the district, ultimately leading to the discovery of the Archimedes Pit in 1994. Homestake’s success led to increased activity elsewhere in the district in the early and mid-1990’s, with extensive exploration for such deposits since then.
5.1.1. Windfall Exploration Programs
Idaho Mining Corp. began exploring the Windfall area beginning in 1967 with surface sampling, and in 1968, with staking and leasing ground around the old Windfall and Rustler underground mines (W. Wilson, 1986). Idaho Mining ran soil and rock sample programs, mapped the area and began drilling. Idaho Mining drilled over 1,000 conventional rotary holes and discovered 3 million tons of low-grade material amenable for a heap leach operation (Wilson, 1984), which were then mined from 1976 to 1984. Mining continued at Windfall through a joint venture between Windfall Ventures and Trans Western Mining from 1984 to 1986. Norse Mining (“Norse”) purchased the property in 1986 and operated until 1988, when Norse went into bankruptcy. The properties held by Norse, including Lookout Mountain, went into receivership with patented lands being granted to creditors of Norse debt, and Windfall Ventures re-staking unpatented claims in the Windfall area.
Gold exploration in the Windfall area was minimal after the Norse bankruptcy. Tenneco Minerals and Cyprus Amax had small programs in the New York Canyon claim block in 1989-1991. Tenneco drilled 14 holes totaling 5,680.0 feet in New York Canyon, and 11 holes on Hamburg Ridge. Cyprus drilled 2 holes in the New York canyon claim block, completed a rock-sampling program, and mapped the area before relinquishing the property.
Exploration expanded quickly after Homestake Mining Company announced the discovery of the Archimedes deposit in 1994. Prior to 1994, Homestake explored the New York Canyon and Goodwin Canyon regions between 1991 and 1993, and again from 1995 to 1998. Pathfinder exploration was active in the area, beginning in 1992. Pathfinder worked in the south end of Secret Canyon from 1992 to 1993. In 1993, Pathfinder signed a lease to explore Hoosac, New York Canyon, and Hamburg Ridge. Pathfinder completed a regional soil grid over Hoosac Mountain and Hamburg Ridge, collecting 1,930 samples, completed a geologic map and a ground magnetic survey of the area, and drilled 28 holes. Cambior sublet the lease from Pathfinder from 1995 to1997 and drilled 26 reverse circulation holes on Hoosac Mountain totaling 19,867.0 feet. Cambior relinquished the lease back to Pathfinder in 1998. The property sat idle for several years after 1998.
Century Gold LLC. began staking claims in the Secret Canyon area in 2003. In 2004 Century Gold acquired a lease on the Lookout Mountain Claims from Rocky Canyon Mining Company, acquired a
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lease on the Windfall Patents from the Vining Family Trust, and acquired the unpatented claims from Windfall Ventures, consolidating the South Eureka Properties. Staccato Gold acquired the Lookout Mountain lease from Century Gold LLC in late 2004 through its wholly owned subsidiary BH Minerals. Staccato was also working on acquiring the remaining assets of Century Gold in 2005 and 2006, at first through acquiring the lease from Pathfinder Exploration, but ultimately purchasing Century Gold’s assets via an all-stock purchase in 2006.
Staccato undertook an exploration program in 2008 consisting of 1:2400 scale mapping, rock-chip sampling, data compilation, ground magnetics, and drilling at Windfall beginning in 2008. The company focused on developing targets along the Windfall trend, from the Paroni Pit South to the Paige Corwin Mine at the South end of Hamburg Ridge, on Hoosac Mountain, and in the old open pits. A small drill program was started in the latter half of 2008 with 4 holes targeting mineralization in the Rustler Pit to assess historical drilling and determine the extent of mineralization below the pit floor. From 2008 to 2010, nineteen drill holes, totaling 14,870 feet, were drilled into various targets along the Hamburg Ridge – Windfall project, and below the open pits.
Timberline took control of Staccato via a merger in June 2010 and continued exploring the Windfall claim groups, completing 15 additional reverse circulation drill holes, purchasing the Windfall and other patented claims, undertaking a detailed mapping program covering Hoosac Mountain and Hamburg Ridge. The 15 holes were designed to follow up on earlier drilling results and new geologic targets generated for drilling along Hamburg Ridge. Drilling started in late August 2010 and continued into 2011 at Hoosac Mountain and in Dale Canyon.
In mid-2011 the company wanted to assess the viability of exercising the option to purchase the Windfall Patented claims from the Vining Family Trust. A program of drilling, with geologic and mineralization modelling, was initiated to assess the economics of a potential purchase. Drilling was planned to increase the level of geologic understanding of mineralization below the pit floors and increase confidence in the mineralization modeling. The decision to purchase the patents was made in early February of 2012 after the program and modelling were complete. Timberline drilled six additional RC holes in late 2014 / early 2015 targeting gaps in higher grade mineralization. These were the last holes Timberline drilled at Windfall, allowing the property to sit idle until the acquisition by McEwen Inc.
5.1.2. Lookout Mountain Exploration Programs
Exploration at Lookout Mountain began with Cordero Mining working the area in the 1960s. Cordero Mining Co. (Sun Oil Company) drilled several core and rotary holes in the Pinnacle Peak and Lookout Mountain areas. The drilling was investigating mercury-vapor anomalies, but no results are available (Jonson, 1991).
Newmont Mining Corp. (“Newmont”) drilled one hole in the Prospect Peak/Rocky Canyon area to the north of Lookout Mountain in 1963 while exploring for porphyry molybdenum mineralization. A log with a database printout of assays for core hole (#609) was among the data provided to Staccato Gold. Hole 609 was drilled to a depth of 1,525 feet and intersected 50 feet averaging 0.023 oz Au/ton from 450 to 500 feet in a silicified, pyritized fault zone (Jonson, 1991). That hole
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also intersected metasomatic alteration associated with granitic dikes that included magnetite, quartz, sericite, pyrite, molybdenite, fluorite, and calcite mineralization (Mako, 1993a). Amselco followed up with six rotary holes (RCR series) in 1981 during exploration efforts for gold mineralization at Lookout Mountain with poor results. Drill logs list the project as the Moly Porphyry Project and indicate that the holes were drilled by conventional rotary drilling.
The Lookout Mountain property was idle from 1963 until 1974, when the Bisoni brothers staked 48 Rat-series claims on Ratto Ridge, based on anomalous gold, arsenic, antimony, and mercury results from rock chip sampling. The original Bisoni Rat-series claims are part of the current property.
The largest exploration program at Lookout Mountain was begun by Amselco Exploration Inc. (“Amselco”) in 1978 with exploratory rock sampling. After signing a lease with option to purchase agreement with the Bisoni brothers in April of 1979 (Hauntz, 1985) Amselco staked 138 Selrat-series claims that adjoin the Rat claims. Amselco conducted extensive geologic mapping, soil and rock geochemical sampling (1,100 rock samples), and an initial 15-hole RC drilling program. The drill program tested gold mineralization identified by geochemical anomalies and jasperoid bodies developed along the north-trending Ratto Ridge fault, which forms the crest of Ratto Ridge. This drilling discovered significant sediment-hosted disseminated gold mineralization. Amselco ultimately drilled 307 conventional rotary and RC holes and two core holes between 1979 and late 1985, which led to the discovery of mineralization that eventually became the Lookout Mountain open pit mine at the northern end of Ratto Ridge. Amselco also discovered five additional areas along Ratto Ridge which contain partially developed gold mineralization: South Lookout Mountain, Pinnacle Peak, Triple Junction, South Ratto Ridge, and South Adit. In the summer of 1985, Amselco discovered mineralization in Devonian rocks on the crest of Ratto Ridge, west of the known mineralization in Cambrian rocks.
Amselco optioned their Lookout Mountain property to Norse Windfall Mines Inc. (“North Windfall Mines”), a joint venture between Norse, Viking Minerals (owned by consultants Campbell Foss and Buchanan (CFB)), and SSI Miami in July 1986 (Cargill, 1988). The joint venture was called the Eureka Venture, Inc., which in turn owned a company called Norse Windfall Mines (Cargill, 1988). Norse Windfall Mines was the operator of the Eureka property, with day-to-day management of the operation by CFB on a contract basis. Also in 1986, Amselco was acquired by BP Minerals Company (BP).
Norse Windfall Mines continued work at Lookout Mountain. They collected 943 rock samples over the 2.5-mile length of Ratto Ridge, which identified at least nine areas of “strong mineralization” (Jonson, 1991). Norse Windfall Mines drilled 20 LM-series exploration holes in 1986 and put the Lookout Mountain mine into production in 1987. Norse Windfall Mines mined at Lookout Mountain in 1987 and 1988, hauling the ore 5.6 miles to leach pads at the Windfall Mine. Cargill (1988) and Jonson (1991) reported that Norse Windfall Mines mined 180,196 tons of mineralized rock averaging 0.12 oz Au/ton in 1987. The ore was agglomerated and leached to produce 17,700 ounces of gold at a recovery rate of 81%. No information on production from 1988 is available. Financial, management, logistical, and metallurgical problems halted operations, and the property was returned to the original landowners.
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EFL Gold Mine, Inc. (EFL) purchased the Rat- and Selrat-series claims from Bisoni and Amselco/BP in 1990 (Jonson, 1991). They collected bulk samples from the floor of the Lookout Mountain pit that returned assays of 0.10 to 0.135 oz Au/ton. EFL drilled 11 RC holes in 1990 (EFL-1 through EFL-9, M1, M1-A), two of which drilled 500 feet into the floor of the pit and intersected both oxide and sulfide gold mineralization below the pit floor (Jonson, 1991).
Summit Minerals, Inc. acquired the property from EFL in December 1990 (G.I.S. Land Services, 2008; Jonson, 1991). Rocky Canyon Mining Company acquired the Lookout Mountain claim group from Summit Minerals, Inc. through an agreement in November 1991 (G.I.S. Land Services, 2008; Jonson, 1991).
Barrick Gold Exploration Inc. (“Barrick”) leased the Lookout Mountain property from Rocky Canyon Mining Company in February 1992 (Mako, 1993a). Barrick completed geologic mapping, acquired more than 500 soil samples to expand and fill in Amselco’s grid, and drilled primarily along Ratto Ridge and for about a mile north of the ridge. Drilling targeted favorable stratigraphy at depth near fault intersections (Mako, 1993a, 1993b). North American Exploration, Inc. conducted the soil sampling survey over the same two grids used for the ground magnetic survey described below. The soil samples were collected on 300-foot by 300-foot sample spacing, and samples were analyzed for 15 elements by ICP-ES (inductively coupled plasma emission spectrometry) analysis at the laboratory of MB Associates. Several anomalous areas were found east of Ratto Ridge.
Work by Barrick also included airborne and ground geophysics (Mako, 1993a). Aerodat Ltd. surveyed 160 line-miles at a line spacing of 0.125 miles over Lookout Mountain and surrounding area in March 1992. This airborne survey included magnetic, electromagnetic, apparent resistivity, VLF-EM, and radiometric surveys. Barrick found the magnetic data to be the most useful, and identified three significant anomalous areas: a circular positive anomaly in the Rocky Canyon area, a series of magnetic highs between the historical Lookout Mountain pit and Surprise Peak that extends about a mile south along Ratto Canyon, and a linear zone in the drainage west of Grays Canyon in the southwest part of the property. Geo-Western was contracted to survey three reconnaissance ground induced polarization/resistivity (IP) lines in the Lookout Mountain pit area to determine if the high-grade sulfide mineralization below the pit could be detected by this method. At the time of Mako’s (1993a) report, anomalies had been identified but not drill tested, and no further information is available. North American Exploration, Inc. was contracted to conduct ground magnetic surveys over two grids: one between Ratto Ridge and Ratto Canyon and the second covering the aeromagnetic anomalies and local jasperoid occurrences in Magnetic Canyon. Some of the magnetic highs are associated with areas mapped as being underlain by Paleozoic rocks, which suggests the presence of concealed intrusions. Most of the magnetic anomalies in Magnetic Canyon appeared to be associated with outcrops of Tertiary volcanic tuff.
A geochemical vectoring study was conducted by MagmaChem Exploration, Inc. (Mako, 1993a) for Barrick to define hydrothermal fluid pathways and aid in the search for high-grade mineralization. The geochemical study was made along Ratto Ridge and included collection of approximately 800 rock and drill samples with multi-element ICP-ES and graphite furnace-AA analyses by MB Associates in California, and ICP-ES and neutron activation analysis by Activation Laboratories in Canada (Russell, 2005, 2007). This study showed that groups of elements common in sediment-hosted gold deposits in other areas were also statistically significant at Ratto Ridge. Mapping,
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together with results of geochemistry, indicated that mineralization was apparently strongly controlled by east-northeast- and north-northwest- to northwest-trending cross structures near or at the point they intersect the north-trending Ratto Ridge fault and the Cambrian Dunderberg Shale and Hamburg Dolomite. This work identified 14 exploration targets in the Ratto Ridge area (Mako, 1993a).
Much of Barrick’s drilling was wide-spaced, with 50% of the drilling on Ratto Ridge and east of Lookout Mountain. Barrick’s work focused on the deeper potential in the Cambrian Dunderberg Shale east of the Ratto Ridge fault. Three holes were drilled West of Ratto Ridge to test the potential of Devonian Nevada Group rocks, especially the Bartine Limestone, west of the Ratto fault. Outcrops of Bartine Limestone in the area show weak gold mineralization, strong alteration, and anomalous pathfinder element geochemistry. Barrick drilled a total of 40 RC holes on the current Lookout Mountain project. Drilling of their geological and geochemical targets, as well as additional drilling in areas of known mineralization previously discovered by Amselco, encountered insufficient mineralization to meet Barrick’s corporate objectives and led them to drop the project in June 1993.
Echo Bay Exploration, Inc. (“Echo Bay”) leased the Lookout Mountain claim group in August 1993 from Rocky Canyon Mining Company (G.I.S. Land Services, 2008; Jonson, 1991). They conducted mapping, soil- and rock-chip sampling, and scattered drilling in the area, exploring deep high-grade potential in the Cambrian Dunderberg Shale and Hamburg Dolomite and testing Devonian Nevada Group targets west of the Ratto Ridge fault. Their sampling in 1994 through 1996 covered the non-alluvial-covered areas of nearly the entire claim block with a total of 2,343 soil samples collected and analyzed for gold, silver, arsenic, antimony, and mercury. Some samples were also analyzed for base metals. Echo Bay also collected about 150 surface rock chip samples during 1994 and 1995. Numerous anomalies were identified through these geochemical sampling programs. They also undertook a CSAMT (Controlled Source Audio-Frequency Magneto-Telluric) survey in the Ratto Canyon area in 1994. According to Emmons (1998), Echo Bay drilled 106 RC holes at Lookout Mountain from 1994 through 1997, for a total of 71,535 feet, although records show only 105 holes were drilled, which is the number of Echo Bay drill holes in the resource database. Most of Echo Bay’s drilling took place in Rocky Canyon, just north of Lookout Mountain (Edmondo, 2008b). Their best intercepts were as follows (the true thickness of all intercepts is uncertain):
| ● | 110 feet grading 0.043 oz Au/ton in the Dunderberg in EBR-27; |
| ● | 115 feet grading 0.043 oz Au/ton in the Nevada Group in EBR-9; and |
| ● | 90 feet grading 0.028 oz Au/ton in an offset of EBR-9. |
Alta Gold Company (“Alta”) sub-leased 227 of Echo Bay’s 373 claims in December 1997, staked five additional claims, and began permitting a delineation-drilling program (Alta Gold Co., 1999). Alta conducted metallurgical test work on mineralized pit samples and drill cuttings from the Lookout Mountain open pit in 1997 as part of their due diligence study (Langhans, 1997). In 1999, Alta acquired the remaining 146 claims from Echo Bay that covered the Rocky Canyon area in the northern portion of the Lookout Mountain project (Wilson, 1999). Jennings and Schwarz (2005) indicated Alta had studied the dataset for Lookout Mountain from 1997 to 1999 but aborted their plans for permitting, exploration, and development of the Lookout Mountain mineralization. No
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information on any other exploration that Alta may have conducted on the property is available. Alta dropped the property in May 1999 (G.I.S. Land Services, 2008).
Century Gold LLC (“Century”), a privately held exploration firm, leased the Lookout Mountain claim block from Rocky Canyon Mining Co. in August 2003 (G.I.S. Land Services, 2008), along with four other claim blocks in the Eureka district. Century did not perform any work on the property and sublet the lease to Staccato in 2004.
A three-hole core drilling program was initiated in the historical Lookout Mountain pit on November 5, 2005, and 16 core holes were drilled in and immediately adjacent to the south end of the pit between February 5 and July 13, 2006. Staccato continued drilling through the spring of 2007. The drill programs were designed to confirm the existence of mineralization encountered in previous RC and conventional rotary drilling, to compare the results from core and rotary drilling, and to collect higher-quality geologic information through core drilling. Based on their drilling, Staccato recognized that the mineralization is hosted in collapse breccias formed by decalcification of the host rocks. Additionally, they identified iron-rich dolomite, zebra dolomite, sooty pyrite, and other alteration types commonly associated with Carlin-type deposits (Mathewson, 2006). Staccato drilled a total of 25 core holes (BH-series) from 2005 to 2007.
In 2008, after management changes, Staccato began a new exploration program designed to test gold mineralization outside of the Lookout Mountain pit area, and a technical program was initiated that was designed to bring the Lookout Mountain resource to a pre-feasibility stage. Staccato drilled an additional seven core and 18 RC holes (BHSE-series) in the South Adit, Pinnacle Peak, Triple Junction, and Rocky Canyon areas during this phase. Another goal of the drilling was to develop a better structural and stratigraphic understanding of the numerous gold zones present along Ratto Ridge. The seven core holes were drilled primarily for stratigraphic purposes and covered the strike extent of Ratto Ridge.
In addition to drilling, Staccato extended soil sample grids by taking an additional 1,100 samples, completed a detailed ground magnetic survey to identify structural trends important to mineralization, and began surface geologic mapping. Staccato mapped surface exposures at 1:2,400 and 1:4,800 scales along Ratto Ridge. To generate consistency in identification of formations, Staccato initiated re-logging of old drill cuttings and core and began three-dimensional modeling efforts. This work was ongoing up to the merger with Timberline in 2010, and the results of this work were used to re-interpret geology, structure, and mineralization necessary for pre-feasibility work (Edmondo, 2010b). Timberline acquired the Eureka property, including the Lookout Mountain project, in June 2010 through its acquisition of Staccato (Timberline press releases dated March 23, June 1, and June 3, 2010). Timberline continued the exploration programs started by Staccato in 2008 with the intent of bringing Lookout Mountain into production. This work included geologic modeling, baseline studies for mine permitting, and work toward generative exploration purposes. From the acquisition of Staccato to 2015, Timberline completed additional ground magnetic surveys, soil sampling, and rock sampling, throughout the property. Fifteen additional holes were drilled at Windfall to assess the purchase of patented ground, and 10 Reverse circulation holes were drilled in Dale Canyon and the Paige Corwin area as exploration drilling. Most drill footage between 2010 and 2013 focused on Lookout Mountain for metallurgical, resource, infill, and PEA studies to assess potential mining operations.
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In 2014, Timberline initiated a program to test high-grade mineralization at depth for both Windfall and Lookout Mountain. At Windfall, five RC holes were drilled into better-grade areas at the South end of the Windfall Pit. Holes BHWF-037 and BHWF-041 encountered significant high-grade mineralization where cross structures were interpreted to cut the main North-South Windfall Fault trend. At Lookout Mountain, holes BHSE-171, BHSE-172, BHSE-173, and BHSE-174 were drilled as offsets to BHSE-152 which ended in high grade gold. BHSE-152 was a pilot hole to a monitor well installed in 2012, and was lost at 1100 feet, with the last 15 feet averaging 0.138 oz/ton Au. All four offset holes encountered significant high-grade mineralization, with the newly found mineralization being called the Water Well Zone.
Between 2015 and 2019, Timberline did no direct work at Lookout Mountain and Windfall. The company focused on land issues at Windfall and assessing other properties held by Timberline outside the Eureka District. In July 2019 Timberline announced a Joint venture with PM&G Gold Mines to explore the Lookout Mountain area. The Joint Venture ended June 28, 2020, when PM&G Gold mines were unable to raise sufficient funding to continue the venture. Starting at the announcement of the venture, Timberline re-interpreted geology and mineralization and began drilling on the property in 2020 after the venture ended. From 2020 to 2022, Timberline drilled 65 reverse circulation and core holes for 55,841.3 feet, mainly into the Water Well Zone, completed IP and CSAMT surveys at Lookout Mountain and Windfall (Figure 5-1), and conducted gravity and geochemical surveys throughout the property.
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Figure 5-1 Ground RTP Magnetics map showing IP and CSAMT Lines at Lookout Mountain and Windfall (McEwen, 2026)

McEwen Inc. acquired Timberline in August of 2024. McEwen has moved forward with drilling and generative exploration programs at both Lookout Mountain and Windfall. Early programs involved data review and drill planning with confirmation drilling at Windfall in 2024 totaling 14,405.0 feet. McEwen initiated exploration-oriented activities and planned additional drilling in late 2024 and early 2025 for the 2025 drill program. Details for the 2025 program are in section 7.
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5.2.Past Production
As stated in section 5.1, District-wide production is poorly known due to inadequate record keeping from 1869 to 1902, the period of greatest production. Nolan (1962, 1967) estimated from 600,000 to over 1,000,000 ounces of gold were produced in the Eureka District between 1869 and 1962. Later Shawe and Nolan (1989) stated 1.65 million ounces of gold were produced from the district.
In the southern portion of the District (formerly known as the Secret Canyon District) there has been small historic production of silver, lead, zinc, and gold of unknown quantities. Vanderburg (1938) reports much of this came from the Geddes Bertrand mine in Secret Canyon where county records indicate $629,468 in gross production revenue. Underground production from the Windfall mine to 1938 is estimated at $349,428 from 65,132 tons of ore (Ingersoll, 1934). Sookochoff (1984) reports an average grade of 0.356 ounces per ton gold for the Windfall underground production.
Wilson (1990, 1986) gave resource figures for the Windfall area of 3 million tons of material averaging 0.03 ounces gold per ton in 1984 and reported 1.0 Mt of ore at an average grade of 0.03 ounce/ton for Windfall and 1.8 Mt at an average grade of 0.029 ounce/ton at Rustler prior to mining in 1974. Actual production figures for the three open pits vary by report. Cargill (1988) reports production from the Windfall mine of 1,458,274 tons of ore, recovering 31,077 ounces of gold. Sookochoff (1984) reports 650,000 tons of ore were mined at an average grade of 0.035 for Windfall and 300,000 tons mined at Rustler grading 0.026 ounces gold per ton. Sookochoff also reports delineation of other non-mined mineralization of 531,000 tons grading 0.024 ounces gold per ton at Rustler to 153,000 tons grading 0.086 ounces gold per ton at South Paroni. Russell (2005) provides production figures for the three open pits at Windfall to be 2.8 million tons at an average grade of 0.04 ounces gold per ton.
Norse Windfall Mines operated the heap-leach mine at Lookout Mountain between 1987 and November 1988 (Jonson, 1991). Production from January through December 1987 totaled 180,196 tons averaging 0.12 oz Au/ton and yielded 17,700 ounces of gold; recovery was 81% (Cargill, 1988; Jonson, 1991). No information is available regarding the actual production between January and November 1988.
Lookout Mountain ore was hauled 5.6 miles from the pit to the Windfall Mine for crushing, agglomeration, and heap-leaching. Recovery was expected to be 85 to 90%, but problems by the mining contractor resulted in the lower recovery (Jonson, 1991, citing an August 1988 report which is unavailable). The cutoff mining grade was 0.02 oz Au/ton due to the long haul to the agglomerator (Jonson, 1991). Mining reportedly was discontinued due to unspecified financial, management, logistical, and metallurgical problems, as well as a lawsuit (Russell, 2005; Alta Gold Co., 1999).
It should be noted that any references in the previous paragraphs relating to “resources”, “reserves” or “ore” production are historic in nature, do not necessarily conform to current S-K 1300 guidelines and should not be relied upon as current. Current mineral resources for Lookout and Windfall are described in Section 11.
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6. | GEOLOGIC SETTING AND MINERALIZATION |
6.1.Geologic Setting
6.1.1. Regional Geology
The following information on regional geology has been taken from Russell (2007), Nolan et al. (1956), Jennings and Schwarz (2005), and Cargill (1988), which in part summarize work by Roberts (1960) and Roberts et al. (1967).
Mineralization in the Eureka Mining district is hosted in a series of sedimentary rocks of Cambrian through Permian age that were deposited in a marine carbonate shelf environment along a passive plate margin. Limestone, dolomite, quartzite, and shale make up the Paleozoic section (Figure 6-1). Beginning in the Mississippian era, compressional tectonics during the Antler Orogeny initiated the Roberts Mountains Thrust (RMT). The Paleozoic Antler Orogeny was characterized by east-directed compression and thrust faulting that transported siliceous and volcanic rocks from the west over shelf sequences in eastern Nevada along the Roberts Mountains thrust, which is exposed just west of the Eureka district. While the Roberts Mountain thrust does not cover the Lookout Mountain area, it exerted a major influence on the structural features of this area in the form of near-surface disturbances in front of the advancing thrust. In response to the Antler Orogeny, Mississippian to Permian age Siliciclastic and carbonate strata were deposited along the Eastern margin of the thrust belt through central Nevada, representing fluvial continental and shallow marine deposition from the Antler highlands. Subsequent compression during the Sevier Orogeny further deformed the Mississippian and Permian rocks, and older rocks again, in the Eureka area. Long et al. (2014) interpret the Eureka area to represent a structural culmination at the forefront of the Cretaceous Sevier fold-thrust system.
A period of erosion occurred from the Triassic into the Jurassic as marked by unconformable deposition of late Jurassic and Cretaceous conglomeratic sediments (Nolan and Merriam 1956). In East-central Nevada, the Newark Canyon Formation representing non-marine clastic deposition is widely distributed (Nolan et al, 1956, Merriam, 1963), including within the Eureka District. Plutonic rocks of Jurassic and Cretaceous ages (168-143 Ma and 105-87 Ma; Silberman and McKee 1971) were intruded into Paleozoic sediments, forming a variety of hydrothermal ore deposit types throughout central Nevada. Age dating of alteration at Eureka, Mount Hamilton, Cortez, and other localities in central Nevada shows mineralization of various types to be associated with the late Cretaceous pluton ages. The Ruby Hill stock and Graveyard Flat intrusions of late Cretaceous age are thought to have been responsible for the Carbonate replacement Pb-Zn-Ag replacement bodies in the Eureka District.
In contrast, extensional tectonics dominated the Tertiary in northeastern Nevada, culminating in formation of the block-faulted Basin and Range physiographic province. Several periods of Tertiary igneous activity have been identified throughout Nevada where younger ages show progressions westward, (Axen and Taylor, 1993; Dickinson, 2006). In central Nevada, andesitic to rhyolitic volcanic rocks and granitic intrusions were emplaced between 43 and 34 Ma, which coincides with deposition of most of the Carlin style gold mineralization in the region. Rhyolitic and quartz latitic ash-flow tuffs erupted from calderas between 34 and 17 Ma, particularly in the Battle Mountain
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area. From 17 to 15 Ma, basaltic andesite volcanism, dike emplacement, and related gold mineralization took place along the northwest-trending Northern Nevada Rift and parallel structures, followed by peralkaline and rhyolitic volcanism in northern and western Nevada from 14 to 6 Ma.
The Eureka district lies on the southern end of the Battle Mountain-Eureka trend, also known as the Cortez trend, which hosts many sediment-hosted gold deposits and base-metal replacement deposits. The trend extends about 100 miles from Battle Mountain (Phoenix, Cove McCoy, Marigold mines) on the northwest through the Lewis, Hilltop, and Cortez districts (Pipeline, Cortez and Cortez Hills mines; Fourmile, Hilltop, and Goldrush resources) and the Tonkin Springs, Gold Ridge, and Gold Bar mines, ending at the Eureka district on the southeast (Archimedes gold Mine; Ruby Deeps and Mineral Point gold resources, FAD shaft and Ruby Hill CRD Mines). The trend, which strikes N25°W, does not lie parallel to any topographic feature, known structure, or type of lithology.
6.1.2. Local Geology
The following information has been taken from Russell (2007), Shawe and Nolan (1989), Steininger et al. (1987), Hauntz (1985), and Cargill (1988), which in part summarize the work of Nolan (Nolan et al., 1956, Nolan, 1962) and Roberts et al. (1967).
The Eureka district lies at the northern end of the Fish Creek Range and is underlain by a miles-thick sequence of Cambrian through Devonian calcareous and siliciclastic sedimentary rocks that were affected by the Late Devonian to Early Mississippian Antler Orogeny. Above that strata are post-orogenic coarse clastic units commonly referred to as the Overlap Sequence of shallow marine siliciclastic sediments of Mississippian to Permian ages, which are then overlain by Lower Cretaceous freshwater sedimentary rocks and megabreccia of the Newark Canyon Formation. Tertiary volcanic rocks cap the sequence.
A variety of intrusive rocks of both Mesozoic and Tertiary age occur locally within the Eureka district. The Cretaceous aged Ruby Hill stock in Zulu Canyon is an equigranular to porphyritic granodiorite to quartz diorite. The surface exposure is small, but drilling, magnetic data, and alteration patterns show the stock to be much larger, forming the footwall to the Ruby Hill Fault which hosts the most productive mines in the district (Vikre, 1989). The Bullwacker sill crops out on Mineral point and the Graveyard Flats intrusion to the East of the Bullwacker sill was encountered in underground workings. Nolan also mapped a series of quartz porphyry dikes occurring in a north-south zone along the east flank of Prospect Mountain. Mapping by Staccato and Timberline staff in the southern portion of the district encountered several dikes at surface on Hoosac Mountain, Ratto Ridge, in Secret Canyon, and in the Windfall Pit. Dikes have also been intersected in drilling at Lookout Mountain. A small granodiorite stock is present at the Paige Corwin mine in Dale Canyon at the Windfall project.
Extrusive volcanic rocks in the district have two known local sources. Richmond Mountain, East of the town of Eureka, is an andesitic to dacitic volcanic center, and near Pinto summit a nested rhyolitic dome complex occurs in Dale Canyon immediately Southeast of Hoosac Mountain. Extrusive rocks occur throughout the district. Most exposures are ash flow and ash fall sheets filling paleo depressions and as broader sheets on older peneplane surfaces.
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Vikre (1998) presented isotopic age dates for igneous rocks and alteration in the northern portion of the district in his discussion of intrusive relationships to skarn and carbonate replacement mineralization. Age data were compiled from sources that used K-Ar methods for radiometric dating. The age dates indicate granodiorite to quartz monzonite intrusions provide age ranges from 99 to 106 Ma, alteration from vein selvages using muscovite and K-feldspar range from 68 to 107 Ma, clustering near 88 to 96 Ma, and Tertiary aged dikes ranging in age from 30.9 to 36.8 Ma. Tertiary ages from dikes dated at Ruby Hill and Mineral Point match well with Ar/Ar dates analyzed by Long et. al (2014) for extrusive and intrusive igneous rocks in the southern portion of the district where age dates range from 34.5 to 37.8 Ma.
The district is structurally complex. Rocks as young as Permian were deformed and cut by thrust faults, which themselves were deformed into a series of north-trending folds by compression that continued into Cretaceous time. Nolan (1962) mapped a large north-striking anticline with a core of Cambrian strata. Cambrian and Ordovician Strata on the East flank of Prospect Mountain dip steeply east and are bounded by Mississippian and Devonian strata also dipping east. Small anticlines and synclines are seen in the Mississippian units which may represent the limb of a syncline seen in the Diamond range to the northwest of Eureka. West of Prospect peak Ordovician rocks show variable dips but generally show gentle westerly to gentle east dipping units that are in fault contact with the Eldorado Dolomite. Siluro-Devonian strata west of Ratto Ridge have flat lying to gentle east dips.
Nolan (1962) identified several thrust sheets in the underground workings where Cambrian strata has been thrust over Ordovician, Devonian, and Silurian strata. At Lookout Mountain deep core holes have penetrated a thrust plane which juxtaposes Lower Cambrian strata on top of Ordovician and Silurian strata. Thrusting is complex with many potential interpretations.
The Compressional tectonic features developed during the Antler and Sevier orogenic events have been cut by Eocene and younger extensional events. In the heart of the district there are several large-offset north-south striking normal faults that may influence control of Carlin-style mineralization in the district (Hoge et al, 2015).
At the North end of the District two faults named the Jackson and Lawton-Bowman faults control much of the CRD and Carlin style mineralization, indicating the faults were active in the Cretaceous. The Jackson and Lawton-Bowman faults are sub-parallel faults with several west-northwest and east-west cross faults. The Lawton-Bowman strand has been mapped along Mineral Point S into the west-northwest striking Ruby Hill Fault where it has been offset to the east (Nolan, 1962). Nolan extends the Lawton Branch up Zulu Canyon and along Prospect Ridge, where it terminates against the Silver Connor Fault, a north-east striking fault displacing Eldorado Dolomite against Hamburg Dolomite.
Nolan (1962) maps the Jackson fault from Mineral Point, East of the Holly fault, extending South where it is covered by Tertiary Volcanics adjacent to the FAD shaft, and into Goodwin Canyon. Hoge et al (2015), as Nolan (1962), maps the Jackson as cutting the Ruby Hill fault in the vicinity of the old Jackson Shaft. From the old Jackson shaft, Nolan (1962 ) maps the Jackson joining the Lawton-Bowman at the Silver Connor fault, extending the main branch to the southwest and then south along the east flank of Prospect Ridge where they believe the fault is responsible for mineralization in the Diamond, Berryman, Lord Byron, and Industry Mines.
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McEwen staff believe the Jackson Fault, or a splay off the Jackson-Lawton-Bowman system, extends south down to the Windfall area based on the locations of splays, the alignment of rhyolitic intrusions, alignment of gold only mineralization from the Rustler Mine, north into carlin style mineralized drill intercepts near the Catlin and Dunderberg shafts, and the alignment of the Catlin, Dunderberg, Eureka, Uncle Sam, and Hamburg Mines. This interpretation implies the Jackson and Lawton faults are offset by the Silver Connor Fault. The Jackson fault is believed to have significant control over Carlin-style mineralization in the district (Hoge et al, 2015).
Similarly at Lookout Mountain two large north-striking faults with large displacement occur. The Dugout, or Oswego Fault bounds the east side of Ratto Canyon. It is a steep west dipping fault separating Eldorado Dolomite from Ordovician Eureka Quartzite and Pogonip group limestone. Mineralization at the Oswego Mine is controlled by the Dugout Fault. The Dugout fault extends from the South end of Secret Canyon Ridge up to Prospect Peak where it has been cut by a northeast cross fault. The Ratto Ridge, or Lookout Mountain Fault, extends from Prospect Ridge, ½ mile west of Prospect Peak, through Rocky Canyon, along Ratto Ridge, and beneath volcanic cover at the south end of Ratto Ridge. The Ratto Fault separates Prospect Mountain Quartzite from Ordovician strata at the north end, and Middle Cambrian strata from Devonian strata along Ratto Ridge. Gold mineralization is found on both faults with higher gold grades at intersections with or entirely in northwest and northeast cross faults.
6.1.3. Project Geology
The following information on the geology of the Lookout Mountain project is taken from Russell (2007), Morris (2007), Steininger et al. (1987), Alta Gold Co. (1999), Cope (1992), Cargill (1988), and geologic mapping and drilling by Staccato and Timberline, unless otherwise noted. The Windfall and Lookout Mountain projects share many similarities including host rocks, mineralization styles, and structural complexity (Figure 6-2). Both occur on or within sets of North oriented major structural zones with gold deposition within the Hamburg dolomite at and near the contact with the Dunderberg Shale. Significant differences are present though, including mineral control, structural setting, and alteration patterns. Both systems, geochemically and mineralogically represent Carlin Style mineralization.
6.1.3.1.Lookout Mountain Geology
The Paleozoic section in the Lookout Mountain project area is dominated by lower Paleozoic calcareous rocks that are complexly folded and faulted. The Cambrian rocks throughout the Eureka district are part of a Paleozoic thrust system that, at Lookout Mountain, places Cambrian rocks on top of Ordovician and Silurian rocks. Within the Cambrian sequence, internal thrusting and ramp faulting have created an imbricate set of lower-angle faults (Nolan, 1962), which cuts out most of the Cambrian Hamburg Dolomite beneath Lookout Mountain and Ratto Ridge (Edmondo, 2010a). Remnants of Hamburg Dolomite are found beneath the Dunderberg Shale within the core and along the east flank of an antiformal feature beneath Lookout Mountain and South Lookout Mountain. The Hamburg Dolomite along these zones is a dolomitized limestone that has largely been dissolved, forming a collapse breccia controlled by the anticline and a north-trending, 60°E-dipping fault system interpreted as a ramp structure (Edmondo, 2010a)
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Figure 6-1 District Geology with Jackson-Lawton Fault system and the Ratto Ridge – Dugout fault system. (McEwen 2026)

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Figure 6-2 Stratigraphic Column of the Eureka District (McEwen 2026). Not to scale

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Figure 6-3 Geologic Map of the Eureka Property

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Steininger et al. (1987) described several episodes of structural deformation in the Ratto Canyon region, noting that structural relationships at Ratto Canyon are obscured in places by widespread silicification of the Paleozoic rocks. Amselco mapped at least two potential thrust faults along Ratto Ridge, with a third thrust that may exist west of the South Adit area (Hauntz, 1985). Conodont ages show that Cambrian rocks have been thrust over Ordovician and Silurian rocks at depth (Edmondo, 2010b, citing a 2009 Staccato internal company report). Three principal sets of normal faults which strike northeast, northwest, and east-west have been identified cutting thrust faults (Hauntz, 1985). There are also strike-slip faults that appear to be tear faults associated with the thrusting.
A pronounced north-trending high-angle fault zone, the Ratto Ridge fault system (also referred to as the Ratto Canyon fault and the Lookout Mountain fault), has localized jasperoid development and gold mineralization in sedimentary units along more than 3.5 miles of strike length (Figure 6-5). This fault juxtaposes gently dipping Cambrian sedimentary rocks on the east against gently dipping Devonian sedimentary rocks on the west, an offset of perhaps 7,000 feet vertically along Ratto Ridge. The Ratto Ridge fault system is cut by several northeast- and east-trending, steeply south-dipping faults, and by less prominent northwest-trending, steeply south-dipping sets of faults. A second large north-northwest trending fault is present in the Oswego mine, one mile East of Lookout Mountain. This fault is sub-parallel to the Ratto Ridge Fault and has similar stratigraphic displacement. The relationship between the two faults is unknown. DiFiori (2014) believes the faulting in the Lookout Mountain area structurally represents an accommodation or relay zone between these two major faults active during the Tertiary. Drilling in 2020-2023 has been re-evaluated by McEwen geologists to be a graben-like structure, which would be compatible with mapping by DiFiori (2014) (Figure 6-4).
Favorable stratigraphic units, including the Cambrian-aged Hamburg Dolomite and Dunderberg Shale among others less well explored, have focused up-dip gold deposition at fault/stratigraphic intersections. Other potential host rocks include the Ordovician Pogonip Group, the Devonian Bartine Limestone, and the Devonian Oxyoke Canyon Sandstone. Cambrian, Ordovician, and Devonian units are known to host gold deposits elsewhere in the region, such as at the Ruby Hill mine in the northern part of the Eureka District, Gold Bar (40 miles to the northwest), and at Bald Mountain (80 miles to the northeast). Tertiary intermediate flows and tuffs with minor porphyry dikes and sills intrude and unconformably overlie the Paleozoic section in the area and are part of the Eureka and Pinto Summit volcanic centers. The under-explored stratigraphic units at Lookout Mountain are potential targets for future exploration efforts.
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Figure 6-4 Section through the Lookout Mountain Pit

There are breccias of multiple origins in the Lookout Mountain pit and the Staccato drill core (Mathewson, 2006). Mathewson noted that breccias, folds, and fault structures within the stratigraphy appear to have disrupted individual stratigraphic units. The prospective horizon for significant gold deposits, whereby shale overlies limestone, is common in numerous Carlin-type gold deposit settings, and this setting is particularly conducive to the development of dissolution-induced collapse-breccia-hosted, high-grade gold deposits. Examples include Meikle, Gold Strike, Deep Star, portions of Gold Quarry, Rain, and perhaps Cortez Hills.
At Lookout Mountain, high-grade gold mineralization is present almost exclusively within reduced (sulfidic) collapse breccia along the contact between the Dunderberg Shale and Hamburg Dolomite. Most breccias appear to be collapse breccias, but there are also tectonic, and probably, depositional breccias. Low-grade mineralization, mostly oxide, is broadly distributed in oxidized and silicified and/or oxidized and dolomitized breccia zones. The majority of these breccias occur along Ratto Ridge and are collectively referred to as the Lookout Mountain breccia.
Based on additional surface mapping and sampling and re-logging of over 400 drill holes in 2009 and 2010 (Edmondo, 2009, 2010c), Staccato and Timberline generated a new geological interpretation of Ratto Ridge. The new interpretation identified the Ratto Ridge fault zone, separating Devonian and Cambrian, as the main control of alteration and mineralization along the ridge. This was consistent with previous workers. The trace of the Ratto Ridge fault zone is often indistinct due to alteration, colluvial cover, crosscutting faults, and jasperoid bodies. There are numerous intrusive bodies along the fault zone. West of the fault zone lies a gently north-dipping,
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relatively undisturbed sequence of Devonian dolomites, while on the east side of the fault are the Cambrian Windfall, Dunderberg Shale, and Hamburg Dolomite formations.
Figure 6-5 Geologic Map of Lookout Mountain

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Figure 6-6 Geologic Map of the Windfall Trend

Conodont age determinations in core drill hole intersections of quartzite and dolomite below the Secret Canyon Shale show the Cambrian section to have been thrust over the top of the Silurian Lone Mountain Dolomite and Ordovician Eureka Quartzite. An internal fault in the Cambrian section above the thrust plane has removed most of the Hamburg Dolomite from between the Secret Canyon and Dunderberg Shales on the east flank of Lookout and South Lookout Mountains, and is interpreted as ramp structures that are important controls of mineralization.
According to Timberline’s interpretation, most gold mineralization is hosted in a solution or karst breccia (Lookout Mountain breccia) formed in the overthrusted remnants of Hamburg Dolomite that lie in the footwall of faults below the crest of Ratto Ridge. Collapse breccia sediment derived from the dissolution of multiple rock types, especially the Hamburg Dolomite and other dolomites, and subsequent re-deposition of fine-grained sediment along fluid pathways is the primary host of
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mineralization (Edmondo, 2009). These collapse breccia sediments are usually lithified but maintain high permeability and are easily altered and mineralized, often with 5 to 10% (or more) of sulfides in unoxidized rocks. Drilling indicates there is very little mineralization in the Secret Canyon Shale, but the overlying Dunderberg Shale hosts significant high-grade gold mineralization.
6.1.3.2.Windfall Geology
The geology of the Windfall area has been discussed by Wilson (1984, 1986), and Nolan (1962). Mineralization at Windfall is hosted largely in the Hamburg Dolomite, at and below the contact with the Dunderberg Shale (Figure 6-6). Mine evaluation reports (Ingersoll, 1934; Young, 1937) noted from underground that two North striking “veins” of siliceous oxidized ore were mined that contained numerous cross structures also carrying high grade gold. One vein, on the east side of the mine was along the contact between the Hamburg Dolomite and Dunderberg Shale. The other vein was along a high angle north striking structure completely within the Hamburg Dolomite. Mining by open pit methods in the 1970’s and 1980’s exposed these structures and showed the contact between the Hamburg Dolomite and Dunderberg Shale to be faulted. These two structures are referred to as the Windfall Fault Zone (Figure 6-6). Historic mapping and drilling show these two structures to extend well North into New York and possibly Goodwin Canyons, and South along Hamburg Ridge into Round Top Mountain at the South end of Hamburg Ridge, a distance of 5 miles. These structures may represent the southern extension of the Jackson Fault.
Exposures of the Secret Canyon Formation on the West flank of Hamburg Ridge indicate a general northerly strike and moderate east dip. Exposures in road cuts show an antiformal feature to exist between the lower contact with the Geddes Limestone and the upper contact with the Hamburg Dolomite. Bedding turns steep near the Hamburg contact and the structures which control mineralization along the Windfall trend. Bedding remains steep East of the Windfall Fault zone until the faulted contact with Mississippian strata at the top of Hoosac Mountain and along the east flank of Jewel Ridge is reached. Strata between the Windfall fault zone and the Mississippian section includes the Hamburg Dolomite, Dunderberg Shale, Windfall Formation, Goodwin Limestone, and Eureka Quartzite. The section is markedly thinned, which may be related to an attenuation fault system related to the Hoosac Fault (Long et. al., 2014).
Pit mapping and drill data from McEwen and Timberline geologists indicate the steep easterly dipping strata are consistent to the south, beyond the extent of the Rustler Pit, but cross faulting has offset the strata, particularly the Hamburg/Dunderberg contact. The largest cross fault identified to date is the Nolan Fault, a northeast striking, steep southeast-dipping fault between the Windfall and Rustler pits. The Nolan fault offsets the Hamburg/Secret Canyon contact, the Hamburg Dunderberg contact, and volcanic rock in a down-to-the-south fashion. Other cross faults affecting the contact include E-NE faults in the Rustler Pit which down drop volcanic rocks to the North. As described in historic underground reports (Ingersoll, 1934), the Windfall mine has numerous east-northeast cross faults carrying gold. These structures are seen in the highwall of the Windfall pit where east-west to northwest-striking fracture and fault sets are observed. Dips are variable with both high-angle and low-angle features present. Drilling by McEwen shows these cross faults to carry higher grade mineralization at Rustler and Paroni pit areas, as historical reporting indicates at Windfall.
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A notable feature observed in the Windfall pit and in drill pads up to the Paroni pit shows the Hamburg/Dunderberg contact to be near-vertical to steeply east-dipping and likely structurally controlled. This may be traceable south but volcanic cover between the Windfall and Rustler Pits obscures the nature of the contact. Exposures on the east wall of the Rustler pit, and drill intercepts, indicate a steep easterly dip to the Hamburg-Dunderberg contact. Drilling to date is insufficient to determine if the contact remains steep at depth or becomes more gentle.
As at Lookout Mountain, breccia of several varieties is important along the Windfall trend as well. Throughout Hamburg Ridge, the Hamburg Dolomite is well brecciated which obscures bedding fabric and is likely due to diagenetic dolomitization or dolomitization due to solution collapse during hydrothermal activity. Solution collapse, sedimentary, and/or karst style brecciation is present and particularly well developed in the Windfall pit. Although karst and cave fill are present at Windfall, much of the mineralization, particularly high-grade material, is associated with structural brecciation along fractures and faults. Solution collapse and likely sedimentary breccia appear as important localizers for both high- and lower-grade mineralization within the Hamburg Dolomite.
6.2.Alteration and Mineralization
Alteration and mineralization at Windfall and Lookout Mountain are typical of Carlin-style systems elsewhere in Nevada. Both projects contain argillic alteration, decalcification, and silicification associated with pyrite and iron-oxide mineralization. Thin section and Scanning Electron Microprobe (SEM) studies of high-grade sulfide mineralization in shale from Lookout Mountain show that gold and arsenic are found in arsenian pyrite rims on diagenetic and hydrothermal pyrite, often with realgar and minor arsenopyrite, and an associated quartz-kaolinite-illite ferroan dolomite alteration suite typical of Carlin-style mineralization at Carlin, Cortez, Getchell, and Jerrit Canyon (Muntean, 2012).
6.2.1. Lookout Mountain
Alteration at the surface and in the subsurface is widespread, with decalcification and silicification being the most common types. This alteration is present for the entire length of Ratto Ridge and extends up to several thousand feet on either side of the main Ratto Ridge fault zone. Argillic alteration is also present, distinguished by the presence of abundant, multi-colored gumbo-like clays within the Dunderberg Shale. There appears to be a close spatial relationship between silicified zones and argillically altered zones (Hauntz, 1985). While skarn systems are known in the northern portion of the Eureka District, the development of skarn at or near Lookout Mountain is only known from the Newmont drill hole on the Rocky Canyon magnetic anomaly (Cargill, 1988). However, hornfelsed sediments were also noted in drillhole BHSE-206C located immediately northeast of Lookout Mountain, and marble textures have been recognized occasionally in drillholes through carbonate-rich intervals.
Alteration at Lookout Mountain is dominated by the presence of massive jasperoid breccia. At surface, jasperoid bodies are found along the crest of Ratto Ridge, extending for 2.5 miles from Lookout Mountain pit to the South Adit area. Jasperoid is also found in fault zones along the east
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flank of Ratto Ridge, near the Lookout Mountain pit. Gold mineralization is associated with jasperoid that caps Ratto Ridge downward to drilled depths of up to 1,500 feet vertically below the highest surface exposure (Gustin, 2013, 2023). Jasperoid is extensively developed in the Hamburg Dolomite, with Dunderberg shales showing strong silicification and locally jasperoid development, likely in limestone beds of the Dunderberg. Jasperoid bodies are silica replacement bodies of dolomitic and mix shale-dolomite breccia zones. At surface the jasperoid is dense, usually retaining lithologic textures, and variegated in color. In the deeper breccias within the Water Well Zone, jasperoid, or silicification, is vuggy and saccharoidal to very finely crystalline in nature.
Argillic alteration is present in the Dunderberg Shale along faults and at the margins adjacent to jasperoid bodies. Zones of pervasive argillic alteration are present but generally small in size and associated with large faults. Decalcification is also present, affecting limestones in the Dunderberg and within the Hamburg Dolomite. Much decalcification is adjacent to jasperoid, within fault zones, and as large swaths within Hamburg dolomite and Devonian strata at surface. Although present, “sanding”, which is a form of advanced decalcification, is less abundant at Lookout Mountain and typically associated with Hamburg Dolomite. Dolomitization and formation of iron carbonates and iron-rich (ferroan) dolomite were identified in the Staccato drill holes by Mathewson (2006) using alizarin staining techniques. The extent of this alteration is unknown but is spatially associated with decalcification.
Mineralization is typical of classic Carlin-style mineralization. Gold is hosted in arsenian pyrite and the oxidation products generated from arsenian pyrite. In fresh rocks, gold is associated with pyrite, realgar, quartz, and clay (Alta Gold Co., 1999). Surface jasperoid bodies are associated with a trace-element geochemical signature consisting of arsenic, mercury, and antimony in soil, rock chip, and drill samples. Multi-element geochemical analyses on drill samples (Mathewson, 2006; Edmondo, 2008a) demonstrate that gold mineralization in the Lookout Mountain area is rich in arsenic, with high-grade zones being particularly arsenic-rich. The high-grade zones are generally unoxidized, sulfidic, and, in addition to arsenic, consistently anomalous to very anomalous in thallium, antimony, and mercury. High-grade gold mineralization typically consists of 0.1 to 0.4 oz Au/ton, occasionally up to multiple ounces of gold per ton, and contains several thousand ppm arsenic up to values in the percent range. Several tens to hundreds of ppm mercury, several tens of ppm antimony, and several tens to hundreds of ppm thallium are also typical of high-grade gold zones. Silver is generally low within these high-grade gold zones (Mathewson, 2006). Low-grade gold zones of 0.01 to 0.1 oz Au/ton generally contain anomalous arsenic in the upper hundreds of ppm to several thousand ppm and are predominantly oxidized. These lower-grade gold zones also typically contain a few hundred ppm antimony, several tens to hundreds of ppm mercury, and up to one hundred ppm thallium.
6.2.2. Windfall
Decalcification is the dominant alteration type at Windfall and occurs along a zone approximately 100 to 200 meters wide and is present from the Paroni Pit to the South end of Hamburg Ridge. The Hamburg dolomite is thoroughly “sanded” in that the rock, although competent, can be dug out of the pit walls with one’s fingers, breaking down into “beach sand” where the rock thoroughly disaggregates. Decalcification is well developed throughout the Hamburg within the bounding
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faults of the Windfall fault zone. Associated with decalcification is zebra dolomite, an alteration consisting of leaching certain elements with the addition of iron and magnesium. It is characterized by alternating bands of light (sparry) and dark (replacement) dolomitic material with the lighter material being more calcium rich and the darker material more iron/magnesium rich. Zebra dolomite is well exposed in the Rustler and Windfall Pits where it is near vertical and occurs within and along the bounding North striking structures. The banding represented by the zebra dolomite can represent either diagenetic (Diehl et al, 2010) or structural processes (McCormick et al, 2025). It is not clear whether the zebra dolomite at Windfall represents structural or bedding control, but much is near-vertical in nature suggestive of structure. Zebra dolomite is also prevalent in Carbonate Replacement Districts as an early hydrothermal event. Given the presence of lead-silver replacement bodies along and within the Windfall trend the zebra dolomite may represent an earlier alteration event.
Silicification is present but in minor quantities. Mild to moderate silicification is present on faults, fractures, and locally along the Hamburg-Dunderberg contact. Drilling in 2024 and 2025 by McEwen has shown the silicified zones to be more prominent within and adjacent to high-angle cross structures and appears associated with higher-grade mineralization. Argillic alteration is seen mainly in the Dunderberg shale along faults and fractures, and along the Hamburg-Dunderberg contact. High grade sulfide mineralization, with realgar in the Windfall and Rustler pits is associated with argillically altered Dunderberg shale.
Geochemistry of mineralization at Windfall is similar to that at Lookout Mountain, in that gold mineralization is associated with elevated values of Arsenic, Antimony, Mercury, and thallium. At Windfall though, high grade gold (>3 g/t) zones are highly elevated in arsenic and antimony with many also elevated in Pb-Zn-Ag. Twenty-two base metal assays exceed 1% Pb, with two over 8% lead. All twenty-two assays have Ag > 25 ppm, and Zn > 1000 ppm with ten Zn assays > 1%. High grade gold does occur with low Pb-Zn-Ag results, and usually with higher Hg results (>5 ppm) although Mercury can be quite high (>10 ppm) with very high Pb-Zn-Ag. Low grade gold results (<1 ppm) are associated with elevated to moderately anomalous As, Sb, and Hg and variable to generally low base metal values. However, there are 83 drill assays with elevated Pb-Zn-Ag values exceeding 1000 ppm Pb and Ag > 2 ppm, including 12 with > 1000 ppm Zn.
The potential for the presence of carbonate replacement systems mixed with Carlin systems is high in the Eureka District. Dilles et al (1996) and Hastings (2006) describe cross cutting field and petrographic relationships showing Carlin style gold over printing Pb-Zn-Ag base metal replacement and skarn mineralization in the East Archimedes pit. Replacement Pb-Zn-Ag mineralization has been mined in the Windfall region historically. The Hamburg Mine, less than ¼ mile North of Paroni Pit and the Hoosac Mine on Hoosac Mountain were mined for their Pb-Ag content in the late 1800’s. The percentage of drill holes with multi-element geochemical assay results at Windfall is less than 10% and more geochemical analyses are needed to determine the extent of CRD and Carlin style mineralization in the Windfall area. The presence of high concentrations of Pb-Zn-Ag indicates the Windfall Fault zone also was a prominent pathway for cretaceous age CRD deposits. However, the geochemical signature at Windfall is suggestive that overprinting by Carlin systems on Pb-Ag CRD mineralization is likely.
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6.2.3. Gold Resource Areas
As discussed in sections 6.2.2, karst and/or solution/collapse breccia within the Hamburg Dolomite, at or beneath its upper contact with the Dunderberg Shale, is an important control on mineralization at the Lookout Mountain and Windfall projects. Mathewson (2006) recognized that extensive zones of hydrothermal-related dissolution and associated brecciation caused cavitation and collapse at the Hamburg-Dunderberg contact at Lookout Mountain. This collapse propagated in an upward stoping process that did not stop until well into the overlying shale unit, creating large, almost flat-lying breccia bodies. This ‘ground preparation’ became highly conducive to the introduction of subsequent fluids, including the gold-bearing solutions. This process likely operated during formation of carbonate replacement bodies in the district as described by Nolan (1962) at Ruby Hill. Large structural zones are important for the development of these collapse features, with cross structures and minor parallel structures to the main fault zones acting as important modifiers to the overall morphology.
6.2.3.1.Lookout Mountain
Exploration groups have described the Lookout Mountain deposit in various ways, but all workers have described the mineralizing system as being strongly controlled by structures and favorable host rocks. Steininger et al. (1987), reporting on Amselco’s discovery, described Lookout Mountain as follows: The mineralized zone trends north-northwest and dips 20 to 70 degrees to the east-northeast. Mineralization occurs in both jasperoid and in adjacent altered Dunderberg Shale, with the highest grades in altered shale adjacent to jasperoid. Gold occurs where the contact zone between the Dunderberg Shale and Hamburg Dolomite forms the hanging wall of the Ratto Ridge fault zone and where east- and northeast-trending faults provided ground preparation for mineralization.
Asher (1986) described the mineralizing system as a structurally controlled jasperoid body with an easterly dip of 60 degrees, and with several low-angle zones controlled by bedding occurring as offshoots of the main structure.
Barrick recognized five styles of gold mineralization (Mako, 1993a):
· | Low-grade gold disseminated in silicified Dunderberg Shale with locally higher grades in and near faults; |
· | High-grade gold in carbonaceous Dunderberg Shale that appears to be stratabound, including the sulfide zone beneath the historical Lookout Mountain pit; |
· | Gold-bearing jasperoid in the Hamburg Dolomite; |
· | High-grade gold mineralization in thin, fault-controlled zones; and |
· | Gold mineralization in silicified Bartine Limestone. |
Strong solution brecciation at Lookout Mountain has formed along a north-trending, 60° east-dipping structural zone that lies just east of the main fault separating Devonian from Cambrian stratigraphy along Ratto Ridge. The entire thickness of the Hamburg Dolomite along Ratto Ridge
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displays strong karstic- and collapse breccia textures. This section of Hamburg Dolomite and the overlying Dunderberg Shale hosts most of the mineralization at Lookout Mountain, and it is referred to as the Lookout Mountain breccia. The base of this breccia from Lookout Mountain to South Lookout Mountain is formed along a 50-60o East dipping fault interpreted as a ramp fault which separates Secret Canyon shale from Hamburg Dolomite and Dunderberg Shale. High-angle faults in the hanging wall of this north 60° east fault place Dunderberg Shale in contact with Hamburg Dolomite along the faults, creating a more bulbous or wedge-shaped nature to jasperoid development and mineralization within and below the pit (Figure 6-7). Heading south, jasperoid development and mineralization become more lenticular along the 60°-east-dipping fault zone. At the north end of South Lookout Mountain, the breccia zone transitions from a more lenticular body to a flat-lying breccia body floored by Secret Canyon shale, with North striking structures forming a near vertical surface between Dunderberg shale and the breccia body capping South Lookout Mountain,
Strongly altered and mineralized northeast- and east-northeast-trending faults, with moderate offset, cut faults related to the main Ratto Ridge structural zone, with west-northwest-trending faults in the Lookout Mountain area potentially localizing higher-grade mineralization (>= 0.10 opt Au). These high-grade zones are typically irregularly shaped discontinuous pods that occur at and near the contact between the Dunderberg Shale and the Hamburg Dolomite. There are four high-grade zones presently identified by drilling: one at the surface at the Lookout Mountain pit, another about 200 feet in depth, a third between 300 and 400 feet in depth, and the Water Well zone between 900 and 1100 feet in depth. The highest-grade zones are typically hosted within unoxidized to partially oxidized breccia bodies enclosed in limestones within the lower Dunderberg Shale or along the contact with the Hamburg Dolomite.
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Figure 6-7 Section Through the Lookout Mountain Pit
(McEwen, 2026)

6.2.3.2.Windfall
As described by old reports (Ingersoll, 1934; Bailey, 1975) mineralization at Windfall is controlled along two parallel north-striking, steeply east-dipping faults with significant east-west, east-northeast and northwest-trending cross faulting and internal fracture zones. Solution and fault breccia occurs on and between these north-striking steeply east-dipping structures. These structures are collectively called the Windfall Fault zone, and they are mappable from the Rustler pit north into New York Canyon and possibly into Goodwin Canyon. Alteration and mineralization are tightly constrained within the zone and consist dominantly of pervasive decalcification (sanding) and zebra dolomite alteration. This alteration weathers and erodes easily, forming more subdued topography rather than the bold cliffs and outcroppings seen at Lookout Mountain. High-grade mineralization within the zone is strongly structurally controlled with low-grade disseminations within sanded dolomite between the North Striking bounding faults. Low-grade disseminated material occurs as gently- dipping to flat-lying bodies with cross -faulting helping to control localization of mineralization.
Drilling by Timberline and McEwen thus far has been encountering mostly oxidized material. Sulfide material is usually encountered in the Dunderberg shale near the contact with the Hamburg Dolomite. This is best seen at the north end of the Rustler pit where fine “sooty” pyrite and realgar are seen in well brecciated and argillized shales. Sulfide material in drilling has been encountered in few holes. Where observed, the sulfide mineralization is very similar to that at Lookout Mountain and is indicative of Carlin-style mineralization encountered north of Windfall in New York Canyon, and at the Ruby Deeps resource of i80 Gold at Archimedes. The bulk of low-grade mineralization is
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present between the two high-angle faults and is hosted in strongly-decalcified and brecciated Hamburg Dolomite (Figure 6-9).
Jasperoid development at Windfall is minimally developed. Although areas of silicification occur locally, the large bodies of jasperoid as at Lookout Mountain are lacking along the Windfall trend. South of the Rustler pit there is moderate jasperoid development along the Hamburg/Dunderberg contact on Hamburg Ridge and historic drilling in the area indicates the presence of gold. North of Rustler, silicification is constrained to the fault and fracture sets, expanding only in regions of cross faults and structures. Spatially, the jasperoid and siliceous material are confined within and adjacent to the Windfall Fault zone.
6.2.4. Other Gold Occurrences in the Eureka Property
Surface gold anomalies, geology, and alteration features in the Cambrian through Devonian sections define multiple exploration targets on the property. These occurrences are located outside of the existing gold resource areas at Lookout Mountain and Windfall (Figure 6-8).
6.2.4.1.Rocky Canyon Area
A mineralized zone containing over 0.01 oz Au/ton based on very widely spaced drill holes extends at least 1.4 miles north from the Lookout Mountain deposit into the Rocky Canyon area. Scattered altered outcrops mark this north-trending zone, which appears to be at least 600 feet wide just north of the Lookout Mountain deposit and perhaps 1,400 feet wide near drill hole RCR-3 (approximately 1.25 miles to the north). The Haul Road anomaly is an outcrop of silty shale directly below massive Eureka Quartzite that contains an 80-foot section averaging 0.03 oz Au/ton in rock chip samples. It occurs about 3,500 feet northeast of the peak of Lookout Mountain (Jonson, 1991).
A large magnetic anomaly is located approximately 1.25 miles north of Lookout Mountain in the northern portion of the Rocky Canyon area and is believed to be caused by an intrusion. Newmont drilled a deep core hole in the area in a search for molybdenum and intersected skarn and a granitic intrusion (Cargill, 1988) dated with a U-Pb analysis of 87.42 Ma (Long et al., 2014) confirming a Cretaceous age. Hole 609 was drilled to a depth of 1,525 feet and intersected 50 feet averaging 0.023 oz Au/ton from 450 to 500 feet in a silicified, pyritized fault zone (Jonson, 1991). That hole also intersected metasomatic alteration associated with granitic dikes with magnetite, quartz, sericite, pyrite, molybdenite, fluorite, and calcite mineralization (Mako, 1993a).
Echo Bay drilled 75 holes in the Rocky Canyon area. Of these holes, 42 were drilled into the South Pogonip Anomaly, where 16 holes encountered “significant” gold mineralization (Alta Gold Co., 1999). Hole EBR-58-96 intersected 40 feet of 0.101 oz Au/ton, and EBR-77-97 intersected 45 feet of 0.131 oz Au/ton; the author cannot determine if the reported lengths represent true widths.
Gold mineralization in the Rocky Canyon area is hosted primarily in Siluro-Ordovician rocks, which are separated from the Lookout Mountain gold resource by faults in the Relay Zone (Figure 6-5). Silver is notably more common than in the Cambrian rocks that host the Lookout Mountain gold resource. Approximately one half of the drillholes in the Rocky Canyon Zone have at least a single-sample silver intercept of greater than 0.291 oz/ton.
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6.2.4.2.South Ratto Ridge
South Ratto Ridge has a similar structural setting to that of South Lookout Mountain except that the Eureka Quartzite is absent at South Ratto Ridge. Gold mineralization is present and is stronger near the thrust contact in the jasperoid and sanded dolomite of the Devonian Nevada Group. Existing drilling shows a strong structural control in the Southern Ratto Ridge area with mineralization and geochemistry showing strong similarities to Lookout Mountain. Jasperoid bodies are not as prevalent as they are to the North.
6.2.4.3.Pinnacle Peak
This area is about 1,000 feet south of the South Lookout Mountain area. It consists of three separate gold anomalies along a 1,500-foot strike length. Jasperoid bodies are present and make up the crest of Ratto Ridge with northeast cross faults offsetting lithologic contacts. Timberline drilled two holes at Pinnacle Peak in 2011, BHSE-097 and BHSE-098. Hole BHSE-097 intersected 65 feet at 0.025 oz per ton Au (0.846 g/t) and hole BHSE-098 intersected anomalous gold from 110 to 245 feet which averaged 113 ppb gold. Amselco drilled 20 RC holes in the general area, of which the six closest to the geochemical anomaly had intersections with assays of 0.03 oz Au/ton or better. Average distance between holes at Pinnacle peak is greater than 200 feet.
6.2.4.4.Triple Junction
Gold mineralization at Triple Junction is found at the Dunderberg Shale - Hamburg Dolomite contact, associated with steeply dipping normal faults in the crest of a south-plunging anticline. Triple Junction was first identified as a target by Amselco rock geochemical sampling in 1983 and lies east of the north-trending Ratto Ridge in an area of sparse outcrop. Amselco drilled eight RC holes in the area, with intercepts of 0.04 to 0.085 oz Au/ton in three of them. Staccato drilled 2 holes at Triple Junction with Hole BHSE-015, drilled in 2008 intersecting 85 feet at 0.014 oz per ton Au.
6.2.4.5.Water Well Zone
The Water Well Zone (“WWZ”) exploration target is located down-dip to the east of and outside of the gold resource in the Lookout Mountain area (Figure 6-8). The WWZ was discovered by Timberline in 2012 and was extensively drilled in 2020 through 2022. The zone is currently defined as an area of approximately 1,500 feet north to south and 200-300 feet east to west based on multiple high-grade gold intercepts ranging between 0.1 oz/ton and 0.5 oz/ton (Table 6-1). Vertical depths to the top of the WWZ mineralization range from approximately 460 to 1,200 feet below surface. The Dunderberg Shale – Hamburg Dolomite contact is the key host horizon in the WWZ. Gold is strongly associated with variably silicified (claystone to jasperoid) breccia, abundant sooty pyrite, and often carbonaceous material. The gold zones are highly anomalous in arsenic, antimony, thallium, zinc, and often, barium. The underlying Hamburg Dolomite is typically oxidized, variably brecciated and at least weakly gold anomalous.
The strongest intercepts in the WWZ appear to be associated with high-angle faults, some of which have been well drilled and mapped and others remain subject to better definition. Timberline continues to explore the WWZ, and it remains open down-dip to the east and southward.
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Table 6-1 Significant Drillhole Intercepts in the Water Well Zone (2014 - 2021)
Drill Hole | From ft | To ft | Length ft1 | Gold | Au GT |
BHSE-171 | 990.1 | 1075.1 | 85.0 | 0.074 | 6 |
including | 990.1 | 1044.9 | 54.8 | 0.099 | 5 |
including | 1020.0 | 1040.0 | 20.0 | 0.159 | 3 |
BHSE-172 | 895.0 | 1055.4 | 160.4 | 0.095 | 15 |
BHSE-173 | 935.0 | 1000.0 | 65.0 | 0.067 | 4 |
BHSE-187 | 875.0 | 960.0 | 85.0 | 0.064 | 5 |
including | 875.0 | 899.9 | 24.9 | 0.131 | 3 |
BHSE-205 | 455.0 | 575.1 | 120.1 | 0.031 | 4 |
BHSE-211C | 752.0 | 787.1 | 35.1 | 0.086 | 3 |
BHSE-212C | 1037.1 | 1171.9 | 134.8 | 0.147 | 20 |
including | 1042.0 | 1131.9 | 89.9 | 0.213 | 19 |
including | 1042.0 | 1106.9 | 65.0 | 0.277 | 18 |
including | 1042.0 | 1062.0 | 20.0 | 0.493 | 10 |
including | 1077.1 | 1102.0 | 24.9 | 0.234 | 6 |
BHSE-220C | 461.9 | 606.9 | 145.0 | 0.120 | 17 |
including | 461.9 | 537.1 | 75.1 | 0.182 | 14 |
including | 497.0 | 537.1 | 40.0 | 0.268 | 11 |
(1) Drill thickness – True widths of drill intercepts have not been determined
6.2.4.6.Oswego
The Oswego target occurs at a fault zone separating the Cambrian Eldorado Dolomite from the Cambrian Secret Canyon Shale and may represent the eastern margin of the gold system which crops out approximately 0.8 miles to the west at Lookout Mountain (Figure 6-8) and as identified in the subsurface at the WWZ. In 2022, Timberline geologists collected rock samples in a systematic chip, channel, and trenching campaign at the Oswego gold occurrence (see Section 7.4 for further details) along a splay of the Dugout Tunnel Fault.
Oswego is the site of a historical gold mine, and the historical Geddes-Bertrand silver mine is located approximately 0.5 miles to the north-northeast (Figure 6-8).
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6.2.4.7.Windfall Project
Hoosac
The historical Hoosac mine is a silver-lead (Ag-Pb) mine at the top of Hoosac Mountain with minor past production. The mine is on one of a series of large north striking structures (Hoosac Fault Zone) which separate Eureka quartzite from Mississippian Diamond Peak and Permian Carbon Ridge Formations. The structures are altered at surface, hosting jasperoid and argillic alteration, which affects the Mississippian, Permian, and Ordovician stratigraphy. Rock sampling shows anomalous gold along the trend of the fault zone, and IP data from 2021 Timberline surveys shows a large IP anomaly below Hoosac Mountain.
Pathfinder, Cambior, and Staccato drilled in the area with all encountering significant thickness of gold mineralization, including BHWF-026 (80’ @ 0.012 oz/t), HR-93-15 (45’ @ 0.015 oz/t), and CHR-95-3 (70’ @0.023 oz/t). BHWF was collared in Mississippian Diamond Peak and was lost in mineralization before crossing the fault.
Hamburg Ridge
The crest of Hamburg Ridge is formed by jasperoid and silicified shales at the contact between the Hamburg Dolomite and Dunderberg shale along the southern strike extent of the Windfall fault zone. Idaho Mining put in approximately 20 short rotary holes. All had intersections of gold mineralization. Amselco drilled hole HBR-002 in the early 1980s to test down dip of the Idaho Mining holes and intersected 130 feet at 0.010 ounce per ton gold (0.341 g/t). This hole has not been followed up.
Paige-Corwin, Roundtop Mountain.
The Paige Corwin area is at the extreme southern extent of Hamburg Ridge where the Paige Corwin Ag-Pb mine is located. Strong alteration is present, including jasperoid and decalcification, which has been mapped on the west and south flanks of Round Top Mountain. The area has seen drilling from Cambior, Pathfinder, and Staccato, all with short intervals of highly anomalous (> 0.100 ppm) gold. Hole HR-93-7 intersected 80’ @ 0.027 oz/t Au which remains open.
Jewel Ridge
The strategic acquisition of Golden Lake Exploration has opened the northern extension of the Windfall Fault zone that has been drilled over several decades, including by Homestake Mining Company, Golden Lake, and Galli Mineral Development. The trend is host to many historical CRD mines and drill intercepts of gold-only mineralization.
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Figure 6-8 Exploration Targets
(McEwen, 2026)

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Figure 6-9 West-East Cross Section Paroni
(McEwen 2026)

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Figure 6-10 West-East Cross Section South Windfall Area
(McEwen 2026)

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Figure 6-11 West-East Cross Section Rustler Pit
(McEwen 2026)

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6.3.Deposit Type
The Eureka property mineralization occurs as Carlin-type, disseminated, sediment-hosted mineralization. Gold in these deposits is typically hosted by carbonaceous silty limestones and calcareous siltstones, but significant deposits also occur in dolomite, shale, and quartzite.
The characteristic alteration types in Carlin-type deposits include decalcification, argillization, and intense silicification, which is often called jasperoid. Gold is accompanied by similar or lesser amounts of silver, as well as pathfinder elements that commonly include arsenic, thallium, mercury, antimony, and barium (Mako, 1993a). Weakly anomalous amounts of lead, zinc, and copper are locally present in the gold systems as well. Typical minerals accompanying gold include pyrite, arsenian pyrite, stibnite, realgar, orpiment, carbon, and their oxidation products. At the Eureka property, gold mineralization was deposited in favorable Cambrian, Ordovician, and Devonian calcareous sedimentary units where they are intersected by northwest-, northeast-, and north-trending faults and fractures that are commonly also mineralized.
6.4.Gold Deposit Paragenesis
The paragenesis of mineralization at the Lookout Mountain deposit was summarized by Mathewson (2006). Mineralization at Windfall is similar chemically, structurally, and mineralogically to that at Lookout Mountain, and it is likely Windfall was formed by the same geological processes as described by Mathewson (2006). Additions and clarifications added to reflect McEwen’s current understanding are as follows:
· | The hydrothermal event began with dissolution of the upper Hamburg Dolomite by hydrothermal acidic solutions along multiple structurally enhanced fluid pathways. The overlying Dunderberg Shale acted, at least in part, as an aquiclude to the ascending sulfur-bearing hydrothermal fluids. These same solutions likely transported magnesium and iron derived from the underlying units. |
· | An infusion of iron and magnesium into the upper Hamburg Dolomite carbonates occurred, depositing dolomite (ferroan), siderite, and ankerite. The dolomitization caused volume loss with accompanying increased permeability, further enhancing carbonate dissolution. The limestone unit in the Dunderberg cavitated and collapsed under overlying lithostatic pressures. The collapsing process stoped well upward into the overlying shale and limestone. The large volume of open space in the breccias provided permeability and porosity for simultaneous to subsequent mineralization. |
· | Silicification of large portions of the breccia occurred as silica solubility decreased with cooling and fluid mixing. |
· | Hydrothermal fluids began to be desulfidized with fluid mixing as iron in the altered carbonate rocks precipitated the sulfur as both sooty and brassy pyrite with likely later introduction of pathfinder elements, including arsenic. |
· | Gold-bearing solutions were introduced into the breccias and other porous permeable zones, with gold deposition likely linked to the destabilization of a bi-sulfide transporting |
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complex, resulting in gold precipitation with ultra fine-grained arsenical pyrite rims over earlier pyrite. Other elements being transported in a reduced sulfide complex, such as antimony and thallium, likely precipitated close in time.
· | Multiple pulses of mineralization occurred. Many of the breccias exhibit a multi-stage character suggestive of zones of repeated collapse and related development of new breccia. This likely provided for overlapped and enhanced zones of mineralization. |
· | The system may have undergone limited late-stage hypogene oxidation by introduction of oxygenated ground waters during the waning and cooling periods of the hydrothermal system. Oxygenating solutions penetrated certain permeable portions of the system driven by the pressure gradients created by heat flow. Strong oxide to locally massive gossanous material, comprised largely of hematite including specularite, is present in the deepest portions of the system penetrated by drill core to date. |
· | Post-mineral supergene oxidation occurred as indicated by the presence of iron oxides, dominantly goethite, in the shallow portions of the deposits. This oxidation probably occurred during the time of recent uplift commensurate with associated weathering processes. |
Carlin-type sedimentary-rock-hosted deposits were formed by most of the mineralizing processes summarized above.
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7. EXPLORATION AND DRILLING
7.1.Introduction
Drilling in 2025 at Windfall included a mix of infill and exploratory RC and core drilling. Metallurgical core drilling was also completed. Drilling at Lookout Mountain in 2025 was designed as confirmation drilling, with infill to track structures carrying higher gold grades to the South from the pit area. Data review, validation, geologic modeling, and compilations were carried out through 2025 on both properties. Orix Geoscience from Toronto, Canada completed compilation work on historical data in 2025.
By the end of 2025, McEwen drilled 86 holes for 47,953.0 feet at the Windfall project for confirmation, infill and expansion, and metallurgical purposes. Drilling included a mix of reverse circulation and core drilling. Core drilling was completed using standard HQ oriented core for geologic purposes and PQ core for metallurgical purposes. At Lookout Mountain, a total of 20,770.9 feet were drilled for infill, expansion, and metallurgical purposes. Drilling included a mix of HQ core and reverse circulation methods.
7.2.Geologic Mapping
McEwen continued Timberline’s exploration program by building on the existing mapping and sampling programs to develop additional exploration targets. McEwen geologists completed mapping at the Windfall Pit and extended mapping into the Rocky Canyon and Oswego mine areas to the north and east of Lookout Mountain, respectively.
7.3.Geophysical Exploration
McEwen is compiling all the geophysical data produced by previous companies into 3D software and utilizing it to build a geologic exploration model. The geophysical data package includes induced polarization/resistivity (IP) surveys, magnetic surveys, gravity surveys, and controlled-source audio-frequency magneto-telluric (CSAMT) resistivity surveys. These geophysical methods can help identify faults, areas of alteration, and subsurface geology. McEwen geologists are combining geophysical data with surface geologic mapping and geochemistry, and drilling data, to develop and refine additional exploration targets at Lookout Mountain, Windfall and the entire Eureka property.
7.4.Geochemical Exploration
There are approximately 3,847 surface rock sample gold assays that have been collected from exploration programs in the Eureka Property database (Figure 7-1). McEwen Geologists are currently reviewing this data in light of drilling to further target areas of drill-indicated mineralization and generate new prospective target areas.
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After acquiring the Eureka property in 2024, McEwen sampled the Windfall trend pit areas to better understand mineralization surrounding the existing pits. A total of 142 rock samples were collected from multiple alteration styles, including argillization, oxidation, sanded dolomite, fractures, and fault planes, to support development and exploration drilling programs. Sample grades ranged from below detection limits to greater than 3.0 grams per tonne.
In 2024, the company used two-acid digestion for geochemical analysis before transitioning in 2025 to four-acid digestion with mercury analysis for all development and exploration drill holes. Trace-element results associated with Carlin-style mineralization and Carbonate Replacement Deposits are reviewed and integrated to help refine potential large- and small-scale mineralization trends across the land package.
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Figure 7-1 Gold in Surface Rock Samples in Lookout Mountain Project Area
(McEwen, 2026)

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7.5.Drilling
Summary
The Windfall and Lookout Mountain projects have been drilled by a variety of companies. Drilling on the property, as of the Effective Date of this report, is comprised of 2,526 holes totaling 898,875 feet, based on the database provided (Table 7-1).
At Lookout Mountain, Newmont, Amselco, Barrick, Echo Bay, Norse Windfall Mines, EFL, Staccato, Timberline, and McEwen have drilled. The Lookout Mountain project has 773 holes drilled totaling 434,213.4 feet. The following companies drilled at the Windfall Project: Windfall Ventures, Western States, Norse Windfall Mines, Amselco, Pathfinder Exploration, Cambior Exploration, Tenneco Minerals, Staccato, Timberline, and McEwen. For Windfall, 1,551 holes totaling 377,516.1 feet were drilled. The database includes assay data from conventional rotary, RC, and core holes drilled on both properties. Figure 7-2 and Figure 7-3 show the location of drill holes from which the resource estimates were determined.
Table 7-1 Lookout Mountain and Windfall Project Drillhole Summary
Company | Period | Hole | Core | RC+Core Tails | RC or Rotary | Total | | ||||
No. | Feet | No. | Feet | No. | Feet | No. | Feet | | |||
| |||||||||||
Newmont | 1960s | NMT-609C | 1 | 1,537 | | | | | 1 | 1,537 | |
| | F-, M-, P-, PA- | | | | | | | | | |
Windfall | 1972- | , R-, SW-, W-, | | | | | 1373 | 271,548 | 1,373 | 271,548 | |
Ventures | 1981 | WNW-, WP-, | | | | | | ||||
| | | | | | | | | |||
| | WR-, Z-, ZA- | | | | | | | | | |
| 1978- | RCR-, RTC- | | | | | | | | | |
| 1979 | | | | | | | | | | |
Amselco | | 2 | 1,086 | | | 315 | 107,059 | 317 | 108,145 | | |
1982- | RTR-, HBR- | | | | |||||||
| | | | | | | | | | ||
| 1985 | | | | | | | | | | |
| | | | | | | | | | | |
Western | | | | | | | | | | | |
Minerals | 1983 | WSR- | | | | | 19 | 4,220 | 19 | 4,220 | |
Exploration | | | | | | ||||||
| | | | | | | | | | | |
| | | | | | | | | | | |
Norse | | LM-, N84-, | | | | | | | | | |
Windfall | 1986 | | | | | 38 | 7,045 | 38 | 7,045 | | |
NW-, W- | | | | | | ||||||
Mines | | | | | | | | | | | |
| | | | | | | | | | | |
EFL | 1990 | EFL- | | | | | 8 | 2,733 | 8 | 2,733 | |
TVR | 1990- | SS- | | | | | 10 | 5,765 | 10 | 5,765 | |
1991 | | | | | | ||||||
| | | | | | | | | | | |
Barrick | 1992- | BR- | | | | | 40 | 33,285 | 40 | 33,285 | |
1993 | | | | | | ||||||
| | | | | | | | | | | |
Pathfinder | 1993 | HR-, NY- | | | | | 28 | 17,460 | 28 | 17,460 | |
Echo Bay | 1994- | EBR- | 3 | 671 | | | 102 | 70,774 | 105 | 71,445 | |
1997 | | | | ||||||||
| | | | | | | | | | | |
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Company | Period | Hole | Core | RC+Core Tails | RC or Rotary | Total | | ||||
No. | Feet | No. | Feet | No. | Feet | No. | Feet | | |||
| |||||||||||
Cambior | 1995- | CHR- | | | | | 26 | 19,867 | 26 | 19,867 | |
1997 | | | | | | ||||||
| | | | | | | | | | | |
Tenneco | UNK - | EU-, NYC- | | | | | 14 | 5,680 | 14 | 5,680 | |
1997 | | | | | | ||||||
| | | | | | | | | | | |
Staccato | 2005- | BH-, BHSE-, | 30 | 32,267 | | | 34 | 26,305 | 64 | 58,572 | |
2010 | BHWF- | | | | |||||||
| | | | | | | | | | ||
Timberline | 2010- | BHSE-, | | | | | | | | | |
BHMW-, | 41 | 33,181 | 16 | 16,054 | 193 | 124,050 | 250 | 173,285 | | ||
2022 | | ||||||||||
| BHWF- | | | | | | | | | | |
| | | | | | | | | | | |
GMDC | UNK | GM | | | | | 10 | 1,985 | 10 | 1985 | |
Homestake | UNK | HRC-,HRH- | | | | | 14 | 9,365 | 14 | 9,365 | |
| | | | | | | | | | | |
Minnova | UNK | SS- | | | | | 9 | 3,026 | 9 | 3,026 | |
| | | | | | | | | | | |
Stockon | UNK | SS- | | | | | 46 | 19,794 | 46 | 19,794 | |
| | | | | | | | | | | |
Cyprus-Amax | UNK | NY- | | | | | 2 | 900 | 2 | 900 | |
| | | | | | | | | | | |
McEwen | 2024 | WF | | | | | 28 | 14,405 | 28 | 14,405 | |
Nevada | | | | | | ||||||
| | | | | | | | | | | |
McEwen | 2025 | WF, LM | 21 | 11,454 | | | 103 | 57,270 | 124 | 68,724 | |
Nevada | | | | ||||||||
| | | | | | | | | | | |
| TOTAL | | 98 | 80,196 | 16 | 16,054 | 2,412 | 802,536 | 2,526 | 898,785 | |
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Figure 7-2 Location Map of All Lookout Mountain Drill Holes
(McEwen 2026)

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Figure 7-3 Location Map of All Windfall Drill Holes
(McEwen, 2026)

7.5.1. Historical drilling at Lookout Mountain
Historical drilling was primarily conducted using RC drilling systems with a down-hole hammer, although some of the early drilling employed conventional rotary with a down-hole hammer. Specific problems with drilling were discussed in only one report referred to by Russell, 2007, on the South Lookout Mountain area, where two of five drill holes were not completed because of lost circulation.
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Many drill holes at Lookout Mountain have vertical or subvertical orientations, which cut the predominant mineralized zones at relatively high angles. A significant number of angled holes were also completed, which are approximately perpendicular to the mineralization. Mineralization at Lookout Mountain has both moderately east-dipping and flat-lying morphologies with some high-angle control in the hanging wall of east-dipping faults. Windfall has strong near vertical control on high grade mineralization with a disseminated low-grade halo. In either case of drill orientation, the drill data provided by the holes were appropriate for the modeling of the mineral resources at the Lookout Mountain project.
RC drilling was completed with industry-standard drill rigs utilizing hammer bits and dual-tube drill rods, through which drill cuttings were directed from the bit under air pressure into a cyclone recovery system capable of capturing a representative sample of approximately 14 pounds from each 5-foot interval. At depth, particularly if significant groundwater was encountered, the hammer was often changed to a tri-cone bit to allow continued penetration towards target depth.
No apparent drilling-related sampling or recovery factors that may materially impact the mineral resources discussed in Section 11 were noted in historic drilling prior to Staccato. While RC down-hole contamination does present a sample integrity issue in some holes, as discussed in Section 7-17, the recognition and exclusion of the intervals of suspected contamination have adequately addressed the problem.
There is very little information on the details of sampling programs by operators prior to Staccato, but there is no evidence in the data available of serious recovery problems. RC chips were logged by a number of company geologists. Sample weights, volumes, or estimated recoveries are rarely available in historical documentation, with the exception that intervals of no recovery were locally common (Russell, 2007).
The predominant sample length for the drill intervals used directly in the resource estimation is 5 feet, with 10-foot intervals used in some holes and intervals less than 5 feet common in some of the core holes. These interval lengths are significantly less than the thickness of the bulk-tonnage style of mineralization that dominates both Lookout Mountain and Windfall mineralization. Drill-sampling procedures provided samples that are sufficiently representative and of sufficient quality for use in the resource estimations discussed in Section 11.
7.5.2. Historical Drilling at Windfall
Drilling at Windfall is a mix of conventional rotary and Reverse Circulation drilling. Drilling prior to 1984 (Historic drilling) by Idaho Mining and Windfall Ventures was done with conventional rotary and hammer drills and vertical holes. This includes the N, P, R, W, WD, SW, WSW, F and Z series drill holes. Sample lengths used were 5 or 10 feet. Sampling methods were outlined in Standard Operating Procedures which called for:
· | Collection of material at the collar with pans placed around the drill steel. |
· | Samples from the pans were then split using a Jones splitter with material placed in sample bags labeled with hole ID and footage, |
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· | Samples were then taken to the mine logging and assay facility where the samples were logged for lithology and alteration prior to assaying. |
Despite the inherent problems associated with vertical holes, and contamination issues with conventional rotary drilling, these procedures were standard and customary for the time period. Assays and lithology from these drill holes were the basis for reserve calculations prior to historical mining. Drill spacing of approximately 50 feet with tighter spaced drilling around higher grade regions was achieved before reserves were calculated. Even though potential bias with vertical drilling along near-vertical structures could produce incorrect results, these holes formed the basis for mining the Windfall, Rustler, and Paroni open pits.
The vertical nature of drilling was partially due to drill rig limitations in the early years of exploration. Subsequent drill programs (Pathfinder, Cambior, Staccato, and Timberline) utilized angled drilling to test mineralization. Staccato, Timberline, and McEwen drilling programs on the project drilled all holes at less than 90°. Geologic modeling by McEwen shows that disseminated low grade mineralization exists in sanded dolomite between higher grade fractures. While vertical drilling may be biased with respect to near vertical fractures, angled drilling has allowed for more accurate sampling of the higher-grade zones. Additional drilling programs will further this understanding.
A variety of groups engaged in exploration drilling around the Windfall open pit mines since cessation of mining in 1988. Tenneco Minerals drilled 11 RC holes on Hamburg Ridge South of Rustler. Pathfinder and Cambior drilled on Hoosac Mountain, Hamburg Ridge, and at the Paige Corwin Mine. Amselco drilled 8 HBR series holes on Hamburg Ridge in 1985.
Staccato, and then Timberline, drilled a series of holes targeting mineralization below the old Rustler and Windfall open pits from 2008 to 2015 and several exploration holes on Hoosac, in Dale Canyon, and at the Paige Corwin Mine. Timberline drilling focused on extending mineralization below pit levels to confirm and extend known mineralization to make a decision for purchasing the Windfall Patents, and to follow up on historic high-grade intercepts from Idaho Mining and Windfall Ventures drilling.
7.6.Newmont Mining Corp.
A drill log and a database printout of assays from a single core hole drilled by Newmont (hole 609) in Rocky Canyon in the 1960s were provided by Amselco. Hole 609 was drilled on a magnetic high targeting porphyry molybdenum mineralization. A descriptive summary of this hole by Echo Bay indicates that it was drilled by Eklund Drilling Co., Inc. (“Eklund”) using NX to BX core. The core was typically sampled on 10-foot intervals. The Core was also reviewed by Timberline staff and the Nevada Bureau of Mines and Geology in 2012. This hole is north of the current resource at Lookout Mountain.
7.7.Windfall Ventures/Idaho Mining
Idaho Mining and Windfall Ventures drilled 1,373 holes at Windfall, covering the Windfall trend including the Rustler, Windfall, and Paroni open Pits. Drilling was also completed at Hamburg Ridge (F and Z series drilling). Exploration drilling was completed with conventional rotary and
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conventional percussion rotary methods, and sampling was completed on 5- and 10-foot intervals. Protocols for exploration drilling are the same as discussed above, and in section 8.
7.8.Amselco Exploration Inc.
Amselco drilled a total of 309 RTR-, RCR-, and RTC-series holes at the Lookout Mountain project from 1979 through 1985. According to information reviewed by Gustin (2013), Amselco’s drilling included 159 conventional rotary, 140 RC, two core drill holes, and eight holes presumed to be RC.
The two core holes were drilled by Boyles Brothers Drilling. The remaining RC and conventional rotary holes were drilled by Lang Drilling, Eklund Drilling, Cooper & Sons, TW Enterprises, Becker Drilling, Young Drilling, Hackworth Drilling, Drilling Services, Layne, and Tonto Drilling. A tabulation compiled by Amselco (Hauntz, 1985) shows the following types of rigs used by the various drillers:
Company | Drill Rig type | Drillhole type |
Becker | CSR 1000 | RC |
Boyles | Longyear 44 | Core (NC, NX) |
Cooper & Sons | Speedstar SS 15 | Conventional Rotary |
Eklund | Ingersol Rand TH60 | RC |
Eklund | Ingersol Rand TH100 | RC |
Hackworth | CP700 | RC |
Lang | CP650 | RC / Conv. Rotary |
Lang | CP650? | Conventional Rotary |
TW Enterprises | Schramm T64 | Conventional Rotary |
Young | Gardner Denver | Conventional Rotary |
Drilling Services | Ingersol Rand TH100 | RC |
Drilling Services | Ingersol Rand Rotary | RC |
Amselco holes RCR-1 through 6 and RTR-1 through 200 were sampled on 5-foot lengths, whereas holes RTR-203 through 296 were sampled on 10-foot lengths with some 5-foot samples. Five-foot samples were collected and logged by the geologist at the drill rig but were apparently then combined into 10-foot samples for assay for the holes with 10-foot sample intervals (Jonson, 1991). Jonson (1991) notes that the change to 10-foot sample lengths occurred during the latter part of Amselco’s drilling program, apparently in an effort to reduce assay costs. The two Amselco core holes were sampled on irregular intervals determined by geology.
A total of 159 of the first 177 holes drilled by Amselco were drilled by conventional rotary methods; the remaining 150 holes were either core (two holes) or reverse circulation. Conventional rotary holes can be more susceptible to sample loss than RC holes, with or without loss of representativity. Down-hole contamination issues may also be exacerbated in rotary holes. The general issue of contamination is discussed in Section 7.17.
At Windfall, Amselco drilled eight reverse circulation holes on Hamburg Ridge in 1985, totaling 2,560 feet. Drilling was done approximately 3,800 feet South of the Rustler Pit, on the southern extent of the Windfall fault zone. Layne Drilling Services was the contractor, with rig type not mentioned on the logs. Amselco sampled on 10-foot intervals with assays completed at the company laboratory in Sparks, Nevada using Fire assay with an AA finish.
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7.9.Norse Windfall Mines
Norse Windfall Mines drilled 20 LM-series RC holes at the Lookout Mountain project in 1986. As recorded on drill logs, the drilling contractor for these holes was Leroy Kay Drilling, using a Pollock Driltech D40K drill. Norse Windfall Mines did not drill at Windfall but did drill north of the Paroni pit in New York Canyon.
7.10.EFL
EFL drilled 11 holes in the Lookout Mountain project in August and September 1990 (EFL-1 through EFL-9, M1, M1-A) for a total of 3,545 feet (Johns, 1990), although the M1 and M1-A holes are not in the database. Drill records show that Brown Drilling of Kingman, Arizona was the drill contractor for all 11 holes, using a Chicago Pneumatic CP 650 RC drill with either 5.25- or 5.5-inch bits.
The nine EFL- RC holes were sampled at five-foot intervals. Both wet and dry samples were channeled directly into a Gilson splitter from the cyclone or into a bucket before passing through a Gilson splitter (Johns, 1990). The sample was continually split until enough material remained to fill an 11 by 17-inch olefin drill bag. Johns (1990) noted that wet splitting was difficult due to the lack of a wet splitter and that samples were frequently heavily laden with clay, which made keeping a clean, evenly split sample very difficult. He further noted that due to the large volume of water and material produced in some holes, fine-grained rock was often washed away, leaving only the gravel portion to be sampled.
7.11.Barrick
Barrick drilled 40 BR-series RC holes at Lookout Mountain in 1992 and 1993. Lang Exploratory Drilling was the contractor for Barrick’s 28 RC holes drilled in 1992 (Mako, 1993a). No information on the drill contractor for Barrick’s 1993 drilling or on the type(s) of rig used is available.
The drill cuttings from Barrick’s 1992 RC drilling were sampled at five-foot intervals.
Some of the 1992 drill sites in the vicinity of the historical Lookout Mountain pit were surveyed by Eric Pastorino. Barrick staff supervised the drilling and logged the drill cuttings (Mako, 1993a).
7.12.Echo Bay
Echo Bay drilled 106 EBR-series holes in the Lookout Mountain project from 1994 to 1997, according to Emmons (1998), although the project database has 105 Echo Bay holes. Three of the holes were core and the rest RC.
The contractor for the three core holes was Wink Drilling, who used a Hagby rig and drilled NQ core. There were various contractors for the RC drilling: Eklund Drilling and Drift Exploration Drilling (“Drift”) used MPD-1000 rigs, while Eklund Drilling also used an MPD-1500. Lang Exploratory Drilling used a TD-25 track rig.
RC holes were sampled at five-foot intervals. The three Echo Bay core holes were sampled irregularly, but predominantly at five-foot intervals.
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7.13.Staccato
Staccato drilled a total of 25 BH-series core holes at the Lookout Mountain project from 2005 through 2007. These were primarily HQ core holes, with a reduction to NQ-diameter (1.875 inch) core utilized to complete deeper holes. Boart Longyear from Salt Lake City, Utah, the drill contractor for the holes drilled in 2005 and 2006, used a Longyear LS 244 rig. TonaTec Exploration (“TonaTec”) completed the core drilling in 2007 using an LF90 drill rig.
Sampling of the drill core generated by Staccato’s 2005-2007 core drilling programs was under the supervision of Staccato personnel. The sampling intervals in mineralized areas were determined and marked by a geologist. The core was sawn by technicians under the supervision of the geologist, and the split core samples were delivered to the ALS Minerals (“ALS”) sample preparation facility in Elko, Nevada; ALS Minerals was known at the time as ALS Chemex.
From 2008 to 2009, Staccato drilled an additional 25 BHSE-series holes, five of which were core and the remainder RC. TonaTec was the drill contractor for the core holes, again using an LF90 drill rig. Eklund Drilling was the contractor for the RC holes and used an MPD1500 track-mounted drill.
During this same time period Staccato completed 14 BHWF series holes at Windfall utilizing the Eklund MPD1500 track mounted drill from Lookout Mountain. The initial 4 holes were drilled from within the Rustler pit to confirm mineralization below pit floor and to drill gaps in high-grade mineralization identified by historic drilling. Ten holes from this program drilled beneath the Windfall pit, in the un-mined region between pits, and beneath the Rustler pit. Sampling protocols for both projects were the same.
Samples for RC drilling were collected at five-foot intervals, utilizing standard techniques for RC drilling. Samples were collected in buckets beneath a rotary splitter and placed into marked sample bags by the driller’s helper. Samples were laid out on the drill site in sequence to dry, if necessary. Once the rig left site and samples were dried, they were then collected from the drill site by Inspectorate America Corp. (“Inspectorate”) personnel, and experienced geotechnical personnel working for Staccato, and placed into an Inspectorate truck for shipment to Inspectorate’s lab in Sparks, Nevada.
Core drilling utilized a five-foot dual-tube core barrel for sampling with a maximum sample length of five feet. The length of individual core runs was based on driller’s discretion and was determined by the presence of broken, caved, or other bad ground, which often led to smaller than five-foot drill-run intervals. After logging, individual samples were selected based on the down-hole depth from-and to-values of the drill runs. No sample was taken that crossed over drill-depth marking blocks. This was to ensure that material from drill runs with poor recoveries was not mixed with material from runs with good or complete recovery. Samples were also collected within runs, based on lithologic, alteration, or structural characteristics.
All core samples were marked with depth intervals written on wooden blocks in red permanent marker and placed at the appropriate footage in the core box for samples that were collected within runs. A red border was placed on the block marking the drill-run, with a mark placed on the core box where the depth block for the run was placed.
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After photographing, core was then cut in half using a 14-inch ceramic saw at the company’s office in Elko, Nevada. One half of the core was placed in a marked bag for sampling, and the other half placed back in the appropriate position in the core box for future needs. Samples were then picked up by Inspectorate personnel and delivered to the lab.
Sample bags for both core and RC samples were marked using the drillhole ID and a three-digit number starting with 001 and continuing in sequence to a number necessary to cover all assay intervals contained within the drill hole (e.g., BHSE-015 001, BHSE-015 002 ... BHSE-015 235). This was done to allow for the insertion, in stream, of blank material and certified standards. For RC drilling, footages were correlated to bags via a sampler’s log sheet and pre-numbered chip trays showing sample number, depth from, and depth to for each interval. For core drilling, footage intervals were correlated to sample numbers via a sampler’s record sheet. Depth-from and depth-to values for each sample number were filled out by the geologist logging the core hole and making sample breaks.
7.14.Timberline
Timberline drilled 173,285 ft at Lookout Mountain since acquiring the project in 2010 from Staccato (Table 7-1). The drill programs were comprised of RC and diamond core for multiple purposes including exploration, resource infill and expansion, metallurgy, geotechnical, and hydrogeologic purposes.
7.14.1. Drilling from 2010 to 2011
Timberline’s 2010-2011 RC drilling totaled 58,264 feet at the Lookout Mountain project. The purpose of the drilling program was to refine the geologic model and bring nominal drill spacing to 200-foot centers through North and South Lookout Mountain. This drilling included 14 RC and one core hole at the South Adit area. RC drilling began in September 2010 using a Schramm 660 track-mounted drill; New Frontier Drilling Co. (“New Frontier”) was the drill contractor. A second RC rig, a Foremost MPD 1000, was added by New Frontier in October 2010. A third buggy-mounted RC rig was added to help finish drilling in January 2011, and O’Keefe Drilling Co. was the drill contractor. When RC drilling resumed later in 2011, New Frontier, Diversified Drilling LLC, and Boart Longyear were the drill contractors.
Three pilot groundwater-monitoring holes were drilled by RC methods in 2011 by Boart Longyear, who then completed one as a groundwater monitoring well (BHMW-001).
Timberline also conducted a 5,827-foot core drilling program of seven HQ holes and two PQ holes for geological and metallurgical purposes. Core drilling began in the South Adit area in July 2010. Timberline Drilling, at that time a division of Timberline Resources Corp., was the drill contractor for the core drilling and used a skid-mounted LF90 core drill.
Drilling at Windfall consisted of 20 reverse circulation drill holes and 1 deep core hole. The core hole was drilled by Timberline Drilling to a depth of 1,410.5 feet. A total of 15,488 feet were drilled by New Frontier. Six holes were drilled below the Rustler and Windfall pits to augment the 2008 and 2009 drilling by Staccato for a decision to purchase the patented claims. The remainder were drilled on Hoosac Mountain, Hamburg Ridge, in Dale Canyon, and at Round Top Hill and the Paige-Corwin Mine.
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7.14.2. Drilling from 2012
Timberline’s 2012 drill program was comprised of 33 RC and 17 core holes, all drilled at Lookout Mountain. Besides exploration drilling, 24 RC and three core holes were designed as resource infill drilling of the Lookout Mountain deposit, with the core also used for metallurgical testing. An additional 12 HQ core holes were drilled specifically for metallurgical testing, with emphasis on the massive jasperoid-type of mineralization from North and South Lookout Mountain.
Two core holes were drilled as oriented core using an ACT3 digital orientation device specifically for geotechnical information (BHSE-157C, BHSE-160C) in Devonian carbonate rocks that would form the highwall to a potential open pit, with this core also used for metallurgical testing.
Seven RC holes were drilled for further hydrologic work, which resulted in establishing three additional groundwater-monitoring wells (BHMW-002, BHMW-007, BHMW-003); the other four holes were dry.
For Timberline’s 2012 drilling, Timberline Drilling conducted the core drilling using a UDR 10 rig; a truck-mounted rig was used for a few holes. New Frontier conducted all the RC drilling in 2012 using the same rigs as previously used on-site. Boart Longyear installed the three monitoring wells drilled in 2012, as well as the one installed in 2011.
7.14.3. Drilling from 2014 to 2015
After a hiatus in 2013, drilling resumed in 2014 with initial follow-up to the WWZ discovery hole BHSE-152 drilled in 2012 (east of the resource area). Timberline drilled three offsets to the discovery hole, which confirmed the presence of high-grade gold in breccia at the base of the Dunderberg Shale overlying altered Hamburg Dolomite. Boart Longyear drilled one hole by RC methods through the complete Cambrian Windfall-Dunderberg-Hamburg stratigraphic section, through the Ratto Canyon thrust fault and into Silurian Lone Mountain Dolomite and Ordovician Eureka Quartzite. Timberline Drilling drilled two additional holes as RC pre-collars with HQ core tails, which cut the entire mineralized section. An additional RC hole was drilled within the resource area immediately southeast of Lookout Mountain.
Timberline drilled at Windfall in early 2015 to offset high grade intercepts in historic drill holes. Targets were cross faults identified by mapping and cross section work. Two holes were drilled into the South End of the Rustler Pit, two targeting Northeast cross faults at the South end of the Windfall pit, and one targeting the North end of the Windfall pit. Timberline drilled 10,071 feet during the program.
7.14.4. Drilling from 2020 to 2022
No drilling occurred at the Lookout Mountain project area between 2016 and 2019. Drilling resumed in 2020 and continued through 2021 and 2022, during which time 65 drillholes were completed including RC, core, and RC with core tails. These holes were drilled primarily adjacent to the then resource for exploration purposes and totaled approximately 55,240 ft (Table 7-1). No drilling was done at Windfall during this period.
This phase of drilling was primarily concentrated in the Water Well Zone (WWZ), as exploration follow-up to the 2014-2015 drilling (see Section 7.14.3). Seven RC holes were drilled within the
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gold-bearing area to confirm the extent of high-grade (>0.1 oz Au/ton) gold in the vicinity of historical conventional rotary drillholes, and as infill within the zone. Additional holes were drilled north and northeast of the WWZ to intersect faults into or within the Relay Zone and as initial tests of Siluro-Ordovician stratigraphy. There was also limited exploration drilling outside the WWZ immediately southwest of the historical Lookout Mountain open pit, and in the Oswego area.
RC drilling during 2020 and 2021 was completed by New Frontier Drilling with a Foremost MPD 1000 buggy rig as utilized earlier, and by HD drilling of Winnemucca, NV in 2022 with a Reichdrill TE90-W truck-mounted rig. The drilling and sampling systems were similar to those of previous campaigns at Lookout Mountain.
Timberline’s sampling methods were consistent with Staccato’s methods from 2008. For RC drilling, samples were collected by the driller’s helper under Timberline personnel supervision in a five-gallon bucket beneath the rotary splitter from the rig and then put into marked sample bags, which were laid out for drying. Timberline personnel then transferred samples to Timberline’s logging facility in the town of Eureka to await pickup by lab personnel or for transfer to the lab by Timberline.
Core drilling was initiated in 2020 by Redcor Drilling, who was later replaced by Big Sky Exploration in the 2021-2022 programs. Both contractors utilized a Boart LF-90 track-mounted rig and typically drilled PQ (3.3-in diameter) near-surface and HQ (2.5-in diameter) to final depth. Once drilled, individual core runs were placed into core boxes. From and to depths for each run were marked by wood or plastic blocks with the corresponding depths and recoveries written on the block in black permanent marker. Timberline personnel picked up full core boxes from the drill site and transported them daily to the core logging facility in the town of Eureka.
7.14.5. RC and Core Processing
Representative RC drillhole chip samples from the various drilling campaigns were collected for logging on 5-foot intervals in industry standard chip trays. Upon completion of drilling of each hole, the chip samples were systematically logged for lithology, alteration, visible mineralization, structures, and oxidation. The data were recorded in spreadsheets or by direct input into a digital drillhole database. Sample depths and intervals were systematically checked against drill contractor records for consistency.
For core, boxes were laid out in the Company’s logging facility in sequence as drilling progressed. Box numbers, drill depths, and intervals as noted on wooden blocks inserted by drillers were checked for sequential and interval accuracy. Each box of core was washed and photographed prior to logging. Core recovery percentage, rock quality designation (“RQD”), lithology, alteration, mineralization, and structural data were recorded and compiled in spreadsheets or directly into the project drillhole database. Sample breaks were identified and marked with wood blocks, and footages with associated sample numbers written on a sampler’s record sheet.
Core holes drilled for geological and assay purposes typically utilized a 10-foot core barrel for a maximum recovered interval of 10 feet. Core drilling for metallurgical purposes typically utilized a dual-tube five-foot core barrel with a maximum sample interval of five feet. The length of individual core runs was based on driller’s discretion and was determined by the presence of broken, caved,
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or other bad ground, which often led to drill-run intervals smaller than five-feet. As core was logged, Timberline geologists determined sample intervals based on drill runs, lithology, alteration, and/or structural breaks.
After logging and photographing, core for standard assay was split or sawed into halves and sampled as marked by Timberline geologists. Core for metallurgical testing that was within mineralized zones was sampled as whole core and shipped to KCA in Reno, Nevada, for processing. Since whole core was to be used for metallurgical testing, Timberline only sent the core representing the mineralized intervals plus an assumed unmineralized buffer of 10 feet on either side.
As with Staccato’s sampling, Timberline’s sample numbers prior to 2021 for both core and RC used the drillhole ID and a three-digit number starting with 001 and continuing in sequence to a number necessary to cover all assay intervals contained within the drill hole (e.g., BHSE-056 001, BHSE-056 002 to 235). This was done to allow for the insertion, in stream, of blank material and certified standards. For RC drilling, footages were correlated to bags via a sampler’s log sheet and pre-numbered chip trays showing sample number, depth from, and depth to for each interval. For core drilling, footages were correlated to sample numbers via a sampler’s record sheet. Depth from and depth to values for each sample number were filled out by the geologist logging the core hole and making sample breaks.
Beginning in 2021, Timberline implemented a “blind” numbering system wherein drillhole numbers and footages were not revealed in the sample numbers. Instead, a sequential numerical series was utilized; later sampling used bags with pre-printed bar code tags for the blind numbering.
7.15.McEwen Nevada.
As of the date of this report, McEwen has drilled 104,009.5 ft after acquiring the property from Timberline in August 2024 (Table 7-1). RC and diamond core drilling programs have been drilled for various purposes that included exploration, resource definition and expansion, metallurgy and hydro-monitoring.
7.15.1. 2024 Drilling
McEwen began RC drilling in late October, totaling 28 holes with a footage of 14,405 ft in the Windfall project area. The objective of the campaign was to confirm legacy mineralization underneath the Windfall and Rustler pit floors. The RC drill used was a Foremost MPD 1500 track-mounted rig operated by Boart Longyear.
Sampling methods utilized a rotary wet splitter on the drill, capturing the sample in a 5-gallon bucket and putting it in 20x24-inch sample bags. Bags were laid out to dry and then brought to the logging shed for pickup by Paragon Geochemical Labs. Sample bags were numbered using sample numbers in sequence for insertion of blank material and certified reference standards.
7.15.2. 2025 Drilling
McEwen’s 2025 drilling year included 103 RC and 21 core holes. The majority of holes were designed for resource definition, expansion and metallurgical testing at both project areas of
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Windfall and Lookout Mountain. Sixteen core holes were drilled in and around the Windfall pit area using an ACT3 digital orientation tool to assist with measuring planar structures to help determine mineralization controls. Four PQ metallurgical core holes were drilled for the purpose of collecting samples of the mineralized zones of the Dunderberg and Hamburg contact, sanded dolomite zones, and jasperoid alteration near structures. Seventy RC holes were planned to gain confidence in areas of higher-grade mineralization, and decrease the drill spacing to approximately 125 ft. Sampling and sample security followed the same protocols as in 2024.
Core Drilling
In 2025 McEwen had 2 RC rigs and 2 Diamond core rigs. The RC contractors, Boart Longyear and George DeLong Construction, each used a Foremost MPD 1500 track-mounted rig. The core rigs were operated by Big Sky Exploration, using one LF-90 track-mounted and an LF-230 rig which typically drilled PQ (3.3-in diameter) near-surface and HQ (2.5-in diameter) to final depth. Individual core runs were placed into core boxes with the from and to depths marked by wood or plastic blocks with the corresponding depths and recoveries written on the block in black permanent marker. The Big Sky drill crews would take full core boxes from the drill site and transport them after each shift to the Core Shed Facility in the town of Eureka.
RC and Core processing
Representative RC drillhole chip samples from the various drilling campaigns were collected for logging on 5-foot intervals in industry standard chip trays. Upon completion of drilling of each hole, the chip samples were systematically logged for lithology, alteration, visible mineralization, structures, and oxidation. The data were recorded in spreadsheets then uploaded into a digital drillhole database by a Database Manager. Sample depths and intervals were systematically checked against drill contractor records for consistency.
For core, boxes were laid out in the Company’s logging facility in sequence as drilling progressed. Box numbers, drill depths, and intervals as noted on wooden or plastic blocks inserted by drillers were checked for sequential and interval accuracy. Each box of core was washed before starting data collection. The core recovery percentage, rock quality designation (“RQD”), lithology, alteration, mineralization, and structural data were recorded and compiled in spreadsheets to be uploaded into a digital drillhole database by a Database Manager when finalized. Sample breaks were identified and marked with wood blocks, and footages with associated sample numbers written on a sampler’s assay-interval spreadsheet.
All core holes drilled for geological, metallurgical, and assay purposes utilized a dual-tube five-foot core barrel with a maximum sample interval of five feet. The length of individual core runs was based on driller’s discretion and was determined by the presence of broken, caved, or other difficult ground, which often led to shorter than five-foot drill-run intervals. As core was logged, McEwen geologists determined sample breaks based on drill runs. Sample intervals were selected based on lithology, alteration, and/or structural breaks. Then the core was photographed with all marked sample intervals before going to be split or sawed lengthwise.
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7.16.Collar Surveys, Down-Hole Surveys, and Project Coordinates
Based on various reports by Amselco (Hauntz 1985), Barrick Gold (Mako, 1993), and Echo Bay (Emmons, 1998), historic drill holes were located via a variety of methods. All drill programs up to 2002 utilized the Amselco grid system at Lookout Mountain.
Amselco (Hauntz, 1985) surveyed most drill holes using standard survey equipment and techniques of the time in 1980 when survey control and scribed photogrammetric topography were established. Earlier holes, particularly in 1979, were located by topography or by Brunton and chain methods. Except when noted on logs all Amselco holes from 1980 to 1985 were surveyed by company mine surveyors into the Amselco grid system (Hauntz, 1985). Amselco drilling at Windfall was surveyed by Windfall Ventures into their local grid system.
Echo Bay, utilizing the Amselco grid system, generated detailed topography with survey monuments to survey their collar locations. Most collar locations were surveyed. Those that were not surveyed were located via ortho photography and topography. Collar locations not surveyed were noted on the drill log (Dave Emmons, pers communication 2009).
Barrick located most drill collars by topography with several, in later years, captured by Eric Pastorino, former survey engineer for Norse Windfall Mines.
All Staccato 2005 through 2007 drill collars were surveyed by Carlin Trend Mining Services of Elko, Nevada using high-resolution GPS equipment. Collar coordinates were provided in the UTM Zone 11N NAD1927 grid system. Down-hole surveys were performed at regular intervals for most of the Staccato core holes, including vertical holes. Most holes were surveyed within the first 100 feet, again at 500 feet, and then at or near the bottom of the hole (~1,000 feet). All holes showed a plunge deviation of less than three degrees, except angle hole BH-06-16, which steepened from a 45-degree plunge at the collar to 52 degrees at the bottom of the hole.
The Staccato 2008, 2009, and Timberline 2010 drillhole collar locations for Lookout Mountain and Windfall were surveyed by company geologists utilizing a Trimble AG132 sub-meter GPS system. The AG 132 unit utilized an Omnistar space-based differential correction service to achieve sub-meter accuracy in the x and y directions. Timberline 2011 through 2015 collar locations were surveyed using a Trimble GeoXH submeter GPS with an Omnistar differential correction for <1m accuracy.
All drillhole surveys were collected into handheld data collectors utilizing ArcPad software. Collection times for each point utilized 60-second averaging on spatial coordinate readings collected every second. Due to the inherent inaccuracy in elevation data for non-survey grade GPS units, elevation values from the GPS were not used in the project database. Timberline flew an aerial survey in July 2010 that enables an engineering accuracy of +5 feet on scribed topography. Drillhole elevations were generated using the digital terrain model (DTM) data from the aerial survey. RESPEC ‘pressed’ the Staccato and Timberline drill holes to this topography, essentially assigning the “z” value of these holes in the project database on the basis of the digital topography.
Collars from 2020 to 2022 exploration drillholes were located using handheld GPS units recording data in UTM NAD83, Zone 11N datum metric coordinates. Elevations were recorded and compared to “z” values in the DTM elevation model and pressed if elevation differences exceeded 3 meters.
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International Directional Services (“IDS”), with an office in Elko, Nevada, completed all down-hole surveys for the Staccato 2008 and Timberline 2010-2012 and 2020-2022 drill programs. IDS utilized a surface recording gyroscope, which required an initial setup to establish true north for the gyro. A technician measured an azimuth with a Brunton compass from a point on the surface to the gyro, and then utilized that direction in a computer program to calculate the azimuth. The survey tool has a built-in inclinometer to determine plunge angle. All data were recorded digitally to a computer, processed, and presented to the client on-site. There are no down-hole surveys for the following holes due to caving, loss of the hole, or stuck pipe: BHSE-127, -129, -129A, -136, and - 160C.
In 2024 and part of 2025 McEwen drilling, drillhole collar locations were surveyed by company geologists/ geotechnicians utilizing a Trimble Geo XH Geoexplorer 5000 series GPS system. Collar locations were captured by collecting readings for 180 seconds for each collar location in the data collector software. When the collar surveys were complete the unit was synced and the data downloaded. The data manager then post-processed the data using Trimble’s Pathfinder office software to achieve submeter accuracy in the X-Y dimensions. Post processing provided for more accurate Z values which were used in the database.
In the last quarter of 2025, McEwen switched to a Trimble DA2 GNSS receiver, a sub-meter GPS system, due to the post-processing software no longer being supported. The Trimble DA2 GNSS receiver has a correction service to achieve sub-decimeter (<10 cm) accuracy in the X, Y, and Z directions.
From late 2024 to the date of this report, McEwen rented a REFLEX OMNIx42 downhole survey gyro tool from Reflex USA, which has a support office in Elko, Nevada. The lead driller placed the survey tool at the top of the collar then began collecting data every 50 feet down hole to final depth. The process was repeated while raising the tool out of the hole, collecting data every 50 feet until the gyro tool reached the collar surface. All data were recorded digitally to a computer that can be presented to the McEwen geologist before being synced to cloud software where the data were checked by the Database Manager. Only two core holes have a partial survey due to caving and loss of the hole: WF035 and WF040.
Coordinate Conversions
The Amselco (Lookout Mountain) and Windfall drill programs utilized local mine grids for their programs prior to 1994. Windfall established a local mine grid in 1968, as described below, and Amselco established a local grid based on the old Nevada State Grid system.
Staccato staff initiated a program in 2008 to re-survey existing historical drill holes and survey control points at Lookout Mountain after speaking with Allan Morris (pers communication, 2008) and then finding a Barrick document which discussed errors in the detailed topographic base generated by Echo Bay Exploration. The errors were found by comparing the Echo Bay topographic base to the Pinto Summit and Spring Valley Summit 7.5’ USGS topographic maps.
The program was completed under the guidance and methods outlined by SRK surveyors and included converting the Windfall local grid system as well. Historic holes and survey control points
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were surveyed using a Trimble AG132 GPS with U.S. Coast Guard beacon differential correction and post processing in 2008. In 2009 an Omnistar differential correction, which provided better accuracy, was used. In 2008 handheld GPS units with approximately +5-meter accuracy were used to capture some historic drill holes (Edmondo, personal communication, 2011).
At Lookout Mountain, a total of 30 Amselco, one Barrick, and two Echo Bay holes and 12 control points were found and surveyed using the Trimble unit with Omnistar differential correction, while 16 Amselco, six Barrick, and one Echo Bay hole were surveyed using the US Coast Guard beacon differential corrections. Handheld GPS units were used for four Amselco holes and one hole each for Echo Bay and EFL. Reclamation of drill access roads and drill sites precluded the surveying of the remainder of the historical holes.
The 2009 sub-meter GPS survey data from historical drill holes and survey points were compared to original coordinates reported in Amselco documents, and these data, in combination with the detailed topography, were used to determine translation/rotation parameters for correcting the discrepancies in the historical coordinates. The resultant first-order polynomial equation was used to transform the unsurveyed historical data into Nevada State Plane East zone projection of 1984, NAD27 coordinates that were used in the 2008-2015 project database.
Windfall drill hole coordinate conversions
Coordinates for historic Windfall drilling prior to 1990 were surveyed using standard techniques with collar coordinates in a local mine grid established in 1968 by Idaho Mining. The grid system was surveyed, and local control points were established, with an origin point from a USGS Benchmark (BM -R-49-1931) with a false Northing of 50,000 and False Easting of 100,000. The grid was established using U.S. survey feet and was surveyed to be true North-South. The local grid was modified in 1974 by changing the false easting to 50,000 to create a new origin of 50,000N/50,000E on the same benchmark, and establishing additional control points. Survey control points are listed in several historic documents as well as in the Surveyors master survey book.
Under the 2008 and 2009 coordinate conversion program Windfall local grid survey control points were surveyed and any drill hole locations that were not mined out and visible were surveyed with the AG132 system using Omnistar. For the Windfall area 13 control points were found and surveyed. Due to extensive mining and ground disturbance only 4 historic drill holes with unknown ID were found. All Control points were captured by collecting 5 minutes of location data at each point into Arcpad software on the data collector. Coordinates were captured in WGS84 Lat Lon and the Nevada State Plane East Zone projection system of 1984 using the North American datum of 1927, in US survey feet. SRK completed the coordinate conversion of drill holes using Pathfinder office software and a standard “Rubber Band” (polynomial) conversion into NV State Plane East Zone coordinates.
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Other Windfall drilling
Pathfinder collar locations were located from either topography (earlier 1992 and 1993 drill holes) or surveyed by a contract surveyor. Coordinates were given in a local grid system and a conversion to UTM zone 11N using the North American Datum of 1927 was provided to Windfall Ventures.
Cambior Drilling was located by topography and orthophotography and transferred to USGS 24,000 scale USGS topography.
Coordinate systems used
Timberline, in 2019, used the UTM Zone 11 North projection in meters in the North American Datum of 1983. State Plane Coordinates from the 2015 Project database for both Lookout Mountain and Windfall drill holes were converted using ArcGIS.
McEwen is using the UTM Zone 11 North projection with the North American Datum of 1983 in international Feet. Drill hole coordinates from the Timberline 2024 drill hole database were converted using Pathfinder office by the database manager.
7.17.Rotary and Reverse-Circulation Drillhole Sample Quality
This section discusses sample quality from historical to more modern 2022 drilling and was presented in a previous technical report (Timberline NI43-101, 2023). The author has reviewed the work and based on experience with the historical programs believes the discussion to be adequate and accurate.
Due to the nature of conventional rotary and RC drilling, the possibility of contamination of drill cuttings from intervals higher in the hole is to be noted, especially when groundwater is encountered or significant quantities of fluids are added during drilling. Drill logs indicate that some holes intersected groundwater at Lookout Mountain, and water was sometimes injected by the drillers (this was always the case with the Timberline 2010 through 2012 RC drill holes).
Down-hole contamination can often be detected by careful inspection of the RC drill results in the context of the geology, by comparison with adjacent core holes, and/or by examining down-hole grade patterns.
Review of historical data shows 14 RC holes (one Barrick, five Echo Bay, and eight Timberline) that clearly exhibit cyclic down-hole patterns in the gold assays of deeper portions of the holes. These patterns are detected by examining the gold results of each set of four samples derived by the drilling of the same 20-foot drill rod (or sets of two samples in the case of 10-foot rods). In a classic case, the first sample of a drill rod will have the highest-grade, while the following three samples will gradually decrease in grade. This classic ‘decay’ pattern in grade is caused by the accumulation of mineralized material (derived from some level higher in the hole) at the bottom of the hole as the drilling pauses and a new drill rod is added to the drill string. When drilling resumes, the first sample has the greatest amount of contamination, and the successive samples are
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gradually ‘cleaner’ as the accumulated contamination is removed; and the continuing contamination experienced during the drilling is diluted by the material being drilled. This decay pattern is usually possible to detect only while drilling barren or very weakly mineralized rock. Even in cases where this cyclic gold contamination is of such low-grade as to have minimal impact on resource estimation, its presence suggests that similar, and possibly more serious, contamination is occurring higher in the hole within mineralized zones, where the contamination may be difficult to recognize.
The geologic context can also be used to detect contamination. The Secret Canyon Shale, which lies below the mineralized Lookout Mountain breccia, is only locally mineralized. Mineralized intersections within the Secret Canyon Shale that are not supported by adjacent holes must therefore be considered as possible candidates for contamination. Four such intercepts were identified, including one Barrick and three Timberline RC holes (one of the Timberline holes was also included with those with cyclic patterns).
The mineralized zones in two Echo Bay RC holes, one Amselco RC hole, six Amselco conventional rotary holes, and one Timberline RC hole appeared suspicious in comparison to surrounding holes, but these holes lacked clear cyclic patterns and the intercepts were within permissive geology. The logs of such holes were checked, and, in the case of the two Echo Bay RC holes and one Amselco rotary hole, notations of suspected or definitive contamination accompanied by high water flows were found.
All the suspected contaminated intervals discussed above were excluded from the mineral domains used in the resource modeling. Even the purely suspicious intervals that lack supporting evidence noted in drill logs were deemed to be too anomalous for use in the modeling and therefore were also excluded. The excluded samples are typically low-grade.
There are eight sets of holes at Lookout Mountain that are sufficiently close to be considered twin holes. Some of these twin sets are useful for comparisons of the type of gold analyses and are discussed below. Other twin sets are more germane to considerations of sample quality and potential down-hole contamination; a few of the more revealing pairs are summarized below using graphical down-hole gold plots. Figure 7-4 compares two Amselco rotary holes that are approximately five feet apart.
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Figure 7-4 Amselco Rotary – Rotary Twin-Hole Comparison

The mineralized zone in the upper portion of the hole is within colluvium/alluvium. Hole RTR-49 clearly intersected a mineralized zone in the middle of the hole that RTR-133 did not, while the lower mineralized zone was intersected by both holes. It is interesting to note that RTR-49 shows evidence of down-hole smearing in both mineralized zones that occur in bedrock, while RTR-133 appears to be ‘clean.’ The smearing of the middle zone in RTR-49 is also characterized by a strong cyclic decay pattern in the gold values, with a periodicity of 10 feet. It is likely that RTR-49 intersected a thin high-grade structure that RTR-133 did not, and this high-grade zone contaminated down-hole intervals in a cyclic fashion. This mineralized zone was excluded from the resource modeling.
Figure 7-5 and Figure 7-6 compare an Amselco core-RC-rotary twin set, with the rotary and RC holes lying about 10 feet from the core hole. Over comparable intervals, the core hole is lower grade than the rotary hole and higher-grade than the RC hole. It is difficult to draw conclusions from these relationships, other than the holes may be demonstrating natural grade variations. Note the lack of depth in the trough (at a depth of approximately 50 feet down-hole) in both the RC and rotary holes (as compared to the core hole). This is likely due to smearing of grade, which is not unusual in RC and rotary drill holes.
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Figure 7-5 Amselco Core – Rotary Twin-Hole Comparison

Figure 7-6 Amselco Core – RC Twin-Hole Comparison

An Amselco RC hole is compared to a Staccato 2007 core hole that is six-feet distant in Figure 7-7. Considering natural variability, the morphologies of the graphs compare well. The mean and median of the rotary hole (as displayed on the figure) are lower than the core hole over the interval 0 to 160 feet; loss of core hinders direct comparisons in deeper portions of the holes.
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Figure 7-7 Staccato Core – Amselco RC Twin-Hole Comparison

Figure 7-8 compares another Staccato core hole with a Barrick RC hole. The holes have a separation distance of 16 feet. The morphologies of the down-hole plots show excellent correspondence between the holes, and there is no evidence of down-hole contamination in the Barrick RC hole. The relatively close correspondence of the means and medians of the twin data reflects these relationships.
Figure 7-8 Staccato Core – Barrick RC Twin-Hole Comparison

The twin-hole data, a portion of which is discussed above, support conclusions reached by the author during the sectional modeling of the gold mineralization, i.e., there is local evidence of down-hole contamination of gold in the rotary and RC drill holes. In recognition of this, the mineral-
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domain modeling used in the resource estimation excluded the mineralized samples suspected of being contaminated. It should be noted, however, that the identification of suspect assays is interpretational; the author believes it is possible that some relatively small amount of the excluded mineralization is ‘real,’ and it is likely that some mineralized samples included in the resource estimation are affected by contamination.
In light of these observations, RC drilling and sampling protocols need to be developed and implemented to minimize the injection of drilling fluids, decrease the likelihood for down-hole contamination, and increase sample representativity.
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8. SAMPLE PREPARATION
The commercial analytical laboratories used by all operators that contributed data to the project drillhole database, as well as the analytical procedures used by the laboratories to obtain the gold assays for Lookout Mountain and Windfall, are, or were at the time, well recognized and widely used in the minerals industry (Table 8-1). In-house mine laboratories were used for the Norse Windfall Mines/Windfall Venture drill assays and some of the Amselco holes, however, and many of these analyses appear to have used partial-gold extractions such as cyanide. The Norse Windfall Mines gold data clearly understate grades in at least some of the holes at Lookout Mountain (Figure 8-3).
Table 8-1 Compilation of Analytical Laboratories and Assay Methods
Company | Assay Laboratory | Assay Method(s) | |
| Monitor Geochemical | | |
| Laboratory | | |
| Rocky Mountain | Fire Assay (FA) with unknown finish process | |
Amselco | Geochemical | | |
| Hunter Mining Laboratory | | |
| | | |
| In-house (Sparks, NV) | Fire assay using gravimetric or Atomic Absorption | |
| (AA) | | |
| | | |
Norse | In-house, Union Assay, | | |
Windfall and | Rocky Mountain | Atomic Absorption following cold cyanide shake- | |
Windfall | Geochemical, Skyline | leach digestion | |
Venture | Laboratories | | |
EFL | American Assay | Gold cyanide solubility assays, and Fire assay | |
Barrick | American Assay | Fire assay of 30-gram charges with gravimetric or AA | |
finish | | ||
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Echo Bay | Cone Geochemical, | Fire assay of 20- and 30-gram charges with an AA | |
Barringer (check assays) | finish | | |
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Pathfinder | Barringer | Fire assay on 30-gram charges with an AA finish | |
Exploration | | ||
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Cambior | Barringer | Fire assay on 30-gram charges with an AA finish. ICP | |
Exploration | | ||
IPL | MS for geochemical determinations | | |
US | | ||
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| | Fire assay of 50-gram charges with AA finish; | |
Staccato | ALS | Samples >3 ppm re-analyzed by FA with gravimetric | |
| | finish | |
| | Fire assay of 30-gram charges with AA finish; | |
Timberline | Inspectorate | Samples >3 ppm re-analyzed by FA with gravimetric | |
| | finish | |
| | Fire assay of 30-gram charges with either AA or ICP- | |
Timberline | ALS | ES finish; over-limits (>10 ppm) re-analyzed by 30- | |
gram FA with gravimetric finish. During 2020 – 2022 | | ||
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| | campaigns, samples assaying >0.2 g/t (200 ppb) were | |
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Company | Assay Laboratory | Assay Method(s) | |
| | analyzed by a 30-gram cyanide shake digestion with AA or ICP-ES finish | |
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McEwen Nevada | Paragon Geochemical | Samples are analyzed for gold using three primary · 30-gram fire assay with Atomic Absorption · Gold extraction through 10g cyanide leach (AuCN-10). · In both methods, >10 ppm over limits, are re- · 500g Photon Assay analysis | |
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McEwen Nevada | MSALABS (Photon Check) | 500g Photon Analysis | |
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McEwen Nevada | ALS Geochemistry (Fire Assay Checks) | Samples are analyzed for gold using two primary · a 30-gram fire assay with Atomic Absorption · If the gold concentration exceeds 10 ppm, | |
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To mitigate the under-reporting of the partial extraction assays, Gustin (2013 and 2023) replaced many of the Amselco in-house cyanide assays with check fire assays performed at commercial laboratories. This methodology was intended to limit the impact of the downgraded in-house assays on the resource estimation.
Records of drilling prior to that of Staccato have few details on sample preparation, QA/QC, or sample security. Information Gustin (2013 and 2023) identified is reported below, along with details on analyses of samples taken from Russell (2007), unless otherwise cited. All the historical operators were reputable, well-known mining/exploration companies, and there is ample evidence that these companies followed accepted industry practices relating to sample preparation and analytical techniques.
In consideration of this information, in addition to other data examined in accompanying sections of this report, the author believes the analytical data are of sufficient quality for use in the resource estimation.
8.1.Amselco
Amselco drilled at Lookout Mountain from 1979 to 1985. Amselco also drilled 11 holes at Hamburg Ridge on the Windfall Project in 1984. Amselco used the following commercial assay laboratories for the analyses of their drill samples: Monitor Geochemical Laboratory Inc. (“Monitor”), Rocky
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Mountain Geochemical Corporation (“Rocky Mountain”), and Hunter Mining Laboratory, Inc. (“Hunter”). Amselco also used their in-house American Selco Laboratory in Sparks, Nevada. Records reviewed by Gustin (2013 and 2023) indicated that the samples sent to the commercial laboratories were analyzed by fire assay methods, but the finish was not often specified.
The in-house laboratory analyzed samples by fire assay using gravimetric or atomic absorption (“AA”) finishes. Other in-house analyses are specified as “AA” in the documents examined. Based on other notations found in some cases, the author believes many, and perhaps all, of these “AA” samples were analyzed by AA after either cyanide or aqua regia digestions. Since aqua regia will not fully digest sulfide minerals and silicates, and cyanide leach will only digest gold particles that are available to solution (and may not fully digest this gold if the particles are coarse), both methods utilize partial-gold digestions. Fire assaying, by contrast, is considered to be a total gold analysis. Some of the partial-digestion data are therefore expected to understate grades in comparison to those determined by fire assay methods.
Figure 8-1 compares two Amselco holes drilled 11 feet apart. The interval from 50 to 90 feet in RTR-21 was analyzed by the “AA” method (pink line on graph in Figure 8-1) at Amselco’s in-house laboratory, while the remainder was analyzed by Rocky Mountain by fire assay. All RTR-21A samples were analyzed by fire assay by Monitor (blue line on graph in Figure 8-1). The interval analyzed by “AA” is anomalously low-grade compared to the Monitor fire assays, which is likely the result of the partial digestions used by the in-house laboratory.
Figure 8-1 Amselco RC – RC Twin-Hole Comparison

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8.2.Norse Windfall Mines and Windfall Ventures
Windfall Ventures and Idaho Mining have a long history at the Windfall project. The drill programs spanned from 1969 to 1984 prior to the purchase by Norse Windfall Mines of the property in 1986. Prior to 1974 when mining began at Windfall, drill assays were completed at third-party Laboratories. Review of the data and assay certificates found show Idaho Mines used Union Assay, Skyline Assay Laboratories, and Rocky Mountain Geochemistry for drill hole assays. This was done for various Z, F, and early W series drill holes. Skyline was also used for geochemical analyses (As, Hg). All assays sent to these labs were analyzed by Fire assay with an AA finish as indicated on certificates. No digestion method was stated.
During initial production of the Windfall mines in 1974, Windfall Ventures began using the in-house mine assay laboratory for drill hole analyses. Standard operating procedures for drill sampling and assaying were documented (WV Standard Operating Procedures internal company Master Book Manual, of unknown date). A summary of the procedures is as follows:
Drill samples were collected at the rig and passed through a Jones splitter before bagging. Bags were identified by hole number and footage. Cuttings were then logged for mineralization and lithology. Assay protocols required 100-gram pulps to be created for primary assays which were done by cold cyanide leach of the entire 100-gram pulverized sample. If, based on logging, the sample contained sulfide or was complex in nature (mixed oxide-sulfide), a second 100-gram pulp was created and sent to a third-party assay lab (Union or Rocky Mountain Geochemistry) for fire assay with an AA finish. If an assay from the in-house lab was greater than 0.015 ounce per ton, a duplicate pulp was created and sent to a third-party lab for Fire assay check.
These procedures were also followed by Norse after the purchase of Windfall venture assets in 1986 for all assays up to 1988, when mining ceased. These protocols were followed for the P, R, W, SW, WSW, and Norse (LM, N, V, VA) series drilling at Windfall and Lookout Mountain (LM series drilling).
To assess the quality of results from partial digestion and the cyanide assay process used by Norse for LM series holes drilled in 1986, Gustin (2013, 2023) provided the following analysis.
The following graphs compare two Norse Windfall Mines RC holes (LM series) that twin an Amselco RC hole (Figure 8-2) and an Amselco core hole (Figure 8-3). Both of the Amselco holes were analyzed by fire assay methods. The Norse Windfall Mines data are systematically lower than the fire assays from the Amselco holes. In the case of Figure 8-3, the divergence between the results increases with depth. These data are consistent with observations made by the author during grade modeling, i.e., the Norse Windfall Mines holes are, in many cases, anomalously low-grade with respect to surrounding holes. These observations are explained by the partial digestions used in the analyses of the Norse Windfall Mines drill samples.
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Figure 8-2 Norse Windfall RC (LM-15) – Amselco RC (RTR-56) Twin-Hole Comparison

Figure 8-3 Norse Windfall RC (LM-5) – Amselco Core Twin-Hole (RTC-201) Comparison

The case Gustin (2013) was making was that the lower cyanide AA historic assay results were downgrading the gold values compared to fire assay.
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Comparison of Windfall historical check fire assays to the original cyanide AA assays.
The author compared one hundred sixty-five check fire (FA) assays and cyanide AA (CN) assays from the Windfall Ventures era. Plots (Figure 8-4 and Figure 8-5) comparing CN versus FA using quantiles with a 1:1 regression line show good correspondence between the two methods.
W-series hole samples show relatively good correspondence, although the number of samples is few. R-series hole samples show distinct variability but of low variance, with most samples plotting along or adjacent to the 1:1 regression line. Variability at the low end for both R-series and W-series holes plots is larger due to detection limit differences.
Figure 8-6 shows gold assay values for CN and FA pairs for various holes and depths. Large grade differences are seen between several value pairs. Differences are generally larger in higher grade samples. Differences between the two assay methods can be accounted for by the presence of sulfide, deleterious elements such as copper, mercury, silver, and others that affect cyanide solubility.
Other reasons would include poor splits of reject material for pulp preparation, or acid generation gangue material.
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Figure 8-4 Q-Q Plots of Fire assay vs Cyanide assay results for Windfall Venture R-series holes.

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Figure 8-5 Q-Q Plots of Fire assay vs Cyanide assay results for Windfall Venture W-series holes.

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Figure 8-6 Hole and assay depth showing cyanide vs fire assay pairs for Windfall Venture R series drill holes.

It was not customary during the time period this drilling took place for the use of blank and standard material to be inserted in the drill sample stream to check the validity of assays. Windfall ventures used standard protocols for drill samples and a process that was followed for assay checks which involved creation of new pulps for sulfide and high-grade samples to be sent to a third-party laboratory for analyses. Assay certificates for check assays were included in the historic hard copy data provided by Windfall Ventures. The available check assays were reviewed and compared to cyanide assays for variance by this author and the Database Manager. Primary assay sheets from the mine laboratory were also reviewed for completeness, legibility (due to hand-entry of values) and correspondence to the database. The drill data, including lithology and assay data, were used by Windfall Ventures to assess the viability for mining purposes and to build the reserves that were subsequently mined. It is the opinion of this author that assay data from Windfall Ventures and Norse Windfall Mining is sufficient to support resource estimation at the Windfall and Lookout Mountain projects.
8.3.EFL
Summit Minerals drilled 9 EFL series holes and 2 M series holes at Lookout Mountain in 1990. EFL used American Assay Laboratory (“American Assay”) for their analyses. American Assay performed gold cyanide solubility assays (lab code CN15) for Fire assay results over 100 ppb gold. Primary assays were done by fire assay methods for gold (lab code FA30) and silver according to assay certificates that accompany the drill logs. Fire assay data were used in the resource modeling.
8.4.Barrick
Barrick drilled at Lookout Mountain from 1992 to 1993. Barrick used American Assay for the analytical work on their 40 holes. The samples were analyzed by fire assaying of 30-gram charges with either gravimetric or AA finishes. Select cuttings samples and composites of some of the
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geologically interesting intervals were analyzed by ICP for a 15-element suite by MB Associates (Mako, 1993a).
8.5.Echo Bay
Echo Bay drilled at Lookout Mountain from 1994 to 1998. Echo Bay used Cone Geochemical (“Cone”) for the analytical work on their drill holes, with some check assays completed by Barringer Laboratories Inc. (“Barringer”) and ALS. Records examined by RESPEC indicate that the samples were analyzed by fire assaying of 20- and 30-gram charges with an AA finish (Gustin 2013, 2023).
8.6.Pathfinder Exploration
Pathfinder Exploration drilled on Hoosac Mountain at the Windfall project and sent drill samples to Barringer Laboratories Inc. facilities in Reno, Nevada for drill assays at Windfall. Assays for gold were done by fire assay methods using an AA finish. Standard preparation procedures were followed for crushing and pulverizing and the digestion method was not stated on certificates. Pathfinder inserted standard material into the sample stream although no information is known about what assay grades and standard types were sent. Pathfinder drilling has no material impact on the Windfall resource but has been included for the completeness of exploration history in the database.
8.7.Cambior USA Inc
Cambior drilled on Hamburg Ridge and Hoosac Mountain at the Windfall project. Cambior Exploration utilized Barringer Laboratories of Reno, Nevada and IPL (International Plasma Labs) of Vancouver, Canada. Gold assays were performed by fire assay with an AAS finish using 30-gram charges at both laboratories. Multi-element geochemistry on composited samples was completed using ICP MS methods at Barringer Laboratories Inc. in Reno, Nevada for drill assays at Windfall and Hamburg Ridge. Cambior drilling has no material impact on the Windfall resource but has been included for the completeness of exploration history in the database.
8.8.Staccato
Staccato drilled at Lookout Mountain and Windfall from 2005 to 2010. ALS prepared and assayed the samples from Staccato’s drilling from 2005 through 2007 by fire assaying of 50-gram charges with either AA (method AA24) or gravimetric (method GRA22) finish.
The 2008 drill samples were prepared and analyzed by Inspectorate, who used fire assay with an AA finish. All samples exceeding 3 ppm (0.088 oz Au/ton) were re-analyzed by fire assay with a gravimetric finish. Fifty-element ICP geochemical analyses were performed for individual holes on
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pulp composites as outlined by Staccato staff. Composites were created by Inspectorate using standard techniques for blending splits from original assay pulps.
For Reverse circulation drilling:
Drill samples were taken at the rig on 5-foot intervals. Samples were captured in a cloth or olefin sample bag placed in a plastic bucket. Bags were labeled with hole ID and sample number which was a sequence beginning at 1 and increasing by one till end of hole. This allowed for the blind insertion of blank and standard material, at the rate of 1 per 10 samples, into the sample sequence. At the drill a duplicate sample was taken every 20 samples and given a letter designation. Sample numbers were tied to footages via a sample record sheet. Samples were picked up on site by the assay laboratory and transported to Inspectorate America facilities in Sparks, NV for processing and analyses.
The process for sampling core drill holes is as follows:
· | Core Boxes were transported by geologic staff to Staccato’s Elko office facility daily where they were logged for lithology, alteration, mineralization, oxidation state, and geotechnically for core-recovery and RQD. |
· | Once logged, assay samples were broken out by the geologist based on lithology and alteration. Driller run blocks were utilized as much as possible for sample breaks, with lithology and alteration the over-riding concern. Samples were marked with red markers. If sample breaks were made at run blocks the block was highlighted in red and a sample tag was placed at the end of the sample. If the sample started or ended between run blocks the location was marked in red along the top of the corrugated separator, and a wood block with the end footage labeled in red ink placed between core at the sample break. A sample tag was then stapled to the side of the separator by the mark where the sample ends. |
· | Samples were cut on site by a contract core cutter. Sample cut sheets tying sample numbers to footage were created by the geologist and provided to the core cutter. Blank and standard material were outlined on the cut sheet and bagged when sampling core to maintain number sequence continuity. Samples were cut in half with half placed into bags labeled with the hole number and sample number. Half of the core was retained for additional testing. |
· | Samples were picked up at the office by the assay lab and transported to Reno for preparation and analysis. |
8.9.Timberline
Timberline drilled at Lookout Mountain and Windfall from 2010 to 2015, and at Lookout Mountain from 2020 to 2023. Drilling from 2010 to 2015 followed the protocols listed in section 8.8 for Staccato.
From the Timberline 2023 technical report:
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During drilling, RC drillhole samples were collected in five-foot intervals in five-gallon buckets beneath a rotary splitter. Samples were labeled with a unique ID, with footages correlated to sample bags via a sampler’s log sheet and with pre-numbered chip trays showing depth from and to for each interval (typically in intervals of five feet). Samples were initially laid out sequentially at the drill site to dry until completion of each hole and demobilization of the rig. The samples were then relocated to Eureka where they were secured within the fenced and lockable Company facility.
The samples were sorted into numerical sequence and cross-checked with [drillers’] logs for interval consistency. Analytical blanks and certified reference standards were then inserted under Company supervision. After drying, the samples were transported in batches sorted by drillhole (either by laboratory pickup or transport by company personnel) to either Inspectorate America in Sparks, Nevada, or ALS Minerals (formerly ALS Chemex) in Elko, Nevada for sample preparation and later analysis in either Reno, Nevada or North Vancouver, British Columbia.
Sampling of drill core was completed under Company supervision. Sample intervals were designated by a geologist during core logging and marked in core boxes with breaks typically correlated to driller’s depths noted by wooden blocks, or at significant lithological breaks, typically not exceeding five [foot] intervals. The core was sawn or split into halves by technicians under the supervision of Company geologists. One half of the core was bagged and labeled with a unique sample number or unique pre-printed bar code. Selected sample intervals of the half-core were resawed into quarters for analysis as field duplicates. The unsampled core from each hole was then catalogued and placed in secure dry storage in shipping containers at […] Timberline’s locked Eureka facility. Certified reference standards and blanks were inserted blindly into the sample stream. Geologists and technicians recorded the sample interval data onto sample dispatch forms before pickup by, or delivery to, the laboratory as with RC samples.
Timberline used Inspectorate for sample prep and assay during its 2010-2012 and 2014-2015 drilling campaigns. Samples were picked up by Inspectorate and taken to their laboratory in Sparks, Nevada, for sample preparation and analysis using standard 30-gram fire assays with AA finishes. Samples with gold values greater than 3 ppm were re - analyzed using a 30-gram fire assay with a gravimetric finish.
ALS completed check analyses on selected Inspectorate pulps as part of Timberline’s quality assurance/quality control (“QAQC”) program. The pulps were analyzed by methods identical to those used by Inspectorate (all samples by ALS code Au -AA25; samples yielding results greater than 3 ppm by Au-GRA21).
Timberline utilized ALS for sample preparation and assay during its 2020-2022 drilling campaigns. The samples were transported to Timberline’s secure Eureka facility, where the samples were further examined before being delivered to ALS in Elko, Nevada for sample preparation and later analysis. The rock samples were assayed by ALS for gold by fire assays of […] 30-gram charges with AA or ICP-ES finishes (ALS code Au-AA23). The over-limits for gold samples assaying above 10 g/t (0.292 oz/ton) were determined by a 30-gram fire assay with gravimetric finishes. Silver and other trace elements (up to 33
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elements), when analyzed, were determined by multi-acid digestion and ICP-ES finish. Timberline’s standard methodology was continued from earlier programs and included the insertion of analytical control samples before laboratory submission.
Analytical pulps from available pre-Staccato exploration RC and core drill samples, and all Staccato and Timberline samples are preserved in dry storage in the on-site shipping containers in Eureka.
8.10.McEwen Nevada
RC drilling samples were collected at consistent 5-foot intervals directly from the cyclone and splitter system attached to the drill rig. Representative samples are collected in labeled sample bags and logged into the sampling database. Care was taken to minimize contamination and maintain sample integrity during collection and transport. Diamond drill core is geologically logged, photographed, and marked for sampling. Core intervals are selected based on geological boundaries and mineralization characteristics. The core is cut longitudinally using a diamond saw, with one-half submitted for laboratory analysis and the remaining half retained for reference and verification purposes.
A comprehensive QA/QC program is implemented throughout the sampling and analytical process to ensure data quality, accuracy, and precision. Certified reference materials (standards) are inserted at about every 10th sample. These include blank samples to monitor contamination, field duplicates, and coarse duplicates used to assess sampling precision. Laboratory pulp duplicates were used to monitor analytical repeatability.
Strict sample security procedures are maintained from the drill site to the analytical laboratory to preserve the chain of custody and prevent sample tampering or loss. Samples are placed into securely labeled sample bags immediately after collection. Sample bags are sealed and grouped into larger secured containers. Unique sample identification numbers and barcode tracking systems are used throughout the process. Samples are either picked up by the laboratory personnel or by one of our geologists and taken directly to the laboratory. The laboratory receipt is verified against the shipment manifests upon delivery by sending a sample batch receipt confirmation email to McEwen staff.
External check assays for Photon and fire analyses were conducted by MSA Labs and ALS respectively, to validate analytical accuracy and laboratory performance from Paragon.
Additionally, Paragon utilizes Photon Assay for gold analysis. This technique involves bombarding samples with high-energy X-rays, which excite atomic nuclei, resulting in the emission of gamma rays at specific energies. This allows for the detection of gold in the samples.
8.11.Laboratory Accreditation
During the drilling that predated Staccato’s involvement with the property, accreditation of laboratories was not common. There is no information on accreditation of the laboratories used by
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the historical operators prior to Staccato. However, Monitor, Hunter, Rocky Mountain, American Assay, Cone, Barringer, ALS, IPL, and Inspectorate were all widely used commercial laboratories in the mining industry at that time.
Currently, ALS is registered to ISO 9001:2008, and the Nevada and North Vancouver facilities have received ISO 17025 accreditations for specific laboratory procedures relevant to the assaying processes, according to their website. Inspectorate is also accredited to ISO 17025 standards according to their website.
Paragon Geochemical is an ISO 17025:2017 accredited geochemical testing laboratory providing analytical services to the mining industry in North America and beyond.
MSA Labs maintains the highest quality standards and follows the guidelines of ISO17025 accreditation and ISO9001, ISO14001, and ISO45001 certification
8.12.Quality Assurance / Quality Control
Little information is known regarding quality assurance and quality control procedures that may have been implemented by historical operators prior to Staccato. Available drillhole records indicate that Amselco regularly inserted control samples into the drill-sample stream for assaying. The expected values of these control samples are not known and therefore cannot be evaluated. It is not known if further QA/QC procedures were implemented by Amselco. No records have been found that describe the types and extents of QA/QC programs that may have been implemented by Norse Windfall Mines, EFL, Barrick, or Echo Bay. However, Staccato and Alta completed check analyses using various drill-sample materials from Amselco, Barrick, and Echo Bay that serve to partially mitigate the lack of original QA/QC results from these operators.
In addition to the confirmatory work completed on various drill-sample materials of prior operators at the Lookout Mountain project, Staccato also sent pulps from their own drill samples to a third-party laboratory for check assaying. Timberline undertook fully developed, modern QA/QC programs as part of their drilling programs.
The 2013 and 2014 Technical reports from Timberline provided an evaluation of QA/QC data from all operators at Lookout Mountain and detailed statistical evaluations of the results were given. These evaluations are summarized in Section 9. Evaluation of QA/QC for the McEwen 2024 and 2025 drill programs at the Windfall and Lookout Mountain Projects was done by the database manager as assay reports were received.
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9. DATA VERIFICATION
The following summarizes the authors’ verification of the project data that are relevant to the estimation of the current project resources.
9.1.Metallurgical Data
The Qualified Person (QP) reviewed the metallurgical test work data provided to McEwen by predecessor companies, for use in this technical report. Data verification activities focused on confirming the consistency, completeness, and suitability of the metallurgical information supporting the process design criteria and recovery assumptions utilized in this study.
The metallurgical dataset was compared against information reported in previous technical reports, metallurgical studies, laboratory reports, and supporting project documentation. The review included verification of reported recoveries, grades (where applicable), test conditions, sample identification, and key processing parameters used in prior evaluations.
The QP found that the metallurgical results presented are generally consistent with the results reported in previous studies and technical reports. No material discrepancies were identified that would adversely affect the conclusions of this technical report. The data reviewed are considered reasonable and suitable for the level of study represented by a technical report.
The QP did not independently re-sample, re-test, or audit the original metallurgical test work programs. Reliance was placed on the accuracy and completeness of the metallurgical information supplied by McEwen and documented in previous technical reports. Based on the verification procedures completed, the QP considers the metallurgical data to be of sufficient quality and reliability for use in this technical report.
The data verification process was limited to a review and comparison of available metallurgical data and supporting documentation. No material limitations were identified that would significantly impact the use of the metallurgical information in this technical Report. The QP is not aware of any factors that would materially affect the validity of the metallurgical assumptions adopted for the purposes of this technical report.
9.2.Drillhole Database
A validation review was completed for all assay data from previous exploration campaigns. The review process included about 90% verification of the digital assay database against original laboratory assay certificates to confirm the accuracy and completeness of the recorded analytical results.
Drill hole identifiers, sample intervals, analytical values, and associated metadata were systematically cross-checked, and any discrepancies identified during the review were resolved.
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The validation confirmed that the assay information incorporated into the geological database and subsequently utilized for Mineral Resource estimation was consistent with the original laboratory records and considered reliable for resource evaluation purposes. No material issues were identified that would adversely affect the integrity of the assay dataset.
A review of the drill hole survey data was undertaken to assess the availability and completeness of downhole deviation information. Approximately 80% contained downhole survey measurements obtained from the original IDS survey files, providing recorded borehole orientation data along the length of the drill holes. These measurements were used to define the actual drill hole trajectories and provide spatial control for geological interpretation and Mineral Resource estimation.
All logging was done using Geo Sequel with geologists logging directly into the database. The database captured lithology, alteration, mineralization, and for core, structure and RQD data were also captured. Hardcopy logs were printed for each hole. McEwen geologic staff reviewed 25% of the logs and found the data on the logs and the data in the database matched.
9.3.Quality Assurance/Quality Control Data
The authors have reviewed summaries in previous technical reports, especially Gustin (2023), which evaluated in detail the historical QA/QC data collected by various project operators. The authors consider this work to be thorough and of a quality such that the data can be used in the resource estimations in this report.
As the author of chapters 7 and 8, this QP has been familiar with the data from his role as Senior Exploration Manager and QP for Staccato Gold from 2008 to 2010, and District Geologist and Co-QP for Timberline from 2010 to 2015. During this time frame the author was responsible for creating the QA/QC policies for both Staccato and Timberline and was actively involved in the planning and implementation of geological and drill programs at both the Windfall and Lookout Mountain Projects from 2008 to 2015. This author was not involved with Timberline from 2020 to 2023. This author’s opinion, based on institutional knowledge and review of data personally from 2008 to 2015, is that historical drill data up to 2015 is sufficient to support resource estimation for the Lookout Mountain Project
During tenure with Staccato and Timberline, the author was in charge of compiling and building the initial Windfall database from data available to Staccato at that time. This data was augmented by a complete data set sent by W.L. Wilson, co-owner and principal officer of Idaho Mining and the Windfall Ventures and this was made available to McEwen staff. The data, now over 50 years old, has been re-compiled by McEwen database personnel and third-party consultancy services provided by Orix Geosciences with help and oversight from this author. The consultancy service collated, categorised, digitised and catalogued the large volume of historic data available, usually in paper form. Specific comments made in Chapters 7 and 8 regarding this data were made based on review and working with the hardcopy data. Assay certificates, in-house laboratory reporting sheets, drill logs, check assay data, and standard protocols for both drilling and the assay laboratory were reviewed by both the author and the database manager. This author was also previously responsible for converting collar coordinates for both projects, as described in Chapter
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7, under the guidance of professional surveyors at SRK. The historical work by the author was utilized by Gustin (2023) in his thorough analysis of historical QA/QC data from Staccato and Timberline.
It is the author’s opinion that the drill hole and assay data for the Windfall and Lookout Mountain Projects are sufficient to support resource estimation for this report.
9.3.1. McEwen Nevada 2024-2025 Program
The Quality Assurance and Quality Control (“QA/QC”) program implemented during the 2024-2025 sampling campaigns was designed to monitor the accuracy, precision, and potential contamination associated with the analytical process. QA/QC measures included the routine insertion of Certified Reference Materials (“CRMs”), blank samples, and field duplicate samples into the sample stream submitted to the analytical laboratory.
Certified Reference Materials
Three CRMs were inserted into the sample sequence to monitor analytical accuracy and laboratory performance. CRMs were selected to represent a range of expected grades and mineralization styles encountered during the program. The standards used were commercially prepared and certified by independent suppliers, with accepted values and standard deviations established through inter-laboratory testing.
During the 2024 sampling campaign, CRMs were inserted at an approximate rate of one CRM sample for every 15 to 17 routine samples submitted. CRM analytical results were routinely reviewed upon receipt from the laboratory. Results falling outside three standard deviations above or below the expected value (± 3SD) were investigated, and where necessary, batches were flagged for re-assay.
Figure 9-1 shows the quality control performance of the three CRMs analyzed a total of 151 times by the Fire Assay method. The majority of the results fall within two standard deviations (±2SD) of the expected values, indicating that the analytical process demonstrates strong accuracy and that overall quality control is high. Summary statistics for the CRM analyses are provided in Table 9-1.
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Figure 9-1 Fire Assay Normalized CRM Control Chart

Table 9-1 Fire Assay Normalized CRM Control Chart Table
Fire Assay Normalized CRM Control Chart Table Windfall and Lookout Mountain - 2024/2025 | ||||||||||
CRM | N | Mean Z | SD(Z) | Min Z | Max Z | >2 | >3 | >2 SD | >3 SD | Status |
CDN-GS-2X | 43 | -0.10 | 0.82 | -1.97 | 2.82 | 1 | 0 | 2.3% | 0.0% | Excellent |
OREAS 235 | 58 | -0.42 | 0.98 | -2.13 | 1.55 | 1 | 0 | 1.7% | 0.0% | Good |
OREAS 264 | 50 | 0.23 | 0. | -1.73 | 2.00 | 0 | 0 | 0.0% | 0.0% | Excellent |
Expected >3 SD rate ≈ 0.27%; Expected >2 SD rate ≈ 4.55%
Fire Assay Executive Summary | ||
| ||
Metric | Based On | Assessment |
| | |
Accuracy | Mean Z | Excellent |
| | |
Precision | SD (Z) | Excellent |
| | |
Warning Rate | >2 SD % | Better than Expected |
| | |
Failure Rate | >3 SD % | Excellent |
| | |
Evidence of Drift | Control Chart Review | None Observed |
| | |
Overall QA/QC Performance | Combined Assessment | Excellent |
| | |
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In 2025, the insertion frequency was increased to approximately one CRM for every 10 routine samples to enhance monitoring of analytical accuracy and to provide a higher level of confidence in the analytical dataset. Figure 9-2 presents the quality control performance of the three CRMs, which were analyzed a total of 1005 times using the Photon Assay method. Most CRM results fall within ±2SD of their certified values, demonstrating good analytical accuracy and indicating that the assay process was under acceptable statistical control throughout the period of analysis. Summary statistics for the CRM results are provided in Table 9-2.
Figure 9-2 Photon Assay Normalized CRM Control Chart

Table 9-2 Photon Assay Normalized CRM Control Chart Table
Photon Assay Normalized CRM Control Chart Table Windfall and Lookout Mountain - 2024/2025 | ||||||||||
CRM | N | Mean Z | SD(Z) | Min Z | Max Z | >2 SD | >3 SD | >2 SD % | >3 SD % | Status |
OREAS 264 | 361 | 0.00 | 0.82 | -2.25 | 2.41 | 3 | 0 | 0.8% | 0.0% | Excellent |
OREAS 235b | 344 | -0.19 | 0.98 | -3.02 | 2.44 | 15 | 1 | 4.4% | 0.3% | Good (1 |
OREAS 239b | 300 | 0.12 | 0.73 | -1.88 | 2.16 | 1 | 0 | 0.3% | 0.0% | Excellent |
Expected >3 SD rate ≈ 0.27%; Expected >2 SD rate ≈ 4.55%
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Photon Assay Executive Summary | ||
Metric | Based On | Assessment |
| | |
Accuracy | Mean Z | Excellent |
| | |
Precision | SD (Z) | Excellent |
| | |
Warning Rate | >2 SD % | Excellent |
| | |
Failure Rate | >3 SD % | Good |
| | |
Evidence of Drift | Control Chart Review | None Observed |
| | |
Overall QA/QC Performance | Combined Assessment | Excellent |
Blank samples
Blank samples were inserted into the sample stream to monitor potential contamination during sample preparation and analytical procedures. Blank material consisted of barren or unmineralized material considered to contain negligible concentrations of the target analytes. A total of approximately 616 blank samples were submitted to Paragon for analysis. As illustrated in Figure 9-3, all blank sample results were considered acceptable, with no assays exceeding the established failure criterion of ten times the lower detection limit (0.05 g/t Au). The results indicate no evidence of systematic gold contamination during the analytical process. A summary of the blank sample performance and the number of samples analyzed is provided in Table 9-3.
Figure 9-3 Blanks

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Table 9-3 Blanks
Year | Standard Name | No of Blanks |
2024/2025 | MEG-SiPrepBlank.20.99 | 616 |
Duplicates and check samples
Field duplicate samples were collected to assess sampling precision and the inherent variability associated with the sampled material. Field duplicates from reverse circulation (RC) rigs were generated by collecting a second representative sample from the same sampling interval and submitting it to the laboratory as a separate sample with a unique sample identification number. No field duplicates were collected from core holes.
Field duplicate samples were inserted into the sample stream at an approximate frequency of one duplicate sample for every 20 routine samples collected. Duplicate results were evaluated using relative percent difference and scatter plot comparisons to assess the reproducibility of the sampling and analytical process. Results from the field duplicate assay program (Figure 9-4) and Figure 9-5) demonstrate an acceptable level of correlation between the original assays and the duplicates.
Figure 9-4 Fire Assay Log QQ Plot – Original vs Duplicate

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Figure 9-5 Photon Assay Log QQ Plot – Original vs Duplicate

During the 2024 drilling and sampling program, a total of 53 pulps were selected for external check assay analysis to verify the accuracy and precision of the primary analytical laboratory results. The check assays were completed by ALS Geochemistry using conventional fire assay analytical methods with atomic absorption or gravimetric finish, depending on the grade range of the sample. Only samples with reported gold grades greater than or equal to 0.05 g/t Au were selected.
Results from the check assay program (Figure 9-6) demonstrate an acceptable level of correlation between the original assays and the ALS Geochemistry check assays. Minor deviations are observed in the lower tail of the distribution; however, the data points generally plot close to the reference line, indicating an overall good fit to a normal distribution.
No material analytical bias or systematic discrepancy was identified between the primary assay results and the umpire laboratory data. The comparison supports the conclusion that the analytical procedures employed during the 2024 program are reliable and appropriate for use in mineral resource evaluation.
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Figure 9-6 Fire Assay Log QQ Plot – Original vs Check

For the 2025 drilling and sampling program, an expanded check assay program was implemented utilizing Photon Assay technology. A total of 1,480 samples with assay values greater than or equal to 0.05 ppm Au were selected and submitted to MSA Labs for verification analysis.
As illustrated in Figure 9-7, the results exhibit minor deviations in the lower tail; however, the data points generally plot close to the reference line, indicating an overall good fit to a normal distribution.
Comparison between the original Photon Assay results and the MSA Labs check assays demonstrates strong overall agreement. No material bias or systematic variance was identified between the primary laboratory assays and the MSA Labs Photon Assay verification results, supporting the reliability and consistency of the analytical dataset.
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Figure 9-7 Photon Assay Log QQ Plot – Original vs Check

It is the opinion of the QP that the QA/QC program is considered appropriate and adequate for the stage of exploration and consistent with industry-standard practices for mineral exploration programs conducted in support of mineral resource disclosure.
9.4.Site and Field Office Inspections
Michael Baumann visited the Lookout and Windfall Project areas on September 8, 2025 and March 16, 2026 with Jason Rizzolo a McEwen geologist. This site visit included inspections of active drill rigs and examination of sampling procedures by drill crew. At Lookout Mountain, the site visit included walking into the Lookout Mountain pit where there are visible oxides and sulfides in the Dunderberg shale. There is extensive silicification along the Lookout trend.
At Windfall, the mineral trend along the footwall of the Rustler, Windfall, and Paroni pits was traversed from south to north. Several crosscutting structures were observed in the hanging wall of the Windfall Trend and, in places, offset the Dunderberg and Hamburg formations.
Robert Kastelic has visited the Lookout Mountain and Windfall project areas many times since 2024, most recently on March 19, 2026 with Gary Edmondo. The site visit included the Lookout
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Mountain, Paroni, and Windfall legacy pits. Drilling and sampling were observed at one RC rig, which was collecting samples of cuttings every 5 ft as the hole was being drilled. A core rig was observed drilling in the Windfall resource area. Alteration consisting of decarbonatization of the Hamburg dolomite was observed from the Paroni pit south to the Rustler pit, associated with, and along the mineralized Windfall Trend.
Gary Edmondo has visited the Lookout and Windfall projects regularly. This included visits with Robert Kastelic and Michael Baumann in March of 2026 where visits were conducted at the Paroni and Windfall Pits, and the Lookout Mountain Pit. The visit included observations of geology and alteration at all three pits, and observation of visible sulfide on the floor of the Lookout Mountain Pit. During those visits, observations concerning sampling were made at a reverse circulation drill, and the general flow of recovering and boxing core at the core drill.
9.5.Additional Data Verification
McEwen’s exploration geology team modeled the Lookout Mountain geology and mineralized envelopes in Micromine software using formation logs. Michael Baumann and Gary Edmondo reviewed the models in late 2025 and early 2026. Mineralization trends north and dips east along faults and ramp faults near the contact between the Cambrian Dunderberg Shale and the Hamburg Dolomite. The team applied low- and high-grade cutoffs of 0.005 and 0.030 opt Au, respectively, to define the mineralized shapes. Project data were reviewed visually and statistically for the separate populations. The Project data was verified during the resource modeling.
The Windfall project, initially modeled using sectional methods, was updated with Micromine CoPilot software to define low-grade (0.005 opt gold) and high-grade (0.030 opt gold) mineralized shells. Two main domains emerged: a north domain with steeply dipping mineralization to the east and a south domain with lower-angle bedding and mineralization dipping to the east; these zones are separated by the NE-trending Nolan Fault. Geological controls were evaluated by Michael Baumann, Jason Rizzolo, and the Exploration Geology team.
Most of the historical drilling at Lookout and Windfall project areas has been done with vertical holes and there may be high-angle structures in some areas that would not be adequately evaluated by vertical drilling. A decision was made in 2024 to use primarily angled holes to drill across steep structures to evaluate the true thickness of mineralization and thereby improve the geological and resource models.
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10.MINERAL PROCESSING AND METALLURGICAL TESTING
The information provided below summarizes relevant metallurgical test work completed on Lookout Mountain project mineralization, and in some cases provides opinions of the metallurgists. The author’s opinions are restricted to comments on the nature, location, and representativity of the metallurgical samples, a statement of the independence of the metallurgical laboratories, and a summary statement in Section 10.7.
Metallurgical gold-recovery test programs have been completed on surface bulk samples, RC drill cuttings, drill-core intervals, and drill-core composites from the Lookout Mountain resource area between 1985 and 2014/2015 by Amselco, Tenneco, Norse Windfall Mines, Alta Gold, and Timberline (Table 10-1). The programs included cyanide bottle-roll tests, column-leach tests, agglomeration testing, screen analyses by size fraction, head and deleterious-element analyses, and preliminary HPGR crush-response testing, as summarized in Table 10-1. No additional completed metallurgical test results are available for inclusion in this report.
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Table 10-1 Summary of Lookout Mountain Metallurgical Testing | |||
| | | |
Program / | Sample Basis | Test Work | Relevance |
Laboratory | | | |
1985 Amselco – | Six (6) RC-cutting | Bottle-roll tests; | Early leach-response |
Hazen | composites: | unground and ~-200 | screening by rock type and |
| oxidized claystone, | mesh | oxidation state |
| unoxidized | | |
| claystone, jasperoid | | |
| | | |
| Two (2) RTC-201 drill- | 4-inch column tests; | Preliminary column testing of |
1986 Amselco – | |||
Hazen | core composites | minus ½-inch feed | oxidized claystone |
| | | |
1986 Tenneco – | Ten (10) nominal ¼- | Bottle-roll tests | Leach-response screening by |
Heinen- | inch RC-cutting | | depth and oxidation state |
Lindstrom | composites | | |
| | | |
1987 Norse | Approx. one-ton bulk | Three agglomerated | Bulk-sample heap-leach |
Windfall – KCA | sample from | column tests; one | response by crush size |
| historical pit area | bottle-roll test | |
| | | |
1997 Alta Gold – | Five (5) bulk pit | Head assays, ICP/Hg | Leach response and |
McClelland | samples; four tested | analyses, bottle-roll | deleterious-element |
| metallurgically | tests | screening of pit material |
| | | |
2010–2011 | Four (4) bulk | Head assays, screen | Coarse-crush and ROM heap- |
Timberline / | samples from | analyses, bottle-roll, | leach response of bulk |
Staccato / BH | historical pit area | agglomeration, and | material |
Minerals – KCA | | column tests | |
| | | |
2011 Staccato / | 144 core intervals | Bottle-roll, | Core-composite heap-leach |
BH Minerals – | composited into | agglomeration, and | response by lithology |
KCA | three lithologic | six column tests | |
| composites | | |
| | | |
2012–2013 | 872 selected core | Bottle-roll tests over | Recovery variability and |
Timberline – | intervals | multiple crush sizes | crush-size sensitivity |
KCA | composited into 75 | | |
| composites | | |
| | | |
2014 Timberline | Three (3) regional | Head assays, screen | Jasperoid heap-leach |
– KCA | jasperoid | analyses, bottle-roll | response by area and crush |
| composites | and column tests | size |
| | | |
| HPGR products from | HPGR screen analyses | HPGR/crush-product leach- |
2014 Timberline | |||
– KCA / | jasperoid | and bottle-roll tests | response comparison |
McClelland | composites | | |
| | | |
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10.1.Introduction
The scope of metallurgical testing on mineralized material at Lookout Mountain includes approximately 8,600 drill samples assayed for cyanide (NaCN)-leachable gold, approximately 450 bottle-roll tests (“BRTs”) on RC or core drill samples, and 21 column-leach tests (“CLTs”) on bulk samples and from composites of drill core material.
The NaCN assays in the project database provide an initial assessment of the leachability of gold and have proven useful for assessing oxidized vs unoxidized mineralized rock. Only limited metallurgical testing has been completed to date on unoxidized mineralized rock.
Samples collected for metallurgical testing were selected from the gold resource area and chosen by rock type and area, including North Lookout Mountain and South Lookout Mountain, and from surface bulk samples and drill core.
Lithologic samples selected for CLTs represent composites of oxidized claystone (shale), jasperoid/silicified breccia, or collapse breccia/fault gouge (representing dominantly sanded dolomite). Rock material was typically composited from multiple drillholes within a given area (Table 10-1).
The samples on which the Lookout Mountain project metallurgical test work has been performed were selected as representative of oxidized mineralization in terms of grade and areal distribution. The Amselco samples are clustered in the area of the existing open pit at North Lookout Mountain. Timberline tested a number of samples from this area as well but has also tested a significant number of samples from various drillholes at South Lookout Mountain.
The available metallurgical database is primarily representative of the Lookout Mountain resource area and includes limited metallurgical information for the Windfall area. The Lookout Mountain and Windfall areas have been subject to additional drilling in 2024 and 2025. Windfall samples have been selected for forthcoming recovery test work, but completed metallurgical recovery results for the Windfall area are limited at this time, consisting primarily of historical cyanide shake data from approximately 8,000 drill samples.
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10.2.Metallurgical Laboratories
Four metallurgical laboratories have completed BRTs and/or CLTs on Lookout Mountain gold-bearing rock. These include Hazen Laboratories (“Hazen”) of Denver, Colorado, Heinen Lindstrom Consultants of Sparks, Nevada (“Heinen”), and Kappes, Cassiday & Associates (“KCA”) and McClelland Laboratory (“McClelland”) of Reno, Nevada. The laboratories are well-known, independent, commercial metallurgical laboratories that have served the mining industry for a long time.
Hazen holds analytical certifications or accreditation from state regulatory agencies and from the US Environmental Protection Agency. The company participates in performance evaluation studies to demonstrate competence in these areas of certification.
McClelland is certified through the International Accreditation Service, ILAC-MRA, and they are NDEP approved (Nevada State Certified NV-00933) for MWMP & HC Testing Procedures & Wastewater Certification on select analytes associated with MWMP & HCT.
No further information is available on Heinen as the company no longer exists. It is known that the metallurgical test work reported by Heinen on Lookout Mountain was authored by Mr. Gene McClelland, later of McClelland Laboratory. Heinen and Lindstrom undertook significant work for the US Bureau of Mines.
KCA is a well-respected, Nevada-based consultancy founded and led by Mr. Daniel Kappes (P.E.) and has provided services to the international mining industry for cyanide process, laboratory testing, project feasibility study engineering design, construction, and operations management since 1972.
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Figure 10-1 Lookout Mountain Metallurgical Testing Sample Areas and Composite Column Test Locations
(Timberline / KCA 2011 and KCA 2014)

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10.3.Metallurgical Testing by Historical Operators
BRTs and CLTs were conducted on mineralized samples from Lookout Mountain resource area by Hazen, Heinen, McClelland, and KCA from 1985 to 1997 (Figure 10-1).
Figure 10-2 Historical Lookout Mountain Pit Area Metallurgical Drillhole and Bulk Sample Locations
(Compiled from historical Amselco, Tenneco, Norse Windfall, Alta Gold, and Timberline sample locations)

Hazen conducted preliminary cyanide leach BRTs on six composites of RC cuttings from Lookout Mountain for Amselco in 1985 (Gathje, 1985). There were two samples each of three rock types (Klessig, 1985): unoxidized claystone, oxidized claystone, and jasperoid. Each sample was tested twice, once without grinding and once after grinding to approximately -200 mesh. The leaching conditions were 30% solids, pH 10.5 to 11 maintained with hydrated lime, and a cyanide
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concentration maintained at 1g NaCN/l. The leach liquors were sampled at 4, 8, 24, and 48 hours and assayed for gold and cyanide. Gold dissolutions varied considerably from sample to sample, ranging from about 10% to about 90%, but did not vary significantly by grind size (Gathje, 1985) (Table 10-2). Dissolution rates were rapid, and generally there were no experimentally significant differences in the gold dissolutions at four hours compared to 48 hours. Cyanide consumptions were high, ranging from 1.7 to 4.5 lbs NaCN/ton, and they increased significantly as the leach times increased.
Table 10-2 Amselco 1985 Hazen Bottle-Roll Test Results on RC Cutting Composites
(Hazen Research, 1985)
| | Assay | Au | Au | Depth Below | |
Composite | Description | Grade | Extraction | Extraction | | |
Surface | | |||||
| | (oz Au/ton) | (no grind) | (grind) | | |
| | | | | | |
| | | | | | |
| | | | | | |
| oxidized claystone from | | | | | |
85-1-OAC | RC holes RTR-92, 131, 161, | 0.048 | 81.4% | 78.5% | <=80 ft | |
| 163, 177, and 187 | | | | | |
| oxidized claystone from RC | | | | | |
85-2-OHC | holes RTR-44A, 71, 98, and | 0.408 | 91.3% | 90.4% | <= 55 feet | |
| 153 | | | | | |
| | | | | | |
85-3-RAC | unoxidized claystone from | 0.047 | 28.6% | 27.3% | Mixed, 1/2 < 70 | |
holes RTR- 161, 163, and 257 | and 1/2 >340 ft | | ||||
| | | | | ||
85-4-RHC | unoxidized claystone from RC | 0.362 | 10.6% | 12.1% | >430 and < 480 | |
holes RTR-134, 190, and 191 | ft | | ||||
| | | | | ||
| | | | | | |
85-5-AGJ | jasperoid from holes RTR-92, | 0.034 | 48.9% | 62.7% | < 150 ft | |
96, 97, 157, 164, and 178 | | |||||
| | | | | | |
| | | | | | |
85-6-HGJ | jasperoid from holes RTR-71, | 0.284 | 80.2% | 89.7% | < 45 ft | |
98, and 122 | | |||||
| | | | | |
Hazen conducted subsequent CLTs on two core composites from a single Lookout Mountain drill hole for Amselco in 1986 (Gathje, 1986; Figure 10-2). Each composite was stage crushed to minus ½ -inch, and splits of about 14 kilograms were leached in 4-inch-diameter columns using a solution feed of 1 g NaCN/t applied at the rate of 0.005 gpm/ft2. Four-kilogram splits of the minus ½-inch material for each sample were screened, and the fractions were fire assayed for gold and silver. Preliminary results before actual tailings assays were available are shown in Table 10-3.
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Table 10-3 Amselco 1986 Hazen Preliminary Column-Leach Results on RTC-201 Core Composites
(Hazen Research, 1986)
Composite | Description | Assay Grade | Au Extraction | Depth Below | |
(hole ID and footage) | oz Au/ton | Surface | | ||
| | | |||
| | | | | |
RTC-201 0-95 | oxidized claystone | 0.243 | 82.3% | <100 feet depth | |
RTC-201 160-225 | oxidized claystone | 0.087 | 93.7% | >150 < 250 feet depth | |
| | | | | |
Heinen conducted BRTs in 1986 for Tenneco on ten composite samples of nominal 1/4–inch RC drill cuttings from selected Amselco holes drilled at Lookout Mountain (McClelland, 1986; Asher, 1986).
A wide variation in recovery and reagent requirements was observed between some of the samples. Gold extractions ranged from 33% to 81% (Table 10-4). Cyanide consumptions were low for eight of the ten composites, ranging from 0.2 to 0.9 pounds NaCN/ton. Lime requirements were also low for nine of the composites at 2.0 pounds CaO/ton. One of the composites with high cyanide consumption had no gold (composite 6), while the second (composite 3) also experienced high lime consumption and contained large quantities of unoxidized sulfide minerals. The leach-rate profiles for most of the composites indicated the presence of sulfide minerals or the presence of free-milling visible gold (McClelland, 1986). The leaching conditions were 40% solids, pH of about 11 maintained with lime, and a cyanide concentration maintained at 2.0 pounds NaCN/ton. Leaching was carried out for 72 hours. For samples tested that lie up to 200 feet below the surface, extractions were 60 to 80%; below 200 feet, the samples tested were refractory, and the deep high-grade mineralization at the southwestern end of the deposit did not leach well (Asher, 1986).
Table 10-4 Tenneco 1986 Heinen-Lindstrom Bottle-Roll Results on RC Drill-Cutting Composites
(Heinen-Lindstrom, 1986)
Composite | Hole ID | From-To | Head Assay | Calculated Head | Au Extraction | |
(feet) | (oz Au/ton) | (oz Au/ton) | (72 hours) | | ||
| | | ||||
1 | RTR-056 | 15-40 | 0.069 | 0.080 | 75.0% | |
2 | RTR-056 | 150-180 | 0.025 | 0.032 | 75.0% | |
3 | RTR-181 | 260-280 | 0.145 | 0.142 | 33.8% | |
4 | RTR-071 | 5-45 | 0.262 | 0.329 | 80.8% | |
5 | RTR-179 | 105-185 | 0.021 | 0.024 | 62.5% | |
6 | RTR-189 | 290-365 | No value | No value | No value | |
7 | RTR-138 | 310-425 | 0.040 | 0.033 | 33.3% | |
8 | RTR-097 | 80-110 | 0.030 | 0.031 | 38.7% | |
9 | RTR-097 | 135-160 | 0.096 | 0.098 | 61.2% | |
10 | RTR-097 | 160-275 | 0.027 | 0.029 | 75.9% | |
KCA conducted three CLTs and one BRT on a bulk sample submitted by Norse Windfall Mines in 1986 from Lookout Mountain (Dix, 1987) (Table 10-5). The sample consisted of four 55-gallon
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drums with a combined weight of about one ton. Edmondo (2008a) indicated that the bulk sample was taken from an unknown location within the historical pit. Gold recovery in the three column tests was rapid, with 93% of the recoverable gold leached in the first seven days. All three column tests were run on agglomerated samples.
Table 10-5 Norse Windfall 1987 KCA Column-Leach Results on Historical Pit Bulk Sample Material
(KCA, 1987)
Description | Sample Type | Tests | Assay Grade | Au Extraction | |
(oz Au/ton) | | ||||
| | | | | |
nominal 3” particle size | 9:1 claystone: silica | column leach | 0.301 | 91.01% | |
nominal 1.5” particle size | 9:1 claystone: silica | column leach | 0.298 | 89.82% | |
| | | | | |
nominal 0.5” particle size | 9:1 claystone: silica | column leach | 0.286 | 90.30% | |
In addition, KCA completed a single agitated BRT on a pulverized (minus 100 mesh) portion of the bulk sample that had a calculated head grade of 0.318 oz Au/ton. The test achieved an extraction of 90.57%.
McClelland conducted BRTs on five (5) bulk exploration samples from the historical Lookout Mountain pit for Alta in 1997 (Langhans, 1997) (Table 10-6; Figure 10-2). Alta collected bucket samples of exposed gold mineralization and drill cuttings from within the pit for the test work. The samples reportedly represented the predominant rock and mineralization types as logged in the drilling by various companies (Russell, 2007). One of the samples, LM-4, contained what was considered to be an insignificant quantity of gold and was not subject to metallurgical testing. Leach conditions were 40% solids, adjustment of pH of the pulps to 10.8 to 11.2 by addition of lime, and cyanide addition equivalent to 2.0 pounds NaCN per ton of solution. Leaching continued for 96 hours. Both of the higher-grade samples were readily amenable to cyanidation treatment at the P8010M feed size, with gold recoveries of 86% and 91% in 96 hours of leaching. The gold recovery rate was rapid for all samples, with extraction substantially complete within 24 hours of leaching. Cyanide and lime consumptions were extremely high for sample LM-1 at 6.72 and 52.5 lbs/ton of material, respectively. Cyanide consumption was low for the other three samples; lime requirements were moderate for sample LM-3 and low for the other two samples.
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Table 10-6 Alta Gold 1997 McClelland Bottle-Roll Results on Historical Pit Bulk Samples
(McClelland Laboratories, 1997)
Composite | Description | Assay Grade | Au Extraction | |
(oz Au/ton) | | |||
| | | | |
LM-1 | unoxidized claystone with realgar | 0.322 | 85.80% | |
LM-2 | oxidized silicified claystone | 0.035 | 45.50% | |
LM-3 | oxidized silicified claystone | 0.576 | 91.30% | |
LM-4 | Not Run | 0.012 | Not Run | |
| | | | |
LM-5 | oxidized jasperoid | 0.040 | 61.50% | |
Lightner (2007) summarized the historical metallurgy and suggested that there is potential for a run-of-mine heap-leach operation at Lookout Mountain but noted that some materials may be problematic. Several samples of jasperoid from BRTs suggest silica encapsulation may affect gold extraction, and sulfide material showed very poor leaching capability. Lightner recommended a metallurgical program to include the following:
· | Thorough testing of sulfide mineralization using several process variations to determine the potential for commercial development; |
· | Establishment of a better understanding of oxide, sulfide, and mixed or transition material types, as well as quantification of various lithologies within oxide material; and |
· | Considerable additional metallurgical testing after appropriate geological modeling of both lithology and oxidation is completed. |
Finally, microprobe analyses of several Amselco mineralized samples in 1984-1985 indicated that gold exists in solid solution with arsenic in pyrite and as native gold in jasperoid up to 15 microns in size (Russell, 2007, as corrected by G. Edmondo, 2011, personal communication).
10.4.Metallurgical Testing By Timberline
Timberline implemented a test program in 2010 with the goal of better defining the metallurgical characteristics of mineralization at the Lookout Mountain project. The program used drill core and bulk samples to assess the potential for a run-of-mine heap-leach processing scenario. Timberline took four (4) bulk samples from the historical open pit and drilled six (6) PQ and HQ sized core holes (Figure 10-2) for the purpose of obtaining samples for metallurgical testing (an additional metallurgical core hole drilled at Rocky Canyon failed to intersect significant mineralization). Each sample and composite underwent CLTs and BRTs, as well as screen-size fraction analyses, with a focus on examining crush sizes that are as coarse as possible from the bulk, PQ core, and HQ core materials. In addition, samples of sulfide (unoxidized) material from both the core and bulk
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samples were tested to assess leaching characteristics and to evaluate pressure-oxidation extraction technologies for this material type.
Timberline drilled twelve (12) HQ3 (triple-tube core barrel) core holes in 2012 specifically to obtain representative samples of mineralized jasperoid for metallurgical testing. The samples were sent to KCA to identify how much and which types of jasperoid may cause encapsulation problems, based on poor extractions from 2010 column testing on jasperoid from drill core samples. Questions about KCA’s results led to re-analysis by both McClelland and KCA. This work is summarized in Section 10.4.3.
10.4.1.2010 Bulk Samples
Four (4) bulk samples, representing various mineralization types, were taken by Timberline from the lower two (2) benches of the historical Lookout Mountain pit (Table 10-7 and Figure 10-2). Locations were chosen based on channel sampling that was completed to locate gold mineralization specifically for the bulk tests. Each bulk sample consisted of two (2) to three (3) 55-gallon drums of material. The samples were collected from the mine bench face using an excavator with a reversed bucket after the faces had been cleaned. Samples LMB-1, LMB-2, and LMB-4 are located in the footwall of a northeast-dipping fault zone found in the pit that separates dolomite, collapse breccia, and jasperoid breccia in the footwall from argillized Dunderberg Shale in the hanging wall. Samples LMB-1 and LMB-2 consist of oxidized collapse breccia, with LMB-1 containing significant jasperoid clasts and breccia material from an east-trending fault/fracture set. LMB-2 contains largely collapse breccia material with fault gouge and jasperoid, while LMB-4 consists entirely of oxidized jasperoid breccia. Sample LMB-3 consists of argillized Dunderberg Shale with high-grade sulfide mineralization and weak oxidation along open fracture sets and bounding faults that occur along the hanging wall of the northwest-trending fault. Drill core from the Timberline and prior programs indicates these are the dominant mineralized types present in the Lookout Mountain gold system.
Table 10-7 Timberline 2010 Historical Pit Bulk Sample Descriptions
(Timberline / KCA, 2011)
ID | Avg. Head Assay | Type | Lithologic Type |
| | | |
LMB-1 | 0.018 | Oxide | Mix of collapse breccia, jasperoid breccia, and decalcified |
| | | |
LMB-2 | 0.032 | Oxide | Decalcified dolomite collapse breccia with jasperoid |
| | | |
LMB-3 | 0.361 | Sulfide | Argillized shale with sulfide (LMB-3A with realgar) |
| | | |
LMB-4 | 0.079 | Oxide | Jasperoid breccia |
| | | |
Results from testing of the bulk samples were received from KCA (Kappes, Cassiday & Associates, 2011a, 2011b), including head assays, analyses for deleterious elements (e.g., copper, carbon, and mercury), screen analyses by size fraction, BRTs, agglomeration tests, and CLTs. The screen-size analyses suggest a significant proportion of gold is in the finer-size fractions for samples LMB-1
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through 3, with the opposite relationship for sample LMB-4. The results of this testing are summarized below.
BRTs were completed on pulverized (p80 200 mesh) splits from each of the four bulk samples. All leach tests were run for a period of 96 hours. Table 10-8 summarizes the results of the BRTs.
Table 10-8 Timberline 2010 KCA Fine Bottle-Roll Results on Bulk Samples, P80 200 Mesh
(KCA, 2011)
| Calc. Head | | Leaching | NaCN | Ca(OH)2 | |
ID | Au Extraction | Consumption | Addition | | ||
(oz Au/ton) | Days | | ||||
| | (lbs/ton) | (lbs/ton) | | ||
| | | | | ||
LMB-1 | 0.0135 | 81% | 4 | 0.38 | 4.0 | |
LMB-2 | 0.0323 | 86% | 4 | 0.14 | 4.0 | |
LMB-3 | 0.3331 | 84% | 4 | 11.2 | 42.0 | |
LMB-4 | 0.0708 | 88% | 4 | 0.45 | 4.0 | |
BRTs were also completed on a crushed (p80, -10 mesh) portion of the four (4) samples.
Table 10-9 summarizes the results of this testing on the coarse material.
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Table 10-9 Timberline 2010 KCA Coarse Bottle-Roll Results on Bulk Samples, P80 10 Mesh
(KCA, 2011)
| Calc. Head | | Leaching | NaCN | Ca(OH)2 |
ID | Au Extraction | Consumption | Addition | ||
(oz Au/ton) | Days | ||||
| | (lbs/ton) | (lbs/ton) | ||
| | | | ||
LMB-1 | 0.0188 | 83% | 4 | 0.23 | 2.0 |
LMB-2 | 0.0339 | 81% | 4 | 0.22 | 2.0 |
LMB-3 | 0.3141 | 95% | 4 | 9.91 | 38.0 |
LMB-4 | 0.0774 | 72% | 4 | 0.08 | 1.5 |
Agglomeration tests were conducted using 2-kilogram portions from samples of the LMB-2, LMB-3, and LMB-4 material that were crushed and sorted to 100% passing 1 inch. Each sample was tested using 0 (no added cement or solution), 5, 10, and 15 pounds of cement per short ton. The percolation tests were conducted in small columns at a range of cement levels with no compressive load applied. The purpose of the percolation tests was to examine the permeability of the material under various cement agglomeration levels.
These tests indicated that no agglomeration with cement was required for the LMB-2 and LMB-4 material. Agglomeration with upwards of ten (10) pounds of cement per short ton was required to maintain permeability of the LMB-3 material in the small column tests; therefore, this material was agglomerated prior to subsequent CLTs.
Each bulk sample was placed into a separate column without crushing in order to simulate a run-of-mine heap-leach scenario. The column diameters were 17.5 inches for samples LMB-1 and 2, and 14.5 inches for samples LMB-3 and 4. The differences in column diameters were due to the amount of material available, with the controlling factor being the height of the columns. Testing occurred over 112 days, with the majority of gold extracted within 20 days or less. Table 10-10 summarizes the results from this testing.
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Table 10-10 Timberline 2010 KCA Column-Leach Results on Historical Pit Bulk Samples
(KCA, 2011)
| | Calc. | | Leaching | NaCN | Ca(OH)2 | Cement |
| Crush-Size | Head | | ||||
ID | Au Extraction | Consumption | Addition | Addition | |||
(inches) | Assay | Days | |||||
| | (lbs/ton) | (lbs/ton) | (lbs/ton) | |||
| | (oz Au/ton) | | | |||
| | | | | | | |
LMB-1 | As-Rec’d | 0.0198 | 79% | 112 | 0.63 | 4.02 | 0.00 |
LMB-2 | As-Rec’d | 0.0360 | 76% | 112 | 0.62 | 4.02 | 0.00 |
LMB-3 | As-Rec’d | 0.3470 | 91% | 112 | 6.52 | 34.30 | 9.49 |
LMB-4 | As-Rec’d | 0.0821 | 74% | 112 | 0.57 | 4.07 | 0.00 |
| | | | | | | |
An overall summary of the KCA metallurgical test work on the four bulk samples is shown on Table 10-11 and Figure 10-3.
The highly reactive LMB-3 material continued to show a moderately low pH through most of the column-leach phase, but gold extraction after 112 days was high (91% based upon a calculated head grade of 0.3470 oz Au/ton). KCA noted that additional test work is required to confirm the high NaCN consumption of the LMB-3-type material and to determine if this sodium cyanide consumption could be minimized.
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Table 10-11 Timberline 2010 KCA Summary of Bulk-Sample Bottle-Roll and Column-Leach Results
(KCA, 2011)
ID | Test Type | Sample | Calculated | Au | Tail | Au | Days | NaCN | Ca(OH)2 | Addition |
| | As-rec’d | | | | | | | | |
LMB -1 | Column | (p80 | 0.0198 | 0.0156 | 0.0042 | 79 | 112 | 0.63 | 4.02 | 0.00 |
2.10 | % | |||||||||
| | | | | | | | | ||
| | inches) | | | | | | | | |
LMB -1 | Bottle | P80 10 | 0.0188 | 0.0157 | 0.0031 | 83 | 4 | 0.23 | 2.0 | 0.00 |
% | ||||||||||
| | | | | | | | | | |
LMB -1 | Bottle | P80 200 | 0.0135 | 0.0110 | 0.0025 | 81 | 4 | 0.38 | 4.0 | 0.00 |
% | ||||||||||
| | | | | | | | | | |
| | | | | | | | | | |
| | As-rec’d | | | | | | | | |
LMB -2 | Column | (p80 | 0.0360 | 0.0272 | 0.0088 | 76 | 112 | 0.61 | 4.02 | 0.00 |
2.10 | % | |||||||||
| | | | | | | | | ||
| | inches) | | | | | | | | |
LMB -2 | Bottle | P80 10 | 0.0339 | 0.0276 | 0.0064 | 81 | 4 | 0.22 | 2.0 | 0.00 |
% | ||||||||||
| | | | | | | | | | |
LMB -2 | Bottle | P80 200 | 0.0323 | 0.0276 | 0.0047 | 86 | 4 | 0.14 | 4.0 | 0.00 |
% | ||||||||||
| | | | | | | | | | |
| | | | | | | | | | |
| | As-rec’d | | | | | | | | |
LMB -3 | Column | (p80 | 0.3470 | 0.3160 | 0.0310 | 91 | 112 | 6.52 | 34.30 | 9.49 |
2.10 | % | |||||||||
| | | | | | | | | ||
| | inches) | | | | | | | | |
LMB -3 | Bottle | P80 10 | 0.3141 | 0.2983 | 0.0158 | 95 | 4 | 9.91 | 38.0 | 0.00 |
% | ||||||||||
| | | | | | | | | | |
LMB -3 | Bottle | P80 200 | 0.3331 | 0.2791 | 0.0540 | 84 | 4 | 11.2 | 42.0 | 0.00 |
% | ||||||||||
| | | | | | | | | | |
| | As-rec’d | | | | | | | | |
LMB -4 | Column | (p80 | 0.0821 | 0.0609 | 0.0212 | 74 | 112 | 0.57 | 4.07 | 0.00 |
2.10 | % | |||||||||
| | | | | | | | | ||
| | inches) | | | | | | | | |
LMB -4 | Bottle | P80 10 | 0.0774 | 0.0558 | 0.0216 | 72 | 4 | 0.08 | 1.5 | 0.00 |
% | ||||||||||
| | | | | | | | | | |
LMB -4 | Bottle | P80 200 | 0.0708 | 0.0622 | 0.0087 | 88 | 4 | 0.45 | 4.0 | 0.00 |
% | ||||||||||
| | | | | | | | | |
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Figure 10-3 Timberline 2010 KCA Cumulative Gold Extraction Curves for Bulk-Sample Column Tests, LMB-1-4
(KCA, 2011)

10.4.2.2010 Core Samples
Timberline drilled seven (7) core holes in the area of the Lookout Mountain open pit (Table 10-2) and one (1) at South Adit for metallurgical purposes. BRTs, agglomeration tests, and CLTs on the core samples were completed by KCA (KCA Core Composite Report, 2011). A total of 144 core intervals were delivered to KCA, from which two (2) intervals were selected for coarse and fine BRTs. Selected crushed intervals were then composited into three (3) samples representing jasperoid/silicified breccias, brecciated jasperoid, and collapsed breccias/fault gouge for BRTs, agglomeration testing, and CLTs. The results of these column tests are summarized in Figure 10-4
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Figure 10-4 KCA Column Test Gold Recoveries
Jasperoid/Silicified Breccias, Brecciated Jasperoid, Collapsed Breccias/Fault Gouge
(KCA Core Composite Report, 2011)

Bottle-Roll Tests on Sulfide Core Intervals. BRTs were run for 120 hours on two sulfide core intervals, with each interval separated into two (2) samples, one (1) crushed to p100 5/8 inch and the other crushed to p80 200 mesh. Results are summarized in Table 10-12.
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Table 10-12 Timberline 2010 KCA Bottle-Roll Results on Sulfide Core Intervals BHSE-029C-094 and 029C-108
(KCA Core Composite Report, 2011)
Sample | Target | Calculated | Au | Calculated | Ag | NaCN | (Ca(OH)2 |
Consumption | |||||||
Crush- | Head | Extraction | Head | Addition | |||
| | ||||||
Description | Size | (oz Au/ton) | | (oz Ag/ton) | Extraction | | (lbs/ton) |
| | (lbs/ton) | |||||
| | | | | | | |
BHSE-029C- | 5/8 inch | 0.5590 | 15% | 0.02 | 12% | 6.41 | 9.50 |
094 | |||||||
| | | | | | | |
BHSE-029C- | pulverize | 0.5747 | 20% | 0.02 | 7% | 10.16 | 24.00 |
094 | d | ||||||
| | | | | | ||
BHSE-029C- | 5/8 inch | 0.2776 | 1% | 0.02 | 11% | 1.80 | 5.00 |
108 | |||||||
| | | | | | | |
BHSE-029C- | pulverize | 0.3059 | 3% | 0.01 | 23% | 5.86 | 7.00 |
108 | d | ||||||
| | | | | |
Bottle-Roll Test on Core Composites. BRTs were conducted on pulverized (p80 -200 mesh) and crushed (p100 10 mesh) portions of the three (3) composite samples 47030, 47032 and 47034. All tests were run for 96 hours. Results are summarized in Table 10- 13.
Table 10-13 Timberline 2010 KCA Composite Bottle-Roll Results on Core-Composited Oxide Material
(KCA Core Composite Report, 2011)
| Est. p80 | | Calculated | | NaCN | (Ca(OH)2 | |
Sample | Size | Head | Au | | |||
Head | Consumption | Addition | | ||||
Description | (mesh | (oz | Extraction | | |||
(oz Au/ton) | (lbs/ton) | (lbs/ton) | | ||||
| Tyler) | Au/ton) | | | |||
| | | | | | ||
Jasperoid/silicified | 200 | | 0.0279 | 82% | 0.59 | 2.00 | |
breccia | | | |||||
| 0.0281 | | | | | | |
Jasperoid/silicified | 10 | 0.0284 | 66% | 0.13 | 2.00 | | |
| | ||||||
breccia | | | |||||
| | | | | | | |
Brecciated | 200 | | 0.0172 | 85% | 0.44 | 2.00 | |
jasperoid | | | |||||
| 0.0168 | | | | | | |
Brecciated | 10 | 0.0184 | 73% | 0.13 | 2.00 | | |
| | ||||||
jasperoid | | | |||||
| | | | | | | |
Collapsed | 200 | | 0.0261 | 90% | 0.55 | 6.00 | |
breccia/fault gouge | | | |||||
| 0.024 | | | | | | |
Collapsed | 10 | 0.0227 | 84% | 0.35 | 4.00 | | |
| | ||||||
breccia/fault gouge | | | |||||
| | | | | | |
Agglomeration Tests. Agglomeration tests were conducted using 2-kilogram portions from each sample. Each sample was tested using zero (0) (no added cement or solution) and five (5) pounds of Portland Type II cement per short ton. The percolation tests were conducted in small columns at
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a range of cement levels with no compressive load applied. The purpose of the percolation tests was to examine the permeability of the material under various cement agglomeration levels.
KCA noted that this type of agglomeration test work is very preliminary but does provide an indication of whether agglomeration may be required for processing the Lookout Mountain material, with cement requirements for a single-lift heap having an overall height of not more than 20 feet. A table summarizing the results shows a “Pass” for each of the tested materials, but it does not discuss the results of the test work further.
Column-Leach Tests. Two (2) column-leach tests were performed on each of the three (3) core composites at different crush sizes (p100 1 ¾ inches and p100 ¾ inches). The material was leached for 69 days. Results are summarized in Table 10-14.
Table 10-14 Timberline 2010 KCA Column-Leach Results on Core Composites 47030, 47032, and 47034
(KCA Core Composite Report, 2011)
| Est. | Head | Calculated | | NaCN | (Ca(OH)2 | |
Sample | p100 | Au | | ||||
(oz | Head | Consumption | Addition | | |||
Description | Size | Extraction | | ||||
Au/ton) | (oz Au/ton) | (lbs/ton) | (lbs/ton) | | |||
| (inches) | | | ||||
| | | | | | | |
Jasperoid/silicified | 1 3/4 | | 0.0264 | 59% | 1.04 | 2.01 | |
breccia | | | |||||
| 0.0281 | | | | | | |
Jasperoid/silicified | 3/4 | 0.0285 | 62% | 1.70 | 2.01 | | |
| | ||||||
breccia | | | |||||
| | | | | | | |
Brecciated jasperoid | 1 3/4 | 0.0168 | 0.0172 | 53% | 0.84 | 2.02 | |
| | | | | | | |
Brecciated jasperoid | 3/4 | 0.0177 | 61% | 1.12 | 2.02 | | |
| | ||||||
| | | | | | | |
Collapsed breccia/fault | 1 3/4 | | 0.0296 | 77% | 1.61 | 3.16 | |
gouge | | | |||||
| 0.024 | | | | | | |
Collapsed breccia/fault | 3/4 | 0.0265 | 84% | 2.50 | 3.18 | | |
| | ||||||
gouge | | | |||||
| | | | | | |
10.4.3.2012 Core Samples
Unless otherwise indicated, this information is derived from a summary by Timberline.
Timberline drilled 12 HQ3 core holes in 2012 specifically for the purposes of the ongoing metallurgical study, including BHSE-126C, -128C, -130C, -134C, -140C, -145C, -147C, -148C, -149C, -150C, -151C, and -153C. They were drilled in the area of the historical open pit at North Lookout (Figure 10-2) and at various locations at South Lookout Mountain (). A total of 2,018 samples were sent to KCA in 2012 (KCA, 2013). This testing was planned to identify the types of jasperoid that may cause encapsulation problems, with the intent of further investigating the poor extractions in the 2010 column testing of jasperoid samples from drill core.
Timberline logged lithology, formation, and alteration, and defined assay-sample breaks before sending the whole core to KCA for sample preparation. Samples were first crushed to 100% passing 1.75 inches. A one-kilogram split of the crushed material from each sample interval was then pulverized to 80% passing 200 mesh and sent to Inspectorate for gold analysis (KCA, 2013).
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Composites were generated for each hole for BRTs. The planned testing program consisted of crush-size recovery analysis using bottle rolls followed by column testing.
The bottle-roll leach tests were completed at top sizes of p100 - 1.75 inches (100% passing 1.75 inches), p100 - 0.75 inches, p100 - 0.5 inches, and p100 – 0.066 inch (10-mesh Tyler). The crushing process, as described by KCA, was as follows:
· | Where possible, 10-kilogram composite samples composed of intervals designated by Timberline were created; |
· | 4-kilogram splits of the composites were used for BRTs of 1.75-inch material; |
· | The remainder of each composite was stage crushed to p100 0.75 inches, and a 2-kilogram split of each was used for BRTs; |
· | The remaining material from each original composite was stage crushed to p100 0.5 inches, and a 2-kilogram portion was split out for a BRT; |
· | The remaining material from each composite was stage crushed to p100 10-mesh Tyler, and a 1-kilogram portion was split out for BRTs; and |
· | The reject 10-mesh Tyler material was stored by KCA. |
Gold recovery from KCA’s BRTs on jasperoid mineralization, even on 10-mesh-sized materials, was uniformly low, significantly lower than previous BRTs of coarse reject material from nearby RC holes. As a check on these results, eight (8) samples covering a range of head grade assays were sent to McClelland, with a split of some of these samples sent for re-analysis by KCA. These samples were tested by McClelland and originally KCA at two (2) size fractions – 1.75 inch and 10 mesh (0.066 inch). Comparison of the results from McClelland’s check and KCA’s original and re-assays is shown in Table 10-15 and on Figure 10-5
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Table 10-15 Timberline 2012–2014 Comparison of Jasperoid Bottle-Roll Results from KCA and McClelland
(KCA 2013; KCA 2014; McClelland 2014)
McC | KCA | Composite | Size | Au | Au | Au | Au |
CY-09 | 66304 D | BHSE- | 0.066 | 63.9% | 37% | 66% | 67% |
CY-10 | 66305 D | BHSE- | 0.066 | 62.5% | 9% | 59% | 62% |
CY-11 | 66309 D | BHSE- | 0.066 | 69.8% | 11%* | 64% | |
CY-12 | 66326 D | BHSE- | 0.066 | 57.1% | 16% | 53% | |
CY-13 | 66330 D | BHSE- | 0.066 | 53.3% | 42% | 48% | |
CY-14 | 66337 D | BHSE- | 0.066 | 46.2% | 16% | 53% | |
CY-15 | 66338 D | BHSE- | 0.066 | 54.3% | 22% | 56% | |
CY-16 | 66353C | BHSE- | 0.066 | 63.0% | 34% | | |
CY-17 | 66355 D | BHSE- | 0.066 | 71.0% | 13% | | |
CY-1 | 66304 A | BHSE- | 1.75 | 37.5% | 20%** | | |
CY-2 | 66305 A | BHSE- | 1.75 | 25.5% | 22% | | |
CY-3 | 66309 A | BHSE- | 1.75 | 43.2% | 43% | | |
CY-4 | 66326 A | BHSE- | 1.75 | 23.4% | 13% | | |
CY-5 | 66330 A | BHSE- | 1.75 | 9.5% | 4% | | |
CY-6 | 66337 A | BHSE- | 1.75 | 15.2% | 8% | | |
CY-7 | 66338 A | BHSE- | 1.75 | 11.2% | 11% | | |
CY-8 | 66355 A | BHSE- | 1.75 | 53.1% | 40% | | |
* KCA’s original preliminary report indicated 11%; KCA now reports the final value as 49%.
** KCA’s original preliminary report indicated 20%; KCA now reports the final value as 38%.
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Figure 10-5 McClelland Re-Analyses vs. Original KCA Bottle-Roll Results
(modified from Timberline; 2012 testing)

McClelland’s results for recovery are systematically higher than the original KCA results for samples crushed to 10 mesh; the mean of the KCA extractions is less than half of the mean of the McClelland extractions. For samples crushed to 1.75 inches, however, the results of the two (2) labs are close. KCA’s re-analyses of 10-mesh samples are also close to the results of McClelland.
From these data, Timberline concludes that (1) the original KCA results of the 10-mesh material are likely flawed; (2) McClelland’s results showing poorer recovery at coarser sizes compared to smaller size fractions suggests some portion of the gold is encapsulated in silica; and (3) crushing of jasperoid material will likely be required. The author finds these conclusions to be reasonable, and they are consistent with results obtained from the 2010 testing.
Because of questions about KCA’s initial BRTs, the planned column testing was not completed as part of that initial 2012 bottle-roll phase. Subsequent KCA column leach testing was completed in 2014 on selected North LM, North End South LM, and South End South LM jasperoid composites at 3/4-inch and 3/8-inch crush sizes, and those results are discussed with the later column-leach program. Further testing will be required to determine the degree of crushing to be required.
10.5.Preliminary HPGR Crushing Test
A preliminary study of BRT gold recovery following crushing by high-pressure grinding rolls (“HPGR”), as compared to conventional crushing, was completed in 2014-2015. Three (3) composites of jasperoid in drill core from North Lookout Mountain, the north end of South Lookout Mountain, and the south end of South Lookout Mountain were tested under single- and double-pass edge and center runs through the crusher. KCA prepared the HPGR crushed material and completed BRT testing by area, crusher product and roll position. McClelland completed additional BRT testing on the North LM Jasp. and North End South LM Jasp. Composites. Test work results are presented in Table 10-17.
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Leach data after ten (10) days from these preliminary tests suggests recovery in jasperoid could increase by approximately 10% following crushing by HPGR as compared to conventionally crushed material depending on area, product stream and crush size. Table 10-17 provides the summarized results for the HPGR test work as well as the conventional crush test work that was performed on the South End South LM Jasp. composite. Additional work will be required to further evaluate the potential of HPGR crushing on gold recovery.
Table 10-16 Comparison of Bottle-Roll Test Gold Recovery in Jasperoid by HPGR Crush Product, Area, and Conventional Crush Where Available
| | | | Passing | Calc. | KCA | | |
| | | p80 | 10 | Au | McClelland | | |
Area | Crush/Product | Position | head (oz | | ||||
(in) | mesh | ext. | Au ext. (%) | | ||||
| | | Au/st) | | ||||
| | | | (%) | (%) | | | |
| | | | | | | ||
| | | | | | | | |
North LM Jasp. | HPGR single | Edge | 0.42 | 24.8 | 0.0218 | 38 | 45.3 | |
pass | | |||||||
| | | | | | | | |
North LM Jasp. | HPGR single | Center | 0.28 | 40 | 0.0213 | 48 | 56.3 | |
pass | | |||||||
| | | | | | | | |
North LM Jasp. | HPGR double | Edge | 0.28 | 41.7 | 0.0207 | 45 | 51 | |
pass | | |||||||
| | | | | | | | |
North LM Jasp. | HPGR double | Center | 0.2 | 52.5 | 0.0198 | 53 | 62 | |
pass | | |||||||
| | | | | | | | |
North End South LM | HPGR single | Edge | 0.4 | 26.3 | 0.0097 | 37 | 49.6 | |
Jasp. | pass | | ||||||
| | | | | | | ||
North End South LM | HPGR single | Center | 0.28 | 40.1 | 0.0091 | 48 | 58.7 | |
Jasp. | pass | | ||||||
| | | | | | | ||
North End South LM | HPGR double | Edge | 0.25 | 40.6 | 0.0087 | 52 | 56.5 | |
Jasp. | pass | | ||||||
| | | | | | | ||
North End South LM | HPGR double | Center | 0.2 | 52.8 | 0.0091 | 51 | 66.3 | |
Jasp. | pass | | ||||||
| | | | | | | ||
South End South LM | Conventional, | -- | 0.72 | 11.9 | 0.0127 | 37 | -- | |
Jasp. | 3/4 in. | | ||||||
| | | | | | | ||
South End South LM | Conventional, | -- | 0.32 | 16.7 | 0.0136 | 40 | -- | |
Jasp. | 3/8 in. | | ||||||
| | | | | | | ||
South End South LM | HPGR single | Edge | 0.41 | 23.3 | 0.0153 | 39 | -- | |
Jasp. | pass | | ||||||
| | | | | | | ||
South End South LM | HPGR single | Center | 0.34 | 33.3 | 0.0157 | 56 | -- | |
Jasp. | pass | | ||||||
| | | | | | | ||
South End South LM | HPGR double | Edge | 0.31 | 34.5 | 0.0153 | 41 | -- | |
Jasp. | pass | | ||||||
| | | | | | | ||
South End South LM | HPGR double | Edge | 0.31 | 30.7 | 0.0157 | 48 | -- | |
Jasp. | pass | | ||||||
| | | | | | | ||
South End South LM | HPGR double | Center | 0.19 | 52.2 | 0.0139 | 52 | -- | |
Jasp. | pass | | ||||||
| | | | | | |
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*McClelland testing was performed only on the North LM and North End South LM HPGR products available to McClelland; South End South LM values shown are KCA results only.
Table 10-17 Summary Results for Bottle-Roll Test Gold Recovery in Jasperoid by HPGR Crush vs. Conv. Crush KCA, Jasperoid: Low-Grade
| | Calc. p80 | Calculated | Au | Average | Leach | |
No. | Crush Type | Size | Head | Extraction | Au | Time | |
| | (inches) | (oz Au/ton) | by position | Extraction | (days) | |
3 | HPGR single pass Edge | 0.41 | 0.016 | 38% | 45% | 10 | |
3 | HPGR single pass Center | 0.3 | 0.015 | 51% | | ||
| | | |||||
4 | HPGR double pass Edge | 0.27 | 0.015 | 47% | 50% | 10 | |
3 | HPGR double pass Center | 0.20 | 0.014 | 52% | | ||
| | | |||||
| | | | | | | |
KCA, Conventional Crush-Comparison (South End South LM Jasp.) | | ||||||
1 | -0.75 in. | 0.72 | 0.0127 | 37% | N/A | 10 | |
1 | -0.375 in. | 0.32 | 0.0136 | 40% | 10 | | |
| | ||||||
10.6.Historical Mine Recovery
In 1987, Norse Windfall Mines mined approximately 180,000 tons of primarily oxidized gold mineralization at an average reported grade of 0.12 oz Au/ton (Cargill, 1988; Jonson, 1991). The mineralized rock was hauled 5.6 miles from the Lookout Mountain pit to cyanide heap-leach pads at the Windfall Mine, where they achieved an estimated 81% recovery from the agglomerated ore.
10.7.Discussion of Metallurgical Results
The author believes the samples on which the metallurgical test work has been performed, taken as a whole, are representative of the Lookout Mountain project mineralization in terms of grade, types of mineralization, and areal distribution.
Sample analysis programs are ongoing, from drilling completed in 2024 and 2025 for both the Lookout Mountain and Windfall areas. Further metallurgical testing is planned for Lookout Mountain, and a separate metallurgical program is planned for Windfall. The Windfall metallurgical database is currently limited relative to Lookout Mountain, with available information consisting primarily of historical cyanide shake data, current ICP analytical data, and selected samples identified for future recovery test work. Additional bottle-roll, column-leach, reagent-consumption, and deleterious-element testing will be completed to support future recovery assumptions, evaluate metallurgical variability, and confirm whether Windfall material behaves similarly to or differently from the tested Lookout Mountain material.
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The author reviewed the metallurgical test data and believes that the information summarized in this section is sufficient for the purpose for which it is used in this report, which is to support the assertion that the Lookout Mountain and South Adit oxidized materials are potentially amenable to heap-leach processing and unoxidized materials are potentially amenable to off-site toll milling.
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11. | MINERAL RESOURCE ESTIMATES |
11.1. | Introduction |
Mineral Resource estimates for the Lookout Mountain and Windfall projects were carried out and reported using Item 1300 of Regulation S-K. The mineral resources were calculated under the supervision of Michael Baumann who meets the qualifications and criteria as a Qualified Person (QP). He is a Registered member of SME (RM#185920) and a Certified Professional Geologist (#10674) with AIPG. Mr. Baumann has over 30 years’ experience in Geology and Resource modeling of Carlin-type Gold Deposits.
This report presents updated gold resources for Lookout Mountain and Windfall. The current resources demonstrate reasonable prospects for potential economic extraction (RPEEE) by applying open pit optimizations to constrain the resources using current economic parameters. Mineral reserves have not been established at this stage for either the Lookout Mountain or Windfall projects.
Project resources are classified in order of increasing geological and quantitative confidence into Inferred and Indicated categories in accordance with Item 1300 of Regulation S-K. An Inferred Mineral Resource has a lower level of confidence than that applied to an Indicated Mineral Resource.
Mineral Resource
A Mineral Resource is a concentration or occurrence of solid material of economic interest in or on the Earth’s crust in such form, grade or quality and quantity that there are reasonable prospects for eventual economic extraction. The location, quantity, grade or quality, continuity and other geological characteristics of a Mineral Resource are known, estimated or interpreted from specific geological evidence and knowledge, including sampling.
The term Mineral Resource covers mineralization and natural material of intrinsic economic interest which has been identified and estimated through exploration and sampling and within which Mineral Reserves may subsequently be defined by the consideration and application of Modifying Factors. The phrase ‘reasonable prospects for eventual economic extraction’ implies a judgment by the Qualified Person in respect of the technical and economic factors likely to influence the prospects of economic extraction. Assumptions include estimates of cutoff grade and geological continuity at the selected cutoff, metallurgical recovery, smelter payments, commodity price or product value, mining and processing method and mining, processing and general and administrative costs.
Inferred Mineral Resource
An Inferred Mineral Resource is that part of a Mineral Resource for which quantity and grade or quality are estimated based on limited geological evidence and sampling. Geological evidence is
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sufficient to imply but not verify geological and grade or quality continuity. An Inferred Mineral Resource is based on limited information and sampling gathered through appropriate sampling techniques from locations such as outcrops, trenches, pits, workings and drill holes. An Inferred Mineral Resource has a lower level of confidence than that applying to an Indicated Mineral Resource and must not be converted to a Mineral Reserve. It is reasonably expected that the majority of Inferred Mineral Resources could be upgraded to Indicated Mineral Resources with continued exploration.
There may be circumstances where appropriate sampling, testing, and other measurements are sufficient to demonstrate data integrity, geological and grade/quality continuity of a Measured or Indicated Mineral Resource, however, quality assurance and quality control, or other information may not meet all industry norms for the disclosure of an Indicated or Measured Mineral Resource. Under these circumstances, it may be reasonable for the Qualified Person to report an Inferred Mineral Resource if the Qualified Person has taken steps to verify the information meets the requirements of an Inferred Mineral Resource.
Indicated Mineral Resource
An Indicated Mineral Resource is that part of a Mineral Resource for which quantity, grade or quality, densities, shape and physical characteristics are estimated with sufficient confidence to allow the application of Modifying Factors in sufficient detail to support mine planning and evaluation of the economic viability of the deposit. Geological evidence is derived from adequately detailed and reliable exploration, sampling and testing and is sufficient to assume geological and grade or quality continuity between points of observation. An Indicated Mineral Resource has a lower level of confidence than that applying to a Measured Mineral Resource and may only be converted to a Probable Mineral Reserve.
Mineralization may be classified as an Indicated Mineral Resource by the Qualified Person when the nature, quality, quantity and distribution of data are such as to allow confident interpretation of the geological framework and to reasonably assume the continuity of mineralization.
Modifying Factors
Modifying Factors are considerations used to convert Mineral Resources to Mineral Reserves. These include, but are not restricted to, mining, processing, metallurgical, infrastructure, economic, marketing, legal, environmental, social and governmental factors. There are no Mineral Reserves established at this time for either Lookout Mountain or Windfall.
Mineral resources at both Lookout Mountain and Windfall were modeled and estimated by the following process:
· | Exploration Data Analysis (EDA) - Evaluating and analyzing the raw drill hole database statistically and spatially to determine natural gold populations; |
· | Establishing estimation domains to identify unique gold grade populations; |
· | Establishing a 3D block model and coding the block model to the gold mineral domains; |
· | Geostatistical Analysis - Calculate variograms to understand spatial continuity; |
· | Grade Interpolation – Estimate gold grades into defined 20 x 20 x 20-foot block model by domain using Inverse Distance (ID3), Ordinary Kriging and Nearest Neighbor; |
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· | Classify Resources - Classifying the model into categories of increasing confidence; |
· | Validate the Model – through swath plots, visual checks on plans and sections; |
· | Report Resource - Constrain the model with basic economic parameters to determine Reasonable Prospects of Eventual Economic Extraction using optimized open pit shells. |
11.2. | Lookout Mountain Resource Modeling |
11.2.1. | Mineral resource database |
Geological and 3D block models were created for estimating the gold resources for the Lookout Mountain deposit from data generated historically by Amselco, Barrick, Echo Bay, Norse Windfall Mines, EFL and more recently by Staccato, Timberline and McEwen, including information derived from RC, rotary, and core drill holes. These data, as well as digital topography of the project area, were incorporated into a digital database in UTM NAD1983 International feet coordinates. All 3D block modeling and estimation of the Lookout Mountain project resources were performed using Datamine Studio RM software. The data extraction cut-off date was November 12, 2025.
Table 11-1 Drill hole data compilation
Drill Hole Type | # holes | % of holes | Total feet drilled |
Core | 81 | 9% | 70,736 |
Core Tail | 16 | 2% | 16,054 |
Conventional Rotary | 159 | 18% | 41,334 |
Monitoring | 3 | 0.3% | 2,050 |
Reverse Circulation | 601 | 70% | 340,019 |
Total | 860 | 100% | 470,193 |
Table 11-2 Drill hole Footage by Company
Company | Total feet drilled |
Amselco | 105,585 |
Barrick | 33,285 |
BH Minerals USA, Inc. | 73,214 |
Campbell, Hoss, Buchanan, Inc. | 3,885 |
Hackworth | 2,550 |
Echo Bay Exploration | 71,445 |
EFL Mines | 2,733 |
McEwen Nevada | 20,770 |
Minnova | 3,026 |
Newmont | 1,537 |
Pathfinder | 300 |
Rimrock | 3,215 |
Timberline | 128,855 |
Other | 19,794 |
Total | 470,194 |
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11.2.2.Geological modelling
The gold mineralization at Lookout Mountain is primarily hosted by the Hamburg Dolomite at and near the contact with the Dunderberg Shale (Figure 11-1). The Hamburg Dolomite and Dunderberg Shale have gone through one or more dissolution and collapse events that have been called the Lookout Mountain Breccia. Breccia has a northerly strike and moderate dip to the east. At the surface the breccia is quite wide and typically thins down-dip, which creates a wedge shape in cross-section that tilts in a westerly direction. South of the Pit area, the Breccia is strongly structurally controlled having a tabular lens shape and is controlled at its base by the faulted Secret Canyon contact which has a 60-degree dip to the east. At Lookout Mountain, the Breccia is largely flat lying with steep contacts on the East and West margins. The basal contact with the Secret Canyon is generally flat lying with minor vertical offset along cross-faults.
Figure 11-1 Geologic model with mineralization and block model
(McEwen 2026)

11.2.3.Mineralization
Much of the Breccia has been altered to jasperoid-rich zones, especially near its contact with the Dunderberg Shale, while the lower portion near the Secret Canyon Shale is often marked by a clear structural zone; both zones are frequently characterized by higher-than-average gold grades. High-grade material is influenced by near vertical hanging wall faults along the length of the resource which form the wedge shape to the breccia. The highest-grade zones at Lookout Mountain appear to be controlled by northwest- and north-striking faults which form the contact between Breccia and the Dunderberg Shale. The Secret Canyon Shale, which immediately underlies much of the breccia, is altered but rarely hosts mineralization.
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11.2.4.Oxide and non-oxide modeling
Based on drillhole logging codes, McEwen’s geologic team revised earlier determinations of oxidized and unoxidized rocks. Several modifications to these sections were made by McEwen geologists, based on revisions to geologic modeling and incorporating cyanide shake-leach analyses into the modeling of the oxidation boundaries. There are limited assays with both common AuFA and AuCN assays in the database. A default of 78% was used based on a study of historical metallurgical test work completed by McEwen’s metallurgist Anthony Kaah (internal communication 02/12/2026 Gold Recovery for Lookout Mountain and Windfall) for oxide mineralized zones. The average ratio for the model from composite assay data is 79.5%, AuCN/AuFA, which aligns closely with test work for oxide gold mineralization.
11.2.5.Composites and grade populations
A composite length of 10 feet was chosen which is half of the potential bench height in an open pit mining scenario considered appropriate here. A Log Probability plot of composite gold grades identifies discrete mineral populations and better defines a higher-grade gold population (Figure 11-2) and demonstrates a proposed population break at 0.030 opt gold.
Figure 11-2 Log Probability plot of the Lookout Mountain total data set 10 ft composites

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11.2.6.Domaining
Mineral Domains
A mineral domain encompasses a volume of rock that ideally is characterized by a single, natural-grade population of a metal that occurs within a specific geologic environment.
To define the mineral domains for the Lookout Mountain project, the natural gold populations were first identified on population distribution graphs that plot the gold grade-distribution of all drillhole assays. This analysis led to the identification of low- and high-grade gold populations (see section above).
Ideally, each of these populations can then be correlated with specific geologic characteristics that are captured in the project drillhole database, which can be used in conjunction with the grade populations to interpret the bounds of each of the gold mineral domains. Ultimately, low-grade (~0.005 to ~0.030 oz Au/ton), and high-grade (>~0.030 oz Au/ton) populations were assigned to gold domains LM_005 and LM_030 respectively.
The Lookout Mountain gold mineral domains were modeled by integrating the gold drillhole assay data, associated drillhole logging codes, documented descriptions of the mineralization, and, to a significant extent, McEwen’s geologic cross sections.
The high density of drilling at North Lookout Mountain, which includes most of the core holes drilled in the resource area, ultimately led to the high-quality geologic modeling by McEwen, which in turn significantly increases the confidence of the modeling in this area.
Initially, vertical, north-looking cross sections spanning a north-south distance of 6,700 feet were used for the modeling of the Lookout Mountain mineral domains. Sections spaced at 50-foot intervals were used for the 850-foot-long section of dense drilling at North Lookout Mountain, while the remainder of the modeling utilized 100-foot sections. The drillhole traces, topographic profile, and geologic and gold interpretations were plotted on the sections, with gold assays and pertinent alteration codes plotted along the drillhole traces. Mineral domain envelopes were interpreted on the sections using available and reasonably assumed geologic criteria to encompass gold values that correspond to each of the defined grade populations. With few exceptions, the mineral domains only model zones with demonstrable continuity.
The cross-sectional mineral-domain envelopes were digitized, pressed three-dimensionally to the drill holes, and then sliced at 20-foot vertical intervals. The resultant slices were used to refine the mineral domains on a set of 20-foot level plans. Also, visual oxidation and sulfides were logged by the Geologist, and sulfide envelopes were created where oxidation was not found.
Composites were then separately selected within the low-grade and high-grade domains to be used later in the interpolation and estimation within domains.
Higher-grade mineralization domain LM_030 is most extensive at North Lookout Mountain. The high-grade zones in this area are characterized by a central cylindrical core of mineralization that has thin extensions emanating outwards. These high-grade zones transgress the Breccia – Dunderberg Shale contact, occurring in both units. The axes of the cylindrical core zones significantly exceed their cross-sectional extents, creating cigar-shaped zones that plunge at gentle
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angles to the south-southeast. One of the core zones occurs near the present-day surface and is largely mined out, while the other lies about 400 to 500 feet down-dip of the upper contact of the breccia.
Domain LM_005 low-grade mineralization encompasses the extents of the mineralized system in the resource areas, which in many areas, more or less outline the extents of the Lookout Mountain Breccia.
A representative cross section showing gold mineral domain interpretations for Lookout Mountain is shown in Figure 11-3.
Figure 11-3 Lookout Mountain Cross Section 14314100 Showing Gold Mineral Domain LM_005
(McEwen 2026)

11.2.7. | Density Modeling |
Atotal of 214 specific-gravity determinations is available from the resource area drilling samples. These data were derived from dry bulk specific-gravity determinations completed on core samples by the water-immersion method using samples coated with wax, including 12 determinations by Thurston Testing Laboratory and 202 from KCA. There are 167 determinations on samples that lie within mineral domains modeled at Lookout Mountain.
A single tonnage factor (13.5 ft3/ton or 2.37 tonnes / m3) was applied to all modeled gold mineralization. This tonnage factor is slightly higher than the mean and median values due to in situ
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open spaces present within the Lookout Mountain Breccia that cannot be captured in samples of drill core and therefore cannot be accounted for in the specific-gravity determinations.
All unmineralized units are assigned a tonnage factor of 13.0 ft3/ton (or 2.46 tonnes/m3) in the Lookout Mountain model. There are several different formations and lithologies present in the model area, so this average number has spatial inaccuracies. Additional sampling for density information was conducted in 2025, but the results were not available at the time of report.
11.2.8.Capping
Gold assay composite intervals were coded to the low grade and high-grade mineral domains using the cross-sectional and level plan envelopes. Descriptive statistics of the coded assays are provided in Table 11-3 for Lookout Mountain.
Table 11-3 Descriptive Statistics of Lookout Mountain Coded Gold Assays and top cut
| # | Avg | Max | # | Mean | Std | | Min. | Max. | Top | Metal |
Domain | Dist | Dist | CV | Cut | Cut | ||||||
DHs | comps | (opt) | Dev | (opt) | (opt) | ||||||
| (ft) | (ft) | | (opt) | (%) | ||||||
| | | | | | | | ||||
LM_005 | 407 | 60 | 379 | 5142 | 0.0102 | 0.0196 | 1.922 | 0.000 | 1.093 | 0.150 | 3.1 |
LM_030 | 276 | 70 | 439 | 1451 | 0.0696 | 0.1074 | 1.544 | 0.000 | 1.771 | 0.900 | 1.0 |
The process of determining assay capping levels included inspection of quantile plots of the coded assays by domain to determine possible high-grade outliers that might be appropriate for capping. Ten samples were capped for the LM_005 domain and three samples were capped for the LM_030 domain. The impact of capping is recorded as Metal Cut from the data population. The low-grade cap of 0.150 opt gold impacted metal by 3.1% and the high-grade cap of 0.900 opt gold impacted metal by 1.0%.
11.2.9.Variography
A variography study was performed with the Lookout Mountain gold 10-foot composites from each mineral domain using Datamine Supervisor software. Acceptable structures modeled on variograms were obtained from composites from domain LM_005 and LM_030. Figure 11-4 demonstrates the three orthogonal structures which guide the size and orientation of the search ellipses in estimation.
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Figure 11-4 Variogram of Lookout Mountain Domain LM_005 Composites

11.2.10.Block Model Parameters, Coding and Estimation
The framework for the block model was established using blocks 20’ x 20’ x 20’ in size based on anticipated mining methods. Sub-cells were not used. No rotation was applied to the model.
Several iterations of block model coding were completed including:
· | The low grade and high-grade mineral domains were used to code the Lookout Mountain block model accordingly. |
· | The percentage of each block that lies below the topographic surface is coded and stored |
for use in the calculation of block tonnages.
·The 20-foot spaced sulfide envelopes modelled previously were used to code the blocks. If greater than 50% of a block is sulfide the block is considered sulfide for the purposes of the application of the resource cut-offs.
· | Each block is assigned a tonnage factor. If a block is coded as having 50% or greater of any of the mineral domains (LM_005 or LM_030), the block is mineralized for the purposes of density assignment of 13.5 cu ft/ton (2.37 tonnes / m3). Blocks having no gold domain coding are unmineralized and assigned a density of 13.0 cu ft/ton (2.46 tonnes / m3). |
Gold grades were interpolated using inverse-distance to the third power and ordinary kriging. In addition, a nearest-neighbor estimation was also completed as a check on the other interpolations and used to determine a Global Bias check. Inverse distance was used to report the mineral resource statement as this technique was judged to provide results superior to those obtained by ordinary kriging. Search neighborhoods are based on variography.
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The parameters applied to the gold grade estimations at Lookout Mountain are summarized in Table 11-4
Table 11-4 Summary of Lookout Mountain Estimation Parameters
| Search ellipse | | Search Distances | Search Distances | ||||||
| orientation | | Pass #1 | Pass #2 | ||||||
Domain | X | Y | Z | Nugget | X | Y | Z | X | Y | Z |
LM-005 | 210 | 40 | 50 | 0.1 | 58 | 26 | 39 | 70 | 55 | 80 |
LM-030 | 100 | 60 | 130 | 0.15 | 148 | 71 | 91 | 237 | 180 | 114 |
For the LM_005 domain, a maximum number of samples is set to restrict the number of samples from any one drill hole to only two samples per hole. This results in the search algorithm to reach out to additional, surrounding drill holes and ensures the model is not informed simply with down hole assays from one drill hole. The search ellipse with a minimum of 6 samples and a maximum of 10 samples used in the estimation and first pass search ellipse distances of 58 ft by 26 ft by 39 ft, the second pass search distance is 70 ft by 55 ft by 80 ft. A subsequent search selection reduced the number of samples required to a minimum of 4 samples and a maximum of 10 samples, and the search distances are enlarged to three times the second search distance. A final search pass reduced the required minimum number of samples to 2 and a maximum number of samples to 10. The final search distances are enlarged to a distance 10 times the second pass distance. This is to inform the model as completely as possible.
For the LM_030 domain, a maximum number of samples is in place to restrict the number of samples from any drill hole to 2 per hole. This requires the search to reach out to surrounding drill holes and not just inform the model with down hole assays. The search ellipse with a minimum of 6 samples and a maximum of 10 samples used in the estimation and first pass search ellipse distances of 148 ft by 71ft by 91 ft, the second pass search distance is 237 ft by 180 ft by 114 ft. A subsequent search selection reduced the number of samples required to a minimum of 4 samples and a maximum of 10 samples, and the search distances are enlarged to three times the second search distance. A final search pass reduced the required minimum number of samples to 2 and a maximum number of samples to 10. The final search distances are enlarged to a distance 10 times the seconds pass distance. This is to inform the model as completely as possible.
The major and semi-major axes of the search ellipses approximate the average strike and dip directions of the gold mineralization in each estimation domain. The first pass search distances take into consideration the results of both the variography and drillhole spacing. The second passes were designed to estimate grade into all blocks coded to the mineral domains that were not estimated in the first passes.
The estimation passes were performed independently for each of the mineral domains, so that only composites coded to a particular domain were used to estimate grade into blocks coded by that domain.
11.2.11. Model Validation
A series of validation check steps were undertaken for the Lookout Mountain resource:
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· | Gold domain volumes coded into the block model were compared to the volumes of the level-plan mineral-domain polygons to ensure close agreement, and all block model coding was checked visually. |
· | A nearest-neighbor and ordinary-krige estimate was used as a check on the ID3 estimation results. Average grade comparisons and grade-distribution plots of assays, composites, and the nearest-neighbor, ordinary-krige, and inverse-distance block grades were evaluated as a check on both the global and local estimation results. No unexpected relationships between the check estimates and the inverse-distance estimate were identified. |
· | For a Global Bias check (Table 11-5), the average model grades at a zero cut-off were compared. The ID3 model is within 5% of the NN model which is considered acceptable for a global bias validation check |
· | Swath plots (Figure 11-5) were constructed that compare grades from the original drill samples to the block of grades from three estimate methods within bands of different widths across the deposit. These were constructed on sections from north to south (100 ft), east to west, and in the vertical direction (elevation) at a constant 20 ft interval. The plots compare well across the deposit. |
· | Finally, the inverse-distance block model grades were visually compared to the drill hole assay data in detail to ensure that reasonable results were obtained (Figure 11-6). |
Table 11-5 Global Bias check of Mineral Resource
| Global Bias Model Grade Comparison (opt) | | ||
Domain | ID3 | NN | OK | ID3 / NN |
| | | | |
LM_005 | 0.0109 | 0.011 | 0.0107 | 99.1% |
| | | | |
LM_030 | 0.0524 | 0.0501 | 0.0515 | 104.5% |
| | | | |
Total | 0.0173 | 0.0171 | 0.0171 | 101.6% |
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Figure 11-5 Swath plot of the low-grade domain through the resource model
comparing 10 ft composite data and Nearest Neighbor, ID3 and OK models

Figure 11-6 Resource model visual check compared to drill intercepts section 14312600N.

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11.2.12. Classification
Lookout Mountain resources are classified on the basis of the number and distance of composites used in the interpolation of a block, as well as the number of holes that contributed composites and the geographic location of the blocks within the model area (Table 11-6).
Table 11-6 Lookout Mountain Classification Parameters
Class | Min. | Additional Constraints | |
No. of Comps | | ||
| | | |
Indicated | 3 | Minimum of two holes within an average distance of 120ft from | |
block | | ||
| | | |
Inferred | 2 | Minimum of two samples within an average distance of 200ft from | |
block | | ||
| | |
Indicated resources are restricted to lie within the densely drilled portion of North Lookout Mountain and the northernmost portion of South Lookout Mountain, where the geology is very well understood.
Inferred resources are defined using composites within 200 feet of block centroid.
A total of 839 sample intervals lie within the modeled mineral domains at the Lookout Mountain deposit and are known, or suspected, to have been analyzed by cyanide shake-leach or aqua regia / AA methods only; no fire assay data are available for these intervals. This represents 7% of the coded assays used in the resource estimation of Lookout Mountain. Since both analytical techniques are partial-gold analyses, the inclusion of these data could result in a minor underestimation of the resources.
There is some evidence of local down-hole contamination in the reverse-circulation of drill data. The mineral-domain modeling used in the resource estimation partially mitigates this problem through the exclusion of mineralized intervals suspected of being contaminated. It should be noted, however, that the identification of suspect intervals is interpretational. It is possible that a relatively small amount of the excluded mineralization is not actually contaminated, while some mineralized samples included in the resource estimation may be affected by contamination. Due to the nature of the drilling methods, rotary drill samples are inherently more prone to sample quality issues than those from RC. Conventional rotary samples amount to 8.8% of the total drill samples. Rotary drilling has limitations in drill depth and sample quality, so it is not as prevalent as it once was.
11.2.13. Reasonable Prospects for Eventual Economic Extraction
To report a Mineral Resource in accordance with Item 1300 of Regulation S-K, the Mineral Resource statement must demonstrate reasonable prospects for eventual economic extraction (RPEEE).
Due to the geometry and location of the Lookout Mountain deposit, the QP considers it appropriate to be mined by open pit methods with heap-leach processing of oxide materials and off-site toll
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milling of unoxidized materials. To meet the requirement of RPEEE of mineral resources, a constraining optimized pit shell was created.
The optimization parameters in Table 11-7 were used to calculate internal cutoff grades that define which blocks lying within the pit optimizations would be available for both heap-leaching of oxidized materials and potential toll milling of sulfide materials. Cut-off grades of 0.005 oz Au/ton (oxide) and 0.050 oz Au / ton (sulfide) were determined.
Table 11-7 Pit Optimization Parameters
Parameter | Units | Value |
Gold Price | US$/oz | 3000 |
Royalty | % / oz | 4 |
Payable gold | % | 99.95 |
Pit wall angle | Degrees | 57 |
Mineralized mining cost | US$ / ton | 3.89 |
Waste mining cost | US$ / ton | 2.81 |
Processing cost (oxide / sulfide) | US$ / ton | 4.93 / 20.00 |
Refining cost | US$ / oz | 0.48 |
Transport & Sales | US$ / ton | 1.54 |
G&A | US$ / ton | 4.00 |
Recovery (oxide / sulfide) | % | 78 / 75 |
Cut off grade (oxide / sulfide) | oz per ton | 0.005 / 0.050 |
The metal price for Au used for the optimisation parameters was based around monthly closing data from March 2024 to March 2026; the approximate two-year trailing average gold price is US$3,190 per ounce. This period reflects a rapid rise in gold prices, starting from approximately $2,251 in March 2024 and exceeding $5,300 by April 2026. A slightly lower price of US$3000 was chosen as this is also inline with the company’s resource reporting benchmarks for other projects.
The reference point at which the mineral resources are defined is in situ.
11.2.14.Mineral Resource Statement
The optimized open pit constrained mineral resources for Lookout Mountain are presented in Table 11-8.
Table 11-8 Lookout Mountain Project Gold Resources
Classification | Quantity (000s tonnes) | Grade (Au gpt) | Contained Au (oz) |
Indicated | 19,570 | 0.64 | 402,300 |
Inferred | 7,292 | 0.57 | 134,200 |
Notes:
· | The QP for the estimate is Mr. Michael Baumann SME-RM, CPG, an employee of McEwen Inc. |
· | Mineral resources are not mineral reserves and do not have demonstrated economic viability. |
· | The mineral resources are potentially amenable to open- pit mining methods and are therefore constrained by optimized pits created using the following parameters: a gold price of US$3,000/oz; metallurgical recoveries of 78% for oxide (heap-leaching) and 75% for potential toll milling of |
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unoxidized materials; mining cost of US$3.89/ton (mineralized) and US$2.81/ton (waste); processing costs of $4.93/ton (oxide) and $20.00/ton (non-oxide); G&A cost of $4/ton processed; refining cost of $0.48/oz Au produced, and an NSR royalty of 4.0%.
· | Cut-off grades for blocks within the pits are 0.005 oz Au/ton (oxide) and 0.050 oz Au/ton (non-oxide). |
· | The Effective Date of the Lookout Mountain resource estimate is March 16 2026. |
· | Figures may not sum due to rounding. |
Sensitivity
Table 11-9 presents the experimental sensitivities of the Lookout Mountain mineral inventory at various cut-off grades above and below that selected for the reported Mineral Resource Statement within the optimized pit shell. These results are provided for comparative purposes only, to illustrate the effect of applying different cut-offs that might reflect future changes in parameters such as metal price, costs and recoveries etc.
It should be noted that these sensitivity cases do not represent Mineral Resources and should not be interpreted as such. The base case (reporting) scenario is highlighted in bold in the table. Figures may not sum due to rounding.
Table 11-9 Sensitivity table for Mineral Inventory at Lookout Mountain
| | Indicated | | | | Inferred | | | |
Cut-off | Tonnes | Grade (gpt) | | Au oz | | Tonnes | Grade (gpt) | Au oz | |
Au oz / ton | | | | ||||||
| | | | | | | | | |
Oxide material | | ||||||||
0.003 | 21,223,200 | 0.516 | | 351,900 | | 8,025,800 | 0.530 | 136,700 | |
0.004 | 20,388,500 | 0.532 | | 348,700 | | 7,734,800 | 0.545 | 135,500 | |
0.005 | 19,131,500 | 0.557 | | 342,400 | | 7,278,000 | 0.569 | 133,200 | |
0.006 | 17,557,400 | 0.590 | | 332,900 | | 6,646,000 | 0.605 | 129,400 | |
0.007 | 15,983,000 | 0.626 | | 321,600 | | 6,068,900 | 0.642 | 125,300 | |
Sulfide Material | | ||||||||
0.03 | 686,300 | 3.197 | | 70,500 | | 26,200 | 1.762 | 1,500 | |
0.04 | 533,300 | 3.775 | | 64,700 | | 15,800 | 2.162 | 1,100 | |
0.05 | 434,900 | 4.280 | | 59,900 | | 12,400 | 2.336 | 1,000 | |
0.06 | 361,000 | 4.775 | | 55,400 | | 7,200 | 2.672 | 600 | |
0.07 | 309,300 | 5.199 | | 51,700 | | 4,500 | 2.944 | 400 | |
11.2.15.Factors that could affect Mineral Resource Estimate
Factors that may affect the Lookout Mountain Mineral Resource estimate include:
·Changes in the local geological interpretations and assumptions used to generate the gold estimation domains
· | Changes in mineralization and geological geometry and continuity of mineralized zones |
· | Changes in assumptions of mineralization and grade continuity |
· | Changes in the treatment of high-grade gold values |
· | Changes in the grade interpolation methods and estimation parameter assumptions |
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·Changes in the confidence assumptions and methods used in the mineral resource classification
· | Changes in the density and the methods used in the density assignments |
·Changes in metallurgical recovery assumptions based on testing including work on Jasperoid or high silica mineralization.
·Changes in metal price and other economic assumptions used in the cut-off grade determination
·Changes in input and design parameter assumptions that pertain to the open pit mining constraints
·Changes to assumptions as to the continued ability to access the mine site, retain mineral and surface rights titles, maintain the operation within environmental and other regulatory permits, and maintain the social license to operate.
No other environmental, permitting, legal, title, taxation, socioeconomic, marketing, political or other relevant factors are known to the QP that would materially affect the estimation of Mineral Resources that are not discussed in this report.
11.3.Windfall Resource Modeling
The modeling and estimation of Mineral Resources at Windfall presented in this document are based on technical data and information available as of December 13, 2025 (the data cut-off date).
The database used to estimate mineral resources is managed by McEwen and is subject to regular review, internal audit, and continuous updating. McEwen believes that current drilling information is reliable enough to confidently interpret mineralization boundaries, where applicable, and assay data is reliable enough to support the mineral resource estimate.
The mineral resources were calculated under the supervision of Michael Baumann who meets the qualifications and criteria as a Qualified Person (QP).
11.3.1.Mineral resource database
Drill data from previous operators BH Minerals USA, Inc, Cambior, Campbell, Hoss and Buchanan, Inc. GC, GMDC, Norse Windfall Mines, Western Minerals Exploration, and Windfall Ventures and most recently by Timberline and McEwen Nevada, included information derived from RC, rotary, and core drill holes. These data, as well as digital topography of the project area, were incorporated into a digital database in UTM NAD1983 International feet coordinates. Geological modelling was performed using Leapfrog software. Grade domains were modelled using Micromine. All remaining tasks including drilling database import, geostatistics, block model generation, interpolation, classification, and validation were performed using Datamine’s Studio RM Version 3.1 geological
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modeling software. The extraction date of drill data used in the resource model was December 13, 2025.
Table 11-10 Drill hole data compilation
Drill Hole Type | # holes | % of holes | Total feet drilled |
Core | 17 | 1% | 9,459 |
Reverse Circulation (RC) | 159 | 11% | 77,885 |
Conventional Rotary | 1,331 | 88% | 265,522 |
Total | 1,507 | 100% | 352,866 |
Table 11-11 Drill Footage by Company
Company | Total feet drilled |
BH Minerals USA, Inc. | 13,131 |
Cambior | 850 |
Campbell, Hoss and Buchanan, Inc. | 1,295 |
GC | 1,360 |
GMDC | 1,985 |
McEwen Nevada | 58,588 |
Norse Windfall Mines | 1,865 |
Timberline | 7,450 |
Western Minerals Exploration | 4,220 |
Windfall Ventures | 262,122 |
Total | 352,866 |
The resource models were created using data developed through 2025. A drillhole database was received for Windfall Project containing 1,507 drillholes for 352,866 ft of drilling and 43,236 samples (Table 11-12). Most drill data is historical, vertical drilling with approximately 17% of new confirmation drilling feet performed by McEwen Nevada in 2024 and 2025 with angled drill holes to verify structural controls to mineralization.
Table 11-12 Global database for Windfall
Statistics | Au_ppm | Au_opt |
# samples | 43,236 | 43,236 |
Min | 0.001 | 0.000 |
Max | 65.131 | 1.900 |
Mean | 0.203 | 0.006 |
Range | 65.130 | 1.900 |
Variance | 1.002 | 0.001 |
Std Deviation | 1.001 | 0.029 |
Kurtosis | 1394.89 | 1394.89 |
Skewness | 28.99 | 28.99 |
CV | 4.926 | 4.926 |
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Figure 11-7 All drill holes in the Windfall project are shown (plan view)

11.3.2.Geological modelling
Sedimentary rocks exposed in the Eureka district are of Cambrian through Devonian age and are made up of limestone, dolomite, and minor amounts of shale and quartzite. These sedimentary units were autochthonous with respect to the Roberts Mountains thrust. They have been intruded by Cretaceous(?) pluton(s), as well as felsic dikes thought to be of Eocene age.
The Eureka district (Figure 11-8) is underlain in part by the Ordovician Goodwin member of the Pogonip Group, the stratigraphic unit that hosts much of the nearby Ruby Hill gold deposit. Portions of the property are also underlain by the Cambrian Dunderberg Shale and Hamburg Dolomite, which host the Lookout Mountain, Windfall, Paroni, and Rustler gold deposits on the Eureka
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property. McEwen geologists created a 3D geological model (Figure 11-9) using Leapfrog software to better understand the lithologies and create a framework for the modelling of mineral domains.
Figure 11-8 Geologic Map of the Windfall project

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Figure 11-9 3D Geological model of the Windfall deposit

11.3.3.Mineralization
The Eureka property mineralization occurs as Carlin-type, disseminated, sediment-hosted mineralization. Gold in these deposits is typically hosted by carbonaceous silty limestones and calcareous siltstones, but significant deposits also occur in dolomite, shale, and quartzite.
The characteristic alteration of Carlin-type deposits is decalcification, argillization, and intense silicification, which is often described as jasperoid. Gold is invariably accompanied by similar or lesser amounts of silver, as well as a halo of pathfinder elements that commonly include arsenic, thallium, mercury, antimony, and barium. Weakly anomalous amounts of lead, zinc, and copper are locally present in the gold systems as well. Typical minerals accompanying gold include pyrite, arsenian pyrite, stibnite, realgar, orpiment, carbon (graphite), and their oxidation products. At the Eureka property, the gold mineralization was deposited in favorable Cambrian, Ordovician, and Devonian calcareous sedimentary units where they are intersected by major northwest-, northeast-, and north-trending faults and fractures that are commonly also mineralized.
The gold mineralized zone at Windfall occurs along the north-south structural trend which typically separates steeply dipping Hamburg Dolomite Formation to the west, from moderate east-dipping Dunderberg Shale Formation to the east (Figure 11-10). Gold appears to be dominantly associated with brecciated dolomite adjacent to and between northeasterly and northwesterly trending cross-faults. Gold grade-thickness anomalies from historic drill hole intercept assays suggest similar structural control on higher-grade gold mineralization. The structures appear to focus gold mineralization within intensely bleached and “sanded”, variably brecciated (collapse-style, and/or
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structural breccias) Hamburg Dolomite Formation. Limited silicification (e.g. as jasperoid) is evident in the rocks which likely relates to the excellent historically-reported leachability of gold at the Windfall Mine.
Figure 11-10 Cross section showing the geology and mineral zone

11.3.4.Oxide Modeling
Based on drillhole logging codes, the Windfall project area is composed of dominantly oxidized rocks. There are limited samples with both common AuFA and AuCN assays in the database which provide information on expected cyanide recoveries. A factor of 79% recovery ratio was used based on a metallurgical study compiled by Anthony Kaah (internal communication 12/02/2026 Gold Recovery for Lookout Mountain and Windfall) for oxide mineral zones.
11.3.5.Composites
Not all intervals of each drillhole through the deposit were sampled on a consistent basis, therefore a regularisation of the sampling width through compositing methods is necessary. Compositing was performed every 10 feet as a fixed length considering all samples in the database. The 10-foot composite is one half the mining bench height in an open pit scenario and allows for some selectivity with the proposed open pit mining method. The data were separated into distinct domains to reflect geologic controls to mineralization.
11.3.6.Domaining
Gold domains were defined in the north and south due to the change in the direction and dip of mineralization. In the north, the strike direction is 340° to 350° and the dip is nearly vertical, while the southern domain has a N-S direction and a dip of 60° to 75° towards the east. The structural boundary is marked by a NE-SW trending fault, the Nolan Fault.
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Figure 11-11 Plan Map of Geological interpretation of Windfall North and South domains

Four domains were created for the Windfall model. Both North and South domains have a low grade (>0.005 to 0.030 opt gold) and high grade (>0.030 opt gold) domain based on the log probability plot population distribution (Figure 11-12).
Figure 11-12 Log Probability plot of the Windfall total data set 10 ft composites

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Figure 11-13 Log Histogram of gold grades in the low-grade south domain (LG_South)

Figure 11-14 Log Histogram of gold grades in the high-grade south domain (HG_South)

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Figure 11-15 Log Histogram of gold grades in the low-grade north domain (LG_North)

Figure 11-16 Log Histogram of gold grades in the high-grade north domain (HG_North)

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11.3.7.Density
Based on historical work at Lookout Mountain, which is comparable in terms of lithologies, the density of the Windfall mineralization is 13.5 ft³/ton (or 2.37 tonnes / m3). The waste density is assigned to be 13.0 cu ft/ton (or 2.46 tonnes / m3). Density samples were collected from the 2025 drilling however, the results of this work were not available at the time of this report. It is difficult to collect coherent samples from the sanded zones for density testing. Because of this, a downhole geophysical method is being deployed to measure the in-situ rock density continuously down the hole.
11.3.8.Capping
Gold assay composite intervals were coded to the low-grade and high-grade mineral domains. The process of determining assay capping levels (Table 11-13) included inspection of quantile plots of the coded assays by domain to identify possible high-grade outliers that might be appropriate for capping. Descriptive statistics of the coded assays by domain and visual reviews of the spatial relationships of the possible outliers and their potential impacts during grade interpolation were also considered.
Table 11-13 Descriptive Statistics of Windfall Domain Coded Gold Composites and Capping levels

A total of 139 composites were capped for the LG South domain, and six composites were capped for the HG South domain. LG North domain capped 241 composites and the HG North domain capped 13 composites.
11.3.9.Variography
A variography study was performed using the Windfall gold composites, collectively and separately, at various azimuths, dips, and lags (Figure 11-17 to Figure 11-20).
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Variogram analyses were performed using the gold composites within each individual domain: LG North, HG North, LG South and HG South as a guide to determine a grade interpolation search distance, ellipse orientation strategy and Mineral Resource classification criteria.
For block estimation, a search ellipse has been selected to capture sample intervals, according to the direction and inclination of the mineralization and variograms.
Figure 11-17 Search ellipse for Domain LG_South.
N-S section looking West

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Figure 11-18 Search ellipse for Domain HG_South
Cross-section 14327750N High Grade Mineral zone structure dipping to the East

Figure 11-19 Search ellipse for Domain LG_North
North-South Section on 1929450E along strike of structure which is near vertical

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Figure 11-20 Search ellipse for Domain HG_North
East-West section along 14328400N looking north along strike of high angle structure

11.3.10.Block Model Parameters, Coding and Estimation
The framework for the block model was established using blocks 20’ x 20’ x 20’ in size based on anticipated mining methods. Sub-cells down to 10’ were used which allows for increased resolution of the mineralized zone. No rotation was applied to the model.
Several iterations of block model coding were completed including:
· | The low grade and high-grade mineral domains (WF_005 or WF_030) were used to code the Windfall block model accordingly. |
· | The percentage of each block that lies below the topographic surface is coded and stored for use in the calculation of block tonnages. |
· | Each block is assigned a tonnage factor. If a block is coded as having 50% or greater of any of the mineral domains WF_005 or WF_030, the block is mineralized for the purposes of density assignment of 13.5 cu ft/ton (2.37 tonnes / m3). Blocks having no gold domain coding are unmineralized and assigned a density of 13.0 cu ft/ton (2.46 tonnes / m3). |
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Table 11-14 Block model parameters
Windfall deposit | X | Y | Z |
Origin | 1,927,840 | 14,323,100 | 6,400 |
Block Size (ft) | 20 | 20 | 20 |
Rotation | 0° | 0° | 0° |
Number of Columns | 150 | 500 | 200 |
The block model was visually inspected to make sure the model was fully informed to the original topographic surface with interpolated values (Figure 11-21).
Figure 11-21 N-S Long section looking East showing the Interpolated block model with gold grades in opt

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11.3.11.Model Validation
A number of validation-check steps were undertaken for the Windfall resource:
· | All block model coding was checked visually. |
· | Nearest-neighbor and inverse-distance estimates were used as checks on the OK estimation results. Average grade comparisons and grade-distribution plots of assays, composites, and the nearest-neighbor, ordinary-krige, and inverse-distance block grades were evaluated as a check on both the global and local estimation results. No unexpected relationships between the check estimates and the OK estimate were identified. |
·For a Global Bias check, the average model grades at a zero cut-off were compared. The ID3 model is within 5% of the NN model which is considered acceptable for a global bias validation check
· | Swath plots were constructed that compare grades from the original drill samples to the block grades from the three estimation methods within bands of different widths across the deposit. These were separated into North and South domains and constructed on sections from north to south (100 ft), east to west and in the vertical direction (elevation) at a constant 20 ft interval. The plots compare well across the deposit (Figure 11-24). |
· | ID3 block model grades were visually compared to the drill hole assay data in detail in both cross-section and plan views to ensure that the block model grades respected the composite grades (Figure 11-22 and Figure 11-23). |
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Figure 11-22 E-W Cross-section 14330250N looking north with Resource pit outline in black.

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Figure 11-23 E-W section 14330200N looking north with resource model and exploration drill holes.

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Figure 11-24 Swath plot (Northings) for South domain
block model gold grades vs. capped composited drill samples

For the Global Bias validation check, results from the three interpolation methods are compared at a zero cut-off. Variation between the different methods is minimal. The Global Bias for ID3, the model chosen for this deposit, is within 5% and from prior experiences ID3 works well with this type of deposit (Table 11-15).
Table 11-15 Global Bias check on interpolation methods
Cut-off | Au OK opt | Au NN opt | Au ID3 opt | Tons | Oz ID3 | OK / NN | ID3 / NN |
| | | | | | | |
Zero | 0.0213 | 0.0223 | 0.0226 | 32,943,735 | 744,364 | 95.4% | 101.2% |
| | | | | | | |
11.3.12.Classification
Classification criteria are based in principle on the assessment of, and confidence in, the geological understanding of the deposit and the geological and mineralization continuity of the deposit.
Windfall resources are classified into Indicated and Inferred categories on the basis of the number and distance of composites used in the interpolation of a block, as well as the number of holes that contributed composites, and the geographic location of the blocks within the model area.
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As a second criterion, technical aspects are considered including drill hole spacing, quality control results and data quality, search and interpolation parameters and analysis of available information.
The following approach was adopted in classifying the Mineral Resources:
· | Indicated Resources (Figure 11-25) were defined in areas where the average distance to the block centroid did not exceed 100 feet using a minimum of three samples, a maximum of 20, derived from a minimum of two drill holes. Consideration is also given to geological structures that are relatively well understood and interpreted. |
· | Inferred Resources (Figure 11-26) were defined in areas outside of the Indicated outlines greater than 100 feet but less than 200feet, using a minimum of two samples and a maximum of 20 samples, derived from a minimum of two drill holes and still showing reasonable strike continuity and down dip extension. |
Figure 11-25 Windfall block model long section showing indicated mineral blocks and grade in opt

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Figure 11-26 Windfall block model long section showing inferred blocks and grade in opt

11.3.13.Reasonable Prospects for Eventual Economic Extraction
To report a Mineral Resource in accordance with Item 1300 of Regulation S-K, the Mineral Resource statement must demonstrate reasonable prospects for eventual economic extraction (RPEEE).
Due to the geometry and location of the Windfall deposit the QP considers it appropriate to be mined by open pit methods with heap-leach processing of oxide materials. To meet the requirement of RPEEE of mineral resources, constraining optimized pit shells were created. Optimization parameters (Table 11-16) were used to calculate an internal cutoff grade that defines which blocks lying within the pit optimizations would be available for heap-leaching of oxidized materials. A cut-off grade of 0.005 oz Au/ton was determined.
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Table 11-16 Pit Optimization Parameters
Parameter | Units | Value |
Gold Price | US$/oz | 3000 |
Royalty | % / oz | 5 |
Payable gold | % | 99.95 |
Pit wall angle | Degrees | 57 |
Mineralized mining cost | US$ / ton | 3.89 |
Waste mining cost | US$ / ton | 2.81 |
Processing cost (oxide) | US$ / ton | 4.93 |
Refining cost | US$ / oz | 0.48 |
Transport & Sales | US$ / ton | 1.54 |
G&A | US$ / ton | 4.00 |
Recovery (oxide) | % | 78 |
Cut off grade (oxide) | oz per ton | 0.005 |
The metal price for Au used for the optimisation parameters was based around monthly closing data from March 2024 to March 2026; the approximate two-year trailing average gold price is US$3,190 per ounce. This period reflects a rapid rise in gold prices, starting from approximately $2,251 in March 2024 and exceeding $5,300 by April 2026. A slightly lower price of US$3000 was chosen as this is also inline with the company’s resource reporting benchmarks for other projects.
The reference point at which the mineral resources are defined is in situ.
Figure 11-27 Oblique plan view of the Windfall pit shell with block model

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11.3.14.Mineral Resource Statement
The optimized open pit constrained mineral resources for Windfall are presented in Table 11-17.
Table 11-17 Windfall Mineral Resource Estimate
Classification | Quantity (‘000 tonnes) | Gold Grade (gpt) | Contained Gold (oz) |
| | | |
Indicated | 9,402.8 | 0.75 | 227,500 |
| | | |
Inferred | 2,596.4 | 1.53 | 127,800 |
| | | |
Notes:
· | The QP for the estimate is Mr. Michael Baumann SME-RM, CPG, an employee of McEwen Inc. |
· | Mineral resources are not mineral reserves and do not have demonstrated economic viability. |
· | The mineral resources are potentially amenable to open- pit mining methods and are therefore constrained by optimized pits created using the following parameters: a gold price of US$3,000/oz; |
metallurgical recoveries of 78% for oxide (heap-leaching); mining cost of US$3.89/ton (mineralized) and US$2.81/ton (waste); processing costs of $4.93/ton (oxide); G&A cost of $4/ton processed; refining cost of $0.48/oz Au produced, and an NSR royalty of 5.0%.
· | Cut-off grades for blocks within the optimized pits are 0.005 oz Au/ton (oxide). |
· | The Effective Date of the Windfall resource estimate is February 11, 2026. |
· | Figures may not sum due to rounding. |
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Sensitivity
Table 11-18 presents the experimental sensitivities of the Windfall mineral inventory at various cut-off grades above and below that selected for the reported Mineral Resource Statement within the optimized pit shell. These results are provided for comparative purposes only, to illustrate the effect of applying different cut-offs that might reflect future changes in parameters such as metal price, costs and recoveries etc.
It should be noted that these sensitivity cases do not represent Mineral Resources and should not be interpreted as such. The base case (reporting) scenario is highlighted in bold in the table.
| Table 11-18 Sensitivity table for Mineral Inventory at Windfall | | | ||||
| | | | | | | |
| | Indicated | | | Inferred | | |
Cut-off | Tonnes | Grade (gpt) | Au oz | Tonnes | Grade (gpt) | Au oz | |
Au oz / ton | | ||||||
| | | | | | | |
| | | Oxide material | | | | |
0.003 | 9,665,500 | 0.736 | 228,700 | 2,632,800 | 1.512 | 128,000 | |
0.004 | 9,590,400 | 0.741 | 228,400 | 2,619,700 | 1.519 | 127,900 | |
0.005 | 9,402,800 | 0.752 | 227,500 | 2,596,400 | 1.531 | 127,800 | |
0.006 | 9,103,755 | 0.771 | 225,700 | 2,554,200 | 1.553 | 127,600 | |
0.007 | 8,677,300 | 0.798 | 222,600 | 2,490,500 | 1.587 | 127,100 | |
11.3.15.Factors that could affect Mineral Resource Estimate
Factors that may affect the Windfall Mineral Resource estimate include:
·Changes in the local geological interpretations and assumptions used to generate the gold estimation domains
· | Changes in mineralization and geological geometry and continuity of mineralized zones |
· | Changes in assumptions of mineralization and grade continuity |
· | Changes in the treatment of high-grade gold values |
· | Changes in the grade interpolation methods and estimation parameter assumptions |
·Changes in the confidence assumptions and methods used in the mineral resource classification
· | Changes in the density and the methods used in the density assignments |
· | Changes in metallurgical recovery assumptions based on test work |
·Changes in metal price and other economic assumptions used in the cut-off grade determination
·Changes in input and design parameter assumptions that pertain to the open pit mining constraints
·Changes to assumptions as to the continued ability to access the mine site, retain mineral and surface rights titles, maintain the operation within environmental and other regulatory permits, and maintain the social license to operate.
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No other environmental, permitting, legal, title, taxation, socioeconomic, marketing, political or other relevant factors are known to the QP that would materially affect the estimation of Mineral Resources that are not discussed in this report.
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12.MINERAL RESERVE ESTIMATES
Neither the Lookout Mountain nor Windfall gold projects have current mineral reserves.
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20.ADJACENT PROPERTIES
i80 Gold Corp. (“i80 Gold”) is actively undertaking underground mine development drilling activities at their Ruby Hill property, located north of McEwen’s Eureka claims (Figure 20-1) (i80 Gold, 2026).
North Peak Resources are exploring their property north of McEwen’s Eureka project, where they have identified five target areas for gold mineralization (NPR, 2026). Numerous other examples of historical gold and/or silver production occur throughout the greater Eureka District on, and adjacent to, McEwen’s property, and are shown on the map in Figure 20-1.
The QP has been unable to verify the above information beyond readily available publicly disclosed sources and historical references. The information is not necessarily indicative of the quality or quantity of mineralization on the Eureka properties that are the subject of this technical report summary.
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Figure 20-1 McEwen’s Eureka Project, Greater Eureka Property, and Adjacent Gold and CRD Occurrences

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21.OTHER RELEVANT DATA AND INFORMATION
McEwen’s Eureka property includes both unpatented BLM and patented claims that are contiguous to the Lookout Mountain and Windfall projects. These claims include many historical small mines and prospects.
The author is not aware of any other data or information relevant to the mineral resource estimate described in this report.
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22.INTERPRETATION AND CONCLUSIONS
Based on the work completed or supervised by the authors, the project data are of sufficient quality for the purposes used in this report. Furthermore, the authors are not aware of any significant risks or uncertainties that could reasonably be expected to affect the reliability of the current mineral resources other than those discussed in this report.
22.1.Lookout Mountain
The modeled gold mineralization at the Lookout Mountain resource extends north-south for almost 7,000 feet in length and is primarily hosted by the Lookout Mountain breccia, which strikes in a northerly direction and dips moderately to the east. The breccia is up to 900 feet wide at the surface and typically thins down-dip to the east. Gold occurs at or near the Dunderberg-Hamburg Dolomite contact and is associated with northeast-trending cross faults. Gold mineralization at the Lookout Mountain project is of the disseminated sediment-hosted, Carlin-type.
The primary controls on the Lookout Mountain mineralization are the north-trending, high-angle Ratto Ridge fault system, which has localized jasperoids and gold mineralization in sedimentary units along more than 2.5 miles of strike length, and the Lookout Mountain breccia. The mineral domains modeled as part of the resource estimation occur predominantly within the Lookout Mountain breccia, with exceptions including mineralization in the Dunderberg Shale in the hanging wall of the breccia, which is often high-grade, minor mineralization in Secret Canyon limestone immediately below the breccia, and gold occurring in colluvium/alluvium.
About 180,000 tons of mostly oxide gold mineralization reportedly grading 0.12 oz Au/ton were mined from the Lookout Mountain open pit during 1987. The ore was hauled 5.6 miles to cyanide heap-leach pads at the Windfall Mine, where an estimated 81% recovery was achieved from the agglomerated ore. This small amount of historical production, in addition to metallurgical testing completed by Timberline and previous operators at the Lookout Mountain project, suggest that the oxidized gold mineralization remaining at Lookout Mountain is amenable to extraction by cyanidation via heap-leaching, although further metallurgical test work is required.
The project database consists of information derived from 92 core holes and 668 RC and rotary holes completed by Newmont, Amselco, Norse Windfall Mines, EFL, Barrick, Echo Bay, Staccato, Timberline, and McEwen. The database was audited and underwent a comprehensive re-compilation of all assay data from Amselco’s RTR- and RTC-series holes. In-house mine laboratories were used for the 20 Norse Windfall Mines holes and some of the Amselco holes, and many of these analyses utilized partial-gold extraction methods. Some of the Norse Windfall Mines gold data clearly understate grades in comparison to adjacent holes. The impact of the in-house assays in the Amselco database was effectively limited by replacing many of them with check analyses performed at commercial laboratories. The author believes the Lookout Mountain analytical data are of sufficient quality for use in resource estimation. The current mineral resources were estimated using this database.
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The Lookout Mountain project gold resources are tabulated using cutoff grades of 0.005 oz Au/ton (0.171 g/t). This cutoff grade was chosen to capture oxidized mineralization that is potentially available to open pit extraction that can reasonably be assumed to be amenable to heap-leach processing. Indicated resources total 19,570,000 tonnes averaging 0.64 g/t (402,300 ounces), with an additional 7,292,000 tonnes averaging 0.57 g/t (134,200 ounces) assigned to the inferred category.
Project risks that could impact the Lookout Mountain project mineral resources include: (i) the potential of unrecognized poor sample quality in some portions of some RC and rotary holes; (ii) potential analytical uncertainties with respect to some of the lowest-grade gold assay data derived from some of the historical project operators; (iii) the modeling of gold mineralization and oxidation state in less densely drilled portions of the South Lookout Mountain area; and (iv) the assignment of rock densities, especially of mineralized material. These risks have been at least partially mitigated by collecting more density measurements and tighter drill hole spacing.
The potential to expand the existing resource base at the Lookout Mountain project is to the north, south and east. Drill holes have intersected mineralized zones along the strike of the resources both to the north (Rocky Canyon) and to the south. The 3,500-foot strike extent between the southern limit of the Lookout Mountain resources and the northern limit of the South Adit area may afford the best opportunity for potential heap-leach resource expansion in the near-term. Encouraging higher-grade drill results down-dip to the east of the project resources, at the Water Well Zone, also offer an opportunity for resource expansion.
22.2.Windfall
The modeled gold mineralization in the Windfall resource extends north-south for over 6,000 feet in length and is primarily hosted by the Hamburg dolomite, which strikes in a northerly direction and dips to the east. Gold occurs in the Hamburg dolomite at or near the contact with the overlying Dunderberg shale, and is associated with strong decarbonatization, argillization, and a series of northeast-trending cross faults. Gold mineralization at the Windfall project is of the disseminated sediment-hosted Carlin-type.
The primary controls on the Windfall mineralization are the north-trending, high-angle Windfall Trend, which is marked by the contact between the Dunderberg and Hamburg. Gold mineralization extends north to south along this contact for nearly two miles of strike length. The mineral domains modeled as part of the resource estimation occur predominantly within the Hamburg dolomite.
The Windfall project gold resources are tabulated using cutoff grades of 0.005 oz Au/ton (0.171 g/t) for oxidized material. No sulfide material was included in the resources. Indicated gold resources total 9,402,800 tonnes averaging 0.75 g/t (227,500 ounces), with an additional 2,596,400 tonnes averaging 1.53 g/t (127,800 ounces) assigned to the inferred category.
Project risks that could impact the Windfall project mineral resources include: (i) the potential of unrecognized poor sample quality in some portions of some RC and rotary holes; (ii) potential uncertainties with respect to some of the lowest-grade gold assay data derived from some of the historical project operators; (iii) the modeling of gold mineralization in less densely drilled portions
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of the resource area; and (iv) the assignment of rock densities, especially of mineralized material. These risks have been at least partially mitigated, with additional density data acquired from drill core.
The potential to expand the existing resource base at the Windfall project is to the north, south and at depth. The 6,000-foot strike length may extend to the north and may afford the best opportunity for potential heap-leach resource expansion in the near-term. Encouraging higher-grade drill results down-dip the project resources, also offer an opportunity for resource expansion.
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23. | RECOMMENDATIONS |
23.1. | Lookout Mountain |
The following recommendations are suggested to improve confidence in the mineral resource estimates, and to provide additional data that can potentially be used for the next stage in the project development, most likely a preliminary economic study (IA) or pre-feasibility study (PFS).
This recommended work program (Phase II) would include approximately 10,000 feet of infill RC and core drilling within the general limits of the current project resources, with the goal of upgrading resource classification, particularly the conversion of current inferred resources to higher categories. Metallurgical testing of core samples is also recommended. The metallurgical program should include additional bottle-roll and column testing at various particle sizes, further crush-size-fraction testing, SEM and other mineralogic characterizations, material type volumetrics, and specific-gravity measurements of both mineralized and unmineralized material.
Updated three-dimensional modeling of the geology (including lithology, alteration, structure, oxidation) needs to be undertaken at a level appropriate to support future economic studies.
The following Phase II work is recommended to advance the project toward the next stage:
· | Additional drilling, including the continuation of infill (5,000 feet of core and RC), exploration (15,000 feet of RC and core), and metallurgical (5,000 feet of core) drilling programs initiated in Phase I; condemnation drilling (10,000 feet of RC) to define potential sites for waste rock storage, heap-leach pad, and other mine facilities; and drilling to support hydrologic studies (10,000 feet of rotary/RC); |
· | A geotechnical program, including pit slope work, shear and compression tests, and stability analyses; the program would also include the drilling of four to eight oriented core holes; |
· | The completion of environmental baseline studies required for a mine Plan of Operation, including biological (threatened and endangered species, migratory birds, critical habitat, sage grouse, etc.) and cultural surveys; |
· | Detailed hydrologic studies, including modeling, preparation of a hydrogeochemical characterization report, and the completion of water monitoring and production wells; and |
· | Preliminary facilities design, including soil geotechnical studies, determination of utility pathway locations and needs, and determination of the location, size, and type of crusher. |
· | Baseline environmental studies are required for the submission of a mine Plan of Operation to the BLM |
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Estimated costs of the Phase II work program are summarized on Table 23-1.
Table 23-1 Recommended Phase II Lookout Mountain Work Program
Item1 | Estimated Cost $ |
Drilling (~45,000 ft). Includes exploration, hydrologic, condemnation, infill, | 4,000,000 |
Drill Access - construction and upgrading | 75,000 |
Drill-Sample Assaying – includes QA/QC samples | 350,000 |
Metallurgical Testing | 250,000 |
Hydrologic Studies | 500,000 |
Environmental Baseline Studies | 1,330,000 |
Preliminary Facilities Design-Related Work | 150,000 |
Total | $ 6,655,000 |
1All landholding, personnel, environmental (reclamation, reclamation bonding, permitting, etc.), and travel costs not included
23.2.Windfall
The following recommendations are to improve the confidence of the mineral resource estimates, and to provide additional data that can be used for the next stage, most likely a preliminary economic study (IA) or pre-feasibility study (PFS)
This work should include approximately 10,000 feet of infill RC and core drilling within the general limits of the current project resources, with the goal of upgrading resource classification, especially the conversion of current Inferred resources to higher categories. Metallurgical testing of core samples is also recommended. The metallurgical program should include additional bottle-roll and column testing at various particle sizes, further crush-size-fraction testing, SEM and other mineralogic characterizations, material type volumetrics, and specific-gravity measurements of both mineralized and unmineralized material.
Updated three-dimensional modeling of the geology (including lithology, alteration, structure, oxidation) needs to be undertaken at a level appropriate to support all future economic studies.
The following Phase II work is recommended to advance the project toward the next stage:
· | Additional drilling, including the continuation of infill (5,000 feet of core and RC), exploration (15,000 feet of RC and core), and metallurgical (5,000 feet of core) drilling programs initiated in Phase I; condemnation drilling (10,000 feet of RC) to define potential sites for waste rock storage, heap-leach pad, and other mine facilities; and drilling to support hydrologic studies (10,000 feet of rotary/RC); |
· | The continuation of the Phase I metallurgical work; |
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· | A geotechnical program, including pit slope work, shear and compression tests, and stability analyses; the program would also include the drilling of four to eight oriented core holes; |
· | The completion of environmental baseline studies required for a mine Plan of Operation, including biological (threatened and endangered species, migratory birds, critical habitat, sage grouse, etc.) and cultural surveys; |
· | Detailed hydrologic studies, including modeling, preparation of a hydrogeochemical characterization report, and the completion of water monitoring and production wells; and |
· | Preliminary facilities design, including soil geotechnical studies, determination of utility pathway locations and needs, and determination of the location, size, and type of crusher. |
Estimated costs of the Windfall Phase II work program are summarized on Table 23-2.
Table 23-2 Recommended Phase II Windfall Work Program
Item1 | Estimated Cost $ |
Drilling (~35,000 feet) - Includes exploration, hydrologic, condemnation, infill, metallurgical and geotechnical core drilling | 2,900,000 |
Drill Access - construction and upgrading | 150,000 |
Hydrology | 450,000 |
Drill and Surface Sample Assaying – includes QA/QC samples | 350,000 |
Metallurgical Testing | 250,000 |
Geologic Modeling and Resource Estimation | 250,000 |
Preliminary Economic Assessment | 150,000 |
Total | $ 4,500,000 |
1All landholding, personnel, environmental (reclamation, reclamation bonding, permitting, etc.), and travel costs not included.
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Jonson, D. C., 1991 (May 6), Exploration potential for gold deposits in the Ratto Canyon area, Eureka County, Nevada: an analysis of Amselco Minerals, Norse Windfall, BP Minerals /Kennecott, and EFL Gold Mines data 1978-1990: Report prepared for Summit Minerals Co., 40 p.
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McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
25.RELIANCE ON INFORMATION PROVIDED BY THE REGISTRANT
For this Technical Report Summary, the information, conclusions, opinions, and estimates contained herein are based on:
| ● | Information available to McEwen and the Qualified Persons (“QPs”) at the time of preparation of this TRS. |
| ● | The assumptions, conditions, and qualifications as set forth in this TRS. |
| ● | Data, reports, and other information supplied by McEwen and other third party sources. |
The QPs have not researched property title or mineral rights for the Property as we consider it reasonable to rely on McEwen’s legal counsel and land manager, who are responsible for maintaining this information.
The QPs have taken all appropriate steps, in their professional opinion, to ensure that the above information from McEwen is sound. The QPs have reviewed and analyzed these data and have drawn independent conclusions based on their professional judgment.
Except as provided by applicable laws, any use of this TRS by any third party is at that party’s sole risk.
204
McEwen Inc. | Lookout Mountain and Windfall deposits |
Initial Assessment Technical Report Summary S-K 1300 | Eureka, Nevada |
THIS PAGE HAS BEEN LEFT BLANK INTENTIONALLY.
205
Exhibit 99.1

Grey Fox Project Prefeasibility Study
S-K 1300 Technical Report Summary
Document No. 25666-00000-PM-RPT-0002
Effective Date: June 8, 2026
Prepared for: | Contributing Firms: |
| |
| McEwen Inc. |
Report Date: | Stantec Consulting Ltd. |
November 9, 2026 | Arcadis |
| DRA Global Ltd. |
Project/File: | |
169525666 | |

| | |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
Revision Record
Revision | Date | Description | Responsible |
A | Click or tap to enter a date. | Document Initiated | Marta Syvertsen |
A1 | Click or tap to enter a date. | Formatted/Edited by Stantec TE/DMDC | |
A1a | Click or tap to enter a date. | Author Incorporation of Changes | |
B | Click or tap to enter a date. | QP Review | |
B1 | Click or tap to enter a date. | Author Incorporation of Changes | |
B1a | Click or tap to enter a date. | Tech Edit/Cleanup for Client Review | |
C | Click or tap to enter a date. | Client Review | |
C1 | Click or tap to enter a date. | Author Incorporation of Changes | |
0 | Click or tap to enter a date. | Final | |
REVISION APPROVAL
Revision | Designation | Responsible | Date |
A | Originator | | Click or tap to enter a date. |
Ax | Document Compliance Reviewer | Marta Syvertsen | 24 July 2026 |
A2 | Quality Assurance Reviewer | Luke Willis | 07 August 2026 |
A2 | Independent Peer Reviewer | | Click or tap to enter a date. |
| | |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
Important Notice
This notice is an integral component of the Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary (“TRS” or “Report”) and should be read in its entirety and must accompany every copy made of the Report. The Report has been prepared in accordance with the requirements of United States Securities and Exchange Commission (SEC) disclosure requirements under Sub-part 229.1300 of Regulation S-K.
This TRS has been prepared for McEwen Inc. with contributions from McEwen Inc., Stantec Consulting Ltd., DRA Global Ltd., and Arcadis. The quality of information, conclusions, and estimates contained herein are consistent with the level of effort involved in the services of Report contributors, based on: i) information available at the time of preparation of the Report, and ii) the assumptions, conditions, and qualifications set forth in this Report.
Each portion of the TRS is intended for use by McEwen, subject to the terms and conditions of its contract with Report contributors. Except for the purposes legislated under United States securities law, any other uses of the Report by any third party is at that party’s sole risk.
The results of the Report represent forward-looking information. The forward-looking information includes pricing assumptions, sales forecasts, projected capital and operating costs, mine life and production rates, and other assumptions. Readers are cautioned that actual results may vary from those presented. The factors and assumptions used to develop the forward-looking information, and the risks that could cause the actual results to differ materially are presented in the body of this Report.
The report authors have used their experience and industry expertise to produce the estimates in the Report. Where these estimates have been made, they are subject to qualifications and assumptions, and it should also be noted that all estimates contained in the Report may be prone to fluctuations with time and changing industry circumstances.
| | |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
Dates and Signatures
Report Title: | Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary |
| |
Property: | Grey Fox Project |
| |
Location: | Timmins, Ontario, Canada |
| |
Effective Date of Technical Report: | November 9, 2026 |
| |
Qualified Persons: | |
| | 9 November 2026 |
Carson Cybolsky, P.Geo. | | |
| | |
| | 9 November 2026 |
Sean Bradley Farrell, P.Geo. | | |
| | |
| | 9 November 2026 |
William Luke Willis, P.Geo. | | |
| | |
| | 9 November 2026 |
Mark Hatton, P.Eng. | | |
| | |
| | 9 November 2026 |
Sheldon Smith, MES, P.Geo. | | |
| | |
| | 9 November 2026 |
Gerd Michael Wiatzka, P.Eng. | | |
| | |
| | 9 November 2026 |
Daniel Weich Morrison, P.Eng. | | |
See Table 2-1 for each Qualified Person’s area of responsibility within this TRS.
| | |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
Table of Contents
Table of Contents
Acronyms / Abbreviations | xii | |
Glossary | | xvi |
| | |
1 | Executive Summary | 1-1 |
1.1 | Introduction | 1-1 |
1.2 | Property Description | 1-1 |
1.3 | Accessibility, Climate, Local Resources, Infrastructure and Physiography | 1-2 |
1.4 | History | 1-2 |
1.5 | Geological Setting, Mineralization, and Deposit | 1-3 |
1.6 | Exploration | 1-3 |
1.7 | Drilling | 1-4 |
1.8 | Sample Preparation, Analyses and Security | 1-4 |
1.9 | Data Verification | 1-4 |
1.10 | Mineral Processing and Metallurgical Testing | 1-5 |
1.11 | Mineral Resource Estimates | 1-7 |
1.12 | Mineral Reserve Estimates | 1-8 |
1.13 | Mining Methods | 1-9 |
1.14 | Processing and Recovery Methods | 1-10 |
1.15 | Infrastructure | 1-10 |
1.16 | Market Studies and Contracts | 1-11 |
1.17 | Environmental Studies, Permitting, and Plans, Negotiations, or Agreements with Local Individuals or Groups | 1-11 |
1.18 | Capital and Operating Costs | 1-12 |
1.19 | Economic Analysis | 1-12 |
1.20 | Adjacent Properties | 1-13 |
1.21 | Interpretation and Conclusions | 1-13 |
1.22 | Recommendations | 1-14 |
| | |
2 | Introduction | 2-1 |
| | |
2.1 | Terms of Reference | 2-1 |
2.2 | Site Visits and Scope of Personal Inspection | 2-2 |
2.3 | Effective Dates | 2-3 |
2.4 | Information Sources and References | 2-3 |
2.5 | Units of Measure | 2-3 |
2.6 | Previous Technical Reports | 2-3 |
| | |
3 | Property Description | 3-1 |
| | |
3.1 | Mineral Tenure and Surface Rights | 3-2 |
3.2 | Royalties and Encumbrances | 3-9 |
3.3 | Agreements | 3-13 |
3.4 | Environmental Liabilities | 3-17 |
3.5 | Significant Risk Factors | 3-17 |
| | |
4 | Accessibility, Climate, Local Resources, Infrastructure, and Physiography | 4-1 |
| | |
4.1 | Accessibility | 4-1 |
4.2 | Local Resources and Infrastructure | 4-1 |
4.3 | Climate | 4-2 |
4.4 | Physiography | 4-2 |
| | |
5 | History | 5-1 |
| | |
5.1 | Grey Fox Project | 5-1 |
| Project: 169525666 | i |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
Table of Contents
5.2 | Stroud Property | 5-4 |
5.3 | Eastern Properties | 5-4 |
5.4 | Stock Property | 5-8 |
5.5 | Western Properties | 5-11 |
| | |
6 | Geological Setting, Mineralization, and Deposit | 6-1 |
| | |
6.1 | Regional Stratigraphy | 6-1 |
6.2 | Mineral Occurrences & Mineralization Types | 6-2 |
6.3 | Stroud Property | 6-7 |
6.4 | Structural Geology | 6-14 |
6.5 | Property Geology | 6-17 |
6.6 | Deposit Types | 6-24 |
| | |
7 | Exploration and Drilling Programs | 7-1 |
| | |
7.1 | General Exploration | 7-1 |
7.2 | Drilling Programs | 7-1 |
7.3 | Drilling Methods | 7-10 |
7.4 | Logging Procedures | 7-12 |
7.5 | Core Recovery | 7-13 |
7.6 | Collar Surveys | 7-14 |
7.7 | Downhole Surveys | 7-15 |
7.8 | Geotechnical, Hydrological and Metallurgical Drilling | 7-16 |
7.9 | Sample Length and True Thickness | 7-16 |
7.10 | Drilling Completed Since Database Close-out Date | 7-17 |
7.11 | QP Comment on Exploration and Drilling Programs | 7-17 |
| | |
8 | Sample Preparation, Analyses and Security | 8-1 |
| | |
8.1 | Sampling Methods and Sample Preparation | 8-1 |
8.2 | Analytical Methods and Laboratories | 8-2 |
8.3 | Quality Assurance and Quality Control | 8-5 |
8.4 | Sample Security | 8-6 |
8.5 | QP Opinion | 8-8 |
| | |
9 | Data Verification | 9-1 |
| | |
9.2 | Property-Specific Verification | 9-2 |
9.3 | Geochemical and Water Analysis Verification | 9-3 |
9.4 | Tailings Storage Data Verification | 9-4 |
9.5 | Water Treatment | 9-5 |
9.6 | Metallurgical Testing and Analysis | 9-5 |
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10 | Mineral Processing and Metallurgical Testing | 10-1 |
| | |
10.1 | Summary | 10-1 |
10.2 | Introduction | 10-4 |
10.3 | Test Work Completed to Date | 10-4 |
10.4 | Historical Metallurgical Testing Results | 10-5 |
10.5 | Recent Metallurgical Testing Results | 10-25 |
10.6 | Process Design Criteria Derived from Test Results | 10-41 |
10.7 | Recovery Model | 10-43 |
10.8 | Deleterious Elements | 10-44 |
10.9 | Interpretation and Conclusions | 10-44 |
10.10 | Recommendation for Future Work | 10-44 |
| | |
11 | Mineral Resource Estimates | 11-1 |
| | |
11.1 | Approach | 11-1 |
| Project: 169525666 | ii |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
Table of Contents
11.2 | Resource Estimation | 11-1 |
11.3 | Grey Fox | 11-2 |
11.4 | Stroud | 11-14 |
11.5 | Black Fox | 11-22 |
11.6 | Froome | 11-29 |
11.7 | Stock Property – West and Main Zone | 11-38 |
11.8 | Stock Project – East Zone | 11-49 |
11.9 | Davidson-Tisdale | 11-56 |
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12 | Mineral Reserve Estimates | 12-1 |
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12.1 | Forward-Looking Statement | 12-1 |
12.2 | Risks | 12-1 |
12.3 | Mineral Reserve Estimate | 12-1 |
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13 | Mining Methods | 13-1 |
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13.1 | Geomechanical | 13-5 |
13.2 | Hydrogeological Considerations | 13-23 |
13.3 | Mine Design and Mining Methods | 13-25 |
13.4 | Productivities | 13-38 |
13.5 | Mine Production Schedule | 13-43 |
13.6 | Blasting | 13-47 |
13.7 | Mobile Equipment Selection | 13-47 |
13.8 | Ventilation | 13-51 |
13.9 | Ore and Waste Handling System | 13-59 |
13.10 | Mine Dewatering | 13-59 |
13.11 | Backfill Distribution | 13-60 |
13.12 | General Underground Infrastructure | 13-62 |
13.13 | General Underground Services | 13-65 |
13.14 | Underground Electrical and Power Distribution | 13-67 |
13.15 | Underground Communication and IT | 13-72 |
| | |
14 | Processing and Recovery Methods | 14-1 |
| | |
14.1 | Process Flowsheet | 14-2 |
14.2 | Process Design Criteria | 14-3 |
14.3 | Process Description | 14-4 |
14.4 | Conclusions | 14-8 |
| | |
15 | Infrastructure | 15-1 |
| | |
15.1 | Existing Infrastructure | 15-2 |
15.2 | Project Site Preparation | 15-4 |
15.3 | Project Access | 15-4 |
15.4 | Buildings and Ancillary Items | 15-6 |
15.5 | Ventilation Collars | 15-10 |
15.6 | Power Distribution | 15-11 |
15.7 | Communications and IT | 15-12 |
15.8 | Ore and Waste Rock Management | 15-13 |
15.9 | Water Management | 15-14 |
15.10 | Tailings Storage Facilities | 15-18 |
15.11 | Sitewide Water and Mass Balance Model | 15-25 |
15.12 | Water Treatment Plant Infrastructure | 15-29 |
| | |
16 | Market Studies and Contracts | 16-1 |
| | |
16.1 | Market Studies | 16-1 |
16.2 | Contracts | 16-1 |
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Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
Table of Contents
16.3 | QP Opinion on Markets and Contracts | 16-1 |
| | |
17 | Environmental Studies, Permitting, and Plans, Negotiations, or Agreements with Local Individuals or Groups | 17-1 |
| | |
17.1 | Existing Environment | 17-1 |
17.2 | Site Water Quality and Geochemistry | 17-3 |
17.3 | Environmental Setting | 17-4 |
17.4 | Regulatory Framework | 17-4 |
17.5 | Environmental Aspects and Sensitivities | 17-7 |
17.6 | Social and Community | 17-8 |
17.7 | Mine Closure | 17-9 |
| | |
18 | Capital and Operating Costs | 18-1 |
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18.1 | Methodology | 18-1 |
18.2 | Total Capital Cost Estimates | 18-1 |
18.3 | Total Operating Cost Estimates | 18-9 |
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19 | Economic Analysis | 19-1 |
| | |
19.1 | Financial Results | 19-1 |
19.2 | Cautionary Statement | 19-2 |
19.3 | Assumptions | 19-3 |
19.4 | Economic Model Parameters | 19-3 |
19.5 | Sensitivity Analysis | 19-8 |
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20 | Adjacent Properties | 20-1 |
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20.1 | Hislop | 20-1 |
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21 | Other Relevant Data and Information | 21-1 |
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22 | Interpretation and Conclusions | 22-1 |
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22.1 | Ownership | 22-1 |
22.2 | Mineral Tenure, Surface Rights, Water Rights, Royalties and Agreements | 22-1 |
22.3 | Geology and Mineralization | 22-1 |
22.4 | Exploration | 22-2 |
22.5 | Metallurgical Testwork | 22-3 |
22.6 | Mineral Resource Estimates | 22-3 |
22.7 | Mineral Reserve Estimate | 22-4 |
22.8 | Mining | 22-5 |
22.9 | Infrastructure | 22-5 |
22.10 | Tailings Storage | 22-5 |
22.11 | Water/Solute Mass Balance and Water Treatment | 22-6 |
22.12 | Market Studies and Contracts | 22-6 |
22.13 | Capital and Operating Cost Estimates | 22-6 |
22.14 | Economic Analysis | 22-7 |
22.15 | Risks | 22-7 |
| | |
23 | Recommendations | 23-1 |
| | |
23.1 | Recommended Work Programs | 23-1 |
23.2 | Estimated Costs | 23-3 |
| | |
24 | References | 24-1 |
| | |
25 | Reliance on Information Provided by the Registrant | 25-1 |
| | |
25.1 | Mineral Tenure, Surface Rights, and Encumbrances | 25-1 |
25.2 | Taxation | 25-1 |
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Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
Table of Contents
25.3 | Royalties | 25-1 |
List of Tables
Table 1-1: | Grey Fox Mineral Resource Estimate, April 2, 2026 | 1-7 |
Table 1-2: | Grey Fox Mineral Resource, Inclusive of Mineral Reserves, April 2, 2026 | 1-7 |
Table 1-3: | Grey Fox Mineral Reserve Estimate, March 27, 2026 | 1-8 |
Table 1-4: | Ore Tonnes by Mining Method | 1-9 |
Table 2-1: | Details of QPs and Site Visits | 2-2 |
Table 5-1: | Summary of Grey Fox Drilling | 5-3 |
Table 5-2: | Summary of Black Fox Drilling | 5-6 |
Table 5-3: | Production History (mined) of the Glimmer Mine from 1997 to 2001* | 5-6 |
Table 5-4: | Production History of the Black Fox & Froome Mine from 2009 to December 2025 | 5-6 |
Table 5-5: | Summary of Froome Drilling | 5-8 |
Table 5-6: | Summary of Stock Drilling | 5-10 |
Table 5-7: | Stock Mine Production History, St Andrew | 5-11 |
Table 5-8: | Production History of the Stock Mine from 2025 | 5-11 |
Table 5-9: | Summary of Buffalo Ankerite Drilling | 5-12 |
Table 5-10: | Summary of Davidson-Tisdale Drilling | 5-13 |
Table 7-1: | Eastern Properties Geophysical Surveys | 7-4 |
Table 7-2: | Summary of Grey Fox and Stroud Drilling Used in Mineral Resource Estimation | 7-1 |
Table 7-3: | Summary of Froome Drilling Used in Mineral Resource Estimation | 7-4 |
Table 7-4: | Summary of Black Fox Drilling Used in Mineral Resource Estimation | 7-4 |
Table 7-5: | Summary of Stock Drilling Used in Mineral Resource Estimation | 7-4 |
Table 7-6: | Summary of the Western Properties Drilling Used in the Mineral Resource Estimate | 7-7 |
Table 8-1: | Analysis Laboratories Used in Resource Estimation | 8-3 |
Table 10-1: | Orebody Breakdown by Zone and BWi | 10-1 |
Table 10-2: | Test work Programs | 10-4 |
Table 10-3: | Head Assays for 147 Zone and CZ Master Composites | 10-6 |
Table 10-4: | Pyrite Liberation Per Size Range for Three Composites | 10-7 |
Table 10-5: | Gravity Recovery for 147 Zone and CZ | 10-7 |
Table 10-6: | Flotation Results for 147 Zone and CZ | 10-8 |
Table 10-7: | Stage Recoveries after Carbon Pre-flotation Results for 147 and CZ Samples | 10-9 |
Table 10-8: | Bottle Roll Cyanidation Results for 147 and CZ MC Samples | 10-9 |
Table 10-9: | Dynamic Solid-Liquid Separation Tests Results | 10-10 |
Table 10-10: | JKTech Results | 10-10 |
Table 10-11: | Sample Compositing Matrix | 10-12 |
Table 10-12: | Head Assays of Composites | 10-12 |
Table 10-13: | Whole-Ore Cyanidation Results | 10-13 |
Table 10-14: | Composites Definitions | 10-15 |
Table 10-15: | Composite Head Assays | 10-15 |
Table 10-16: | Composite Head Assays | 10-15 |
Table 10-17: | Initial Flotation Results | 10-16 |
Table 10-18: | Extended Cyanidation Results | 10-17 |
Table 10-19: | Geomet Units Head Assay | 10-19 |
Table 10-20: | BWi Results by Zone | 10-20 |
Table 10-21: | Geomet Units Cyanidation Results | 10-21 |
Table 10-22: | Geomet Units Flotation Results | 10-21 |
Table 10-23: | Flotation Tailings Cyanidation Results | 10-21 |
Table 10-24: | Flotation Concentrate Cyanidation Results | 10-22 |
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Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
Table of Contents
Table 10-25: | XPS Phase 4 Sample Selection | 10-23 |
Table 10-26: | XPS Phase 4 Flotation Results | 10-23 |
Table 10-27: | Grind-Cyanidation Results | 10-24 |
Table 10-28: | Grind vs Flotation Recovery Results | 10-24 |
Table 10-29: | Grind vs Flotation Concentrate Cyanidation Results | 10-25 |
Table 10-30: | ALS Composite Sample Head Assays | 10-26 |
Table 10-31: | ALS Grind-Whole Ore Cyanidation Results | 10-27 |
Table 10-32: | ALS Variability Cyanidation Results | 10-28 |
Table 10-33: | Underground Samples Head Assays | 10-28 |
Table 10-34: | Screen Metallics Gold Assay | 10-29 |
Table 10-35: | Minerals Composition of the Underground Samples | 10-30 |
Table 10-36: | Sulphide Minerals Proportions in the Underground Samples | 10-31 |
Table 10-37: | BWi Results | 10-31 |
Table 10-38: | Whole-Ore Cyanidation Results | 10-32 |
Table 10-39: | Gravity Concentration Results (2 kg tests) | 10-33 |
Table 10-40: | Gravity Concentration Results (10 kg bulk tests) | 10-33 |
Table 10-41: | Cyanidation of Gravity Tails Results | 10-34 |
Table 10-42: | Rougher Flotation of Gravity Tails Results | 10-35 |
Table 10-43: | Whole-ore Rougher Flotation | 10-36 |
Table 10-44: | Cyanidation of Rougher Flotation Tails | 10-38 |
Table 10-45: | Cyanidation of Rougher Flotation Concentrate | 10-39 |
Table 10-46: | Cyanidation of Rougher Flotation Concentrate | 10-41 |
Table 10-47: | Process Design Criteria | 10-42 |
Table 11-1: | Grey Fox Mineralized Domains | 11-5 |
Table 11-2: | Grey Fox – Metal Removed by Capping Composites | 11-5 |
Table 11-3: | Grey Fox – Density Values by Lithology | 11-6 |
Table 11-4: | Grey Fox Estimation Search Parameters | 11-7 |
Table 11-5: | Grey Fox Mineral Resource Cut-off Grade Parameters | 11-10 |
Table 11-6: | Grey Fox Mineral Resource Statement, April 2, 2026, exclusive of Reserves | 11-12 |
Table 11-7: | Grey Fox Mineral Resource Statement, April 2, 2026, inclusive of Reserves | 11-13 |
Table 11-8: | Stroud – Metal Removed by Capping Composites | 11-15 |
Table 11-9: | Stroud Mineral Resource Cut-off Grade Parameters | 11-19 |
Table 11-10: | Stroud Mineral Resource Statement, March 26, 2026 | 11-21 |
Table 11-11: | Black Fox – Metal Removed by Capping Composites | 11-24 |
Table 11-12: | Black Fox Estimation Search Parameters | 11-25 |
Table 11-13: | Black Fox Mineral Resource Cut-off Grade Parameters | 11-27 |
Table 11-14: | Black Fox Mineral Resource Statement, December 31, 2025 | 11-28 |
Table 11-15: | Froome – Metal Removed by Capping Composites | 11-31 |
Table 11-16: | Froome – Density Values by Mineralized Domain | 11-32 |
Table 11-17: | Froome Estimation Search Parameters | 11-33 |
Table 11-18: | Froome Mineral Resource Cut-off Grade Parameters | 11-35 |
Table 11-19: | Froome Mineral Resource Statement, December 31, 2025 | 11-37 |
Table 11-20: | Stock West & Main – Metal Removed by Capping Composites | 11-41 |
Table 11-21: | Stock West & Main – Density Values by Lithology | 11-42 |
Table 11-22: | Stock West and Main Mineral Resource Cut-off Grade Parameters | 11-46 |
Table 11-23: | Stock Project - West & Main Mineral Resource Statement, December 31, 2025 | 11-48 |
Table 11-24: | Stock East – Metal Removed by Capping Composites | 11-51 |
Table 11-25: | Stock Project – East Zone Density Averages for Host Lithologies | 11-52 |
Table 11-26: | Stock East Mineral Resource Cut-off Grade Parameters | 11-54 |
Table 11-27: | Stock Project – East Zone Mineral Resource Statement, December 31, 2025 | 11-55 |
Table 11-28: | Davidson-Tisdale – Metal Removed by Capping Composites | 11-60 |
Table 11-29: | Davidson-Tisdale Optimization Parameters | 11-63 |
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Table 11-30: | Davidson-Tisdale Mineral Resource Statement April 9, 2026 | 11-65 |
Table 12-1: | Mineral Reserve Estimate, March 27, 2026 | 12-2 |
Table 12-2: | Mineral Reserve Estimate by Mining Method | 12-2 |
Table 12-3: | Mineral Reserve Estimate by Zone | 12-2 |
Table 12-4: | Gold Revenue Assumptions, Modifiers, Unit Costs Used in cut-off grade Calculations | 12-4 |
Table 12-5: | Cut-off Grade Calculations | 12-4 |
Table 12-6: | Stope Dilution Methodology | 12-5 |
Table 12-7: | Mining Recovery Factors | 12-6 |
Table 13-1: | Grey Fox Stope HR | 13-8 |
Table 13-2: | Grey Fox “A” factors | 13-9 |
Table 13-3: | Crown Pillar Acceptable Risk Exposure Guidelines | 13-19 |
Table 13-4: | Ground Support Standards, Ramp and Level Development | 13-22 |
Table 13-5: | Ground Support Standards, Ore Development | 13-23 |
Table 13-6: | Predicted Groundwater Seepage into Open Pit and Underground Mine Workings | 13-24 |
Table 13-7: | Rock Densities | 13-26 |
Table 13-8: | Development Allowances | 13-26 |
Table 13-9: | Ramp Design Criteria | 13-27 |
Table 13-10: | Typical Level Development Drift Profiles and Criteria | 13-28 |
Table 13-11: | Lateral Development Quantities | 13-31 |
Table 13-12: | Vertical Development | 13-32 |
Table 13-13: | Vertical Development Quantities | 13-32 |
Table 13-14: | Primary Ground Support | 13-32 |
Table 13-15: | Intersection Ground Support | 13-33 |
Table 13-16: | Ore Tonnes by Mining Method | 13-33 |
Table 13-17: | Longhole Stope Design Criteria | 13-36 |
Table 13-18: | Cut-and-Fill Stope Design Criteria | 13-36 |
Table 13-19: | Working Days and Shift Schedule | 13-38 |
Table 13-20: | Effective Time Calculations | 13-38 |
Table 13-21: | Total On-site Labor | 13-40 |
Table 13-22: | Lateral Development Productivity | 13-41 |
Table 13-23: | Development Cycle for the Ramp (4.0 m W × 4.3 m H) | 13-41 |
Table 13-24: | Drop Raise Development Productivity | 13-42 |
Table 13-25: | Raise Bore Development Productivity | 13-42 |
Table 13-26: | Alimak Raise Development Productivity | 13-42 |
Table 13-27: | Longhole Stope Productivities | 13-43 |
Table 13-28: | Longhole Stope Average Cycle Times | 13-43 |
Table 13-29: | Summary of Annual Lateral Development Metres Profile | 13-44 |
Table 13-30: | Summary of Production Profile by Mining Method | 13-46 |
Table 13-31: | Grey Fox North Underground Mobile Equipment List | 13-48 |
Table 13-32: | Grey Fox South Underground Mobile Equipment List | 13-48 |
Table 13-33: | Total Operating Equipment by Year for Grey Fox Site | 13-50 |
Table 13-34: | Total Number of Rebuilds and Replacements by Equipment Type | 13-51 |
Table 13-35: | Whiskey Jack Full Production Ventilation Required | 13-52 |
Table 13-36: | Grey Fox North Full Production Ventilation Required | 13-53 |
Table 13-37: | Grey Fox South Full Production Ventilation Required | 13-53 |
Table 13-38: | Main Fan Ventilation Requirements | 13-57 |
Table 13-39: | Auxiliary Fan Ventilation Requirements | 13-58 |
Table 13-40: | Estimate Water Source Flows | 13-59 |
Table 13-41: | Cemented Rock Fill Backfill Factors | 13-61 |
Table 13-42: | Underground Backfill Schedule | 13-62 |
Table 13-43: | Underground Infrastructure Matrix | 13-62 |
Table 13-44: | Service Water required by Equipment Type | 13-66 |
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Table of Contents
Table 13-45: | Grey Fox Mining Load Summary (for peak year – 2038) | 13-72 |
Table 13-46: | Power Schedule by Quarter | 13-72 |
Table 13-47: | Power Schedule by Year | 13-72 |
Table 14-1: | Process Design Criteria | 14-3 |
Table 15-1: | WEA Geometric Design Criteria | 15-23 |
Table 15-2: | WEA Storage Capacity and Operational Life | 15-24 |
Table 15-3: | Tailings Slurry Design Parameters | 15-24 |
Table 15-4: | Summary of Water Quality Geochemical Source Terms and Data Sources | 15-27 |
Table 15-5: | Holding Pond Water Quality during the Project Period | 15-29 |
Table 16-1: | Selling Costs for Gold Doré | 16-1 |
Table 17-1: | Existing Environmental Approvals | 17-5 |
Table 17-2: | Anticipated Provincial Approval/Amendment Requirements | 17-6 |
Table 17-3: | Closure Approaches | 17-9 |
Table 18-1: | Capital Cost Estimate ($ millions) | 18-2 |
Table 18-2: | Mining Preproduction Capital and Sustaining Costs ($ millions) | 18-3 |
Table 18-3: | Underground Construction and Excavation during Project Period | 18-4 |
Table 18-4: | Surface Construction During the Project Period | 18-5 |
Table 18-5: | Annual Sustaining Capital Costs ($ million) | 18-1 |
Table 18-6: | Surface Crusher Costs ($ millions) | 18-1 |
Table 18-7: | Water Treatment Plant Costs | 18-2 |
Table 18-8: | Total Operating Cost Estimate | 18-3 |
Table 18-9: | Summary of Mining OPEX | 18-4 |
Table 18-10: | Operating Development Unit Costs | 18-5 |
Table 18-11: | Stoping Unit Cost by Deposit | 18-5 |
Table 18-12: | Process Plant OPEX Summary ($ millions) | 18-7 |
Table 18-13: | Personnel Costs Summary | 18-8 |
Table 18-14: | Estimated Energy Consumption Costs | 18-9 |
Table 18-15: | Reagent Consumption and Costs | 18-10 |
Table 18-16: | Miscellaneous Consumables Costs | 18-10 |
Table 18-17: | Tailings Storage Costs for Stock Mill WEA | 18-12 |
Table 19-1: | Summary of Economic Metrics for the Project | 19-1 |
Table 19-2: | Calculation of After-tax Cash Flow | 19-1 |
Table 19-3: | Life of Mine Average Metallurgical Recoveries | 19-5 |
Table 19-4: | Metal Price Assumption | 19-5 |
Table 19-5: | Capital Cost Summary (US$ millions) | 19-5 |
Table 19-6: | Life of Mine Operating Cost Summary | 19-6 |
Table 19-7: | Life of Mine Cash Costs C1 & All-In Sustaining Costs | 19-6 |
Table 19-8: | Royalties as % of NSR & Percent of total Oz per Royalty | 19-7 |
Table 19-9: | Royalties as % of NPI & Percent of total Oz | 19-7 |
Table 22-1: | Mineral Reserve Estimate, March 27, 2026 | 22-4 |
Table 23-1: | Estimated Costs for Recommended Work for the Grey Fox Project | 23-3 |
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Table of Contents
List of Figures
Figure 1-1: | Production Profile by Mining Method | 1-10 |
Figure 3-1: | Fox Complex Properties | 3-2 |
Figure 3-2: | Eastern Properties | 3-4 |
Figure 3-3: | Stock Properties | 3-5 |
Figure 3-4: | Western Properties North Parcel Blocks | 3-7 |
Figure 3-5: | Western Properties South Parcel Blocks | 3-8 |
Figure 3-6: | Eastern Properties Royalties | 3-10 |
Figure 3-7: | Stock Properties Royalties | 3-11 |
Figure 3-8: | Western Properties Royalties | 3-12 |
Figure 3-9: | Sandstorm Gold Stream Agreement | 3-14 |
Figure 3-10: | Newmont First Right of Refusal | 3-16 |
Figure 6-1: | Geological Map of the Timmins-Matheson Sector within the Abitibi Subprovince | 6-1 |
Figure 6-2: | Map of the Southern Abitibi Greenstone Belt | 6-2 |
Figure 6-3: | Grey Fox Area Schematic Geological Plan Map with section lines (A-A’ and B-B’) | 6-5 |
Figure 6-4: | Section A-A’ cut perpendicular to the principal C1 vein orientation at Grey Fox | 6-6 |
Figure 6-5: | Section B-B’ cut perpendicular to Whiskey Jack, A1, A3 faults and the Gibson-Kelore | 6-6 |
Figure 6-6: | Basic principles for LIBS scanning | 6-7 |
Figure 6-7: | Plan View Geology Map of the Stroud Deposit | 6-9 |
Figure 6-8: | Longitudinal Section (looking NE) of the Updated Stroud Resource Block Model | 6-10 |
Figure 6-9: | Project-wide Longitudinal Section of Stock | 6-11 |
Figure 6-10: | Exploration Drilling at Stock East, Schematic Cross-Section Looking to Northeast | 6-12 |
Figure 6-11: | Exploration Drilling at Stock West, Schematic Cross-Section Looking to Northeast | 6-13 |
Figure 6-12: | Stratigraphic Column for the General Black Fox – Hislop Area | 6-16 |
Figure 6-13: | Interpreted Geology for the Fox Eastern Property | 6-18 |
Figure 6-14: | Interpreted Geology of the Stock Property and the Significant Gold Mineralized Zones | 6-21 |
Figure 6-15: | Geological Plan View Map of the Timmins Area, which includes the Western Properties 6-22 | |
Figure 6-16: | Stratigraphic column for the Timmins area including McEwen’s Western Properties | 6-23 |
Figure 6-17: | Abitibi Greenstone Belt: Relationship of Gold Deposition to Major Structural Conduits | 6-24 |
Figure 6-18: | Schematic Cross-Section of Main Gold Systems Showing Depth of Emplacement | 6-26 |
Figure 6-19: | Schematic Comparison of Epithermal and Orogenic Environments | 6-29 |
Figure 7-1: | Plan View Geology Map for the Eastern Property | 7-2 |
Figure 7-2: | 2025 High-Res Drone Magnetic Survey over Grey Fox | 7-4 |
Figure 7-3: | Longitudinal Section View of Stock Property | 7-7 |
Figure 7-4: | Distribution of Drilling at the Eastern Properties | 7-3 |
Figure 7-5: | Distribution of Surface Drilling at the Stock Property | 7-6 |
Figure 7-6: | Southern Portion of the Western Properties Drill Hole Collar Location Plan | 7-8 |
Figure 7-7: | Northern Portion of the Western Properties Drill Hole Collar Location Plan | 7-9 |
Figure 10-1: | Modal Compositions of 147 Zone, CZ and Graphite Master Composites | 10-6 |
Figure 10-2: | Head Grade vs Recovery for 147 Zone | 10-18 |
Figure 10-3: | Rougher Flotation Kinetics for Whole-Ore Samples | 10-37 |
Figure 10-4: | Overall Recoveries through Cyanidation versus Flotation for Underground Samples | 10-38 |
Figure 11-1: | Plan View of the Grey Fox Project Lithology Model | 11-48 |
Figure 11-2: | Plan View of the Grey Fox Project Mineralized Zones and Domains | 11-49 |
Figure 11-3: | Section Comparing Block Grades vs Drill Hole Data, Whiskey Jack, Grey Fox Model | 11-53 |
Figure 11-4: | Section Comparing Block Grades vs Drill Hole Data, Gibson Zone N, Grey Fox Model | 11-54 |
Figure 11-5: | Plan View of the Potentially Mineable Stope Shapes at Grey Fox | 11-56 |
Figure 11-6: | Experimental Grade-Tonnage Sensitivities at Various Cut-Off Grades | 11-57 |
Figure 11-7: | Longitudinal View of the Mineralized Domains at Stroud (looking NE) | 11-60 |
Figure 11-8: | Plan View of Blocks and Informing Drill Holes at Stroud, Domains 20 &10 | 11-62 |
Figure 11-9: | Vertical Section of Estimated Blocks and Informing Drill Holes in Domain 20 at Stroud | 11-63 |
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Figure 11-10: | Long Section NE View of the Generated Stroud MSO Shapes | 11-65 |
Figure 11-11: | Experimental Sensitivities at Various Cut-Off Grades | 11-66 |
Figure 11-12: | Long Section Looking North of Black Fox Mineralized Domains | 11-68 |
Figure 11-13: | Experimental Grade Tonnage Sensitivities at Various Cut Off Grades | 11-73 |
Figure 11-15: | East-West Long Section View Comparing Block Grades with Drill Hole Data in Froome Domain 501 | 11-79 |
Figure 11-16: | Plan View at Elevation 9840 Comparing Block Grades with Drill Hole Data | 11-79 |
Figure 11-17: | Long Section Looking North of Potentially Mineable Stope Shapes at Froome | 11-81 |
Figure 11-18: | Experimental Grade Tonnage Sensitivities at Various Cut Off Grades | 11-82 |
Figure 11-20: | Isometric View of Long view of Stock West and Main Mineralized Zones and Background Envelope | 11-85 |
Figure 11-21: | Section View Comparing Block Grades in Domains 10 and 20 with Drill Hole Data | 11-89 |
Figure 11-22: | Plan View Comparing Block Grades with Drill Hole Data | 11-90 |
Figure 11-23: | Long Section View of the Potentially Mineable Stope Shapes at Stock West & Main | 11-92 |
Figure 11-24: | Experimental grade tonnage sensitivities at Various Cut Off Grades | 11-93 |
Figure 11-26: | Isometric View of Long View of Stock East Zone Showing Modelled Domains 1 & 100 (Background) | 11-96 |
Figure 11-27: | Experimental Grade Tonnage Sensitivities at Various Cut Off Grades | 11-100 |
Figure 11-28: | Isometric View of the Davidson-Tisdale North Area, External Contours | 11-103 |
Figure 11-29: | Isometric View of the Davidson-Tisdale North Area, Internal Contours | 11-104 |
Figure 11-30: | Isometric View Looking South of the S Zone Wireframe | 11-105 |
Figure 11-31: | Cross-Section Comparing B Zone Estimated Blocks and Composite Data | 11-107 |
Figure 11-32: | Plan View, Davidson-Tisdale MSO Shapes, Blocks >1.30 g/t Au | 11-109 |
Figure 11-33: | Experimental Grade Tonnage Sensitivities at Various Cut ff Grades | 11-110 |
Figure 13-1: | Grey Fox Mine Zones in Plan View with Google Maps | 13-1 |
Figure 13-2: | Whiskey Jack Zone looking South | 13-2 |
Figure 13-3: | Grey Fox North looking North | 13-3 |
Figure 13-4: | Grey Fox South Looking North | 13-4 |
Figure 13-5: | Grey Fox Length-Weighted and Cumulative RQD Distribution | 13-6 |
Figure 13-6: | Grey Fox Joint Orientations and Critical Joint | 13-7 |
Figure 13-7: | Rock stress factor “A” | 13-9 |
Figure 13-8: | Joint Orientation Factor “B” | 13-10 |
Figure 13-9: | Gravity Adjustment Factor “C” | 13-11 |
Figure 13-10: | Whiskey Jack Stability Graph | 13-12 |
Figure 13-11: | Remainder of Grey Fox Stability Graph | 13-13 |
Figure 13-12: | Wp versus depth BGS, Whiskey Jack | 13-15 |
Figure 13-13: | Wp versus depth BGS, Remainder of Grey Fox | 13-16 |
Figure 13-14: | Sill Pillar Dimensions, Resisting Stress and Normal Stress Vectors | 13-17 |
Figure 13-15: | Fs,crown at increasing Total Thickness | 13-20 |
Figure 13-16: | PF,crown at increasing Total Thickness | 13-21 |
Figure 13-17: | Typical Level Development Whiskey Jack Zone 115 Level | 13-29 |
Figure 13-18: | Typical Level Development Grey Fox North Zone Block 2 165 Level | 13-30 |
Figure 13-19: | Typical Level Development Grey Fox South Block 1 115 Level | 13-31 |
Figure 13-20: | Whiskey Jack Zone Mining Blocks Looking South | 13-34 |
Figure 13-21: | Remaining Grey Fox North Mining Blocks Looking North | 13-35 |
Figure 13-22: | Grey Fox South Mining Blocks Looking North | 13-35 |
Figure 13-23: | Typical Longitudinal Stope Sequence with Center Access (Long Section View) | 13-37 |
Figure 13-24: | Typical Longitudinal Stope Sequence with End Access (Long Section View) | 13-37 |
Figure 13-25: | Annual Lateral Development Metres Profile | 13-44 |
Figure 13-26: | Production Profile by Mining Method | 13-46 |
Figure 13-27: | Ventilation Schematic Initial Ramp Development | 13-54 |
Figure 13-28: | Whiskey Jack Initial Flowthrough Ventilation Established | 13-55 |
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Figure 13-29: | Whiskey Jack Full Production Ventilation System | 13-56 |
Figure 13-30: | Grey Fox North and Grey Fox South at Full Production Ventilation System | 13-57 |
Figure 13-31: | Backfill Placement | 13-61 |
Figure 13-32: | Underground Power Distribution Routing | 13-69 |
Figure 13-33: | Type 1 Electrical Room Layout | 13-70 |
Figure 13-34: | Type 2 Electrical Room Layout | 13-71 |
Figure 14-1: | Block Flow Diagram for the Treatment of Grey Fox Ore | 14-2 |
Figure 15-1: | Grey Fox Site Plan | 15-1 |
Figure 15-2: | Grey Fox and Existing Black Fox Site Plan | 15-3 |
Figure 15-3: | Grey Fox Site Access Road | 15-5 |
Figure 15-4: | Surface Maintenance Shop – Section View | 15-7 |
Figure 15-5: | Example of Typical Warehouse | 15-8 |
Figure 15-6: | Surface Routing of Buried Cables | 15-11 |
Figure 15-7: | Locations of Radio Repeaters at the Grey Fox Site | 15-13 |
Figure 15-8: | Grey Fox Conceptual Water Management General Arrangement | 15-15 |
Figure 15-9: | Conceptual Water Balance Schematic | 15-17 |
Figure 15-10: | Grey Fox to Stock Mill Haul Route | 15-18 |
Figure 15-11: | Stock Mill TMA and Conceptual Western Expansion Area | 15-20 |
Figure 15-12: | Water Balance Schematic | 15-25 |
Figure 15-13: | Water Treatment Plant Conceptual Design | 15-31 |
Figure 19-1: | Undiscounted After-Tax Cash Flow | 19-2 |
Figure 19-2: | Life of Mine Processing Profile (tonnes) | 19-4 |
Figure 19-3: | Life of Mine Production Profile (Payable Au) | 19-4 |
Figure 19-4: | Sensitivity Analysis | 19-8 |
Figure 20-1: | Plan View of Grey Fox and Stroud Projects in relation to Hislop Property | 20-2 |
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Grey Fox Mine Prefeasibility Study S-K 1300 Technical Report Summary
Acronyms / Abbreviations
Acronyms / Abbreviations
Acronym / Abbreviation | | Full Name |
ABA | | Acid-Base Accounting |
AEP | | annual exceedance probability |
ALS | | ALS Metallurgy |
AP | | Acid Potential |
ARD/ML | | Acid Rock Drainage / Metallic Leaching |
Au | | gold |
BGS | | below ground surface |
Bwi | | Bond Ball Mill Work Index |
Ca | | calcium |
CaO | | calcium oxide (quicklime) |
CaCO3 | | calcium carbonate |
CIL | | carbon-in-leach |
CIP | | carbon-in-pulp |
CLDZ | | Cadillac-Larder Lake Deformation Zone |
CN, CN– | | cyanide ion |
CNWAD | | Weak-Acid-Dissociable Cyanide |
CO2 | | carbon dioxide |
COOP | | Central Ontario Orthophotography Project |
Cu | | copper |
CZ | | Contact Zone |
DEM | | digital elevation model |
Dwi | | Drop-Weight Index |
EA | | Environmental Assessment |
ECA | | Environmental Compliance Approval |
EM | | electromagnetic |
ERD | | External Reference Distribution |
FeS2 | | Pyrite (Iron Disulfide) |
FW | | footwall |
FZ | | Fault Zone |
GKDZ | | Gibson-Kelore Deformation Zone |
GRG | | Gravity Recovery Grade |
HCT | | Humidity Cell Test |
HG | | High Grade |
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Grey Fox Mine Prefeasibility Study S-K 1300 Technical Report Summary
Acronyms / Abbreviations
Acronym / Abbreviation | | Full Name |
HPGR | | High Pressure Grinding Rolls |
HR | | Hydraulic Radius |
HW | | hangingwall |
IA | | Initial Assessment |
ICP | | Inductively Coupled Plasma |
JK Tech | | Julius Kruttschnitt Technology |
LG | | Low Grade |
LGC | | Low-grade, low-pyrite |
LGP | | Low-grade, high-pyrite |
LOM | | life-of-mine |
MC | | Master Composite |
MDMER | | Metal and Diamond Mining Effluent Regulations |
MECP | | Ministry of the Environment, Conservation and Parks |
MEM | | Ministry of Environment and Mines |
MIBC | | methyl isobutyl carbinol |
MMER | | Metal Mining Effluent Regulations |
Mo | | molybdenum |
MSO | | Mineable Shape Optimizer |
NaCN | | sodium cyanide |
NE | | northeast |
NHLFZ | | Nighthawk Lake Fault Zone |
NNP | | Net Neutralization Potential |
NP | | Neutralizing Potential |
NPAG | | Non-Potentially Acid Generating |
NPI | | Net Profits Interest |
NPR | | Neutralization Potential Ratio |
NPV | | Net Present Value |
NSG | | non-sulphide gangue |
NSR | | Net Smelter Return |
OPEX | | Operating Expenditure |
PAG | | Potentially Acid Generating |
PAX | | potassium amyl xanthate |
PCS | | Process Control System |
PDDZ | | Porcupine-Destor Deformation Zone |
PEA | | Preliminary Economic Assessment |
PFS | | Prefeasibility Study |
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Grey Fox Mine Prefeasibility Study S-K 1300 Technical Report Summary
Acronyms / Abbreviations
Acronym / Abbreviation | | Full Name |
PMV | | Pillowed Mafic Volcanic |
ppm | | parts per million |
PVD | | prefabricated vertical drain |
PWQO | | Provincial Water Quality Objectives |
P₈₀ | | Particle Size (80th percentile) |
PAX | | Potassium Amyl Xanthate |
PSD | | Particle Size Distribution |
ppm | | parts per million |
PTTW | | Permit to Take Water |
ROM | | Run-of-Mine |
RPEEE | | Reasonable Prospects for Eventual Economic Extraction |
RSD | | Relative Standard Deviation |
SAG | | Semi-Autogenous Grinding |
SAGB | | Southern Abitibi Greenstone Belt |
SABC | | SAG mill–Pebble Crusher–Ball mill Circuit |
SAC | | strong acid cation |
SBA | | strong base anion |
SGH | | Spatiotemporal Geochemical Hydrocarbon |
SGS | | SGS Minerals Services |
SEDS | | Siltstone/Epidote/Diopside Skarn |
SFE | | Shake Flask Extraction |
SO₂ | | sulphur dioxide |
S (or S%) | | Sulphur Content |
SMC | | Steve Morrell Comminution |
SP | | Set Point |
T₈₀ | | Transfer Size (80th Percentile) |
TDH | | Total Dynamic Head |
TOC | | Total Organic Carbon |
TW | | True-Width |
UAV | | Unmanned Aerial Vehicle |
UMW | | underground mine workings |
US$ | | United States dollar |
VTEM | | Versatile Time Domain Electromagnetic |
XPS | | XPS Minerals Services (now ALS Minerals) |
µm | | micrometers |
w/w | | weight-by-weight |
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Grey Fox Mine Prefeasibility Study S-K 1300 Technical Report Summary
Acronyms / Abbreviations
Acronym / Abbreviation | | Full Name |
WAD | | Weak Acid Dissociable |
WEA | | Western Expansion Area |
Units of Measure
Unit | | Definition |
d | | day |
g | | gram |
g/L | | gram(s) per litre |
g/t | | gram(s) per tonne |
gpm | | gallon(s) per minute |
h | | hour |
km | | kilometre |
HP | | horsepower |
kWh/t | | Kilowatt-hours per tonne |
kWh/m³ | | Kilowatt-hours per cubic metre |
kg/t | | kilogram(s) per tonne |
L | | litre |
m | | metre |
m² | | square metre(s) |
m²/t/d | | square metre(s) per tonne per day |
m³ | | cubic metre(s) |
mg/L or mg L –¹ | | milligram(s) per litre |
ppm | | parts per million |
t | | Metric tonne |
T | | Imperial Ton |
t/d | | tonne(s) per day |
t/m²/h | | tonne(s) per square metre per hour |
t/m³/h | | tonne(s) per cubic metre per hour |
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Grey Fox Mine Prefeasibility Study S-K 1300 Technical Report Summary
Glossary
Glossary
Term | | Definition |
Eastern Properties | | The land tenure forming the eastern portion of properties of the Fox Complex, which includes Grey Fox, Froome, and Black Fox. |
Fox Complex | | The entire package of properties owned by McEwen Inc. in Ontario. |
Stock Properties | | The land tenure forming the central portion of properties of the Fox Complex, located in Stock Township. |
Western Properties | | The land tenure forming the western portion of properties of the Fox Complex, known by the names Buffalo-Ankerite and Davidson-Tisdale. It should be noted that previous Technical Reports have referred to the Fuller and Paymaster properties. These were sold in October 2026 to a subsidiary of Discovery Mining Ltd (“Discovery”) and are referred to in this TRS in passing and for historical context only as they are no longer owned or operated by McEwen. |
| Project: 169525666 | xvi |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
1 Executive Summary
1 | Executive Summary |
1.1 | Introduction |
The Grey Fox Project (Grey Fox) is a gold mining project located near Matheson, Ontario, adjacent to the existing Black Fox Mine, and is being developed by McEwen Inc. (McEwen). This Technical Report Summary (TRS or Report) presents the results of a prefeasibility study (PFS) for Grey Fox.
The Project consists of two underground mines, each accessed via dedicated portals and declines. Longhole mining methods are planned for ore extraction at a nominal production rate of 1,500 tonnes per day (t/d) during the first seven years of operation, increasing to 2,700 t/d during the subsequent six years. Ore is expected to be processed at the existing Stock Mill, located approximately 30 km away.
This Technical Report Summary describes several aspects of the Grey Fox Project, including:
· | Mineral Resource estimates. |
· | Mineral Reserve estimates supported by a life-of-mine (LOM) plan. |
· | Capital and operating cost estimates. |
· | An economic analysis of Grey Fox. |
Preparation of this Technical Report Summary was completed with contributions from the following firms.
· | Stantec Consulting Ltd. |
· | McEwen Inc. |
· | DRA |
· | Arcadis |
Unless otherwise stated, all costs are reported in Q1 2026 United States dollars (US$).
Unless otherwise stated, all units of measurement are metric.
1.2 | Property Description |
Grey Fox is part of the Fox Complex, a portfolio of gold properties located in the Timmins–Matheson region of northeastern Ontario, comprising multiple past-producing, operating, and development-stage assets with access to established regional infrastructure and processing capacity. The Grey Fox deposit is made up of six principal mineralized zones: 147, 147NE, Contact, Grey Fox South, Gibson and Whiskey Jack. The Complex is organized into three principal groups—Eastern, Stock, and Western Properties—and includes the operating Froome Mine and Stock Mill, the former Black Fox and Stock mines, and several development-stage and historical deposits.
McEwen holds a majority interest in the mineral tenure across the Complex within a well-established mining jurisdiction. Certain properties are subject to royalties and a gold stream, and Indigenous agreements are in place for the Eastern and Stock Properties, with additional agreements required for the Western Properties.
| Project: 169525666 | 1-1 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
1 Executive Summary
Environmental obligations are managed under approved closure plans, and no material issues have been identified that would preclude project development.
Further details regarding property ownership, agreements, and permitting considerations are provided in Section 3 of the main report.
1.3 | Accessibility, Climate, Local Resources, Infrastructure and Physiography |
The Fox Complex is located within the established Timmins mining district of northeastern Ontario and benefits from excellent year-round accessibility via provincial highways, secondary roads, and nearby commercial air service. The project is situated close to the regional centers of Timmins, Matheson, and Kirkland Lake, where mining services, skilled labor, and supplies are readily available. It is supported by existing infrastructure including electrical power, transportation corridors, and nearby processing facilities.
The region experiences a typical northern Ontario climate with cold winters and warm summers, which permit year-round exploration and mining activities. Physiography across the project area is characterized by low to moderate relief, glacial overburden, wetlands, lakes, and boreal forest vegetation, with elevations generally ranging from approximately 250 m to 330 m above sea level.
Further details on accessibility, climate, local resources, infrastructure, and physiography for the Grey Fox Project and the surrounding area are provided in Section 4 of the main report.
1.4 | History |
Grey Fox is the primary focus of this PFS and represents a key growth and development asset within McEwen’s Fox Complex in the Timmins–Matheson mining district of Ontario, a historically significant gold-producing region. The deposit comprises several principal mineralized zones, including Gibson, Contact, Grey Fox South, and Whiskey Jack.
The project has been advanced through successive phases of exploration and development by prior operators and McEwen, including drilling, underground development, geophysical surveys, trenching, and resource definition programs. Historical work at Gibson included underground development and limited production, while more recent exploration campaigns have refined the geological model and supported Mineral Resource estimation.
Since acquiring the property in 2017, McEwen has completed systematic drilling programs to de-risk known zones, test extensions, and identify additional mineralized lenses. A key refinement in 2019 improved the understanding of mineralization orientation and supported enhanced confidence in geological interpretation and modeling.
The 2025 Mineral Resource estimate forms the basis for this PFS, and previous estimates are considered historical and not relied upon. Further details on the exploration history and development of the Grey Fox deposit are provided in Section 5 of the main report.
| Project: 169525666 | 1-2 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
1 Executive Summary
1.5 | Geological Setting, Mineralization, and Deposit |
The Grey Fox deposit is interpreted to be a multi-domain, structurally controlled gold system hosted within mafic metavolcanic rocks, metasedimentary units, and intrusive rocks known as the Gibson Syenite. The deposit is divided into two principal geological domains, or blocks, separated by the Contact Fault: the 147– Grey Fox South Block and the Gibson Block. Gold mineralization is primarily associated with steeply dipping, northeast-southwest-striking sheeted vein arrays (C-veins), with the principal mineralized zones including 147, 147NE, Grey Fox South, and Gibson. Mineralization is controlled by vein geometry, structural preparation, lithological and rheological contrasts, and host-rock chemistry, with higher-grade zones typically developed in favourable metavolcanic and metasedimentary units.
The geological model is considered appropriate for the current PFS level of study and provides a reasonable basis for Mineral Resource estimation and mine planning, with additional work expected to refine structural controls and mineralization continuity. Further details on the Grey Fox deposit and its geological interpretation are provided in Section 6.
The Grey Fox vein systems exhibit characteristics consistent with a shallow-crustal, epizonal orogenic gold environment, characterized by quartz–carbonate vein-hosted mineralization. Mineralization occurs within a network of structurally controlled vein arrays developed under brittle upper-crustal conditions.
This deposit model supports continuity of mineralized structures and provides a framework for ongoing exploration targeting within similar structural settings across the project area. Further details on deposit characteristics and geological interpretation are provided in Section 6.6 of the main report.
1.6 | Exploration |
Grey Fox represents the principal exploration focus within the Eastern Properties and a key growth component of the Fox Complex. Since acquiring the property in 2017, McEwen has advanced the Grey Fox Project through extensive drilling, geophysical surveys, geological interpretation, UAV imagery, trenching, mechanical stripping, mapping, channel sampling, and surface validation programs designed to define and expand mineralized zones and improve the geological model.
Exploration activities have improved confidence in the interpretation of mineralization and supported the current Mineral Resource estimate. The Grey Fox deposit comprises multiple zones within a broader structural and lithological corridor that remains partially tested along strike and at depth, with surface exploration constrained in part by widespread overburden.
Recent programs have enhanced the definition of structural corridors and identified additional potential beyond the currently defined resources. As a result, the Grey Fox deposit provides a strong opportunity for further resource growth within the PFS framework.
Further details on exploration activities and results for the Grey Fox deposit and surrounding area are provided in Section 7 in the main report.
| Project: 169525666 | 1-3 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
1 Executive Summary
1.7 | Drilling |
Drilling at Grey Fox has been completed over multiple campaigns by historical operators and, more recently, by McEwen, providing the geological, assay, geotechnical, hydrogeological, and metallurgical information required to support the PFS. Historical drilling from the late 1970s through the 1990s included sludge sampling, BQ- and NQ-diameter core drilling, although documentation of some early sampling procedures is limited.
Since 2018, McEwen has advanced the Grey Fox drill database through systematic surface diamond drilling, primarily using NQ core, with work completed by established drilling contractors and logged at controlled company facilities. Further details on drilling programs are provided in Section 7 in the main report.
1.8 | Sample Preparation, Analyses and Security |
Sampling, sample preparation, analytical procedures, quality assurance/quality control (QA/QC), and security protocols for Grey Fox and the Eastern Properties have been implemented in accordance with industry best practices to support Mineral Resource estimation. Current programs utilize systematic, geologically controlled sampling, supported by documented chain-of-custody procedures to maintain sample integrity.
Analytical work has been carried out primarily by ISO/IEC 17025-accredited laboratories using fire assay and, more recently, photon assay techniques, with appropriate multi-element methods applied as required. The QA/QC program, including the insertion of control samples and external verification, demonstrates acceptable accuracy, precision, and absence of material bias. Historical data incorporated into the Mineral Resource estimate has been reviewed and deemed acceptable, with no identified issues that would materially impact data reliability.
The Qualified Person (QP) considers the sampling, analytical methodologies, QA/QC procedures, and sample security measures to be adequate and appropriate, and concludes that the resulting dataset is reliable and suitable for use in Mineral Resource estimation. Further details on sampling, sample preparation and security are provided in Section 8 in the main report.
1.9 | Data Verification |
Data verification for the Grey Fox Mineral Resource has been conducted by the QP through comprehensive review and validation procedures, incorporating drilling data collected from 2014 through 2026 together with relevant historical datasets. Verification activities included database audits against original assay certificates, collar and survey validation, statistical review of QA/QC data, site inspections of core handling and logging practices, and independent umpire laboratory testing.
Historical data from prior operators were selectively validated through certificate reconciliation, confirmatory drilling, and comparison with previous technical studies, with greater reliance placed on modern datasets where documentation is more complete. Minor limitations typical of legacy datasets were identified;
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however, these have been considered in Mineral Resource classification and do not materially affect data reliability.
Overall, verification results demonstrate acceptable accuracy, precision, and consistency of the geological, assay, and survey data, and the QP considers the dataset to be reliable and suitable for use in Mineral Resource estimation. Further details on data verification procedures and limitations are provided in Section 9 in the main report.
1.10 | Mineral Processing and Metallurgical Testing |
Metallurgical testwork conducted on Grey Fox mineralization indicates that the ore is generally amenable to conventional gold recovery methods, with performance varying by domain and sulphide content. Section 10 of the main report provides detailed information on past and recent processing and testing of Fox Complex ores.
1.10.1Comminution
Comminution testing shows that the ore is relatively competent and requires high grinding energy, with Bond Ball Mill Work Index values ranging from approximately 18 kWh/t to 27 kWh/t. The majority of the orebody corresponds to the higher end of this range, and process design has been based on conservative hardness assumptions. Additional variability testing is planned to further refine the hardness distribution.
1.10.2Gravity Testing
Gravity recovery testwork conducted on open pit samples confirmed the presence of coarse free gold, with gravity recoverable gold (GRG) test values ranging between 4% and 32%. Extended gravity recoverable gold (EGRG) tests achieved mass pulls below 0.2% of new feed mass, with high gold grades recovered to a concentrate between 200 g/t and 1,200 g/t Au, confirming the presence of free coarse gold in the samples tested.
Underground samples tested in 2025 contained significantly less GRG compared to the open pit samples tested. For the underground ore, a gravity concentration step is not essential and can be omitted. Inclusion of a gravity recovery step is recommended only for treatment of open pit ores.
1.10.3Flotation
Bulk sulphide flotation has been shown to be highly effective on Grey Fox ore, particularly for pyritic and high-sulphur ore types. Testing on open pit samples yielded gold recoveries ranging from 91% to 97% into an 8% to 12% mass pull concentrate. The highest recoveries exceeding 95% were achieved at finer grind sizes (P₈₀ = 60 µm); however, similar recoveries were also achieved at coarser grind sizes (up to P₈₀ = 120 µm). The flotation concentrates produced are primarily pyrite with lower amounts of base metals that are amenable to direct cyanidation. A carbon pre-float was ineffective but did not significantly impact overall flotation performance. Underground samples yielded marginally lower recoveries, with an average gold recovery of 87.2%.
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For all samples tested to date, a gravity-flotation flowsheet outperformed a gravity-leach flowsheet by approximately 7% to 14% in terms of overall gold recovery. However, the rougher flotation concentrates did not achieve saleable concentrate grades as a standalone product and additional upgrading through cleaning stages would be required.
1.10.4Cyanidation of Flotation Products
Cyanidation of flotation concentrates resulted in variable gold extraction, dependent on pyrite content and grain size. As-floated concentrates (P₈₀ ~60 µm) yielded gold recoveries via cyanidation of approximately 77% to 82% for open pit samples. Regrinding to a P₈₀ of approximately 25 µm improved gold extraction by approximately 2% to 4%, with no additional benefit observed at finer grind sizes, indicating that a portion of the gold is not accessible through cyanidation.
Underground samples showed greater variability and generally lower performance compared to open pit samples. Cyanidation of flotation tailings consistently yielded high extractions, with open pit samples achieving recoveries exceeding 74% and final tailings grades below 0.1 g/t Au, while underground samples yielded an average extraction of 72% and an average final tailings grade of 0.19 g/t Au.
A split-leach approach, comprising separate treatment of flotation concentrates and tailings, is supported by the testwork and has the potential to match or exceed whole-ore leach recoveries while providing flexibility in balancing recovery and grinding requirements.
1.10.5Whole-Ore Cyanidation
Whole-ore leach testwork demonstrated a wide range of recoveries related to head grade and sulphur content. Higher-grade, lower sulphide mineralization achieved gold recoveries of approximately 88% to 94%, whereas lower-grade or higher sulphide material yielded reduced recoveries in the range of approximately 71% to 80%. Recent open pit testwork showed similar variability, with recoveries ranging from as low as 64% to as high as 92% and averaging approximately 80%.
Preg-robbing effects are minimal. Whole-ore cyanidation is considered viable for higher-grade, lower sulphide ores but is less suitable for high-pyrite or low-grade domains due to lower recoveries and high reagent consumption.
1.10.6Cyanide Detoxification
Cyanide destruction using the SO₂/air process is effective and reduces Weak Acid Dissociable (WAD) cyanide concentrations to below applicable regulatory criteria (Ontario Provincial Water Quality Objectives). Treated solutions generally meet water quality guidelines for cyanide and most metals, with minor molybdenum exceedances noted. The process is considered robust and scalable.
Underground samples have not yet been tested but are expected to respond similarly; additional testing is recommended to confirm this assumption.
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1.10.7Sedimentation
Settling tests show that underflow densities of approximately 65% solids (w/w) can be achieved using non-ionic flocculants. Dynamic settling and rheology testing indicate that conventional thickening and deposition strategies are applicable. The sedimentation behavior of the Whiskey Jack and Gibson Zone underground samples has not been tested. Future sedimentation testwork should include flotation concentrate samples to confirm the sizing of a concentrate thickener for the proposed flowsheet.
1.10.8Environmental
Static geochemical testing of waste rock and tailings materials suggests that most samples are non-potentially acid generating (NPAG), with the remainder considered uncertain and subject to ongoing kinetic testing. Tailings residues from cyanidation and detoxification were classified as NPAG. Decant water chemistry met applicable discharge criteria, aside from minor molybdenum exceedances. No environmental testwork was conducted on underground samples as part of the 2025 program.
1.11Mineral Resource Estimates
The Grey Fox Mineral Resource estimate, exclusive of Mineral Reserves, as reported in Section 11, has an effective date of April 2, 2026. The Mineral Resource estimate is presented in Table 1-1.
Table 1-1: Grey Fox Mineral Resource Estimate, April 2, 2026
Classification | | Tonnes (kt) | | Au Grade (g/t) | | Contained Au (koz) |
Indicated | | 9,681 | | 2.25 | | 701 |
Inferred | | 4,696 | | 2.57 | | 388 |
Notes:
· | The QP for the estimate is Mr. Carson Cybolsky, P.Geo, an employee of McEwen. |
· | Mineral Resources are reported above an economic cut-off grade of 1.35 g/t Au, assuming underground extraction methods, a metallurgical recovery of 90%, mining cost of $67.72/t, processing costs of $30.77/t, G&A costs of $16.60/t, a variable net smelter return (NSR) royalty ranging from 0.15% to 3.0%, dilution of 15%, and a gold price of $3,000/oz. |
· | Figures may not sum due to rounding. |
· | Data cut-off date for the Mineral Resource estimate is July 11, 2025 |
Inclusive of Mineral Reserves, the Grey Fox Mineral Resource estimate includes the totals summarized in Table 1-2.
Table 1-2: Grey Fox Mineral Resource, Inclusive of Mineral Reserves, April 2, 2026
Classification | | Tonnes (kt) | | Au Grade (g/t) | | Contained Au (koz) |
Indicated | | 18,819 | | 3.28 | | 1,986 |
Inferred | | 5,056 | | 2.69 | | 438 |
Notes:
· | The QP for the estimate is Mr. Carson Cybolsky, P.Geo, an employee of McEwen. |
· | Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. |
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· | Indicated resources are reported inclusive of reserves reported in Section12. |
· | Mineral Resources are reported above an economic cut-off grade of 1.35 g/t Au, assuming underground extraction methods, mining cost of $67.72/t, processing costs of $30.77/t, G&A costs of $16.60/t, metallurgical recovery of 90%, a variable NSR royalty ranging from 0.15% to 3.0%, dilution of 15%, and a gold price of $3,000/oz. |
· | Figures may not sum due to rounding. |
· | Data cut-off date for the Mineral Resource estimate is July 11, 2025 |
This Report also includes a maiden Mineral Resource estimate for the nearby Stroud deposit, with an effective date of March 26, 2026. The Stroud estimate includes 1,866 kt at 2.80 g/t Au for 168 koz Au in the Inferred category. No Indicated Mineral Resources are reported for Stroud.
Additional deposits within the Fox Complex have also been updated and are included in this report. In addition to Grey Fox and Stroud, Fox East includes Black Fox and Froome. Stock is divided into the Stock West, Stock Main, and Stock East, while Fox West includes Davidson-Tisdale. Mineral Resource statements for these deposits are presented in Section 11.
1.12Mineral Reserve Estimates
The Grey Fox Mineral Reserve estimate, prepared by Stantec and effective March 27, 2026, is based on Indicated Mineral Resources from the block model provided by McEwen. Material not classified as Measured or Indicated Mineral Resources was excluded from consideration for Mineral Reserve estimation. The Mineral Reserve estimate has been prepared using definitions and categories applicable under SEC Regulation S-K 1300.
The Mineral Reserve estimate includes longitudinal stopes, overhand cut-and-fill stoping, ore development, marginal longitudinal stopes, and marginal development, with allowances for external dilution, internal dilution, and mining recovery. Cut-off grades vary by mining method, with undiluted cut-off values of 2.40 g/t Au for longitudinal stopes, 2.00 g/t Au for marginal longitudinal stopes, and 2.70 g/t Au for cut-and-fill stopes. A minimum mining width of 3.0 m was applied for all stoping methods.
Total dilution is estimated at 46.5%, consisting of 11.6% external dilution and 34.9% internal dilution. Total mineable recovery is estimated at 91.2%.
Table 1-3 outlines the estimated Grey Fox Mineral Reserve. Further details on Mineral Reserve estimates are provided in Section 12.
Table 1-3: Grey Fox Mineral Reserve Estimate, March 27, 2026
Classification | | Ore (kt) | | Au Grade (g/t) | | Contained Au (koz) |
Proven | | 0 | | 0.00 | | 0 |
Probable | | 9,406.8 | | 3.24 | | 980.3 |
Total Reserve | | 9,405.8 | | 3.24 | | 980.3 |
Note: Some numbers may not sum due to rounding.
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1.13Mining Methods
Grey Fox will be developed as two underground operations: Grey Fox North, comprising the Whiskey Jack, Gibson, Contact, and 147NE zones, and Grey Fox South, comprising the 147 and South zones. The zones are illustrated in Figure 13-1. Ore will be mined using a combination of longitudinal retreat longhole mining, supplemented by overhand cut-and-fill methods, and hauled to the existing Stock Mill at the Stock Property.
Mining will occur in two phases. Phase 1 (Grey Fox North) begins with development to access the Whiskey Jack Zone, with operations ramping up to approximately 1,500 t/d by 2030. Phase 2 (Grey Fox South) commences in 2035, with combined production reaching approximately 2,700 t/d before ramping down through 2041.
Geomechanical assessments indicate that the proposed mining methods are appropriate for the rock mass conditions, with conventional ground support systems and mine design parameters expected to provide adequate stability. Hydrogeological modelling indicates that groundwater inflows can be managed using conventional mine dewatering systems.
Mining operations will utilize conventional trackless underground equipment supported by mine ventilation, dewatering, backfill, electrical distribution, communication systems, and other underground infrastructure typical of modern underground mining operations. Most of the mineral resource will be extracted using the longitudinal longhole mining method, as summarized in Table 1-4.
Table 1-4: Ore Tonnes by Mining Method
Mining Method | | Grey Fox North | | Grey Fox South | | Recovered Ore Tonnes |
Longitudinal Longhole | | 4,713651 | | 3,009,295 | | 7,722,946 |
Cut and Fill | | 55,165 | | 62,819 | | 117,984 |
Development | | 921,239 | | 643,660 | | 1,564,899 |
Total | | 5,690,055 | | 3,715,774 | | 9,405,829 |
The initial focus at Grey Fox will be the extraction of higher-grade material from the Whiskey Jack Zone. Mining will ramp up to 1,500 t/d within Grey Fox North, and subsequently to 2,700 t/d with the addition of Grey Fox South in 2035. See Figure 1-1 for the production schedule.
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Figure 1-1: Production Profile by Mining Method
Further details regarding mine design, production scheduling, geotechnical and hydrogeological considerations, and supporting infrastructure are provided in Section 13.
1.14Processing and Recovery Methods
Metallurgical testwork indicates that Grey Fox mineralization exhibits variable ore characteristics, with whole-ore cyanidation recoveries ranging from approximately 70% to 95%. Comminution testwork indicates relatively hard and competent ore, with available grinding power at the Stock Mill representing the primary throughput constraint. Although flotation with concentrate regrinding has the potential to improve recoveries for some domains, it was not incorporated into the proposed flowsheet due to cost and operational complexity.
The proposed processing strategy incorporates primary crushing at Grey Fox, with crushed ore transported to the Stock Mill for processing through the existing crushing, grinding, cyanidation, carbon-in-leach, and gold recovery circuits. The operation is designed for a nominal throughput of approximately 1,470 t/d and an overall gold recovery of approximately 88%.
Further details regarding metallurgical testwork, process design criteria, and the proposed process flowsheet are provided in Section 14.
1.15Infrastructure
The Grey Fox Project will consist of a centralized surface infrastructure supporting underground operations via the North and South portals. Principal infrastructure includes a primary crushing facility, ore and waste storage areas, water management systems, ventilation facilities, and supporting site infrastructure.
The Project benefits from integration with existing infrastructure at the nearby Black Fox Mine and Stock Mill, reducing capital requirements and supporting a phased development strategy. Ore will be hauled approximately 34 km to the Stock Mill using existing transportation infrastructure, and power will be supplied through a 27.6 kV grid connection along Tamarack Road.
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Water management systems have been developed to collect, manage, and transfer contact water to existing treatment facilities at Black Fox. A site-wide water balance supports the design, with underground dewatering requirements estimated at approximately 6,540 m³/d at full production.
Further details regarding site infrastructure, transportation, power supply, ore and waste management, and water management are provided in Section 15.
1.16Market Studies and Contracts
Gold is a freely traded commodity with widely established pricing, and the sale of production is considered assured. As such, a detailed market study was not undertaken.
Based on monthly closing data from April 2024 to April 2026, the approximate trailing average gold price is US$3,000 per ounce.
No sales contracts are currently in place for Grey Fox. Future doré sales are expected to follow industry terms.
Refining and transportation costs have been estimated based on comparable operations in the region, with typical refining charges, high gold payability (approximately 99.95%), and nominal shipping costs applied in the economic analysis. Further details regarding market assumptions, pricing, and sales terms are provided in Section 16.
1.17 | Environmental Studies, Permitting, and Plans, Negotiations, or Agreements with Local Individuals or Groups |
The Grey Fox Project is located near Matheson, Ontario, within the Abitibi Greenstone Belt and benefits from existing mining infrastructure, a well-established regulatory framework, and extensive environmental baseline information from current and historical operations.
Baseline studies indicate typical boreal forest conditions with surface water and groundwater systems that are well characterized and monitored. Water management planning includes transfer of contact water to the existing Black Fox treatment facilities. Although certain constituents, including arsenic, are expected to require treatment prior to discharge, established treatment methods are expected to effectively manage water quality.
The Project is subject to federal and provincial regulatory requirements. Based on the current Project design, a federal Impact Assessment is not required. Key provincial approvals include Environmental Compliance Approvals, a Permit to Take Water, and a Closure Plan Amendment.
The Project is located within areas traditionally used by Indigenous communities. Engagement with local First Nations, Métis organizations, regulators, and stakeholders has been ongoing. An Impact Benefit Agreement is in place with Apitipi Anicinapek Nation.
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Closure and reclamation planning includes flooding and sealing of underground workings, stabilization of disturbed areas, revegetation, and removal of infrastructure with the objective of achieving long-term environmental stability.
Overall, environmental studies completed to date, existing infrastructure, and permitting experience at the Black Fox operation indicate that the Project is environmentally and socially viable. Key risks related to water treatment, permitting, and stakeholder engagement are considered manageable through established mitigation measures and ongoing consultation.
Further details regarding environmental studies, permitting, closure planning, and community engagement are provided in Section 17.
1.18Capital and Operating Costs
1.18.1Capital Costs
The capital cost estimate meets the requirements for a Class 3 estimate (AACE), with an expected accuracy of ±15%, and is reported in Q1 2026 US dollars.
Total capital costs are estimated at $350.3 million, comprising $176.6 million in project period capital and $173.7 million in sustaining capital. Including pre-production and closure costs, total capital is estimated at approximately $361.9 million.
Capital costs are primarily associated with underground mine development and infrastructure, with additional costs related to surface facilities, water treatment systems, contingency, and closure.
1.18.2Operating Costs
LOM operating costs are estimated at approximately $1,397.7 million, or $148.6 per tonne processed. Operating costs are dominated by underground mining, with additional contributions from processing, tailings management, and water treatment.
Further details regarding capital and operating costs are provided in Section 18.
1.19Economic Analysis
An economic model was prepared to estimate annual project cash flows based on the engineering, cost, and revenue assumptions for the Project. The economic analysis results are based on forward-looking information that is subject to a number of known and unknown risks, uncertainties, and other factors that may cause actual results to differ materially from those presented herein.
Using a base case discount rate of 5%, the Project returns an after‑tax net present value (NPV) of $282.1 million, an after-tax internal rate of return (IRR) of 24.8%, and after-tax cumulative cash flow of $493.2 million.
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Sensitivity analysis evaluated the impact of changes in key parameters, including gold price, head grade, operating costs, and capital costs. The Project is most sensitive to variations in head grade and gold price.
Further details regarding the economic analysis are provided in Section 19.
1.20Adjacent Properties
The Grey Fox deposit is located proximal to the Porcupine-Destor fault zone in the Abitibi Greenstone Belt, an area well known for historical and current gold production. The Eastern Properties, which include Grey Fox, are surrounded by claims and leases held by exploration companies and operators, including Onyx Gold Inc., STLLR Gold Inc., Mayfair Gold Corp., and Agnico Eagle Mines Ltd.
Further details regarding adjacent properties are provided in Section 20.
1.21Interpretation and Conclusions
The QPs conclude that the Grey Fox Project is technically robust and appropriately defined at the PFS level. McEwen holds a 100% interest in the mineral tenure, with surface rights, royalties, and stakeholder agreements considered typical and sufficient to support development, with no material constraints identified.
Geologically, Grey Fox is interpreted as a structurally controlled epizonal gold system hosted in metavolcanic, metasedimentary, and intrusive rocks. Mineralization is primarily controlled by vein arrays, major fault structures, and lithological contrasts, with multiple domains requiring consideration in modeling and mine planning. Drilling density is generally sufficient, with additional work recommended to improve confidence and support resource conversion.
Metallurgical testwork indicates relatively hard ore with variable recoveries (71% to 94%), and modest gravity recovery potential, highlighting the importance of comminution design and geometallurgical domaining. Mineral Resources are considered reliable and support the defined Mineral Reserve of 9.4 Mt at 3.24 g/t Au (approximately 980 koz), based on a gold price of $2,200/oz.
Mining methods, infrastructure, and water management strategies are conventional and supported by operating experience in the region, with optimization opportunities identified in areas such as tailings management and water treatment.
Economically, the Project demonstrates positive results, including an after‑tax NPV (5%) of $282.1 million and IRR of 24.8%, with sensitivity primarily to gold price and head grade. Overall, the Project is considered viable at the PFS level, with further work focused on reducing geological and metallurgical uncertainties and optimizing design assumptions.
Further details regarding interpretation and conclusions are provided in Section 22.
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1.22Recommendations
The Grey Fox Project is recommended to advance to the next stage of development, supported by targeted technical programs to further de-risk and optimize the Project.
Key recommended programs include:
| ● | Early Works: Surface geotechnical investigations, confirmation of overburden conditions, and refinement of portal and ventilation raise designs. |
| ● | Exploration: Continued diamond drilling to expand and upgrade resources, particularly in the Gibson, Whiskey Jack (at depth), Grey Fox South, and 147 zones, supported by geochemical and structural analysis. |
| ● | Mining: Increased geotechnical characterization, optimization of stope design and sequencing, and evaluation of alternative development strategies and automation. |
| ● | Metallurgy: Additional testwork to optimize recovery and confirm processing assumptions. |
| ● | Tailings: Assessment of alternative tailings storage options aligned with GISTM best practices, including potential use of the Black Fox open pit. |
| ● | Infrastructure: Site investigations and confirmation of integration with existing Black Fox infrastructure. |
| ● | Hydrogeology: Updating of the hydrogeological model to reflect an underground-only mining scenario and validate groundwater inflow assumptions. |
The estimated cost of these programs is approximately $13.5 million.
Further details regarding recommendations are provided in Section 23.
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Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
2 Introduction
2 | Introduction |
2.1 | Terms of Reference |
At the request of McEwen, this Technical Report Summary (TRS) was prepared to support the development of an underground mining operation at the Grey Fox property near Matheson, Ontario. McEwen is headquartered in Toronto, Ontario, is legally domiciled and incorporated in the State of Colorado, and trades on the Toronto and New York Stock Exchanges under the symbol MUX. McEwen holds a 100% interest in the mineral claims and mining leases comprising Grey Fox.
The purpose of this Report is to summarize the findings of the PFS completed for Grey Fox as of the effective date given in Section 2.3.
Users of this Report are encouraged to confirm that this is the most recent TRS for Grey Fox, as it may be superseded by subsequent technical disclosures.
The quality of information contained in this Report is considered consistent with the level of effort associated with the services provided and is based on the following:
· | Data supplied by third-party sources. |
· | Information available at the time of preparation. |
·The qualifications, assumptions, and limitations presented herein.
This TRS includes the following key activities:
· | Review and acceptance of the current Mineral Resource model for Grey Fox. |
· | Preparation of an underground mine design and production schedule using previous hydrogeological modeling and geotechnical information prepared by Stantec. |
· | Preparation of a Mineral Reserve estimate using appropriate modifying factors. |
· | Development of a metallurgical flowsheet for processing Grey Fox material at the existing Stock Mill. |
· | Preparation of specifications for supporting project infrastructure, including access, power supply, water treatment, ventilation, buildings, and tailings storage facilities. |
· | Summary of the environmental baseline work and permitting requirements. |
· | Development of capital and operating cost estimates. |
· | Preparation of an economic model, including discounted cash flow and sensitivity analyses. |
· | Development of recommendations for further work required for the continued development of the Project. |
The presentation of this information requires Qualified Persons (QPs) to derive subtotals, totals and weighted averages that may inherently involve rounding, and consequently, introduce a margin of error. These are not considered material.
This report provides Mineral Resource and Mineral Reserve estimates for Grey Fox. Inferred Mineral Resources are considered too speculative geologically to be included in Mineral Reserves. The Mineral Reserve estimate presented herein represents the first public disclosure of Mineral Reserves for the Project.
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Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
2 Introduction
2.2 | Site Visits and Scope of Personal Inspection |
By virtue of their education, experience, and professional qualifications, the authors of this Technical Report Summary are QPs in their respective disciplines, including resource estimation, mining, geology, metallurgy, engineering, cost estimation, and mineral economics.
Table 2-1 lists the individual QPs responsible for preparation of this Report, their titles, areas of responsibility, and the dates of their site visits.
Table 2-1: Details of QPs and Site Visits
Qualified Person | | Title | | Report Area of Responsibility | | Site Visit |
| | | | | | |
Mark Hatton, P.Eng. | | Senior Mining Engineer | | Sections 1.1, 1.12, 1.13, 1.15, | | Oct 7, 2025 |
Stantec | | | | 1.16, 1.18, 1.19, 1.21, 1.22, 2, | | |
| | | | 12, 13, 15.1 to 15.7, 16, 18.1, | | |
| | | | 18.2, 18.2.1, 18.2.4 to 18.3.1, | | |
| | | | 19, 21, 22.7 to 22.9, 22.12 to | | |
| | | | 22.15, 23.1.1, 23.1.3, 23.1.6, | | |
| | | | 23.2, 24, 25 | | |
| | | | | | |
Carson Cybolsky, P.Geo | | Senior Resource Geologist | | Sections 1.7 to 1.9, 1.11, 5.4.1, | | Actively Works |
McEwen | | | | 8, 9.2, 11.1 to 11.8, 22.6 | | On-Site |
| | | | | | |
Sean Farrell, P.Geo. | | Exploration Manager | | Sections 1.2 to 1.6, 1.20, 3, 4, 6, | | Actively Works |
McEwen | | | | 7, 20, 22.1 to 22.4, 23.1.2 | | On-Site |
| | | | | | |
Luke Willis, P. Geo. | | Director of Resource Modeling | | Sections 11.9, 11.10 | | Jan 17, 2025 |
McEwen | | | | | | |
| | | | | | |
Gerd Wiatzka, P. Eng. | | National Expert, VP, Director of | | Sections 9.3 to 9.5, 15.10 to | | Oct 7, 2025 |
Arcadis | | Mining | | 15.12, 18.2.3, 18.3.3, 18.3.4, | | |
| | | | 22.10, 22.11, 23.1.5 | | |
Niel Morrison, P.Eng. | | Principal Process Engineer | | Sections 1.10, 1.14, 9.6, 10, 14, | | Feb 26, 2026 |
DRA | | | | 15.8, 18.2.2, 18.3.2, 22.5, | | |
| | | | 23.1,.4 | | |
| | | | | | |
Sheldon Smith, MES P.Geo. | | Senior Hydrologist | | Sections 1.17, 15.9, 17, 23.1.7 | | N/A |
Stantec | | | | | | |
Sheldon Smith did not conduct a separate site visit. The QP relied upon verifications performed by the Lead Mining QP during their inspection on Oct 7, 2026, which was deemed sufficient for the economic evaluation. A physical visit would yield no additional verifiable technical data beyond the information provided in the hydrological model and the closure plan.
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Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
2 Introduction
2.3 | Effective Dates |
The effective date of the Grey Fox Mineral Resource estimate is April 2, 2026.
The effective date of the Mineral Reserve estimate is March 27, 2026.
The effective date of this Technical Report Summary is November 9 2026.
2.4 | Information Sources and References |
Key sources of information for this report include:
· | Referenced documents listed in Section 24. |
· | Information provided by the McEwen management team, as described in Section 18 and 17. |
2.5 | Units of Measure |
All currency units and references to “dollars” or “$” are in United States dollars unless otherwise noted.
The metric system is used throughout. References to “t” or “tonnes” refer to dry metric tonnes unless otherwise noted.
2.6 | Previous Technical Reports |
· | “Technical Report for the Black Fox Complex, Canada” April 2018 by SRK for McEwen Mining (under NI 43-101). |
· | “Technical Report Summary on the Initial Assessment of the Fox Complex, Ontario, Canada.” December 2021 by Wood for McEwen Mining. |
· | “Technical Report Summary on the Initial Assessment of the Fox Complex, Ontario, Canada.” February 2025 by McEwen Mining. |
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Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
3 Property Description
3 | Property Description |
The Fox Complex comprises three groups of properties, including past-producing and currently operating mines, as well as a processing facility, located within and around the City of Timmins, in northeastern Ontario, Canada (Figure 3-1).
The Eastern Properties include the currently operating Froome Mine (Froome and Froome West), the Grey Fox property, the Stroud property, Black Fox North, and the formerly operating Black Fox Mine. These properties are located in Beatty and Hislop Townships, approximately 60 km east of Timmins.
The approximate geographic center of the Black Fox Mine is 48° 32’ 2” N and 80° 20’ 2” W (UTM coordinates: 549170 E and 5375871 N, NAD83, Zone 17). Black Fox North is located approximately 4 km north of the Black Fox Mine. The Grey Fox property is located approximately 3 km southeast of Black Fox, and the Stroud property is contiguous with the southwestern portion of Grey Fox.
The approximate geographic center of the Grey Fox property is 48°30’20.0” N and 80°18’20.0” W (UTM coordinates: 551100 E and 5372750 N, NAD83, Zone 17). Surface elevations in the area range from approximately 275 m to 325 m above sea level.
The Stock Properties include the historical Stock Mine, the Stock West and Stock East deposits, and the currently operating Stock Mill. These are centrally located within Stock Township, north of Highway 101, approximately 20 km west of Matheson and 43 km east of Timmins.
In 2024 McEwen started infrastructure-related operations at the historical underground Stock Mine. The approximate geographic center of Stock is 48° 33’ 0” N and 80° 45’ 1” W (UTM coordinates: 518421 E and 5377476 N, NAD83, Zone 17).
The Western Properties include the Buffalo Ankerite and Davidson-Tisdale deposits (and previously included the Fuller and Paymaster properties which are no longer owned by McEwen), located in Tisdale and Deloro Townships within the municipal boundaries of Timmins. These deposits are past producers and form part of the historic Porcupine Gold Camp, which has produced more than 70 Moz of gold over the past 110 years.
The approximate geographic centers are as follows:
· | Buffalo Ankerite: 48° 26’ 31” N and 81° 16’ 14” W (UTM: 479994 E and 5365448 N). |
· | Davidson-Tisdale: 48° 30’ 46” N and 81° 13’ 40” W (UTM: 483186 E and 5373326 N). |
(All coordinates are in NAD83, Zone 17.)
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Figure 3-1: Fox Complex Properties
3.1 | Mineral Tenure and Surface Rights |
The properties of the Fox Complex consist of several blocks of land totaling 135 parcels, representing either patented mining claims, mining leases, and overlapping surface rights, covering approximately 7,234 ha of mining land and 3,461 ha of surface land.
All surface rights and mining rights parcels are located in the Tisdale, Deloro, Stock, Bond, Beatty, and Hislop townships, with boundaries defined by the Cochrane (06) Land Registry Office. The parcels are one of the following: a freehold mining land (mining patent), an unpatented mining claim, a mining lease, a freehold surface land, or a surface lease.
In the figures that follow, parcels with surface holdings without mining rights are shown in green; parcels with mining rights without surface rights are shown in gray, and parcels with both surface and mining rights are shown in orange.
All required fees and duties have been paid, and the claims are in good standing.
The Property Identification Number (PIN) is a numeric identifier issued by the Land Registry Office that references registered transactions associated with the land.
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3.1.1 | Eastern Properties |
McEwen holds a 100% ownership interest in the Eastern Properties, located in Hislop and Beatty townships, covering Grey Fox, Stroud, Froome, Black Fox, and Black Fox North deposits (Figure3-2).
The Eastern Properties comprise 52 parcels with surface and/or mining rights, including 10 mining leases and 3 leased patents, covering approximately 2,184 ha (5,396 ac). The Black Fox North property consists of 50 unpatented claims totaling approximately 650 ha (1,606 ac).
3.1.1.1Grey Fox
The entire mineralized zone for the Grey Fox Project, including Gibson, is situated within the boundaries of the following PINs: 65380-0489, 65380-0556, 65380-0636, 65380-0490, 65380-0491 and 65380-0498. The property is located approximately 3 km southeast of the Black Fox Mine.
3.1.1.2Stroud
The Stroud property is located south of, and contiguous with the Grey Fox property and lies within the boundaries of the following PINs: 65380-0422, 65380-0443, 65380-0444, 65380-0445, 65380-0465 and 65380-0466. These parcels are patented mining claims for which McEwen owns both surface and mining rights, with the exception of surface rights for PINs 65380-0441 and 65380-0442.
3.1.1.3Froome Mine (Main Zone & West Zone)
The Froome Main Zone is situated within the boundaries of the following PINs: 65366-0143, 65380-0552 and 65380-0553. The Main Zone is situated approximately 700 m west of the Black Fox Mine open pit. The Froome West Zone is located within PIN 65366-0143, approximately 200 m west of the Main Zone.
3.1.1.4Black Fox Mine
The Black Fox Mine open pit and underground mine are located within the boundaries of PIN 65380-0556, with the associated mine complex spanning PINs 65380-0676, 65380-0556 and 65380-0670.
3.1.1.5Black Fox North
The Black Fox North property consists of 50 unpatented mining claims, totaling approximately 650 ha (1,606 acres), located approximately 4 km north of the Black Fox Mine. McEwen does not hold surface rights over this property (Figure3-2).
3.1.2 | Stock Property |
McEwen holds a 100% ownership interest in the Stock Property, which comprises 31 parcels, including 14 patented parcels with surface and/or mining rights and 17 mining leases, covering approximately 1,633 ha in Stock Township (Figure 3-3).
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The Stock Mill and related facilities are situated within the boundaries of the following PINs: 65363-0060, 65363-0061,65363-0085, 65363-0086, 65363-0087, 65363-0088, 65363-0232 and 65363-0241.
The entire Stock West mineralized zone is situated within the following PINs: 65363-0061, 65363-0237, and 65363-0240, approximately 1 km southwest of the Stock Mill.

Figure 3-2: Eastern Properties
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Figure 3-3: Stock Properties
3.1.3 | Western Properties |
The Western Properties are located in several parcel blocks, including the Davidson-Tisdale property in the northern part of Tisdale Township and a second block of contiguous parcels comprising the Buffalo Ankerite property to the south in Tisdale and Deloro townships. Surface and mining rights for the northern parcel blocks are shown in Figure 3-4, and those for the southern parcel blocks are shown in Figure 3-5.
3.1.3.1 | Buffalo Ankerite |
McEwen holds a 100% interest in the Buffalo Ankerite property, which consists of 17 parcels with surface and/or mining rights, covering approximately 654 ha in Deloro Township. The property boundaries are
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based on field surveys, historical records, and parcel mapping from the Ministry of Mines’ Mining Lands Administration System (MLAS).
The mineralized zone for the Buffalo Ankerite deposit is located within the following PINs: 65442-0714, 65442-0717, 65442-0718, and 65442-0860.
3.1.3.2 | Davidson-Tisdale |
McEwen holds a 100% interest in the Davidson-Tisdale property, which consists of 14 parcels with surface and/or mining rights, covering approximately 448 ha in Tisdale Township.
The mineralized zone is situated within the boundaries of the following PINs: 65399-0129, 65399-0130, and 65399-0133.
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Figure 3-4: Western Properties North Parcel Blocks
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Figure 3-5: Western Properties South Parcel Blocks
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3.2 | Royalties and Encumbrances |
3.2.1 | Royalties |
The Eastern Properties are subject to royalties shown in Figure 3-6.
Portions of the Grey Fox Project are subject to the following royalties:
· | Schumacher royalty (3% net smelter return [NSR]) |
· | Triple Flag Royalty (formerly Newmont royalty) (2.5% NSR) |
· | Parsons-Ginn royalty (5% net profits interest [NPI] or sliding-scale NSR) |
In addition, a portion of the Grey Fox Project is subject to the Gray royalty (0.15% NSR).
The Froome Mine is subject to two royalties: a 3% NSR on the Steinman parcel and a 1.5% NSR on the Durham parcel. The Durham royalty is not applicable to the current mine plan.
The Black Fox Mine is not subject to royalties; however, both the Black Fox and Froome mines are subject to a gold streaming agreement originally with Sandstorm Resources Ltd. (Sandstorm), now held by Royal Gold Inc. (see Section 3.3.1)
Portions of the Stock Properties are subject to royalties as shown in Figure 3-7. The historical Stock Mine is subject to a 1% NSR payable to Franco-Nevada. The Stock West and Stock East deposits are not subject to these royalties.
The Western Properties are subject to royalties as shown in Figure 3-8. The Davidson-Tisdale property is not subject to royalties in the area of the current Mineral Resources.
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Figure 3-6: Eastern Properties Royalties
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Figure 3-7: Stock Properties Royalties
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Figure 3-8: Western Properties Royalties
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3.2.2 | Stakeholders and Interested Parties |
Stakeholders include the First Nations associated with the Abitibi Indian Reserve 70, which is jointly used by the Abitibiwinn (Québec) and Apitipi Anicinapek (Ontario) First Nations, as well as local private landowners within Hislop and Beatty townships. The Abitibi Indian Reserve 70 is located approximately 25 km east of the Black Fox Mine site.
McEwen has undertaken ongoing consultation with Indigenous communities, the public, and government regulators regarding operations, environmental commitments, and planned activities.
3.3 | Agreements |
3.3.1 | Sandstorm Streaming Agreement |
On November 9, 2010, Brigus Gold entered into a gold streaming agreement with Sandstorm, under which Sandstorm agreed to purchase 12% of gold production from the Black Fox Mine beginning in January 2011 and 10% of future production from the Black Fox Extension, at a fixed price of $500/oz. Sandstorm made an upfront payment of $56.3 million in connection with this agreement.
On November 5, 2012, Brigus Gold exercised an option to repurchase a portion of the stream for $24.4 million, reducing Sandstorm’s interest to 8% of production from the Black Fox Mine and 6.3% from the Black Fox Extension (Figure 3-9).
On October 20, 2025, Sandstorm transferred its interest in the streaming agreement to Royal Gold Inc.
Currently, McEwen sells 8% of gold production from the Froome Mine to Royal Gold Inc. at a base price of $624.86/oz (2026), subject to annual adjustment based on the consumer price index, capped at 2%. Any future production from remaining Black Fox areas would also be subject to this agreement.
The streaming agreement applies to gold produced within the defined agreement boundaries, including Froome and any future mining at Black Fox.
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Figure 3-9: Sandstorm Gold Stream Agreement
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3.3.2 | Indigenous Communities |
McEwen has entered into agreements with First Nations that assert treaty and Aboriginal rights within the areas of the Eastern and Stock properties. These agreements provide a framework for collaboration in the development and operation of the Grey Fox Project and include provisions for financial participation, employment and skills training opportunities, business development, and consultation and dispute resolution.
In addition, McEwen engages with Indigenous communities in connection with permitting applications and ongoing project activities.
An Impact Benefit Agreement has been in place with the Apitipi Anicinapek Nation for the Eastern properties since 2011 and updated in 2026. The Métis Nation of Ontario has also been consulted with respect to the Eastern Properties.
McEwen does not currently have agreements in place with Indigenous communities for the Western Properties. Agreements will be required for those projects to move forward. Nearby operations have agreements in place with Flying Post First Nation, Matachewan First Nation, and Mattagami First Nation through the Wabun Tribal Council, as well as Apitipi Anicinapek Nation.
3.3.3 | Newmont Agreement |
The Newmont agreement (now held by Triple Flag Precious Metals Corp.) was originally executed with Apollo Gold in 2009. Under the terms of the agreement, if McEwen intends to dispose of any interest in property located near the Black Fox Mine (excluding corporate transactions), McEwen must notify the counterparty in writing, which then has the opportunity to consider acquiring all or part of McEwen’s interest in the named property.
On February 4, 2026, a one-time payment of C$1.0 million was made to Maverix Metals Inc. (a subsidiary of Triple Flag Precious Metals Corp.) to satisfy a provision of the agreement related to total gold resources (M+I+I) meeting or exceeding 500,000 oz on specified claims listed in the original agreement with Newmont.
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Figure 3-10: Newmont First Right of Refusal
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3.4 | Environmental Liabilities |
Environmental liabilities related to historical and current mining activities at the Fox Complex properties are addressed through approved closure plans. These plans have been prepared in accordance with regulatory requirements and approved by the Ministry of Mines and the Ministry of Environment, Conservation and Parks.
3.5 | Significant Risk Factors |
The Fraser Institute Annual Survey of Mining Companies (Mejía and Aliakbari, 2024) provides an independent assessment of the overall political risk facing an exploration or mining project across various global jurisdictions. Overall, Ontario ranked 10 out of 86 jurisdictions in the survey on the investment attractiveness index which combines the policy perception index in which Ontario ranked 13th, with results from the best practices mineral potential index where it ranked 14th.
The QP has identified the following risk factors associated with operating in Ontario:
· | Mineral title risk: Uncertainties may exist with respect to mineral tenure, including issues related to boundary definition, assessment work, and overlapping claims. |
· | Environmental regulation: The introduction of stricter standards and enforcement, increased fines and penalties for noncompliance, more stringent environmental assessments of proposed projects, and a heightened degree of responsibility could have an adverse effect on project development. Unknown environmental conditions arising from historical or natural factors may also present risk. |
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4 Accessibility, Climate, Local Resources, Infrastructure, and Physiography
4 | Accessibility, Climate, Local Resources, Infrastructure, and Physiography |
4.1 | Accessibility |
The Grey Fox Project area is accessible from Toronto via Highways 400 and 69 to Sudbury, Highway 144 to Timmins, Highway 11 from Barrie to Matheson, and Highway 101 westward to Timmins. The City of Timmins is also serviced by regularly scheduled commercial flights from Toronto and other regional centers.
The Grey Fox property is accessible from Highway 101 via Tamarack Road (Hislop 2 Road), located approximately 10 km east of Matheson. The Black River-Matheson Township, which includes the communities of Holtyre, Matheson, Ramore, Shillington, Val Gagné, and Wavell, has a population of approximately 2,500. Access within the property is achieved by various drill roads and all-terrain vehicle trails.
The Eastern Properties are located approximately 10 km east of Matheson, 60 km east of Timmins (population approximately 45,000), and 55 km north-northwest of Kirkland Lake (population approximately 8,000). Highway 101 provides direct access through the Black Fox property, with site infrastructure located south of the highway.
All claims pertaining to the Western Properties are located under the municipality of the City of Timmins and are accessible by either provincial or municipal roads. The Buffalo Ankerite property is near, or intersected by, secondary highways. The Davidson-Tisdale property is accessible by an all-weather gravel road north of Crawford Street in South Porcupine.
The Stock Property is located in Stock Township on the north side of Highway 101, approximately 20 km west of the community of Matheson and 43 km east of the City of Timmins. The area encompassing the mine property is not noted as a major tourist attraction or its outdoor recreational esteem. However, there are permanent residences, cottages, and tourist cabins located at Reid Lake (west and upstream of the property) and at Moose Lake (south and downstream of the mine property). The Stock Mine site is easily accessible via an access road from Provincial Highway 101 located approximately 1.5 km to the south. Highway 101 (along with numerous all-weather secondary, concession, and lot roads) provides excellent access to all of the Stock claim groups.
See Figure 3-1 for locations of the properties making up the Fox Complex.
4.2 | Local Resources and Infrastructure |
Supplies and services are available in Kirkland Lake, Matheson, Sudbury or Timmins, and materials can be delivered with a 12-hour turnaround time. Forestry and mining are the primary industries in the region, and the properties are located within well-established mining camps. Therefore, mining and exploration personnel as well as equipment can be locally sourced.
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A 500 kV power line and transformer station are within 2 km of the Buffalo-Ankerite property. Numerous operational gold processing facilities (as well as facilities on care and maintenance) are located in the Timmins area. The closest is the Dome Mill Complex owned and operated by Discovery. This complex has a rated capacity between 12,000 t/d and 14,000 t/d dependent on rock hardness.
Electrical power is available at Stock and Froome and readily available at the Grey Fox Project site via power lines along Tamarack Road.
4.3 | Climate |
The minimum mean annual temperatures in the Timmins region range from -22°C in January to +11°C in July. The maximum mean annual temperatures in the Timmins region range from -10°C in January to +24°C in July. The mean annual rainfall for the region is 543 mm. The mean annual snowfall over the winter is 308 cm (https://climate.weather.gc.ca/).
Rapid melting of accumulated snowfall can produce local flooding on the property for short periods during the spring months. Average monthly wind speeds for the region are 11 km/h to 15 km/h (Dyck, 2007). It is possible to conduct mining and exploration activities year-round.
Operations on all the properties can continue year-round.
4.4 | Physiography |
4.4.1 | Eastern Properties |
The Eastern Properties are predominantly agricultural land with a mature willow shrub, poplar, black spruce, and white birch forest along the southern and eastern edges of the property. The region is characterized by outwash deposits from continental glaciation, including raised beaches, flat clay pans and eskers. The low to moderate topography is marked by rock knobs and ridges (Dyck, 2007). The elevation around the Eastern Properties ranges from 295 m to 330 m above sea level. There is limited bedrock outcrop exposure for the Eastern Properties.
Surface waters around the eastern property include lakes, rivers, and their associated habitats. Lakes include Froome Lake located 0.25 km west of the Black Fox mine; Leach Lake located 1.4 km northwest of the mine; and Lawler Lake located 1.7 km to the south. Two other lakes, Salve Lake and Nickel Lake, are respectively located 5.2 km and 5.9 km north of the mine and form the headwaters of Salve Creek.
The Eastern Properties are located within the Salve Creek and Pike River watersheds, which are both tributaries of the Black River. Black River flows north into the Abitibi River, which in turn flows into Moose River. Moose River ultimately flows into James Bay (Dyck, 2007).
4.4.2 | Stock Property |
The Stock Property consists of an active mill and tailings facility. The historical Stock Mine is in redevelopment with anticipated production to commence late 2026.
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The site is contained in an area of stratified silts and clays and includes wetland depressions. The topography in the vicinity of the property is controlled by a level lacustrine plain of sand and clay bounded by esker/outwash units to the east and west. The ridges are considered to be bedrock-controlled, although available information indicates that overburden thickness over the bedrock is significant.
Local topographic variations range from 267 m to 276 m above sea level. The gentle undulating terrain is characterized by dry-to-moist clay surfaces with shallow wet organics occurring in the depressions. Local areas of moderate relief are generally well drained. In contrast, topographical lows are frequently occupied by organic wetland deposits and are poorly drained. There are no known bedrock outcrop exposures at the Stock Property.
4.4.3 | Western Properties |
The Western Properties are historical mining sites with residential areas adjacent to them, except at Davidson-Tisdale. The area in the vicinity of the properties is typical of glacial regions with low to moderate topographic relief and numerous rivers and lakes. Elevations range from approximately 250 m to 300 m above sea level. Drainages are characterized by creeks and rivers which comprise part of the Arctic watershed. Bedrock outcrop exposure is limited on the properties.
The Timmins area supports boreal forest tree species and an active timber, pulp, and paper industry. Local tree species include the American Mountain Ash, Balsam Fir, Black Spruce, Eastern White Cedar, Eastern White Pine, Jack Pine, Pin Cherry, Red, Tamarack, Trembling Aspen, White Birch, White Spruce, and Speckled Alder.
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5 | History |
Exploration and mining activities have occurred in the Timmins and Matheson areas since the early 1900s with numerous operators, varying ownership structures, partnerships, agreements, and joint ventures with varying degrees of success. The properties that now make up the present-day Fox Complex are the result of an amalgamation of several of these ownership histories culminating in the purchase of both the Lexam VG and Primero Gold Corp. properties and assets in 2017 through separate transactions.
The Fox Complex comprises a group of gold properties in Ontario currently owned by McEwen, including the Eastern Properties, Stock Property, and Western Properties. The Eastern Properties include the Grey Fox, Froome, and Black Fox properties; the Stock Property forms the central portion of the Fox Complex located in Stock Township; and the Western Properties currently comprise the Buffalo Ankerite and Davidson-Tisdale properties; until the recent October 2026 sale to Discovery, the Fuller and Paymaster properties were also part of the Western Properties. See Figure 3-1 for the locations of the McEwen-owned properties.
This section focuses on the Grey Fox Project, which forms the basis of this TRS, followed by relevant and supporting historical context from adjacent properties within the Fox Complex.
5.1 | Grey Fox Project |
The Grey Fox Project is located within the Eastern Properties of the Fox Complex and represents the primary focus of this Technical Report Summary. The project comprises several zones of mineralization, including the Gibson, Contact, Grey Fox South and Whiskey Jack zones, developed through successive exploration programs.
The Grey Fox property was first staked by Frederick Schumacher in the early 1900s. In 1936, the area was mapped by the Ontario Department of Mines. Eventually the claims were patented and worked as farmland until 1992. From 1937 to 1989, there was no reported exploration activity. In 1989, Goldpost Resources drilled an unknown number of holes in the Contact breccia zone, with unspecified results (Atherton, 1989).
In the area of the Gibson deposit, originally called Hislop West, two shafts were sunk between 1933 and 1939. Both were mined to 122 m, with underground and surface diamond drilling, drifting, and crosscutting. In 1946, S.J. Bird (later Martin-Bird) diamond drilled 11 holes totaling 2,972 m. During the period between 1979 and 1980, A.P. Ginn and G.E. Parsons (Parsons) completed geological and magnetic surveys, and diamond drilling. Additional diamond drilling and a VLF-EM survey took place in 1981 by Parsons and Armco Minerals Exploration Ltd. (Armco) in the north half of lot 4, concession 4, which were reported to have intersected high-grade gold tenors (Atherton, 1981).
In 1983, Geddes Resources Ltd. (Geddes Resources) and Armco completed geophysical surveys, trenching, and drilling. In 1986, subsequent to a 2,133 m surface diamond drilling program, Goldpost Resources Inc. (Goldpost Resources) initiated an exploration decline ramp to explore anomalous gold tenors associated with the north-northeast striking Gibson Fault. In 1987, Goldpost Resources mined a 61 m crosscut; diamond drilled 56 holes totaling 7,798 m from underground; and extended the decline ramp an additional 579 m to the 122 m level. In the following year, Goldpost Resources completed a magnetic
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survey, extended the decline ramp by 610 m, drifted 168 m, and diamond drilled more than 7,620 m from underground.
Goldpost Resources reported drill defined material at Gibson, above the 122 m level in 1989.
Mining Corporation of Canada Ltd. (Mining Corp) purchased Gibson from Goldpost Resources and began mining in 1989 (Fenwick et al., 1990; Atherton, 1989). According to Hemlo maps for the Pike River project, about 8,000 t were mined at a grade of 27.4 g/t Au (Ontario Ministry of Mines, n.d.).
According to Buss (2010), Noranda acquired the property in the early 1990s and developed a north-south grid along the Contact Zone in 1993 (Garber, 1997) and conducted a magnetometer and induced polarization resistivity survey on the property in 1994. This was followed up with three exploration holes spaced 200 m apart along the north end of the Contact Zone, for a total of 919 m. Whole rock geochemistry was also performed on one of the drill holes (Garber, 1997).
Noranda optioned the property in 1995 to Hemlo (Buss, 2010). Hemlo and Battle Mountain Gold Company (Battle Mountain) developed an east-west grid over the property and drilled holes on the south end of the zone. Battle Mountain also calculated a resource estimate on the Contact Zone based on results from the previous year’s drilling program.
In July 1996, Hemlo merged with Battle Mountain And (in conjunction with Cameco Gold) drilled holes on the central portion of the Contact Zone at a 200 m spacing and submitted samples for mineralogical examination (Garber, 1997). Additional drilling was conducted on the south end of the Contact Zone in 1997, after which a resource calculation was completed. The property was then transferred back to the Schumacher Estate.
Apollo Gold acquired the property in November 2007 and began drilling the southern extension of the Contact Zone in 2008.
The 2010 and 2011 Brigus Gold exploration drilling programs led to the completion of a Mineral Resource estimate supporting open pit and underground mining in October 2012 (Daigle, 2012).
To upgrade the classification, an updated Mineral Resource estimate followed the 2012 and part of the 2013 drilling programs completed by Brigus Gold (Pelletier et al., 2013).
The 2014 and 2015 Primero drilling programs focused on infill drilling and expanding the Mineral Resources on the 147 Zone, Contact, and Grey Fox South zones.
McEwen began drilling both infill and step-out drill holes at Grey Fox in 2018. That same year, SRK produced an updated Mineral Resource estimate for a Technical Report for McEwen (SRK, 2018).
The 2019 drill programs at Grey Fox focused on deep exploration at Gibson, the discovery of Whiskey Jack and de-risk drilling at 147, 147NE, and Grey Fox South. Successive drilling campaigns from 2020 to 2025 were concentrated on further delineating Whiskey Jack and Gibson with additional drilling at 147 and Grey Fox South. This drilling was designed to identify new lenses of mineralization and continue growing the resource.
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Importantly, up until 2018, the majority of the drill holes at Grey Fox were drilled perpendicular to stratigraphy, a practice that reflected the understanding at the time of the orientation of the mineralization. In early 2019, much of the mineralization (excluding the Contact Zone) was determined to be oriented oblique to stratigraphy (mineralization trending NE-SW). Therefore, many of the subsequent drill holes were reoriented in a SE direction to achieve more optimal drill angles for the mineralization.
McEwen updated the resource estimates for Grey Fox in 2019, 2020, 2021, 2024 and 2025. The 2025 Mineral Resource estimate that forms the basis for this PFS is the most recent and current resource estimate. All previous resource estimates are now considered historical and should not be relied upon.
Drilling history at Grey Fox is tabulated in Table 5-1.
Table 5-1: Summary of Grey Fox Drilling
Company | | Year | | No. Drill Holes | | Metres Drilled | | Target Zone |
|
Abuy Gold Mines | | 1939-1945 | | 16 | | 1,277.0 | | Gibson | |
Martin-Bird Gold Mines | | 1946 | | 11 | | 2,972.0 | | Gibson | |
Nevada Exploration | | 1973-1974 | | 11 | | 610.0 | | | |
A.P. Ginn and G.E. Parsons | | 1979-1980 | | 38 | | 3,910.0 | | Gibson | |
Armco | | 1981 | | 18 | | 884.0 | | Gibson | |
Geddes Resources and Armco | | 1983-1984 | | 28 | | 2,170.0 | | Gibson | |
Goldpost Resources | | 1986-1989 | | At least 56 | | 17,549.0 | | Gibson surface and | |
Noranda | | 1993 | | 21 | | 5,533.0 | | Contact | |
Noranda | | 1994 | | 6 | | 1,367.0 | | Contact | |
Battle Mountain/Hemlo | | 1995 | | 8 | | 2,109.0 | | Grey Fox | |
Battle Mountain and Cameco Gold | | 1996 | | 16 | | 5,872.0 | | Contact, 147, South, Gibson, | |
Battle Mountain and Cameco Gold | | 1997 | | 13 | | 5,367.5 | | Contact, 147, South, Gibson, | |
Glimmer/Exall | | 2001 | | 4 | | 1,667.0 | | Romios | |
Apollo Gold | | 2008 | | 16 | | 3,715.0 | | Southern extension of Contact | |
Apollo Gold | | 2009 | | 53 | | 9,960.0 | | Contact | |
Brigus Gold | | 2010 | | 76 | | 29,084.0 | | Contact, Gibson, South, | |
Brigus Gold | | 2011 | | 274 | | 101,893.0 | | Contact, Gibson, South, 147 | |
Brigus Gold | | 2012 | | 282 | | 87,971.0 | | Contact, 147, Whiskey Jack, South | |
Brigus Gold | | 2013 | | 148 | | 65,417.0 | | Contact, 147, South | |
Primero | | 2014 | | 199 | | 81,933.0 | | Contact, 147, South | |
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Company | Year | No. Drill Holes | Metres Drilled | Target Zone |
Primero | 2015 | 57 | 26,094.0 | Contact Zone, Gibson, South |
McEwen | 2018 | 64 | 25,181.3 | Gibson, 147, 147NE |
McEwen | 2019 | 219 | 89,266.0 | Gibson, 147, 147NE, South, |
McEwen | 2020 | 13 | 4,438.0 | Whiskey Jack |
McEwen | 2021 | 29 | 11,396.0 | Gibson and Whiskey Jack |
McEwen | 2022 | 14 | 6,135 | Gibson and Whiskey Jack |
McEwen | 2023 | 21 | 10,703 | Gibson and Whiskey Jack |
McEwen | 2024 | 128 | 42,419 | Gibson, 147, 147NE, South, |
McEwen | 2025 | 179 | 64,001 | Gibson, 147, South, Contact, |
McEwen | 2026 to date | 12 | 4,700 | Gibson, Whiskey Jack, Stroud |
5.2 | Stroud Property |
The Stroud property is contiguous with the Grey Fox property and forms part of the Eastern Properties of the Fox Complex. The acquisition of the Stroud property by McEwen was completed in late 2024. The first meaningful drilling took place on the property in the early 1970s by Gunnex Ltd. on the Main Zone. Subsequent drilling programs by different operators demonstrated the presence of additional zones of mineralization on the property. An internal and undisclosed historical resource estimate prepared by Atticus Geoscience Consulting in 2021 reported approximately 271 koz of gold (M+I+I). After McEwen’s purchase of Stroud, about 6,500 m of drilling was executed during the 2025 drilling season with the principal purpose of verifying this 2021 historical resource.
5.3 | Eastern Properties |
The following sections summarize the history of other properties within the Eastern Properties of the Fox Complex, which provide regional and operational context to the Grey Fox Project.
McEwen acquired all assets of the Eastern and Stock properties in 2017 from Primero Mining Corp (Primero). All assets associated with the Stroud deposit were acquired in 2024 from Stroud Resources Ltd. Refer to Figure 3-1 for the position of McEwen’s Ontario properties.
5.3.1 | Black Fox Mine |
Drilling on the Black Fox properties was first conducted by Dominion Gulf in 1952, followed by Hollinger Consolidated Gold Mines Ltd. (Hollinger) in 1962. The drill holes were drilled near diabase dykes located in the easternmost part of the properties. In 1988, Glimmer Resources, Inc. (Glimmer) put together the property package using a combination of crown and private lands. In 1989, Noranda Exploration Company Ltd. (Noranda) entered into a joint venture agreement with Glimmer to earn a 60% interest in the properties.
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Between 1989 and 1994, Noranda, and later Hemlo Gold Mines Inc. (Hemlo), completed eight drill programs. In all, 27,800 m of drilling was completed in 142 holes. In addition to diamond drilling, exploration was conducted by way of geological, magnetic and gradiometer surveys, a UTEM survey, and a limited induced polarization survey. In 1996, a final feasibility study on the Glimmer Gold Project was based on probable reserves outlined to a depth of 250 m.
The joint venture advanced an access ramp from surface to 55 m depth in 1996. Exall Resources Ltd. (Exall) purchased the property from Hemlo in April 1996, obtaining approximately 60% interest with Glimmer holding the remaining portion. A bulk sample was taken in 1997 from underground following development of a spiral decline ramp to a depth of 120 m, and 3,800 m of drifting. Commercial production from the Glimmer Mine was achieved in 1998. The sample and production were custom milled at St Andrew Goldfields Ltd.’s (St Andrew’s) Stock Mill from 1997 through 2001, after mineral tests carried out by Lakefield Research and others.
In September 2002, Apollo Gold Corporation (Apollo Gold) completed the acquisition of the assets of the Glimmer Mine from Exall and Glimmer. The project was renamed the Black Fox property. Between 2003 and 2007, Apollo Gold completed five drill programs. In addition to diamond drilling, exploration was conducted by way of induced polarization surveys.
In 2008, Apollo Gold produced a feasibility study declaring Mineral Reserves. On 28 July 2008, Apollo Gold completed the acquisition from St Andrew of its Stock Mill and related equipment, infrastructure, property rights, laboratory, and tailings facilities.
In October 2008, Apollo Gold awarded a contract for the removal of the glacial till material over the open pit site, and work commenced on 23 October 2008. During the same year, Apollo Gold received all necessary permits and approvals required to commence mining activities of the open pit. Apollo Gold received a Certified Closure Plan Approval, an Amended Certificate of Approval for Industrial Sewage Works, and a surface and groundwater Permit to Take Water (PTTW).
Apollo Gold commenced open pit mining at the Black Fox Mine in March 2009. The 2009 drilling program focused on the Pike River property to test the northern extension of mineralization from the adjoining Grey Fox Project.
Apollo Gold and Linear Gold Corporation (Linear Gold) merged to form Brigus Gold Corporation (Brigus Gold) in June 2010. The drilling surface program completed 14 condemnation drill holes (3,468 m) around the Black Fox Mine. A helicopter-borne, high-resolution magnetometer survey was completed in September 2010, covering the 17 km2 Black Fox mine.
Apollo Gold and Brigus Gold continued drilling at the Black Fox Mine from January 1, 2008 to December 31, 2013.
Details of the drilling history at Black Fox is tabulated in Table 5-2.
On March 5, 2014, Primero acquired all issued and outstanding common shares of Brigus Gold.
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5 History
Table 5-2: Summary of Black Fox Drilling
Company | Year | No. Drill Holes | Metres Drilled |
| | | |
Dominion Gulf | 1952 | Unknown | Unknown |
| | | |
Hollinger | 1962 | Unknown | Unknown |
| | | |
Noranda | 1989-1994 | 142 | 27,800 |
| | | |
Glimmer/Exall | 2000-2002 | 1,088 | 96,053 |
| | | |
Apollo Gold | 2003-2007 | 889 | 224,162 |
| | | |
Apollo Gold/Brigus Gold | 2010-2013 | 1,318 | 135,800 |
| | | |
Primero | 2014-2017 | 2,605 | 387,419 |
| | | |
McEwen | 2018-2026 | 1,793 | 247,528 |
| | | |
Total | | 7,835 | 1,118,762 |
5.3.1.1Past Production
Historical production from the Glimmer Mine era is shown in Table 5-3. The Black Fox Mine production between 2009 through December 2024 is summarized in Table 5-4. Note that the Stock Mill production includes material mined from the Froome Mine and from stockpiles.
Table 5-3: Production History (mined) of the Glimmer Mine from 1997 to 2001*
Year | Tonnes | Au Grade (g/t)** | Au (oz) | Recovery (%) |
| | | | |
1997 | 194,460 | 6.62 | 39,884 | 96.4 |
| | | | |
1998 | 308,734 | 6.69 | 64,319 | 96.9 |
| | | | |
1999 | 258,699 | 5.93 | 48,266 | 97.8 |
| | | | |
2000 | 255,234 | 5.83 | 46,418 | 97.0 |
| | | | |
2001 | 81,700 | 4.61 | 11,895 | 98.2 |
| | | | |
Total | 1,098,827 | 6.14 | 210,782 | 97.1 |
Notes:
* From historical records. Some numbers may not sum due to rounding and conversion factors. Grades and recoveries are straight averages
** Grades are calculated from reported production ounces, tonnes and recovery. From 2008 Apollo Gold Corporation Technical Report.
Table 5-4: Production History of the Black Fox & Froome Mine from 2009 to December 2025
Year | Open Pit Tonnes | UG Tonnes | Total Tonnes Mined | Tonnes Milled | Mill Au Head Grade (g/t) | Au Produced (oz) | Recovery (%) |
2009 | 631,000 | - | 631,000 | 531,000 | 3.28 | 52,152 | 93% |
2010 | 792,482 | - | 792,482 | 718,400 | 3.17 | 67,499 | 92% |
2011 | 433,267 | 170,889 | 604,156 | 725,541 | 2.54 | 55,756 | 94% |
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Year | Open Pit Tonnes | UG Tonnes | Total Tonnes Mined | Tonnes Milled | Mill Au Head Grade (g/t) | Au Produced (oz) | Recovery (%) |
2012 | 907,077 | 164,926 | 1,072,003 | 735,573 | 3.43 | 77,374 | 95% |
2013 | 663,428 | 297,110 | 960,538 | 752,959 | 4.34 | 98,710 | 94% |
2014 | 775,403 | 122,249 | 897,652 | 695,131 | 3.00 | 64,018 | 95% |
2015 | 849,668 | 140,836 | 990,504 | 875,833 | 2.58 | 69,733 | 96% |
2016 | - | 234,518 | 234,518 | 913,235 | 2.22 | 62,171 | 96% |
2017 | - | 263,549 | 263,549 | 685,293 | 3.14 | 66,733 | 96% |
2018 | - | 255,982 | 255,982 | 268,288 | 5.57 | 46,672 | 97% |
2019 | - | 213,887 | 213,887 | 243,677 | 4.88 | 37,288 | 98% |
2020 | - | 200,326 | 200,326 | 234,744 | 3.19 | 23,129 | 96% |
2021 | - | 306,962 | 306,962 | 303,377 | 3.24 | 29,290 | 93% |
2022 | - | 419,496 | 419,496 | 344,587 | 3.77 | 37,315 | 89% |
2023 | - | 395,713 | 395,713 | 456,831 | 3.35 | 44,236 | 90% |
2024 | - | 303,979 | 303,979 | 403,669 | 2.54 | 29,430 | 89% |
2025 | - | 285,054 | 285,054 | 290,365 | 2.89 | 23,249 | 86% |
Total | 5,052,325 | 3,775,476 | 8,827,801 | 9,178,503 | 3.19 | 884,755 | 94% |
Notes:
· | UG = underground. |
· | Milling tonne values (for 2016 & 2017) are higher than the mining tonnes due to processing of residual open pit low grade stockpile. |
· | Two milling tonne values (for 2023 & 2024) are higher than the mining tonnes due to re-claiming material because of the higher gold price (originally sent as waste from the open pit waste dump). |
· | 2025 Milled Tonnes, Ounces and Grade calculated from 2025 KPI report, removing as a percentage, material processed from Stock Mine. |
· | Total Head Grade and Recovery calculated from weighted average of 2009-2025 values. |
5.3.2 | Froome Mine (Main Zone and West Zone) |
Noranda began exploration on the Froome Lake claims in 1991 using a ground total field magnetometer and a very low frequency electromagnetic survey (EM), finding results consistent with the geological terrain of the Porcupine-Destor Deformation Zone (PDDZ). This work was followed by geological mapping in both the Froome and Glimmer claims.
The Froome deposit is located on the Durham, Plouffe, and Steinman properties acquired by Apollo Gold. The Durham and Plouffe properties were acquired in 2003 and the Steinman property in 2007.
In 2014, Primero completed a diamond drilling program which discovered the Froome (Main) deposit. This program was targeting an induced polarization anomaly, intercepting 23 m (core length) of silicified rock with disseminated pyrite. Through the latter part of 2015 and early 2016, subsequent diamond drilling defined mineralization over a strike length of approximately 150 m and dip length of approximately 300 m. In addition, drilling in 2016 identified a second zone of mineralization 25 m below the main deposit.
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5 History
By the end of 2025 most of the mineralized material from the main zone at Froome had been mined out and McEwen had transitioned to mining at the West zone which is described in more detail below.
The Froome West zone is located approximately 300 m west of the main Froome zone and saw limited drilling until 2024. The West zone is characterized by generally narrow, orogenic quartz-carbonate veining hosted in mafic volcanic rocks. The mineralization is interpreted to occur in a tight, northwest-southeast trending fold with the fold hinge plunging steeply to the southwest. Currently the zone has been traced approximately 175 m along strike and has a dip component of about 350 m. Most of the higher grade and wider mineralization occurs within the fold hinge.
Drilling history at Froome Mine (through December 2025) is summarized in Table 5-5.
The initial Mineral Resource estimate for the Froome (Main) deposit was calculated in 2017 by Primero. The Primero Mineral Resource estimate is now considered historic as it has been updated numerous times since then, including in this report.
Table 5-5: Summary of Froome Drilling
Company | Year | No. Drill Holes | Metres Drilled |
Noranda | 1991-1994 | 2 | 551 |
| | | |
Glimmer/Exall | 2000-2002 | 1 | 200 |
| | | |
Apollo Gold | 2003-2007 | 1 | 693 |
| | | |
Primero | 2014-2017 | 219 | 65,051 |
| | | |
McEwen | 2018-2025 | 915 | 164,594 |
| | | |
Total | | 1,138 | 231,089 |
5.3.3 | Black Fox North |
The claims pertaining to Black Fox North were acquired by McEwen in 2017 along with the remaining portions of the Eastern Properties. All assessment work performed on these claims, including work completed by McEwen, is publicly available through the Mining Land Administration System (Ontario Ministry of Mines, n.d.).
5.4 | Stock Property |
The Stock Property forms the central portion of the Fox Complex and hosts the Stock Mine and processing facilities, including the Stock Mill, which provide infrastructure support to the Eastern Properties.
The Stock Property was originally staked and drilled by Hollinger Gold Mines Ltd. (Hollinger) from 1959 to 1964 with mineralization being discovered in 1961. This work located auriferous carbonate rocks, volcanic rocks, and porphyries in proximity to the PDDZ, but limited exploration funds and changing exploration priorities postponed further evaluation. The claims were allowed to lapse.
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5 History
Quebec Sturgeon River Mines Ltd. (Quebec Sturgeon) re-staked the property and discovered substantial gold mineralization in 1973. Development began in 1974 and included construction of a headframe with a shaft being collared and driven through 15 m of overburden and 4 m of bedrock.
From 1980 to 1981, Quebec Sturgeon deepened the three-compartment shaft to 82 m below surface, and a shaft station was established on the 61 m level. Some 413 m of drifting and crosscutting were completed on this level along with a total of 4,481 m of underground drilling from 113 holes. Quebec Sturgeon ceased all work in early 1982 due to the drop in gold price.
In 1983, a $14 million equity financing was completed by turning the property over to St Andrew Goldfields Ltd. (St Andrew), a 68% owned subsidiary of Quebec Sturgeon. Development resumed on the property in mid-1983 and the shaft had been deepened to 269 m and underground development had been conducted on four levels by the end of 1985.
In early 1986, St Andrew acquired additional property along the PDDZ by purchasing Labrador Mining and Exploration Company Ltd.’s (Labrador Mining and successor of Hollinger) interest in properties in three townships and by entering into joint venture agreements with Esso Resources Canada Ltd. (Esso) and Quebec Sturgeon. In mid-1987, St Andrew announced that the Stock Township deposit would be brought into production. Financing was raised in Europe in 1988, and an announcement was made that a 454 t/d mill would be constructed by late 1988. Production and milling of stockpiled development material at the Stock Mine began in 1989.
In 1989, St Andrew bought out the remaining interests of Esso. By the end of 1989, five levels in the Stock Mine had been developed and 91,500 t of material had been milled to produce 17,999 oz of gold. The shaft could not be used below the fourth level due to bad ground conditions, and the fifth, sixth and seventh levels had to be accessed by a ramp. Mining methods included cut-and-fill, room-and-pillar, and longhole.
Between 1988 to 2000, production of 130,000 oz of gold from 733,000 t of material at an average grade of 5.5 g/t Au was mined from the N2, West and Central chutes. Mining and milling were suspended in December 2000 to focus on a financial restructuring and to deal with a working capital deficit and debt burden.
In 2004, St Andrew dewatered and rehabilitated the underground workings, and the Stock head frame and hoist were refurbished. An underground development, mining and drilling program was then undertaken. During 2004, 30,500 t grading 2.56 g/t Au were mined and treated at the Stock Mill.
In 2005, underground mining operations were again suspended at the Stock Mine because of the decision to extend the period of the Advanced Exploration Program at the nearby, St Andrew’s-owned Clavos Mine. Daily production levels at the Stock Mine were insufficient for the Stock Mill to operate at profitable levels.
Underground development and drilling in the deeper portions of the Stock Mine did not generate sufficient gold resources to sustain future economic mining operations and the mine was placed on care and maintenance pending further exploration.
In 2006, RPA prepared a technical report on behalf of St Andrew on their properties in and around the Timmins area. No Mineral Resources or Mineral Reserves were reported at Stock (Gow and Roscoe, 2006).
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Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
5 History
The Stock Mine and mill facility were sold in 2008 to Apollo Gold (later Brigus Gold). Brigus Gold purchased and upgraded the Stock Mill to provide milling facilities for its Black Fox project. Refurbishment of the mill was completed in April 2009, and it began operating on 01 May 2009.
McEwen acquired the property and all its assets in 2017.
Stock East was discovered in 2018 by McEwen; Stock West was discovered in 2019. In 2019 a drilling program was laid out and designed to identify mineralization below the Main Zone. By mid 2021 mineralization below the N2 shoot at the Main Zone had been intersected. Successive drilling campaigns at Stock up until early 2024 were primarily designed to expand & delineate additional mineralization at all three of these zones (Stock West, Stock Main/Mine, and Stock East).
Since 2025, McEwen has been developing a new access ramp into the historical Stock Mine workings and is establishing the underground and surface infrastructure needed to support initial production later in 2026. Production is intended to ramp up to 1,500 t/d in 2027. The evaluation of the potential mine life is ongoing.
Drilling history at Stock, including Stock Main, Stock East and Stock West are tabulated in Table 5-6.
Table 5-6: Summary of Stock Drilling
Company | Year | No. Drill Holes | Metres Drilled | Target Zone |
Various companies | 1959-1982 | 315 | 31,950 | |
| | | | |
St Andrew | 1983-2008 | 1,124 | 91,282 | Stock Main, Stock East |
| | | | |
Brigus Gold | 2008-2017 | 6 | 2,164 | |
| | | | |
Primero | 2014-2015 | 35 | 10,541 | |
| | | | |
McEwen | 2018 | 91 | 28,389 | Stock East |
| | | | |
McEwen | 2019 | 108 | 43,219 | Stock East, Stock Main N-2 Chute |
| | | | Extension, Stock West |
| | | | |
McEwen | 2020 | 33 | 17,813 | Stock West |
| | | | |
McEwen | 2021 | 136 | 61,046 | Stock West, Stock Main N-2 Chute |
| | | | Extension |
| | | | |
McEwen | 2022 | 125 | 45,612 | Stock West, Stock Main |
| | | | |
McEwen | 2023 | 209 | 65,505 | Stock West, Stock Main, Stock East |
| | | | |
McEwen | 2024 | 52 | 11,402 | Stock East, Stock West |
| | | | |
McEwen | 2025 | 0 | 0 | |
| | | | |
McEwen | 2026 to date | 25 | 3,064 | Stock East |
| | | | |
Total | | 2,259 | 411,987 | |
5.4.1 | Past Production |
Production commenced in July 1989 and ceased in mid-1994 due to a lack of working capital. The central chute was discovered in 1994 by underground drilling, and the 8-12 decline had almost reached the central shoot when the mine closed.
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5 History
The overall historical production of the Stock Mine to date is shown in Table 5-7. Over half of the production came from the N2 chute where 405,298 t gold was mined, with an average grade of 6.2 g/t Au. The average grade increased in 1992, when production from the higher-grade west chute commenced. From 1992 to 1994, 103,857 tonnes at an average grade of 9.1 g/t Au were mined and processed from the west shoot, recovering 30,425 oz of gold.
Table 5-7:Stock Mine Production History, St Andrew
| | Average Mined Au | | |
Year | Tonnes Milled | Grade (g/t) | Contained Au (koz) | Recovered Au (koz) |
1989 | 90,883 | 3.87 | 11,320 | 10,657 |
| | | | |
1990 | 163,129 | 5.59 | 29,310 | 27,295 |
| | | | |
1991 | 132,191 | 5.62 | 23,897 | 21,961 |
| | | | |
1992 | 173,413 | 6.79 | 37,848 | 36,301 |
| | | | |
1993 | 151,187 | 5.14 | 24,998 | 23,788 |
| | | | |
1994 | 20,677 | 5.38 | 3,578 | 3,403 |
| | | | |
2000 | 68,723 | 5.88 | 12,983 | 12,395 |
| | | | |
2004 | 23,015 | 1.83 | 1,355 | 1,355 |
| | | | |
2005 | 7,527 | 4.78 | 172 | 172 |
| | | | |
Total | 830,745 | 5.48 | 145,461 | 137,327 |
Table 5-8 summarizes the gold ounces recovered in 2025 by McEwen during the development of the new Stock Mine ramp:
Table 5-8: Production History of the Stock Mine from 2025
Year | Underground Tonnes | Total Tonnes Mined | Tonnes Milled | Mill Au Head Grade (g/t) | Au Produced (oz) | Recovery (%) | |
2025 | 16,746 | 16,746 | 15,331 | 0.96 | 408 | 86% | |
| | | | | | | |
Total | 16,746 | 16,746 | 15,331 | 0.96 | 408 | 86% | |
5.5 | Western Properties |
The Western Properties form the western portion of the Fox Complex and include the Buffalo Ankerite and Davidson-Tisdale properties. These properties are not directly material to the Grey Fox Project but provide regional context within the Fox Complex.
McEwen acquired the mineral rights to the Western Properties through the 2017 acquisition of Lexam VG Explorations Inc. The history of the individual property mineral rights ownership is discussed in the history for each property.
| Project: 169525666 | 5-11 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
5 History
5.5.1Buffalo Ankerite Property
Prior to 1935, Buffalo Ankerite was developed by two independent owners. The operations were distinct and covered two different mineralized bodies, the South Zone (Buffalo Ankerite South) and the North Zone (Buffalo Ankerite North). In 1935, the operator of Buffalo Ankerite North, Buffalo Ankerite Holdings Ltd. (BAH, previously Buffalo Ankerite Gold Mines Ltd.) consolidated both properties under its ownership. Since 1935 the property has been held by numerous operators who performed various exploration and mining activities.
Details of the drilling history at Buffalo Ankerite is tabulated in Table 5-9.
Table 5-9: Summary of Buffalo Ankerite Drilling
Company | Year | No. Drill Holes | Metres Drilled | Target Zone |
Various companies | Prior 1953 | Unknown | Unknown | Historical records limited |
Vedron and Pamour | 1982 | 15 | 1,245 | |
Placer Dome | 2001 | 15 | 2,728 | North |
Placer Dome | 2002 | 59 | 6,097 | South |
Lexam VG | 2005-2012 | 66 | 26,806.1 | North |
Lexam VG | 2005-2012 | 159 | 54,419.4 | South |
Total | | 314 | 91,295.5 | |
5.5.1.1 | Past Production |
Production from the Buffalo Ankerite and the March operations between 1926 and 1953 totaled 4.8 Mt with an average grade of 6.5 g/t Au. Total metal produced was 1.02 Moz Au.
Between 1978 and 1982, production came from Pamour extracting the Buffalo Ankerite South crown pillars and milled at their adjacent Timmins Mill. The amount of material mined was not consistently reported by Pamour and the total is unknown. In 1978, Pamour reported milling 38,160 t. The Regional Geologist for Timmins reported 16,300 t in 1982 (Kustra, 1983). A later three-dimensional model created by Dome Mines suggests that a total of approximately 320,000 t of material was removed.
5.5.2 | Davidson-Tisdale Property |
The property was incorporated as Davidson Gold Mines Ltd. in 1911 and was succeeded in 1919 by Davidson Consolidated Gold Mines Ltd. Little work was done from 1945 to the early 1980s.
In 1994, a study commissioned by Placer Dome provided an estimate of an open pit mineable resource.
From 1999 to 2003, Northcott Gold Inc. (Northcott, formerly DTM) drilled several holes. Northcott subsequently optioned the property to Vedron in 2003, allowing Vedron to earn a 50% undivided interest. From 2003 to 2006, Vedron drilled a significant number of holes. In 2004, the company amended the option
| Project: 169525666 | 5-12 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
5 History
agreement to allow earning 75%. In 2005, the option agreement was further amended, resulting in Vedron acquiring 54% of the interest in the property.
A Mineral Resource was estimated by Guy and Puritch in 2007 (Guy and Puritch, 2007). Vedron expenditures on the property had increased the interest to 66% by the filing of their 2007 annual information form in June. Later in 2007, a preliminary economic assessment was filed on Davidson-Tisdale. In 2008, the option expired with Vedron earning a 68.5% interest in the Tisdale property by 2014, with Laurion Mineral Exploration Inc. (Laurion, previously Northcott) holding the remaining 31.5%.
In 2010, Vedron purchased the remaining 31.5% minority stake in Davidson-Tisdale, held by SGX Resources, Inc. (previously Laurion) to fully control the property.
From 2006 to 2010, Vedron continued to drill diamond drill holes from surface.
In 2013, a Mineral Resource estimate and technical report was prepared by P&E and RPA (Armstrong et al., 2013). An updated Mineral Resource estimate was performed for the 2021 Fox Complex IA and this has been updated for this PFS and is now considered as the current Mineral Resource estimate.
Details of the drilling history at Davidson-Tisdale is tabulated in Table 5-10.
Table 5-10: Summary of Davidson-Tisdale Drilling
Company | Year | No. Drill Holes | Metres Drilled |
| | | |
Various companies | Prior 1980 | 24 | 5,267.0 |
| | | |
Dome Mines | 1981 | 11 | 1,118.0 |
| | | |
DTM | 1983-1984 | 35 | 4,576.8 |
| | | |
Getty | 1984-1987 | 537 | 49,165.9 |
| | | |
Midas Minerals | 1989 | 5 | 1,486.2 |
| | | |
Northcott | 1999-2003 | 17 | 399.3 |
| | | |
Lexam VG | 2003-2015 | 97 | 23,397.5 |
| | | |
Total | | 726 | 86,410.7 |
5.5.2.1 | Past Production |
Production from 1918 to 1921 was processed on site with a 10-stamp mill until it burned down in 1924. A reported total of 8,501 t at 8.9 g/t Au was milled, and 2,438 oz gold recovered using mercury amalgamation, with about 20% of the gold content was lost using this process.
From April to November 1988, custom milling of the mined material at Davidson-Tisdale occurred at the nearby Giant Yellowknife Go-Mill. A total of 39,800 t was mined and milled during the Getty period, producing a total of 7,300 oz of gold and 5,665 oz silver.
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6 Geological Setting, Mineralization, and Deposit
6 | Geological Setting, Mineralization, and Deposit |
Property geology described herein for Davidson-Tisdale and Buffalo Ankerite properties was derived from technical reports prepared by P&E (Mineral Resource estimate) and RPA (Armstrong et al., 2013; Ehasoo et al., 2014).
Figure 6-1 is a geological map showing the locations of the Eastern, Stock and Western Properties.

Figure 6-1: Geological Map of the Timmins-Matheson Sector within the Abitibi Subprovince showing Distribution of Gold Mining Operations
6.1 | Regional Stratigraphy |
The Fox Complex properties are underlain by Precambrian rocks of the Southern Abitibi Greenstone Belt (SAGB), located in the central part of the Wawa-Abitibi Subprovince, southeastern Superior Province, of northeastern Ontario (Figure 6-2). The SAGB consists of numerous intercalated assemblages of 2,750 Ma (million years) to 2,695 Ma metavolcanic rocks and their intrusive equivalents, which are unconformably overlain by the younger 2,690 Ma to 2,685 Ma Porcupine and 2,677 Ma to 2,670 Ma Timiskaming metasedimentary assemblages and alkalic intrusive rocks.
| Project: 169525666 | 6-1 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
6 Geological Setting, Mineralization, and Deposit

Source: (Modified after Poulsen et al., 2000, and Dube and Gosselin, 2007)
Figure 6-2: Map of the Southern Abitibi Greenstone Belt
6.2 | Mineral Occurrences & Mineralization Types |
Gold mineralization at both the Eastern and Stock Properties is part of a metallogenetic domain, and shares similarities with ultramafic-hosted and associated deposits that occur along the PDDZ corridor between Nighthawk Lake and the Froome and Black Fox Mines to the East. This domain includes deposits such as those at Nighthawk Lake (Porcupine Peninsular Mine, Hopson Zone, Ronnoco deposit), the Aquarius Deposit, the Taylor Mine (West Porphyry, Shoot and Shaft Zones), and the Black Fox Mine. Similar ultramafic-hosted styles are also present along the Cadillac-Larder Lake corridor to the south, as is exemplified by the Kerr Addison Mine. All these deposits occur in association with sets of reverse quartz shear veins and associated sets of gently to moderately dipping quartz-carbonate-albite extension vein arrays in areas where strong complex rheological control influences the position of mineralization in areas of high strain. Specifically, mineralization at Black Fox, Stock and Froome West is interpreted to be orogenic lode gold deposits. The Grey Fox deposit, located about 3 km Southeast of Black Fox, appears to differ in mineralization style, with studies suggesting an epizonal to high level orogenic deposit based on current lithological, structural, and mineralogical observations.
| Project: 169525666 | 6-2 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
6 Geological Setting, Mineralization, and Deposit
6.2.1 | Grey Fox |
The Grey Fox deposit is hosted within mafic metavolcanic, metasedimentary, and syenite units, likely from the Lower Blake River Formation. The Project is divided into two main blocks with distinct lithological packages (Figure 6-3). The SE block (147-Grey Fox South Block) is a layered mafic metavolcanic sequence comprised of massive, pillowed, and variolitic metavolcanic units with minor interflow metasediment horizons. The NW block (Gibson Block) is comprised of altered metasediments intruded by a syenitic stock (the Gibson Syenite). The metasedimentary and metavolcanic units in both blocks strike ~350° and are steeply dipping at approximately 70° to the east. They are angularly unconformable to the Lower Tisdale mafic and ultramafic metavolcanics to the north, which strike ~140° and dip 45° to the SW. The units are generally weakly foliated, although the foliation can increase locally in the presence of shearing. Some lithologies (including sedimentary horizons and contacts) may have localized displacement, as suggested by cataclastic breccias and narrow semi-brittle shear zones associated with mineralization (Ross and Rhys, 2011).
The two blocks are separated by the Contact Fault which runs N-S along the contact between the metasediments and the mafic metavolcanics. The deposit is constrained to the NE and at depth by the A-1 thrust fault, which is likely part of an imbricate fan of the PDDZ and separates the Grey Fox units from the Lower Tisdale rocks, and to the SW by the sub-vertical Gibson-Kelore Shear Zone.
Most of the mineralization at Grey Fox occurs within numerous sub-parallel NE-SW striking sheeted vein sets referred to as C-1 veins (Figure 6-4) that dip steeply to the NW. These are accompanied by extensional conjugate C-2 veins, which are mainly E-W trending and south-dipping. Collectively known as C-veins, these are the dominant host of the mineralization in the Gibson, 147, 147NE and Grey Fox South zones. A third, flat lying set of veins (C-3) may also exist, but likely play a minor role in mineralization.
The orientation of the C-1 veins varies slightly across the property, striking ~230° at 147 Zone and Grey Fox South, rotating to 245° at 147NE. They are steeply dipping at ~68-70° to the NW. On the west side of the Contact Fault, there is a noticeable difference in the orientation of the veining hosted within the Gibson syenite and metasediments, with the C-1 set with a strike/dip of ~223°/-67° in the south end of the Gibson zone, rotating to 210°/75° near the Gibson portal, and rotating back to ~240°/88° at the north end of the Gibson zone. The differences in the strike/dips of the C-1 veins between the two sides of the Contact Fault is likely due to the rheological contrast between the mafic metavolcanic rocks on the east side of the fault verses the metasediments on the west side.
The C-veins are quartz+albite+ferromagnesian dolomite veins. They commonly display crustiform textures with molybdenite±graphite stylolites and can be brecciated in the larger vein sets. They range in scale from 1 cm-2 cm to 2 m-3 m wide and can occur individually or as anastomosing lenses with strike lengths between 100 m-700 m. The veining appears to have textures associated with epizonal orogenic gold deposits, and this is supported by fluid inclusion studies (Tuba, 2019). Gold occurs as free gold or associated with fine grained sulphides and is found around quartz grains and in the stylolites and along vein margins. The distribution of the gold within the veins tends to be nuggety/inhomogeneous.
The host lithology also plays an important role in gold deposition. Mineralization at the 147, 147NE, and Grey Fox South zones is strongly concentrated where the NE-SW trending C-veins intersect the N-S striking variolitic iron-tholeiite flows. These intersections create strong, steep mineralized plunges to the
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6 Geological Setting, Mineralization, and Deposit
north hosted within the flows. This is likely due to the chemical interaction between the silica+carbonate rich gold bearing fluids in the C-veins and the iron rich metavolcanics creating favorable conditions for gold deposition. Mineralization, especially at the Grey Fox South zone, is associated with hematization which occurs in albite-carbonate dominant alteration assemblages often peripheral to mineralized zones, and also as outer envelopes to some veins. Pyritic carbonate-albite-sericite alteration generally overprints the hematite, suggesting that much of the pervasive hematite is early, although later structurally controlled hematite is suggested in vein envelopes as well. The presence of hydrothermal hematite and carbon in vein envelopes suggest that alternating redox states, potentially in response to fluid mixing or evolution, may have contributed to gold deposition.
Mineralization at the Gibson zone is mainly hosted within C-veins that crosscut the metasediment unit (Gibson metasediments) and into the Gibson Syenite with the highest concentrations within the C-veins in the metasediments and proximal to the intrusion itself. Gold mineralization in the veins within the Gibson metasediments is typically associated with quartz+sericite+sulphide alteration, along with visually significant but unquantified molybdenite±graphite mineralization in stylolites within the veins and along fractures in the host rock.
The concentration of gold in the C-veins within the Gibson Syenite tends to be lower than in the metasediments with a few exceptions such as the historic bulk sample at the Gibson ramp, and the deeper breccia zone to the southeast of the intrusion. The deeper breccia zone is associated with alternating intense biotite+chlorite+albite alteration and amphibole+seritcite+potassium feldspar+dolomite alteration. Drilling has suggested that high grade zones exist below 500 m from surface, although further work is needed to confirm the depth extent of these zones. Minor chalcopyrite-covellite-bornite mineralization is also disseminated throughout the intrusion.
In addition to the sheeted C-veins, gold is also concentrated along the N-S Contact Fault (Contact Zone) and the Whiskey Jack shear. At the Contact Zone, the rheological contrast between the metasediments and the mafic metavolcanics provides a pathway for the gold-bearing fluids. The gold in this area is associated with an increase in quartz+sericite+pyrite alteration in the wall rock, with much of the gold depositing in the metasediment side of the fault.
At Whiskey Jack, the gold mineralization is associated with ferromagnesian dolomite+sericite rich shear veining which occurs extensionally between the A-1 and A-3 shears with a strike/dip of ~125°/65°, parallel to the A-3 fault in that location (Figure 6-5). Veining consists of multiple sets/pulses of cataclasite textured material over widths of up to approximately 7 m. This veining and associated shearing appear more brittle-ductile suggesting a deeper depth of formation than the C-veins. Compared to the nuggety C-veins, the mineralization in the Whiskey Jack shear veins tends to be more continuous with higher average grades, but lower overall contained ounces when compared to other zones at Grey Fox.
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Source: (McEwen, 2024)
Figure 6-3: Grey Fox Area Schematic Geological Plan Map with section lines (A-A’ and B-B’)
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Figure 6-4: Section A-A’ cut perpendicular to the principal C1 vein orientation at Grey Fox

Figure 6-5: Section B-B’ cut perpendicular to Whiskey Jack, A1, A3 faults and the Gibson-Kelore
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In July of 2024 a deportment study (Marchand, 2026) by Jacques Marchand Engineering Consulting on the nature of mineralization at the Whiskey Jack and Gibson zones was commissioned by McEwen. This study included state of the art LIBS (Laser Induced Breakdown Spectroscopy) scanning on select drill core from those two zones. Scanning was performed by an Elemission ECORE LIBS scanning machine in Montreal, QC, Canada. Refer to Figure 6-6 for a diagram on LIBS technology.

Source: (Marchand, 2026)
Figure 6-6: Basic principles for LIBS scanning
Some of the key observations from this deportment study include:
· | Gold primarily exists mostly as finely plated particles in pyrite cleavage surfaces or intergranular. |
· | The gold grains identified are predominantly less than 30µm in size and even as fine as 5 µm. |
· | The presence of magnetite is likely to lower the gold grade in the mineralized host rocks regardless of lithology. |
· | Sulphide content is typically low, less than 1%, and the gangue is composed of a significant amount of carbonate. |
· | A portion of the Grey Fox deposit may be a hybrid type of gold deposit between porphyry copper system and an orogenic gold system. |
6.3 | Stroud Property |
Mineralization on the Stroud property is interpreted to result from a series of continuous structural and hydrothermal events. Following the accumulation of the volcano-sedimentary pile, folding and subsidence,
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accompanied by the regional and local development of stress couples, set up a tensional regime whereby dilatant zones were developed, generally preparing the ground for the subsequent series of hydrothermal events, culminating in gold deposition. The development of the regional and local fabric elements, accompanying the folding and fracturing/shearing formed the channel-ways for the auriferous siliceous fluids, resulting in the present gold-bearing siliceous mineralized structures (Wetmore, 2004).
The structure (or deposit) at Stroud is subdivided into three zones, from NW to SE: the Creek Zone, the Creek Zone Extension and the Main (Gunnex) Zone. The Creek Zone Extension is located in the vicinity of late, unmineralized diabase dykes. Within the mineralized structure, shear intensities and rock types vary, and over a general thickness of approximately 20 m to 45 m in width, the gold mineralization associated with “gray veins” (injection of grey quartz-carbonate veins) and siliceous systems is interpreted to occur in shoots in the form of anastomosing networks in plan and section (Wetmore, 2004).
The 2025 drill program at Stroud confirmed the presence of previously reported mineralization and was also consistent with overall structural models for the deposit. Refer to Figure 6-7 for an updated geological plan view map of the Stroud deposit and Figure 6-8 for a longitudinal section of the updated resource block model.
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Figure 6-7: Plan View Geology Map of the Stroud Deposit
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Figure 6-8: Longitudinal Section (looking NE) of the Updated Stroud Resource Block Model
6.3.1 | Stock Property |
The prospective PDDZ corridor tracks across approximately 7 km through the Stock property. To date, most of the exploration has been focused on assessing a 3 km segment of this and includes the area of the former Stock Mine, as well as at Stock East and Stock West (Figure 6-9). The (historical) Stock Mine deposits (N and M Zones; West and Central zones), have a moderate west plunge defined by the lenticular to lobe-like shapes of hosting mafic volcanic rocks and surrounding carbonate alteration envelope. These are surrounded by lenses of highly strained, talc-chlorite ultramafic rocks (Siragusa, 1994). Limited historical documentation suggests that much of the mined material is comprised of swarms/zones of white quartz veining (both shear and extensional) hosted within sericite-carbonate altered mafic volcanic bands and along mafic-ultramafic contacts. The quartz shear veins were often accompanied by disseminated pyritic mineralization in shear zones. Pyrite altered, albitized dykes formed additional areas of mineralization sometimes associated with the shear veins (Siragusa, 1994).
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Note: Image facing north. All drill results are presented as TWs.
Figure 6-9: Project-wide Longitudinal Section of Stock
Stock East is directly associated with the Nighthawk Lake Fault Zone (NHLFZ) which splays off the PDDZ in proximity to that deposit. Gold mineralization in the Stock East area appears to be related to enhanced gold-pyrite accumulation (often exceeding 10%) and is often located within well-developed quartz breccias. In addition, the deposit is in the hangingwall (HW) of the NHLFZ whereas the Stock West deposit is located between the PDDZ and NHLFZ. See Figure 6-10 for a typical cross-section through the Stock East deposit.
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Figure 6-10: Exploration Drilling at Stock East, Schematic Cross-Section Looking to Northeast
The Stock West deposit was discovered in mid-2019 and is associated with the PDDZ, approximately 1.1 km west of the historical Stock Mine shaft, in an area where the NHLFZ has bifurcated/splayed away from the main PDDZ. The section of the Stock West deposit (which steeply dips to the south) is characterized by the following:
· | Chlorite (talc ± serpentine schists) with variable green carbonate ultramafics Ankerite alteration |
· | Minor mafic volcanic rocks |
o | In the footwall (FW) to the north, these rocks may be silica-sericite altered, pyritized, and quartz veined bound by Porcupine sedimentary rocks. |
o | In the HW to the south, these rocks may be a variably altered feldspar porphyry or relatively undeformed mafic volcanic rocks, likely of the Tisdale Assemblage. |
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In the Stock West drilling program, principal intercepts obtained in 2019 occur over an approximately 300 m by 200 m area within which multiple >5 g/t Au intercepts have been obtained over intervals up to several tens of metres in green carbonate ultramafics. Adjacent holes to the higher-grade areas show that this body thins laterally and is probably lenticular in form (Figure 6-11).

Source: (McEwen, 2024)
Figure 6-11:Exploration Drilling at Stock West, Schematic Cross-Section Looking to Northeast
The overall texture is consistent with a possible origin as a potentially pyroxene‑olivine porphyritic ultramafic intrusion that is now completely altered, which may have been coeval with the finer-grained, probable komatiite flow sequence that is host to the intrusion. Local abrupt variations in its grain size from medium to coarse grained suggest potential for relict textures of pegmatitic phases (Rhys and Ross, 2020).
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6.3.2 | Western Properties |
Many deposits spread over the Porcupine Mining Camp have contributed to approximately 70 Moz of gold production since 1910. Common characteristics of this significant gold deposition are listed below:
| ● | Dominant source of gold is within quartz vein lodes containing locally coarse free gold. |
| ● | Greater than 50% of the major Hollinger deposit’s gold is associated with pyrite formation. |
| ● | Quartz vein lode deposits are structurally controlled areas of dilatancy which permitted the development of vein zones. |
| ● | The majority of gold production in the camp is hosted by rocks of the Tisdale Assemblage. |
Minor production came from 1) pyrite-bearing pyroclastics within the mafic volcanic rocks of the Tisdale Group, 2) vein sets intruding local felsic porphyry bodies (Pearl Lake and Miller porphyries), 3) quartz veins within the sediments of the Porcupine and Timiskaming Assemblage (Dome Mine) where they unconformably overlie productive portions of the Tisdale Assemblage.
The main minerals of these gold-bearing zones are quartz, carbonates, alkali feldspar (most commonly albite), sericite, pyrite, tourmaline, arsenopyrite, scheelite, and molybdenite. Pyrrhotite is common in the deep parts of deposits, as well as in deposits hosted in banded iron formation. Arsenopyrite seems to be common in deposits hosted in sedimentary rocks.
The concentration of gold may be considered a product of the alteration process, as well as the concentrations of barite, tungsten, antimony, tellurium, molybdenum, and arsenic. Although gold in quartz veins is the most distinctive occurrence, the gold in some deposits is found predominantly within the wall rock.
6.4 | Structural Geology |
Major crustal-scale faults, such as the PDDZ and Cadillac-Larder Lake Deformation Zone (CLDZ) commonly occur at assemblage boundaries and are spatially associated with east-west trending belts of Porcupine and Timiskaming assemblage metasedimentary rocks. These major faults record multiple generations of deformation, including normal, strike-slip, and reverse movements. The PDDZ and CLDZ define a corridor of gold deposits, generally known as the Timmins-Val D’Or camp (Robert et al., 2005), which accounts for the bulk of historical and current gold production from the Superior Province.
The PDDZ extends across the Highway 101 area, continuing westward to the Kapuskasing Structural Zone (Ayer et al., 1999a) and eastward through Québec to the Grenville Front area (Mueller et al., 1996) for a total distance of more than 600 km. The PDDZ strikes southeast in Hislop Township and generally becomes more east striking along the rest of Highway 101 (Siragusa, 1994). The deformation zone is complex, with different structural styles restricted to specific segments. Each segment is bound, to a first order approximation, by prominent north-northwest-striking faults that transect the PDDZ (Figure 6-12).
Several important secondary structures occur in the vicinity of the Black Fox Mine. The Gibson-Kelore Deformation Zone (GKDZ) is one of the most recognizable structural features on the Black Fox and Grey Fox properties and is defined by a strongly fractured-broken band of talcose-chloritic schist. Regional airborne geophysical surveys indicate that this splay departs the regional track of the PDDZ and trends
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6 Geological Setting, Mineralization, and Deposit
south-eastwards for approximately 4 km to 5 km, passing off the southern property limits. Studies suggest the steeply southwest dipping GKDZ brittle-ductile structure contains schist, fault gouge and extensive fracturing. West of the Fault, the stratigraphy is an east-striking, south-facing homoclinal sequence. Structural fabrics are commonly nonpenetrative fracture cleavages.
The GKDZ is one of the five regionally bounding cross-faults that separate different segments along the PDDZ from Timmins to Québec. The structural style and setting of gold mineralization in each segment is different and knowledge of these differences can be used to tailor exploration programs specific to each segment (Berger, 2001).
Jensen (1985) identified the Ross Fault as the northwest-striking lineament immediately east of the Ross Mine. Berger (2002) has modified the extent and strike of the fault based on detailed airborne geophysical data. The fault is located near or on the inferred axis of an anticline that closes in the vicinity of the Ross mine.
The Arrow Fault is a local name applied to a shear zone striking 085° located near the southern limit of the Grey Fox cluster of exploration targets. The fault is defined by a prominent linear disruption in airborne magnetic patterns and corresponds to sheared rock on the ground (Berger, 2002).
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Source: (modified after Thurston et al., 2008)
Figure 6-12:Stratigraphic Column for the General Black Fox – Hislop Area
West of the Hislop Fault, the PDDZ strikes southeast to east and dips 45° to 65° to the south. The PDDZ marks the contact between the Porcupine and Tisdale Assemblages and is characterized by mafic and ultramafic schist in zones that range from 250 m to 800 m wide, as well as numerous foliation-parallel and crosscutting brittle faults. The main trace of the PDDZ is accurate between the Hislop and Garrison faults (Berger, 2002).
Clastic and chemical metasedimentary rocks of the Timiskaming Assemblage occur within the deformation zone that varies between 100 m and 1,500 m wide. Talc-chlorite schist occurs along the north margin of the
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deformation zone in the Tisdale Assemblage and is indicative of ductile strain. The southern limit of the deformation zone is marked by brittle-ductile faulting accompanied by diabase dyke intrusions and abrupt contacts between the Lower Blake River and Timiskaming Assemblages. The deformation zone is near vertical and kinematics are poorly constrained. North-northeast and north-northwest brittle and brittle-ductile faults transect and offset the PDDZ.
One splay structure is also important to the Stock Mine property setting. The southwest-trending NHLFZ bifurcates/splays away from the main PDDZ in the vicinity of the Stock East deposit and has been traced by regional geophysical survey responses for approximately 15 km into the historically mined and explored Nighthawk peninsula area.
6.5 | Property Geology |
The Eastern Property straddles a 5 km segment of the regional PDDZ, between the GKDZ to the southwest and the Porcupine sediments to the northeast (Figure 6-13). The Black Fox and Froome mines are underlain by a complex series of faulted-thrusted slabs and wedges structurally emplaced into the 500 to 1,000 m belt that separates the PDDZ from the semi-parallel GKDZ splay structure. These intercalated, nonconformable units are generally composed of Lower Tisdale Assemblage, localized felsic intrusive rocks, and localized wedges of Porcupine and Temiskaming clastic sedimentary rocks. Grey Fox appears to lie stratigraphically above Black Fox and Froome and is possibly part of the Blake River assemblage.
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Figure 6-13: Interpreted Geology for the Fox Eastern Property
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6.5.1 | Grey Fox |
The Grey Fox deposit is underlain by an overturned, steeply east dipping assemblage of metasedimentary and massive, pillowed, and variolitic mafic metavolcanics with minor interflow sedimentary rocks. In the western part of the area, a syenitic to dioritic feldspar porphyry (locally referred to as the Gibson Syenite) intrudes the metasedimentary unit.
The deposit area is bound to the West by the steeply southwest dipping GKDZ (which juxtaposes a chlorite – talc schist, typical of the GKDZ at the Black Fox Complex) and a locally brecciated feldspar porphyry. This fault contact is locally crosscut by diabase dykes, likely of the Matachewan dyke swarm. To the east, the Grey Fox deposit is bound by a moderately- to steeply-dipping to the west/southwest fault. The HW rocks are comprised of mafic metavolcanic rocks, metasediments and the syenite package of the Grey Fox area, while the FW rocks are made up of moderately to steeply southwest dipping ultramafic and mafic metavolcanic rocks correlated with those hosting the Black Fox deposit. A penetrative foliation is developed with the bounding faults, and locally in narrow intra-package shear zones associated with mineralization and along contacts. No tectonic fabric corresponding to the regional fabric has been identified within the metasedimentary-metavolcanic-feldspar porphyry package hosting the deposit.
The metasedimentary package, previously assigned to the Timiskaming Assemblage by Berger (2002), is up to 350 m true width and consists of graded sandstone to mudstone layers, with bedding tops to the west. However, geochronological sampling by McEwen in 2021 of the Gibson syenite, which is observed to crosscut the sediments, returned a date of ~2,688.3 ± 0.9 Ma, suggesting the sediments (and possibly the adjacent volcanics) are part of the older lower Blake River formation.
At the Contact Zone, the metasedimentary-mafic metavolcanic contact is steeply dipping to the east from surface to a depth of approximately 300 m, below which the contact rolls to a steep dip to the west. West of the 147 Zone, the metasedimentary-metavolcanic contact steeply dips to the east from surface to the extent of drilling at 500 m below surface.
The mafic metavolcanic package, originally assigned to the Tisdale Assemblage by Berger (2002) but is now thought be part of the Lower Blake River Assemblage, is situated between the east dipping metasedimentary package to the west and west dipping ultramafic metavolcanic package to the east. The metavolcanic package ranges from 300 m true width in the north to at least 800 m at the southern boundary of the property. The mafic metavolcanic package consists of interleaved massive to pillowed mafic flows and massive to pillowed variolitic mafic interflows, with true widths ranging from 10 m to 130 m true width. The mafic metavolcanic flows dip steeply to the east and are truncated by the A-1 fault at the contact with the ultramafic metavolcanic rocks to the northeast. In the central part of the deposit, an outcrop of pillowed variolitic metavolcanic rock suggest flow tops are to the west.
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6.5.2 | Stroud Property |
The following description of the Stroud property is taken directly from the Hislop Township Gold Project, Matheson Area, Ontario, Technical Qualifying Report (Wetmore, 2004):
“Except where disturbed by faulting and minor folding, the predominantly metavolcanic rocks within the mineralized zone trend northwest and dip some 70 degrees to the southwest. The overlying argillites, arkose and arkosic conglomerates appear to conformably overlie the pillowed and massive metavolcanics. The ultramafic rocks appear to be semi-conformable within the Creek Zone and, in part, somewhat discordant in the Main Zone. The feldspar porphyry, likewise, shows both conformable and cross-cutting relationships to the metavolcanics. The steeply dipping, north to north-west trending diabase dykes cross-cut all rock units.
The hydrothermal alteration accompanying mineralization is typified by increasing carbonatization, sericitization, silicification and (plus or minus) hematite approaching the mineralization. Where hematized, the rocks have a pink cast. Altered metavolcanics, metasediments, and feldspar porphyry sections are subsequently bleached, appearing waxy yellow to buff-coloured, due to serecitization and carbonatization. Ultramafic rocks are generally dark waxy green where serpentinized or buff-coloured where carbonatized.
The indicated faults are generally cross-cutting to sub-parallel and exhibit ductile to brittle deformational characteristics. The most prominent of these is the steeply dipping Hislop Fault, and where encountered in drill core, is characterized by intense hydrothermal alteration, (hematization, sericitization), schistosity and /or fault gouge. The effect that it has on mineralization has not been determined.”
In 2025, McEwen drilled approximately 6,300 m at Stroud which was mainly designed to verify a historical resource. The geology and structures seen in the drill core were consistent with observations made from previous drilling campaigns performed on the property.
6.5.3 | Stock Property |
The Stock property occurs along the PDDZ corridor, which separates moderately- to steeply -south‑dipping Porcupine Assemblage turbiditic metasedimentary rocks to the north from ultramafic and mafic metavolcanic rocks of the Tisdale Assemblage to the south (Figure 6-14). Both the Porcupine and Tisdale Assemblages young to the south, based on graded bedding, pillow facing, and stratigraphic distribution patterns both on the property and in drilling on adjacent properties, although folding in the Porcupine Assemblage results in local inversions. The juxtaposition of South-younging (2,680 Ma to 2,690 Ma) Porcupine Assemblage to the north of the fault towards older structurally overlying and south younging (>2,700 Ma) Tisdale Assemblage rocks to the south indicates substantial reverse displacement along the contact area that forms the main strand of the PDDZ to emplace the older volcanic rocks onto the younger sedimentary units.
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Source: (McEwen, 2026)
Figure 6-14: Interpreted Geology of the Stock Property and the Significant Gold Mineralized Zones
6.5.4Western Properties
Generally, thick accumulations of glacial overburden cover more than 90% of the Timmins area. Only a limited number of bedrock exposures occur in the four Western Properties (Figure 6-15).
The northern sector of the Porcupine Mining Camp is dominated by an irregular accumulation of Tisdale Assemblage volcanic flows, intercalated with several belts and irregular wedges of Porcupine sediments. This stratigraphic sequence is apparently focused along an irregular lineament (known locally as the New Mines Trend) diverging westwards off a southwest-trending flexure of the PDDZ at the Pamour Mine splay-point.
Figure 6-16 is a stratigraphic column for the Timmins area which includes the Western Properties.
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Source: (McEwen, 2026)
Figure 6-15: Geological Plan View Map of the Timmins Area, which includes the Western Properties
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Source: (modified after Dinel et al., 2008)
Figure 6-16: Stratigraphic column for the Timmins area including McEwen’s Western Properties
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The southern sector of the central Porcupine Mining Camp is focused on a belt-sequence of mineralized bodies which extend from the Dome Mine (to east), through Buffalo Ankerite (a McEwen property) and the Paymaster and Fuller claims (non-McEwen properties), to the western Delnite Mine property. They occur within the South Tisdale Anticline sector and are underlain by a sequence of ultramafic and mafic flows of the Hershey Lake Formation, and locally subdivided mafic flows (C-series) of the Central Formation. The discordant contact/delineation between these two formations is locally referred to as the Paymaster Shear (Pope, 2000).
6.6Deposit Types
Numerous studies and exploration results over the past 50 years have focused on gold deposition styles and mineralization controls within the Abitibi Greenstone Belt. Most deposits are unique, with minor differences in geochemical characteristics and/or formational environments (Figure 6-17). Many of these gold deposit types can be grouped into “clans,” or families, of deposits that formed either through related processes or represent distinct products of large-scale hydrothermal systems (Robert et al., 1997; Poulsen et al., 2000).
The Eastern Properties, Stock Property, and Western Properties are all located proximal to an approximately 200 km central segment of the PDDZ, which has generated approximately 100 Moz of gold since 1910. More than 100 gold deposits are distributed along this major crustal-scale fault zone, which exhibits compressional to trans-extensional characteristics. Studies suggest a long-lived, multi-staged orogenic system, with repeated cycles of opening and closing resulting in the emplacement of auriferous quartz-carbonate veins, a major component of the Greenstone deposit clan (Dubé and Gosselin, 2007).

Source: (McEwen, 2026)
Note: Estimated gold production as of December 2025
Figure 6-17: Abitibi Greenstone Belt: Relationship of Gold Deposition to Major Structural Conduits
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6 Geological Setting, Mineralization, and Deposit
At the Black Fox and Froome mines and the Stock and Western Properties, gold-bearing veins are predominantly associated with:
· | Structurally controlled dilatant zones (shearing, brecciation, offsets) |
· | Greenschist facies metavolcanic host rocks |
· | Crustal-scale faults (i.e., the PDDZ) |
· | Syn-tectonic intrusive bodies |
These characteristics are consistently seen at the Western Properties, Stock Property, and Froome sites and are classified as orogenic gold occurrences related to longitudinal shear zones. These greenstone-hosted quartz-carbonate vein deposits represent a sub-type of lode gold deposits (Poulsen et al., 2000) and correspond to structurally controlled, complex epigenetic deposits hosted in deformed, metamorphosed terranes (Dubé and Gosselin, 2007) (Figure 6-18).
Gold mineralization at the Grey Fox deposit, located approximately 3 km southeast of the Black Fox Mine, exhibits the following characteristics:
· | Spatial association with syenite, melanosyenite, and quartz-feldspar porphyritic intrusive rocks. |
· | Strong association with molybdenum, tungsten, and arsenic geochemistry (Kelly, 2018). |
· | Occurrence within narrow quartz-carbonate veins exhibiting crustiform and colloform textures. |
· | Spatial association with sericite-albite-carbonate alteration. |
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6 Geological Setting, Mineralization, and Deposit

Source: (modified after Poulsen et al., 2000; Robert, 2004)
Figure 6-18: Schematic Cross-Section of Main Gold Systems Showing Depth of Emplacement
The current interpretation of the Fox Complex Exploration team is that the Grey Fox deposit could be a combination of epizonal and orogenic gold deposits.
6.6.1Greenstone-Hosted Quartz Carbonate-Vein Deposits
Greenstone-hosted quartz-carbonate vein deposits typically occur in deformed greenstone terranes of all ages (Dubé and Gosselin, 2007), especially those containing commonly variolitic tholeiitic basalts and ultramafic komatiitic flows intruded by intermediate to felsic porphyry intrusions, sometimes with swarms of albitite or lamprophyre dykes (for example, Timmins and Red Lake districts). Deposits are associated with collisional or accretionary orogenic events and are typically distributed along reverse-oblique, crustal-scale major fault zones, commonly marking convergent margins between major lithological boundaries such as volcano-plutonic and sedimentary domains (for example, the PDDZ and the CLDZ). These major structures are characterized by varying increments of strain, resulting in multiple generations of steeply dipping foliations and folds within a complex collisional geological setting.
Crustal-scale faults are thought to represent the main hydrothermal pathways toward higher crustal levels. However, deposits are spatially and genetically associated with higher-order compressional reverse-oblique
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6 Geological Setting, Mineralization, and Deposit
to oblique brittle-ductile high-angle shear zones, commonly located less than 5 km away and best developed in the HW of the major fault (Robert, 1990). Brittle faults may also host mineralization, as illustrated by the Kirkland Lake Main Break, a brittle structure hosting the 25 Moz Kirkland Lake gold deposit. The deposits typically formed late in the tectonic-metamorphic history of the greenstone belts (Groves et al., 2000), with mineralization occurring syn- to late-deformation, typically post-peak greenschist facies and syn-peak amphibolite facies metamorphism (Kerrich and Cassidy, 1994; Hagemann and Cassidy, 2000).
The greenstone-hosted quartz-carbonate vein deposits are also commonly spatially associated with Timiskaming-type regional unconformities. Several deposits are hosted by a Timiskaming-like regional unconformity (e.g., the Pamour and Dome deposits in Timmins) or located next to one (e.g., the Campbell-Red Lake deposit in Red Lake) (Dubé et al., 2003), suggesting an empirical time and space relationship between large-scale greenstone quartz-carbonate gold deposits and regional unconformities (Hodgson, 1993; Robert, 2000; Dubé et al., 2003).
Stockworks and hydrothermal breccias may represent the main host to the mineralization when developed in competent units such as granophyric facies of gabbroic sills. Due to the complexity of the geological and structural setting, and the influence of strength anisotropy and competency contrasts, the geometry of the vein network varies from simple (such as the Silidor deposit in Canada) to complex geometries with multiple orientations of anastomosing and/or conjugate sets of veins, breccias, stockworks and associated structures (Dubé et al., 1989; Hodgson, 1989; Robert et al., 1994; Robert and Poulsen, 2001).
Economic-grade mineralization also occurs as disseminated sulphides in altered (carbonatized) rocks along vein selvages. In this document, the term ore is used in its common industry sense (for example, ore shoots, ore mineral, ore pass) and does not imply Mineral Resources or Mineral Reserves.
Ore shoots are commonly controlled by either:
· | Intersections between different veins or host structures, or between an auriferous structure and a reactive and/or competent rock type such as iron-rich gabbro (geometric ore shoot). |
· | The slip vector of the controlling structure(s) (kinematic ore shoot). For laminated fault-fill veins, the kinematic ore shoot is oriented at a high angle to the slip vector (Robert et al., 1994; Robert and Poulsen, 2001). |
At the district scale, greenstone-hosted quartz-carbonate vein deposits are associated with large-scale carbonate alteration, commonly distributed along major fault zones and subsidiary structures (Dubé and Gosselin, 2007). At the deposit scale, the nature, distribution, and intensity of the wall-rock alteration are largely controlled by the composition and competence of the host rocks and their metamorphic grade. Typically, alteration haloes are zoned and characterized, at greenschist facies, by iron carbonatization and sericitization, with sulphidation of immediate vein selvages (mainly pyrite, less commonly arsenopyrite).
The main gangue minerals are quartz and carbonate, with variable amounts of white micas, chlorite, scheelite, and tourmaline. Sulphide minerals typically constitute less than 10% of the mineralization. The main ore minerals are native gold with pyrite, pyrrhotite, and chalcopyrite, without significant vertical zoning (Dubé and Gosselin, 2007).
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6.6.2Low-Sulphidation Epithermal Gold Deposits
At the district scale or larger, the tectonic setting of epithermal gold deposits is characterized by extension, which localizes and facilitates the emplacement of magma and, at higher levels, hydrothermal fluids (Taylor, 2007). Regionally extensive rift zones can also provide the extensional framework. Pull-apart basins formed between regional strike-slip faults, or at transitions between these faults, provide favourable sites for intrusions and epithermal deposits. Synchronous tectonic and hydrothermal activity is indicated in some deposits by the fact that many of the vein-bearing faults were active during and after vein filling, resulting in tectonic vein breccias and displacement of mineralized and altered rocks.
Low-sulphidation epithermal gold deposits are harder to recognize in ancient terranes because they are often not as intimately associated with igneous rocks, and their commonly occurring alteration mineral assemblages may not be unique or may no longer be preserved, depending on the grade of subsequent metamorphism (Taylor, 2007).
Low-sulphidation epithermal gold deposits are distinguished from high-sulphidation deposits primarily by their sulphide mineralogy (pyrite, sphalerite, galena, chalcopyrite), typically hosted within quartz veins with local carbonate, and by associated near-neutral wall-rock alteration (illite clays) deposited from dilute hydrothermal fluids (Corbett and Leach, 1998).
Nearly any rock type (even metamorphic rocks) may host epithermal gold deposits, although volcanic, volcaniclastic, and sedimentary rocks tend to be more common (Taylor, 2007). Typically, epithermal deposits are younger than their enclosing rocks, except where deposits form in active volcanic settings and hot springs. In these cases, the host rocks and epithermal deposits can be essentially synchronous with spatially associated intrusive or extrusive rocks. Lithological control mainly reflects competent or brittle host rocks that develop throughgoing fractures that act as vein hosts, although permeability is locally important. In interlayered volcanic sequences, epithermal veins may be confined to competent rocks, while intervening less competent sequences preferentially host fault structures (Corbett, 2007).
Low-sulphidation gold deposits that occur further removed from active magmatic vents may be controlled by structural features, with zones of fluid mixing and emplacement of smaller magmatic bodies (e.g., dykes) (Taylor, 2007). Meteoric waters dominate the hydrothermal systems, which are nearly pH neutral in character. Low-sulphidation gold deposit related geothermal systems are more closely linked to passive rather than active magmatic degassing (if at all) and are sustained by the energy provided by cooling subvolcanic intrusions or deeper magma chambers.
The morphology of epithermal vein-style deposits can be quite variable. Deposits may consist of roughly tabular lodes controlled by the geometry of the principal faults they occupy, or comprise interconnected fracture fillings in stockworks, breccias, and lesser fractures, or form by replacement of rock or void space. These deposits may take on the morphology of the lithological unit or porous rock body replaced (e.g., irregular breccia pipes and lenses). Volumes of replacement mineralization may be discordant and irregular, or concordant and tabular, depending on porosity, permeability, and water-rock interaction. In very near-surface deposits, an upward enlargement of altered and mineralized zones may be found centered around hydrothermal conduits. Brecciation of previously emplaced veins can form permeable zones along irregularities in fault planes, resulting in vertically plunging mineralized zones in strike-slip faults and more horizontal mineralized zones in dip-slip faults.
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6 Geological Setting, Mineralization, and Deposit
Structures act as fluid pathways, and dilational portions of these structures may represent sites of enhanced fluid flow, promoting the development of ore shoots that host most mineralization in many low-sulphidation vein systems (Corbett, 2002). Elsewhere, fault intersections host ore shoots at sites of fluid mixing. Several structural settings produce ore shoots of varying orientations. Steeply dipping strike-slip structures develop vertical ore shoots in flexures and fault jogs, where tension veins and dilatant sheeted veins are common. Normal and listric faults in extensional settings host wider and higher-grade veins as flatter ore shoots within steeply dipping vein systems. In compressional settings, reverse faults host flat-plunging ore shoots.
6.6.3Epizonal-Type Gold Deposits
Epizonal gold deposits represent a sub-class of orogenic gold systems formed at shallow crustal levels, typically at depths of less than 6 km and under relatively low temperature conditions of approximately 200°C to 350°C (Gebre-Mariam et al., 1995; Groves et al., 1998). These conditions give rise to a suite of geological and structural characteristics that distinguish epizonal deposits from their mesozonal and hypozonal counterparts. Epizonal deposits are further distinguished from epithermal deposits by the depth of formation, and by the former being derived from orogenic fluids utilizing deep-seated structures as fluid + pathways, whereas the latter are largely formed by circulating meteoric fluids due to heating from a proximal igneous source (Figure 6-19).

Source: (Groves et al. 1998)
Figure 6-19: Schematic Comparison of Epithermal and Orogenic Environments
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6 Geological Setting, Mineralization, and Deposit
Epizonal deposits form under low-pressure conditions characteristic of upper crustal environments and are associated with brittle deformation regimes. Mineralization is typically hosted within fault zones, brittle shear zones, vein arrays, and fracture networks. Ore-bearing vein systems are dominated by quartz–carbonate– sulfide assemblages, occurring as stockworks and sheeted vein sets. Diagnostic vein textures include crustiform banding, comb quartz, open-space filling, and breccias, which collectively reflect the brittle deformation conditions and episodic, high-flux fluid flow events characteristic of the epizonal environment (Groves et al., 1998; Goldfarb and Groves, 2015).
Past and ongoing studies at Grey Fox including fluid inclusion studies, mapping, core logging, and modeling suggest that the Gibson, 147, Contact and Grey Fox South zones may have formed in an epizonal gold setting. The absence of alteration consistent with circulating meteoric fluids suggest an epizonal orogenic environment as opposed to a near-surface epithermal one. Fluid inclusion work at Grey Fox commissioned by McEwen (Tuba, 2019, internal report) suggests a formational depth for the gold veining at Grey Fox at ~1.5 to 2.0 kbar which equates to ~5-7 km depth, deeper than typical epithermal deposits and placing it within the lower epizonal to upper mesozonal regimes (Groves et al., 1998), possibly transitioning from one to the other as vein textures appear to show characteristics of both epizonal (Gibson, 147, Grey Fox South) and mesozonal (Whiskey Jack) environments.
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7 Exploration and Drilling Programs
7Exploration and Drilling Programs
This section summarizes the exploration and drilling programs completed within the greater Fox Complex and the Grey Fox Project area and describes the methods used to collect, document, and validate geological information. Exploration activities have included geological mapping, geophysical surveys, surface sampling, and diamond drilling, which collectively support the geological interpretation, Mineral Resource estimation, and ongoing evaluation of the Project. The section also describes drilling procedures, core handling and logging practices, and other exploration activities relevant to the understanding of the mineralization.
7.1General Exploration
7.1.1Eastern Properties
Following acquisition of the Eastern Properties in 2017, McEwen conducted a range of exploration activities beginning in 2018, including geophysical surveys, drilling, and trenching. Several exploration programs were carried out concurrently across the claim group, allowing evaluation of several targets through property-scale surveys and drilling campaigns.
Figure 7-1 presents a plan view geology map of the Eastern Properties (excluding Black Fox North) and illustrates the locations of the principal zones that make up the Grey Fox deposit (Whiskey Jack, Gibson, Contact, 147NE, 147, and Grey Fox South).
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7 Exploration and Drilling Programs

Figure 7-1: Plan View Geology Map for the Eastern Property
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7 Exploration and Drilling Programs
7.1.1.1 Grids and Surveys
The most recent traditional grid work was completed between 2002 and 2003 to facilitate an EM TITAN-24 geophysical survey over the Grey Fox and Froome areas. In September 2019, a UAV photographic survey was completed over the Grey Fox target area to support geological mapping and target evaluation. Several low-altitude UAV surveys were also conducted over exposed bedrock areas within the 147 Zone.
7.1.1.2 Geological Mapping
The Eastern property is generally overlain by 5 m to 40 m of clay and till overburden, which significantly limits bedrock exposure. Known bedrock exposures are limited to localized areas south of the Black Fox mining operations and at a road cut along Highway 101 west of the property boundary, where mafic volcanic rocks and a Matachewan diabase dyke are exposed. No natural bedrock exposures have been identified within the Grey Fox or Froome areas.
7.1.1.3 Geochemical Sampling
The presence of extensive glacial tills and dense clay overburden, locally up to 40 m thick, limits the effectiveness of conventional soil geochemistry surveys across the Eastern Properties. As a result, such surveys have not been widely utilized.
7.1.1.4 Geophysics
Several vintages of regional airborne geophysical surveys have been conducted across the Eastern Properties, including the Grey Fox, Froome, and Black Fox areas. These surveys have supported regional geological interpretation, including identification of structural features and lithological boundaries.
In 2010, a DCIP TITAN-24 geophysical survey was completed over the majority of the Eastern Properties, with anomalies identified from this program contributing directly to the discovery of the Froome deposit. In 2025, an additional TITAN-24 DCIP and MT survey was completed over the southern portion of the Eastern Properties, specifically Grey Fox (Figure 7-2). Several anomalies were identified, including a broad resistivity high in the Gibson area, which is interpreted to correspond to known mineralization.
Airborne magnetic surveys, including a property-wide survey completed in 2010 and higher-resolution drone-based surveys completed in 2025 over the Grey Fox/Stroud and Froome areas, have helped define the lithological and structural boundaries across the property.
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7 Exploration and Drilling Programs

Figure 7-2: 2025 High-Res Drone Magnetic Survey over Grey Fox
Completed geophysical surveys are summarized in Table 7-1.
Table 7-1: Eastern Properties Geophysical Surveys
Date / | | Service | | | | | | |
Location | | Provider | | Survey Type | | Survey Basis | | Note |
1991 | | Noranda | | Total Field Magnetic & | | - | | Froome Lake Claim |
| | | | VLF Electromagnetic | | | | |
| | | | survey | | | | |
1993 | | Exscis | | Total Field Magnetic VLF | | Survey grid totalling 15.4 line- | | - |
| | Exploration | | Electromagnetic survey | | km | | |
| | Ltd. | | | | | | |
2003 | | Quantec | | Electromagnetic TITAN | | Deep penetrating | | - |
Black Fox | | | | 24 geophysical survey | | | | |
Complex | | | | | | | | |
2010 | | Scott Hogg & | | Airborne magnetics | | - | | - |
Black Fox | | Associates | | | | | | |
| | Ltd. | | | | | | |
2010 | | Quantec | | TITAN 24 survey | | DCIP & MT | | Coverage of the |
| | | | | | | | majority of the Eastern |
| | | | | | | | properties. |
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Date / | | Service | | | | | | |
Location | | Provider | | Survey Type | | Survey Basis | | Note |
2016 | | Exsics | | Down-hole mise-à-la- | | Two holes within Froome | | Sedimentary rock dips |
Froome | | Exploration | | masse electromagnetic | | mineralization | | to the south-southwest |
| | Ltd. | | survey | | | | and strike length of |
| | | | | | | | 125 m-175 m |
2018 | | Geotech Ltd. | | Helicopter-borne | | Two survey grids totalling | | Several conductors |
Black Fox | | | | electromagnetic survey, | | 1,164 line-km split between | | delineated; no follow |
& Stock | | | | high-resolution VTEM | | Black Fox Complex and Stock | | up drilling has |
Mill | | | | | | Mill | | occurred |
2019 | | CGG Canada | | Airborne gravity | | 100 m spaced grid lines flown | | Four target areas |
| | Services Ltd. | | gradiometry employing | | at a height of 35 m. | | outlined for exploration |
| | TERRA | | the HeliFALCON platform | | Filtering was completed to | | follow-up, two of which |
| | Resources | | | | reduce terrain effects, line | | have been previously |
| | | | | | corrections and potential | | drilled and explained. |
| | | | | | impact from underground | | |
| | | | | | voids | | |
2019 | | Quantec | | Orion 3D plus | | 3D depth connection between | | Favourable resistivity |
Grey Fox | | Geoscience | | electromagnetic survey | | responses collected at surface | | likely indicating silica- |
| | | | | | and in situ bedrock. | | albite enrichment at |
| | | | | | Electromagnetic injections | | 500 m level occurring |
| | | | | | within a 1.5 km x 1.8 km | | below current drill |
| | | | | | quadrant – 176 from surface, | | limits. Follow-up with |
| | | | | | 256 subsurface from 7 holes. | | 750 m holes in 2021 |
| | | | | | | | and 2022. |
2025 | | Quantec | | TITAN24 DCIP & MT | | To support mineral exploration | | |
| | Geoscience | | Geophysics Survey | | by using subsurface resistivity | | |
| | | | | | and chargeability data to | | |
| | | | | | identify key geological | | |
| | | | | | features, delineate potential | | |
| | | | | | mineralized zones, and map | | |
| | | | | | lithological variations. | | |
| | | | | | Specifically, the survey aims to | | |
| | | | | | detect structures such as | | |
| | | | | | faults, fractures, and | | |
| | | | | | mineralized areas, distinguish | | |
| | | | | | mineralized from non- | | |
| | | | | | mineralized rock based on | | |
| | | | | | electrical contrasts, and | | |
| | | | | | differentiate rock types to | | |
| | | | | | improve geological mapping | | |
| | | | | | and targeting. | | |
2025 | | Terrascope | | Drone Magnetic Survey | | Drone magnetic survey over | | |
| | Inc. | | | | Grey Fox including Stroud | | |
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7.1.1.5 Pits and Trenches
In September 2019, McEwen exposed a part of the 147NE structure near-surface. High-pressure washing followed by detailed geological mapping confirmed the presence of northwest-dipping veinlets and breccias hosted within massive mafic volcanic rocks. This work provided additional insight into the continuity and relationship between hydrothermal breccias and veinlets within the 147 area that define mineralized structures.
Channel samples were then cut-collected across the exposed mineralized structure. Sample channels were cut with walls 8 cm to 10 cm apart and to depths of approximately 10 cm to 13 cm. Gold assays returned low-grade values.
7.1.1.6 Additional Surveys
In September 2019, Zen GeoMap conducted several low-altitude (<30 m above ground level) UAV survey passes on a grid pattern over the 147-target area, which had recently been exposed by mechanical stripping. This work generated high-resolution imagery of the brecciated vein system and confirmed the intensity, orientation, and structural limits of the breccia-hosted vein model within the Grey Fox area.
7.1.1.7 Exploration Potential
Considerable exploration potential exists for the remainder of the Eastern Properties, including:
· | Untested volcanic stratigraphy within the FW of the Black Fox-Grey Fox trend. |
· | Assessment of the actual track of the PDDZ structure extending approximately 4 km southeast of the Black Fox mining operations. |
· | Northwest of the current Gibson Zone resource at Grey Fox where there is evidence of repeating veins sets associated with contact between the Gibson Syenite and metasediments to the east. |
· | Below 300 m el. at the Whiskey Jack Zone at Grey Fox where the mineralization remains open. |
· | Deeper (>300 m el.) drilling at Grey Fox South where the drilling density is lower when compared to other parts of the deposit. |
An ongoing exploration program at Froome is targeting potential extensions of mineralization at depth and along strike.
Continued drilling at Black Fox North could potentially identify ‘Croesus-style’ veins that may extend along strike from the historic Croesus Mine, located approximately 5 km southeast of the Black Fox North claims.
7.1.2Stock Property
Historically, the lack of sustained exploration funding and limited gold production within the Shillington-Stock area have resulted in exploration efforts being focused primarily on “quick-test” drilling along the east-west track of the PDDZ. Mine infrastructure and hazards commonly limit access into prospective staging points for proposed exploration drilling. A summary of the historical exploration activities at Stock can be found in “Technical Report Summary on the Initial Assessment of the Fox Complex, Ontario, Canada” (McEwen, 2025).
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7 Exploration and Drilling Programs
Since McEwen took ownership of the Stock property in 2017, exploration activities have included aerial and geophysical surveys, structural interpretation and analysis, and drilling. Significant drilling programs have been completed at Stock West, Stock Main, and Stock East over the past nine years.
The majority of exploration at the Stock property since the 1990s has been concentrated within three discrete areas, each approximately 600 m x 400 m in size, or “windows,” that straddle the prominent PDDZ corridor as it tracks across the property. Escalating success at Stock East between 2018 and 2024, followed by success at Stock West from 2019 to 2023, has dominated exploration planning, culminating in updated Mineral Resource estimates, as well as initiation of studies such as an IA, an internal economic study and consultations. Future Exploration drilling should focus on the down plunge components of Stock West, Stock Main (down the ‘N2’ chute) and Stock East (Figure 7-3).

Note: Looking north. All drill hole results reported as TWs.
Figure 7-3: Longitudinal Section View of Stock Property
Drilling at Stock Main from 2021 to 2023 has targeted potential additions to mineralization near surface, at depth, and in proximity to the proposed Stock West decline and portal area.
7.1.3Western Properties
A summary of exploration activities for the Western Properties can be found in a technical report prepared by Roscoe Postle & Associates (Altman et al. 2014), supplemented by internal documentation generated between 2012 and 2015. In addition, all active Mineral Resource estimates for the Western Properties are not material to the Grey Fox Mineral Resource estimate contained in this report.
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7.2Drilling Programs
A significant amount of drilling has been completed at the Fox Complex over the past century, much of which is historical in nature. Drilling described herein includes holes drilled for geological exploration, metallurgical testwork and geotechnical investigations. A complete drilling history is summarized in Section 5. Drill holes used in the Mineral Resource estimations are summarized below.
7.2.1Eastern Properties
The Eastern Properties comprise Grey Fox, Stroud, Froome, and Black Fox properties.
Approximately 1,713 drill holes totaling 633,384.5 m have been completed in the Grey Fox-Hislop-Stroud area by several operators since 1993. Drill holes used in the Grey Fox and Stroud Mineral Resource estimations are summarized in Table 7-2. Figure 7-4 shows the locations of surface drill hole collars for the Eastern Properties. Drilling at Froome from 2000 to the present consists of 1,111 drill holes (221,282 m). The drill holes used in the Froome Mineral Resource Estimate are summarized in Table 7-3.
A total of 7,731 core drill holes, totaling approximately 1,097,796 m, have been completed on the Black Fox Mine property since 1989. Drill holes in the Black Fox Mineral Resource estimation are summarized in Table 7-4.
Table 7-2: Summary of Grey Fox and Stroud Drilling Used in Mineral Resource Estimation
Company | | Year | | No. Drill Holes | | Metres Drilled | | Target Zone |
| | | | | | | | |
Gunnex Ltd. | | 1974 | | 32 | | 2,573 | | Stroud |
Pancontinental Mining Ltd. | | 1980 | | 13 | | 1,691 | | Stroud |
Pancontinental Mining Ltd. | | 1981 | | 6 | | 1,292 | | Stroud |
Chevron Minerals Ltd. | | 1986 | | 9 | | 1,437 | | Stroud |
Chevron Minerals Ltd. | | 1987 | | 23 | | 3,679 | | Stroud |
Chevron Minerals Ltd. | | 1988 | | 38 | | 10,128 | | Stroud |
Chevron Minerals Ltd. | | 1989 | | 5 | | 1,806 | | Stroud |
Noranda, St Andrew | | 1993 | | 10 | | 3,118 | | Stroud, Grey Fox |
Goldfields Ltd. | | | | | | | | |
Noranda | | 1994 | | 4 | | 762.0 | | Grey Fox |
Battle Mountain/ Hemlo | | 1995 | | 8 | | 2,109.0 | | Grey Fox |
Gold | | | | | | | | |
Battle Mountain/ Cameco | | 1996 | | 16 | | 5,872.0 | | Contact, 147 and South Zone, |
Gold | | | | | | | | Gibson and Hislop North |
Battle Mountain/ Cameco | | 1997 | | 13 | | 5,367.5 | | Contact, 147, South Zone, Gibson |
Gold | | | | | | | | and Hislop North |
Glimmer/Exall | | 2001 | | 4 | | 1,667.0 | | Romios |
St Andrew Goldfields Ltd. | | 2006 | | 6 | | 2,058 | | Stroud |
St Andrew Goldfields Ltd. | | 2007 | | 16 | | 5,337 | | Stroud |
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Company | | Year | | No. Drill Holes | | Metres Drilled | | Target Zone |
| | | | | | | | |
Apollo Gold | | 2008 | | 16 | | 3,715.0 | | Southern extension of Contact |
| | | | | | | | Zone |
Apollo Gold | | 2009 | | 53 | | 9,960.0 | | Contact Zone |
Brigus Gold | | 2010 | | 69 | | 26,766.2 | | Contact Zone, Gibson, South |
| | | | | | | | Zone, Hislop North, 147 Zone |
Brigus Gold | | 2011 | | 274 | | 101,893.2 | | Contact Zone, Gibson, South |
| | | | | | | | Zone, 147 Zone |
Brigus Gold | | 2012 | | 268 | | 81,444.4 | | Contact Zone, 147 Zone, South |
| | | | | | | | Zone |
Brigus Gold | | 2013 | | 144 | | 63,816.4 | | Contact Zone, 147 Zone, South |
| | | | | | | | Zone |
Primero | | 2014 | | 187 | | 76,027.2 | | Contact Zone, 147 Zone, South |
| | | | | | | | Zone |
Primero | | 2015 | | 56 | | 25,716.7 | | Contact Zone, Gibson, South Zone |
McEwen | | 2018 | | 46 | | 17,896.5 | | Gibson, 147 Zone, 147NE Zone |
McEwen | | 2019 | | 222 | | 90,341.7 | | Gibson, 147 Zone, 147NE Zone, |
| | | | | | | | South Zone, Whiskey Jack |
McEwen | | 2020 | | 15 | | 5,061.7 | | Whiskey Jack |
McEwen | | 2021 | | 29 | | 11,404.8 | | Contact Zone, Gibson, 147 Zone, |
| | | | | | | | South Zone, Whiskey Jack |
McEwen | | 2022 | | 14 | | 6,561.2 | | Contact Zone, Whiskey Jack |
McEwen | | 2023 | | 21 | | 11,047.8 | | Contact Zone, Gibson, Whiskey |
| | | | | | | | Jack |
McEwen | | 2024 | | 126 | | 41,872.8 | | Contact Zone, Gibson, 147 Zone, |
| | | | | | | | South Zone, Whiskey Jack |
McEwen | | 2025 | | 93 | | 32,900.4 | | Stroud, Grey Fox |
McEwen | | 2026 | | 3 | | 668 | | Stroud |
Total | | | | 1,839 | | 655,990.5 | | |
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7 Exploration and Drilling Programs

Figure 7-4: Distribution of Drilling at the Eastern Properties
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7 Exploration and Drilling Programs
Table 7-3: Summary of Froome Drilling Used in Mineral Resource Estimation
Company | | Year(s) | | No. Drill Holes | | Metres Drilled |
Noranda | | 1989-1994 | | 1 | | 197 |
Glimmer/Exall | | 2000-2002 | | 1 | | 200 |
Apollo Gold | | 2003-2007 | | 1 | | 693 |
Primero | | 2014-2017 | | 219 | | 64,997 |
McEwen | | 2018-2025 | | 890 | | 155,392 |
Total | | | | 1,112 | | 221,479 |
Table 7-4: Summary of Black Fox Drilling Used in Mineral Resource Estimation
Company | | Year | | No. Drill Holes | | Metres Drilled |
Noranda | | 1989-1994 | | 119 | | 23,987 |
Glimmer/Exall | | 1998-2002 | | 876 | | 84,828 |
Apollo Gold | | 2003-2009 | | 898 | | 222,904 |
Apollo Gold/Brigus Gold | | 2010-2013 | | 1,456 | | 146,049 |
Primero | | 2014-2017 | | 2,610 | | 374,368 |
McEwen | | 2018-October 2024 | | 1,772 | | 245,660 |
Total | | | | 7,731 | | 1,097,796 |
7.2.2 | Stock Property |
Drilling at the Stock Property has been completed across multiple target zones, including Stock East, Stock West, and Stock Main, to support Mineral Resource delineation. Drill holes used in the Stock Mineral Resource estimations are summarized in Table 7-5, with drill hole collar locations shown in Figure 7-5.
Table 7-5: Summary of Stock Drilling Used in Mineral Resource Estimation
Company | | Year(s) | | No. Drill Holes | | Metres Drilled | | Target Zone |
St Andrew | | 1983-2008 | | 47 | | 13,320 | | Stock East |
Brigus Gold | | 2011 | | 6 | | 2,166 | | Stock West |
Brigus Gold, Primero | | 2014 | | 15 | | 5,663 | | Stock Main |
Primero | | 2015 | | 19 | | 4,699 | | Stock Main |
McEwen | | 2018 | | 90 | | 26,704 | | Stock East, Main |
McEwen | | 2019 | | 106 | | 46,461 | | Stock East, West |
McEwen | | 2020 | | 30 | | 17,727 | | Stock West |
McEwen | | 2021 | | 142 | | 68,298 | | Stock West, Main |
McEwen | | 2022 | | 126 | | 50,288 | | Stock West, Main |
McEwen | | 2023 | | 185 | | 62,928 | | Stock West, Main, East |
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7 Exploration and Drilling Programs
Company | | Year(s) | | No. Drill Holes | | Metres Drilled | | Target Zone |
McEwen | | 2024 | | 49 | | 9,627 | | Stock East |
Total | | | | 815 | | 307,881 | | |
All drilling data for Grey Fox, Froome, Black Fox and Stock properties are current to the individual drilling database cut-off dates applied in the Mineral Resource estimates, as summarized below:
· | Grey Fox – 11 July 2025 |
· | Froome – 31 December 2025 |
· | Black Fox – 31 December 2025 |
· | Stock – West and Main Zones – 23 October 2023 |
· | Stock – East Zone – 20 May 2024 |
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7 Exploration and Drilling Programs

Figure 7-5: Distribution of Surface Drilling at the Stock Property
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7 Exploration and Drilling Programs
7.2.3Western Properties
The Western Properties include the Davidson-Tisdale and Buffalo Ankerite properties. Multiple phases of exploration and mining activity have occurred on these properties since 1910. Prior to the early 2000s, exploration drilling was sporadic and driven by mineralization boundaries. Historical drilling records are available in paper format and require additional organization to support future work.
Lexam conducted systematic, results-driven exploration programs between 2003 and 2015. Details of drilling procedures during this period are assumed based on review of several available drill logs, maps and cross & longitudinal sections from that era.
A summary of drilling completed on the Davidson-Tisdale property is provided in Table 7-6, with drill hole collar locations shown in Figure 7-6 and Figure 7-7.
Drilling completed at the Buffalo Ankerite deposit does not support a current Mineral Resource estimate and is therefore not considered relevant to this report.
Table 7-6: Summary of the Western Properties Drilling Used in the Mineral Resource Estimate
Company | | Year(s) | | No. Drill Holes | | Metres Drilled |
Davidson-Tisdale Property | | | | | | |
DTM | | 1983-1984 | | 35 | | 4,576.8 |
Getty | | 1984-1987 | | 537 | | 49,165.9 |
Midas Minerals | | 1989 | | 5 | | 1,486.2 |
Northcott | | 1999-2003 | | 17 | | 399.3 |
Lexam | | 2003-2015 | | 97 | | 24,397.5 |
Total | | | | 691 | | 80,025.7 |
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7 Exploration and Drilling Programs

Figure 7-6: Southern Portion of the Western Properties Drill Hole Collar Location Plan
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7 Exploration and Drilling Programs

Figure 7-7: Northern Portion of the Western Properties Drill Hole Collar Location Plan
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7 Exploration and Drilling Programs
7.3Drilling Methods
Early drilling operations conducted from both surface and underground were completed using primarily diamond drilling methods. Historical drill data have not been used to define Mineral Resources unless the data could be verified through documented QA/QC procedures, supported by confirmation from nearby drill holes or re-logged using McEwen’s logging, sampling and QA/QC procedures.
7.3.1Eastern Properties
Surface diamond drilling operations at the Eastern Properties have been conducted by several local drilling contractors since the 1970s. Standard drilling procedures and protocols have remained consistent as rigs shift from target to target within the property area. No underground exploration drilling has been completed at Grey Fox since the late 1980s, when Gold Post Resources conducted an underground drill program at the historical Gibson mine.
Fully hydraulic diamond drill rigs have been commonly utilized by the various drilling contractors since 2010. Advancements such as mechanized rod breaking, remote-control manipulation, and safety-perimeter cages have improved drilling efficiency, with coring performance increasing by approximately 30% to 50%. As a result, typical production rates today range from 80 m to 120 m per 24-hour period.
NQ-diameter coring (47.6 mm) has been the standard drill core size at the Grey Fox and Froome targets since 2010. Drill core is removed from the core tube carrier and immediately placed into wooden core boxes with a capacity of approximately 4.5 m of core. During drilling, contractors place a small wooden block identifying the downhole length of overburden and progressively place depth marker blocks at 3 m intervals of core. Once filled, the core boxes are transported to McEwen’s nearby core facility for logging, photography, and sawing for assay. As drill rods are withdrawn in 3 m lengths, drillers carefully count the rods arriving to surface to verify that the lowest depth-block recorded in the core boxes is accurate.
7.3.1.1 Grey Fox
Sludge samples were collected at Grey Fox during drilling programs in 1979 and throughout the 1980s and were used as a guide for most of the core sampling. Core diameter was NQ from 1983 onwards with BQ used prior to that time. Heath & Sherwood served as the drilling contractor during this period. Reports from Mr. Peter Ginn (claim owner during that period) do not document the core sampling methods used. All information from this time period was acquired from the MLAS (Mining Lands Administration System – Ontario) and does not specify any details.
During Noranda-era drilling (1988-1994), NQ-diameter core was collected and transported to the Hemlo Gold Mines storage facility at the Aunor mine site in Timmins. Core was split for assay. Longyear was the drilling contractor used during this period.
From 2018 to the present, McEwen has employed several surface diamond drilling contractors at Grey Fox, including Norex (now Major Drilling), Black Diamond Drilling, NPLH Drilling, and Major Drilling. The primary core size has remained NQ. Drill core collected from 2018 to 2019 was shipped to temporary logging facilities located at the intersection of Pine Road and Tamarack Road, in proximity to the Black Fox mine.
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7 Exploration and Drilling Programs
From 2020 onward, Grey Fox drill core has been logged at either the Stock Mill facilities or the Black Fox mine core shack.
7.3.1.2 Stroud
Historical drilling (post 1970) on the property was completed by experienced Canadian diamond drill contractors using industry-standard methods of the time. The earliest programs used B- and A-diameter core, while later Chevron and other programs predominantly used wireline NQ core. Drill collars were surveyed from the property grid, and hole deviation was monitored at regular intervals, with gyroscopic surveys used where greater accuracy was required. Core handling, logging, sampling, and QA/QC procedures were conducted in accordance with accepted industry practice for the time, including standards, blanks, and check assays. Most drill core and supporting geological and assay records are still available, providing an adequate basis for interpretation and incorporation into the PFS. Since the McEwen acquisition of Stroud in 2024, the same practice that has been used for Grey Fox, which is described in Section 7.3.1.1, has been implemented.
7.3.1.3 Black Fox
Initial surface stage drilling operations at Black Fox were conducted by Noranda between 1989 and the mid-1990s and was performed using NQ-diameter core, with reduction to BQ diameter where ground conditions required. Drilling during this period was executed by Norex Drilling (since merged with Major Drilling). Drill core was sent to the Hemlo Gold Mines storage facility at the Aunor mine site in Timmins for storage and logging. The core was split and sent for assay.
Subsequent diamond drilling at Black Fox, completed up to 2026, was a combination of surface and underground drilling programs. Specific drilling details are summarized in Table 7-4. Drilling during this period was completed by several drilling contractors. Core diameters varied from HQ to BQ, depending on ground conditions and hole length. The exploration core was processed, split and stored at the Black Fox core facility prior to being sent for assay. Delineation and definition core were similarly processed and sampled at the Black Fox core facility and sent for assay. Any remaining portions of delineation and definition core were discarded.
7.3.1.4 Stock Property
Drilling operations completed at the Stock Property since 2018 have employed the same drilling contractors and operating procedures described for the Eastern Properties, using NQ-diameter core. Sealed core boxes are delivered daily by the foreman to McEwen’s logging facilities at the Stock Mill facility.
Brigus Gold performed a drilling program in 2011 using Norex Drilling. Samples were taken from zones that indicated mineralization or areas that are commonly associated with mineralization.
According to the RPA report for the property (Roscoe et al., 2003), most of the surface diamond drilling was completed between 1961 and 1989, while most of the underground diamond drilling was carried out between 1981 and 1994. Limited documentation is available describing the specific sampling methods used during these time periods. Most underground drilling conducted between 1989 and 1994 utilized AQ-
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7 Exploration and Drilling Programs
diameter core, while most of the surface drilling completed before 1996 used BQ-diameter core. All of the underground and surface drilling from 1996 to 2000 employed NQ-diameter core.
Generally, the diamond drill core was split, with one half being assayed and the remaining half retained. While the mine was in production from 1989 to 1994, assays were carried out on some whole core from infill drilling.
A manual core splitter was used prior to 1994. Since 1996, a diamond core saw with a continuous supply of fresh water has been used for core cutting.
7.3.2Western Properties
Lexam VG exclusively employed Norex Drilling for all surface drilling across the Western Properties. After 2010, the majority of Norex’s drill rig fleet consisted of hydraulic rigs configured to recover NQ-diameter core.
The Western Properties have large footprints from historical underground development. The development is now flooded or infilled with sand. The QP considers it reasonable to assume that drilling contractors reduced the core diameter to BQ (36.5 mm) when a surface-staged exploration drill hole encountered underground voids and proceeded onwards into solid rock.
Under Lexam VG ownership, drill core from the rigs was picked up twice per day by core technicians and taken to core logging facilities in nearby South Porcupine. Towards the end of Lexam VG’s activities, the exploration team was based at the Davidson-Tisdale property.
7.4Logging Procedures
Standard logging procedures (described herein) have been followed since approximately 1996. Since January 2018 regionally accepted gold industry standard practices have been consistently implemented.
Core boxes are opened and immediately checked for missing or damaged core when they arrive to the core shack from the drill rigs. Core is logged immediately or placed into steel holding racks adjacent to the logging stations. Core is first fitted together and aligned to ensure continuity and proper alignment of any structural fabric. The geologist marks off 1 m standard intervals and calculates rock quality data (for every 3 m drilling run). Lithology, alteration, and mineralization styles are identified and logged, and structural features are carefully recorded, including foliations, offsets and displacements, and ductile deformations of linear flow features.
7.4.1Eastern Properties
Gemcom logging software was commonly used on site between 2015 and 2018 and has since been replaced by Datamine DH Logger.
Drill core is photographed from an elevated perspective to capture images of three to five core boxes at a time. These images are downloaded, labelled using a standard numbering format, and stored with the corresponding drill logging records.
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7 Exploration and Drilling Programs
Paper logging of historical drilling includes records of mineralization, lithology, and geological structure.
7.4.2Stock Property
Since 2018, McEwen has followed the same logging procedures at the Stock Property as those for the Eastern Properties.
Paper logging of historical drilling includes records of mineralization, lithology, and geological structure.
7.4.3Western Properties
Lexam followed a consistent core logging protocol for all properties, recording the lithological, structural, alteration, and mineralogical features.
According to the technical report prepared by RPA (Altman et al., 2014), surface drilling at Buffalo Ankerite between 2009 and 2012 followed a system where the Lexam technicians collected rock quality measurements and indicated core recoveries in addition to the usual core logging. Geological features such as alteration, mineralization and rock unit descriptions were logged into the Geotic Log software system. The Geotic lithological legend was later incorporated into the Gemcom GEMS-3D geological modeling software. Drill core was photographed after samples were marked up.
Paper logging of historical drilling includes records of mineralization, lithology, and geological structure.
7.5Core Recovery
7.5.1Eastern Properties
Recovery of diamond drill core during advancement through bedrock is generally reliable across the Black Fox and Froome properties, with recoveries of at least 85% achieved unless localized fault zones or voids are intercepted. The country rock underlying the Eastern Property claims is generally weakly deformed, and faults in the deposit areas are relatively competent when drilled at angles greater than 45° to the structural zone. The majority of modern drilling within the Grey Fox cluster of targets has been oriented at high angles to the north-south foliation. Core recoveries have typically exceeded 85%.
After 2015, drill holes at Froome were designed to dip at high angles to the GKDZ, adjacent to the targeted mineralized zones, maximizing driller’s core recovery. This pattern was intended to reduce the influence of the structural fabric of the Gibson-Kelore Fault, lowering the tendency for core to naturally part along foliation planes within soft chloritic ± talc schistose ultramafic volcanic rocks.
Drill logs from historical drilling that informed Mineral Resource estimates indicate similar recovery values.
7.5.2Stock Property
Country rock underlying the Stock Property targets is relatively strongly deformed due to the proximity of the PDDZ and the Nighthawk Lake fault structures. Core recovery rates between 85% and 100% are achieved when drilling through competent mafic volcanic flows or hard, unfractured felsic intrusive rocks.
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7 Exploration and Drilling Programs
However, localized zones of soft, chloritic and talcose rubble, including chips and gravel, can occasionally impede the driller’s coring to depth. Approximately 5% of drill holes completed since 2018 failed to penetrate such zones to target depth, often resulting in drill rod breakage and loss.
Drill logs from historical drilling used to inform resources indicate similar recovery performance.
7.5.3Western Properties
Country rock in the south-central portion of the Porcupine Mining Camp is moderately to strongly deformed due to the proximity of the PDDZ and associated South Tisdale Anticline structures. According to the technical report prepared by P&E and RPA (Altman et al., 2014), core recoveries of approximately 99% were reported at the Paymaster, Buffalo Ankerite, and Fuller sites where drill holes passed through competent mafic volcanic flows or hard, unfractured felsic intrusives. The QP is unaware of any significant fault gouge or structural conditions that materially limited core recovery at the Davidson-Tisdale exploration site.
Historical drill logs used to inform mineral resource estimation indicate similar core recovery rates.
7.6Collar Surveys
7.6.1Eastern Properties
Historical drill sites were selected and laid out using a 50 m tape from established cuts and were picketed relative to a 1,000 m-spaced gridline system developed along the flanks of Tamarack Road.
Between 2008 and 2015, diamond drill hole collars at the Grey Fox, Froome, and Black Fox targets were spotted in the field using a handheld GPS unit with an accuracy of approximately 1 m. Since 2016, collar locations have been surveyed using a differential GPS accurate to within approximately 1 m and linked to the base station at the Black Fox mine.
Since 2019, drilling contractors have been using Reflex Instruments EZ-Gyro TN-14 gyroscopic tool to capture survey and collar alignment data. The TN-14 tool uses a north-seeking gyroscopic compass digitally linked to the local GPS grid.
Drill holes competed from 1988 onward were surveyed using handheld GPS units. Follow-up surveys using conventional surveying methods were required to accurately locate hole collars.
Drill holes completed prior to 1980 were surveyed using transit methods.
7.6.2Stock Property
Between 2018 and 2019, diamond drill holes were spotted using a handheld GPS with an accuracy of approximately 1 m. Since 2019, McEwen has utilized differential GPS to establish accurate survey control for drill hole collars. All data collected are reported in NAD83 coordinates, UTM Zone 17U, and are referenced to the base station established at the Stock Mill.
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7 Exploration and Drilling Programs
Since October 2020, drillers have been using Reflex Instruments TN-14 collar gyroscopic survey tool.
Since spring 2021, McEwen Inc. began using an independent DeviSight APS differential GPS tool, a true-north azimuth gyro-alignment system, to improve the accuracy of planned collar locations and drill azimuth alignments. In summer 2023, McEwen returned to surveying drill hole collars using differential GPS with real-time kinematic correction.
Earlier drill holes from 1988 were surveyed using handheld GPS units. Follow-up surveys using conventional surveying methods have since been carried out to accurately locate those hole collars.
7.6.3Western Properties
Drill logs coupled with the technical report prepared by RPA (Altman et al., 2014) indicate that drill hole collars were surveyed using a differential corrected GPS instrument commonly achieving positional accuracy of approximately 0.1 m under favourable conditions.
Drill holes dating back prior to 1988 were re-surveyed using handheld GPS units. Conventional surveying methods for the period were used to accurately locate hole collars.
7.7Downhole Surveys
7.7.1Eastern Properties
Between 2014 and 2017, drillers used an EX-Shot downhole survey tool that utilizes a magnetic-north-pointing single-shot gimballed globe compass, with readings collected at 50 m intervals.
Since 2017, drillers have been using Reflex Instruments EZ Gyro or multi-shot Sprint orientation tools, which are north-seeking gyroscopic compasses proven to reduce magnetic effect. This is particularly important given the presence of high-iron mafic and ultramafic rock units within the Black Fox and Froome mines and the Grey Fox stratigraphic sequences. Survey data were collected at 50 m intervals, with downhole data digitally relayed to a handheld receiver at surface. Paper copies were inserted into core boxes at the appropriate survey locations.
Noranda drill logs indicate that Tropari or acid Pajari methods were used for downhole surveys. No indication of downhole survey methods is available on drill logs prepared by Ginn or Parsons.
7.7.2Stock Property
Paper drill logs generated in the 1990s indicate that downhole survey readings were collected on a hole-by-hole basis; however, the survey method and sensitivity are rarely noted. Drill logs from the 1990s indicate that Tropari or acid Pajari methods were used.
From 2018 onward, drillers have followed the same downhole survey procedures as those described for the Eastern Properties, using EZ Gyro tools with data collected at 50 m intervals.
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7.7.3Western Properties
According to the technical report prepared by RPA (Altman et al., 2014), Lexam supervised drillers to collect downhole survey data using a Reflex EZ-Shot instrument, with readings taken at 50 m intervals.
7.8Geotechnical, Hydrological and Metallurgical Drilling
Geotechnical diamond drill holes have been completed on the Eastern and Stock properties.
At Grey Fox, six geotechnical holes totaling 1,218 m were drilled in 2013. Seven NQ-sized holes totaling 525 m were drilled at the Stock Main deposit in 2010.
Twenty-two (22) boreholes have been completed as monitoring wells at Grey Fox, primarily in overburden, with a total length of approximately 375 m. Overburden drilling was typically completed using 200 mm hollow-stem augers, with bedrock portions drilled using NQ-diameter coring. These installations were completed by various consultants between 2011 and 2015.
In 2006, four NQ-diameter holes totaling 630 m were drilled at Black Fox. Ten additional holes totaling 2,017 m were drilled by Primero between 2015 and 2016, with partial geotechnical logging (including weathering, rock strength, rock quality designation, and joint roughness), completed on selected exploration holes. In 2017, six NQ3-diameter holes totaling 1,646 m were drilled along the Black Fox ramp toward Froome.
Forty (40) monitoring wells were installed primarily in overburden at Black Fox in 2004 and 2005. The total length of boreholes with installations is approximately 700 m. Overburden drilling was typically completed using 150 mm to 200 mm hollow-stem augers, with bedrock portions drilled using NQ-diameter coring.
In 2025, an approximately 1,400 m HQ drill program was executed at Grey Fox to support metallurgical studies for the project. In addition, some samples for metallurgical testing were obtained from half-core intervals of NQ-diameter exploration drill holes.
7.9Sample Length and True Thickness
7.9.1Eastern Properties
Mineralization at Grey Fox is controlled by northeast-trending (C1) which dip to the Northwest and East-West trending, south-dipping (C2) structures and, locally, by the interaction of these structures with steeply east-dipping lithological contacts. Due to the variable orientations of these structures, the relationship between sample length and true thickness can be variable.
Most drilling at Grey Fox completed between 2008 and 2016 was oriented in an east-to-west azimuth. This drilling orientation resulted in low-angle intersections of mineralized veinlets and breccias relative to the core axis, in which cases true widths may be as low as 10% to 20% of the drilled core length. Since 2018, the majority of drilling in the Gibson, Grey Fox South, 147, and 147NE zones at Grey Fox has been oriented northwest to southeast, resulting in higher-angle intersections, typically greater than 60° to the core axis, where true widths may be as high as 80% to 90% of the core length. Low-angle south-dipping
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7 Exploration and Drilling Programs
mineralized structures corresponding to the C2 structural set are also intercepted in this northwest to southeast orientation.
7.9.2Stock Property
Exploration drilling over the past 40 years at the Stock Property has been designed to intersect the PDDZ corridor of alteration and mineralization at near-perpendicular angles, with most drill holes oriented toward azimuths between 330° and 360°. The steeply southeast-dipping stratigraphic sequence allows these drill holes to cut the conformable mineralized structures at high angles, typically greater than 60° to the core axis, where the true width may be as high as 80% to 90% of the drilled core length.
7.9.3Western Properties
According to the technical report prepared by RPA (Altman et al., 2014), Lexam attempted to intercept exploration targets at near-perpendicular attack angles. This approach included near-vertical drilling to intersect flat-lying mineralized zones at Davidson-Tisdale, as well as the swinging/reactive dip angles to bracket the folded stratigraphy at the northern and southern target zones at Buffalo Ankerite.
7.10Drilling Completed Since Database Close-out Date
Drilling has continued at Grey Fox and Froome since the Fusion SQL database close-out date of March 31, 2026. Drilling completed since that date includes the following:
| ● | Grey Fox: Drilling has continued, targeting potential mineralization expansion at the Gibson, Whiskey Jack and Stroud Zones. |
| ● | Froome: Infill and definition drilling is ongoing as of the date of this report. |
7.11QP Comment on Exploration and Drilling Programs
Mineral deposits within the Fox Complex are relatively narrow and exhibit variable orientations. As geological understanding improves, drill programs must be reoriented accordingly to more accurately capture the true volume of mineralization. Insufficient drilling in orientations that are perpendicular to the fabric of the deposits risk overestimation of the volumes of the Mineral Resource.
Many of the deposits remain open at depth and along strike.
The QP is of the opinion that the quantity and quality of lithological logging, collar and downhole survey data collected during exploration and infill drilling programs at the Fox Complex deposits are sufficient to support Mineral Resource estimation.
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8 Sample Preparation, Analyses and Security
8Sample Preparation, Analyses and Security
This section describes the sampling methods, sample preparation, analytical procedures, QA/QC programs, and sample security measures used to support the Grey Fox and Stroud Mineral Resource estimates which are part of the Eastern Properties and the main focus of this PFS.
For all other resource areas (remaining Eastern Properties, Stock and the Western Properties) which are not integral to this PFS, technical details of the sample preparation, analysis, QA/QC and security are as described in the 2025 Mineral Resource estimation (IA) Technical Report Summary (McEwen, 2025).
8.1Sampling Methods and Sample Preparation
8.1.1Current Sampling Programs (McEwen)
McEwen’s sampling protocols for drill core are designed to ensure that sample intervals are representative and appropriate for the geological features observed. Sample intervals are selected by McEwen geologists during the core logging process based on geological features such as lithological contacts, alteration, and mineralization. Sample lengths typically range from 0.3 m to 1.5 m, with key geological boundaries not crossed where possible.
Drill core samples are identified using uniquely barcoded sample tags that record the sample from-to interval and relevant notes. Sample tags are placed between the drill core and the core box at the sample interval. Sample booklet stubs are labelled, archived in boxes, and stored adjacent to the sampling facility.
For exploration drill core, the core is sawn into two equal halves using an industry-standard diamond saw. One consistent half of the core sample is returned to the core box in proper sequence, with the corresponding ticket stub placed in the core box. The other half of the sawn core is bagged, tagged with the corresponding sample number, sealed, and grouped into batches for shipment.
Sample bags are grouped into batches of 10 and placed into larger woven polypropylene bags for transport. All sample shipments are assigned specific work order numbers, with digital PDF documentation sent to the receiving laboratory prior to sample arrival.
8.1.1Historical Sampling
Historical drilling data from previous operators that are relied upon for the Mineral Resource estimate includes programs completed by Primero and Brigus Gold, where drill core was logged and sampled by, or under the supervision of, Primero or Brigus Gold geologists. Drill core was cut in half using a diamond saw, with one half submitted for assay and the remaining half retained.
Historical sampling data from Exall, Noranda Exploration, and Apollo Gold were validated through previous Mineral Resource estimate studies performed by McEwen.
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8 Sample Preparation, Analyses and Security
8.2Analytical Methods and Laboratories
8.2.1Analytical Methods
Until 2023, gold analysis was undertaken using fire assay (FA) with atomic absorption (AA) finish (FA-AA) for standard-grade samples and FA with gravimetric finish (FA-Grav) for over-limit samples. Since 2023, McEwen has adopted the PhotonAssayTM analysis method, which uses high-energy X-rays to determine gold content through the measurement of gamma ray emissions. PhotonAssay provides accurate results up to 350 ppm Au, with over-limit values undergoing secondary analysis at reduced X-ray beam intensity. This non-destructive method allows for the re-use of certified reference material (CRM) jars.
Multi-element analysis has been performed using inductively coupled plasma optical emission spectroscopy (ICP-OES) following aqua regia or four-acid digestion.
PhotonAssay differs from traditional fire assay in that it is non-destructive, uses larger sample volumes (300 g–500 g versus 30 g–50 g), and has a broader analytical range without requiring separate over-limit analysis in most cases.
8.2.2Laboratories
A summary of laboratories used for sample preparation and analysis is provided in Table 8-1. All laboratories used since 2018 are commercial facilities operating under ISO/IEC 17025 accreditation. Affiliation with McEwen is noted where applicable.
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Table 8-1:Analysis Laboratories Used in Resource Estimation
Laboratory | Period of | Location | Country | Analysis | Accreditation | Prep facility | Analysis | Affiliation to |
| Use | | | Method | | only | Lab | McEwen |
PolyMet | 2009-2016 | Cobalt, ON | Canada | FA | no information | | X | independent |
Laboratories | | | | | found | | | |
Accurassay | 2012-2016 | Thunder Bay, ON | Canada | FA | ISO 17025 | | X | independent |
Laboratories | | | | | | | | |
Swastika | 2012-2016 | Swastika, ON | Canada | FA | ISO 17025 | | X | independent |
Laboratories | | | | | | | | |
Paragon | 2025-2026 | Timmins, ON | Canada | PA | ISO 17025 | X | | affiliated (27.3%) |
Advanced Labs | | | | | | | | |
Paragon | 2025-2026 | Surrey, BC | Canada | PA | ISO 17025 | | X | affiliated (27.3%) |
Advanced Labs | | | | | | | | |
Paragon | 2025-2026 | Hamilton, ON | Canada | PA | ISO 17025 | | X | affiliated (27.3%) |
Advanced Labs | | | | | | | | |
Paragon | 2025-2026 | Reno, NV | United | FA | ISO 17025 | | X | affiliated (27.3%) |
Geochemical | | | States | | | | | |
MSALABS | 2023-2026 | Timmins, ON | Canada | PA | ISO 17025 | | X | independent |
MSALABS | 2023-2026 | Val-d’Or, QC | Canada | PA | ISO 17025 | | X | independent |
MSALABS, Head | 2023-2026 | Langley, BC | Canada | FA | ISO 17025 | | X | independent |
Office | | | | | | | | |
Pangea | 2021-2023 | Guamuchil, | Mexico | FA | ISO 17025 | | X | affiliated (100%) |
Laboratories | | Sinaloa | | | | | | |
ALS Ltd. | 2017-2020 | Timmins, ON | Canada | FA | ISO 17025 | X | | independent |
ALS Ltd. | 2017-2020 | Vancouver, BC | Canada | FA | ISO 17025 | | X | independent |
Activation | 2014-2022 | Timmins, ON | Canada | FA | ISO 17025 | | X | independent |
Laboratories Ltd. | | | | | | | | |
Activation | 2014-2022 | Ancaster, ON | Canada | FA | ISO 17025 | | X | independent |
Laboratories Ltd. | | | | | | | | |
| Project: 169525666 | 8-3 |
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8 Sample Preparation, Analyses and Security
Laboratory | Period of | Location | Country | Analysis | Accreditation | Prep facility | Analysis | Affiliation to |
| Use | | | Method | | only | Lab | McEwen |
Activation | 2020-2022 | Geraldton, ON | Canada | FA | ISO 17025 | | X | independent |
Laboratories Ltd. | | | | | | | | |
AGAT | 2009-2022 | Timmins, ON | Canada | FA | ISO 17025 | X | | independent |
Laboratories | | | | | | | | |
AGAT | 2009-2022 | Rouyn, QC | Canada | FA | ISO 17025 | X | | independent |
Laboratories | | | | | | | | |
AGAT | 2009-2022 | Mississauga, ON | Canada | FA | ISO 17025 | | X | independent |
Laboratories | | | | | | | | |
SGS Canada | 2011-2017 | Sudbury, ON | Canada | FA | ISO 17025 | | X | independent |
SGS Canada | 2011-2017 | Toronto, ON | Canada | FA | ISO 17025 | | X | independent |
SGS Canada | 2011-2017 | Cochrane, ON | Canada | FA | ISO 17025 | | X | independent |
Notes:
| ● | Method abbreviations: FA = Fire Assay, PA = PhotonAssayTM |
| ● | “Preparation Facility Only” marked with “X” indicates laboratories that only prepare samples. |
| ● | “Analysis Lab” marked with “X” indicates laboratories that perform analysis. |
| ● | Affiliation indicates relationship to McEwen (independent or affiliated with ownership % where applicable). |
| Project: 169525666 | 8-4 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
8 Sample Preparation, Analyses and Security
Exploration samples are shipped multiple times per week to Paragon Advanced Labs for preparation and photon assay analysis. Since September 2025, most photon assay work has been completed by Paragon.
Check assays (approximately 5%) for fire assay are submitted to ALS Vancouver, while PhotonAssay check assays (approximately 20%) are sent to MSALABS (Timmins, Ontario).
8.2.3Historical Laboratories
Historical laboratories used for assays incorporated into the Mineral Resource estimate include those listed below and in Table 8-1.
| ● | Swastika Laboratories (Swastika, Ontario) |
| ● | SGS Canada (Cochrane, Ontario; Rouyn-Noranda, Québec) |
| ● | AGAT Laboratories (Mississauga, Ontario) |
| ● | PolyMet Laboratories (Cobalt, Ontario) |
| ● | Techni-Lab (Timmins, Ontario) |
| ● | ALS Canada (various locations) |
| ● | XRAL Laboratories (Intertek Testing Services-Bondar Clegg) |
| ● | Bell White Laboratories |
| ● | Accurassay Laboratories |
8.3Quality Assurance and Quality Control
8.3.1QA/QC Program
McEwen maintains a QA/QC program that includes the insertion of blank samples, CRMs, and duplicate samples into the drill core sampling sequence.
Blanks are inserted at a ratio of one per 20 samples (or two per 21 samples for photon assay). Prior to 2019, blanks consisted of core blanks from unmineralized core sections and certified blank pulp material. Since 2019, coarse blanks composed of commercial high-silica aggregate purchased in bulk from Technominex in Rouyn-Noranda, Québec, have been used.
CRMs are inserted at a ratio of one per 21 samples. Prior to 2019, CRMs purchased from Rocklabs Ltd. (SK78, SG66, SN75, SE68, Ox98) were used. Beginning in February 2019, OREAS standards replaced Rocklabs standards. For PhotonAssay, CRMs specifically certified for the PhotonAssay process are utilized. Insertion of standards with photon assay is performed at the external laboratory using code-matching CRM jars provided by McEwen.
Duplicate samples were inserted between 2017 to 2019, with pulp duplicates at a ratio of one per 20 samples and field duplicates inserted between 2017 and 2018. Following external review (Bloom and Jolette, 2019), which indicated very good duplicate repeatability, McEwen discontinued the insertion of pulp and field duplicates and now relies on each laboratory’s internal duplicate protocols. For PhotonAssay, duplicate readings of the assay jar are used to calculate a weighted average result, which is reported on the certificate. The lab also performs preparation duplicates at a rate of one per 21 samples.
| Project: 169525666 | 8-5 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
8 Sample Preparation, Analyses and Security
External umpire testing has been conducted since at least 2017, with pulps representing approximately 5% to 7% of the annual assay volume submitted by McEwen for check analysis. Following adoption of Paragon as the primary assay laboratory, the rate of comparison testing has increased to 20%. MSALABS has been designated as the referee sample laboratory.
8.3.2QA/QC Results
The QA/QC results from McEwen’s current sampling programs demonstrate good accuracy and precision. The insertion of CRMs has shown acceptable accuracy, with the vast majority of results falling within acceptable tolerance limits (typically ±2 standard deviations of certified values). Blank results consistently return values below detection limits, indicating minimal contamination. Duplicate analyses show good precision, with coefficient of variation values typically below 20%, indicating acceptable repeatability.
QA/QC performance is monitored daily as assays come in and reviewed as a group on a monthly basis. Where CRM failures are identified, corrective actions are implemented immediately, including re-analysis of affected batches and communication with the laboratory. No systematic bias has been identified in the assay data.
The QP has reviewed the QA/QC data and considers the results sufficient to support the reliability of the assay data used in the Mineral Resource estimate.
8.3.3Historical QA/QC
Historical QA/QC programs from previous operators varied in their approach and rigor. Review of historical QA/QC indicates that programs completed by Primero and Brigus Gold included in-field insertion of blanks, CRMs, and field duplicates, with in-laboratory QA/QC managed by the contracted analytical laboratories. Based on review, the QA/QC program is considered adequate for the data quality.
Historical QA/QC programs from operators whose data are not used in the Mineral Resource estimate (including Apollo Gold, Exall, and Noranda Exploration) have not been relied upon and are not considered material to this report.
Overall, the historical QA/QC data are considered adequate for use in the Mineral Resource estimate and do not introduce material uncertainty.
8.4Sample Security
8.4.1Chain of Custody and Handling
Sample chain of custody is maintained through standardized procedures including tagging, bagging, sealing, and documented transport.
Sample bags are sealed with heavy plastic tie-wraps after filling and labelled with the sample number. Sealed transport bags are stored within a secure area immediately adjacent to the logging and sampling facility. From 2014 to 2021, exploration drill core samples were shipped off site to commercial laboratory preparation facilities. Sample transport was handled by McEwen personnel or contracted carriers.
| Project: 169525666 | 8-6 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
8 Sample Preparation, Analyses and Security
From 2021 to 2023, samples were sent to Pangea Laboratory in collapsible plastic storage containers, sealed using numbered plastic seals. Samples were shipped via Gardewine (intermediary only) to a broker in Naco, Arizona, who then reshipped the samples to the laboratory.
Since 2023, samples have been transported directly to MSALABS and Paragon by McEwen employees. Samples shipped to Paragon facilities in Hamilton, Ontario or Surrey, BC are transported in sealed wooden shipping crates to maintain sample integrity.
Drill core, rejects, and pulps are stored in secure locations at the Fox Complex facility. The core logging facility is locked, with access restricted to authorized personnel.
8.4.2Security Practices by Period
Historical operators maintained sample security through chain-of-custody procedures appropriate for their periods of operation. Drill core was boxed, covered, and sealed at the drill rigs and transported to logging facilities, where company personnel assumed responsibility for core handling. Samples were cut by technicians, bagged, sealed, and grouped into batches for shipment.
8.4.3Databases
Since 2017 when McEwen acquired the Fox Complex from Primero, a SQL database in Datamine Fusion has been the primary location for the collation, storing and tracking of all geological data including the sampling and assaying procedures.
Datamine’s DH Logger software is used to record all logging and sampling data entry. Upon completion of logging, and subsequent satisfaction of a senior geologist and the database manager, the files are compiled, organized, and uploaded to the Datamine Fusion SQL database. Currently, the data from DH Logger is uploaded electronically, as is assay data from the external laboratories. Laboratory data is uploaded by the Database Manager into the Datamine Fusion SQL database.
The Fusion database uses a series of read-write permissions to ensure database integrity; access is restricted only to authorised personnel. Back-ups of the digital data archive are performed on a regular basis.
For the earlier 2014–2017 programmes, drill hole logging data (collar locations, down hole surveys, geology etc.) and related assays were collected and added to Gemcom project files. Separate workspaces were used for Grey Fox and Froome.
Regular QA/QC audits on collar locations, down-hole surveys, and assay certificates were performed over the period. Once verified, drill holes would be locked in the Gemcom project to ensure no changes to the data could occur. After McEwen’s acquisition, four GEMCOM databases were merged into one SQL database in Datamine Fusion.
At the Stock East Zone, early exploration holes (2018 campaign) were logged and processed utilizing the Gemcom software and captured as PDF files using Primero’s formatting. In 2019, the team transitioned to using the Datamine products and procedures described above.
| Project: 169525666 | 8-7 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
8 Sample Preparation, Analyses and Security
Historical information before 1993 is not relied on for resource estimation at Grey Fox.
8.5QP Opinion
The QP has reviewed the sampling methods, sample preparation and analytical procedures, QA/QC programs, and sample security measures described in this section. Based on this review, the QP offers the following opinions:
| ● | The sampling methods used are appropriate and adequate to support representative sample collection for Mineral Resource estimation. |
| ● | Sample preparation and analytical methods, including fire assay, PhotonAssayTM, and ICP techniques, are appropriate for the style of mineralization encountered and are consistent with industry-standard practices. |
| ● | QA/QC procedures implemented by McEwen, including the insertion of blanks, CRMs, and duplicates, along with external umpire testing, are sufficient to demonstrate the reliability of assay data. |
| ● | Sample security measures, including chain-of-custody documentation, sealed transport, and secure storage, are adequate to maintain data integrity. |
| ● | The data derived from the sampling, analytical, and QA/QC programs are suitable for use in Mineral Resource estimation. |
| Project: 169525666 | 8-8 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
9 Data Verification
9Data Verification
9.1.1Drill Core Verification
The QP reviewed all assay, collar, survey, and QA/QC data associated with drilling conducted from 2014 to the most recent results available in 2026, including McEwen drilling programs on the Eastern Properties and relevant historical data incorporated into the Mineral Resource model.
The QPs reviewed prior technical reports and verification studies and conducted independent audits, data checks, and physical inspections, where possible.
The QP applied the following data verification procedures:
| ● | Database Audits: Assay results were cross-checked against original laboratory certificates to confirm data integrity. Assay intervals, sample IDs, and QA/QC sample insertions were validated within the digital assay database. |
| ● | Collar and Survey Verification: Collar locations and downhole surveys were verified against original survey records and field GPS data. Discrepancies were identified for the Stroud project and reconciled. |
| ● | QA/QC Review: The QP reviewed QA/QC data including blanks, CRMs, duplicates, and umpire laboratory results as described in Section 8. Statistical evaluations confirmed acceptable accuracy and precision. |
| ● | Core Inspections: The QP conducted site visits to assess drill core recovery, logging practices, and core storage procedures to confirm consistent geological and sampling protocols. |
| ● | Independent Validation: Randomly selected samples and pulps from the database were independently arranged and submitted for umpire laboratory analysis to confirm assay accuracy, with results reviewed by the QP. |
9.1.2Verification of Historical Data
Historical drilling data incorporated into the Mineral Resource model originates from multiple operators, including Primero, Brigus Gold, Apollo Gold, Chevron Minerals Ltd., Pancontinental Mining Ltd., and Gunnex Ltd. The QP audited a significant portion of these datasets by cross-checking assay certificates, collar records, and QA/QC information against the compiled database.
Verification efforts focused primarily on data generated from the 2010s onward, where documentation is more complete. Key assay results were confirmed where original certificates were available.
Although some early datasets lack complete QA/QC records or chain-of-custody information, most historical data incorporated into the model have been verified either directly or through corroborative evidence, including prior technical reports and independent reviews.
| Project: 169525666 | 9-1 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
9 Data Verification
9.1.3Limitations on Data Verification
The QP notes the following limitations, which are typical of historical exploration datasets:
| ● | Incomplete QA/QC records and missing assay certificates for some early drilling programs. |
| ● | Downhole surveys for certain underground holes completed prior to 1995 rely on collar orientation only, without continuous deviation measurements. |
| ● | Gaps in chain-of-custody documentation for older historical drill programs. |
| ● | Physical core inspection was limited to available core; some legacy core storage conditions were suboptimal but adequately documented. |
These limitations have been considered in the classification of Mineral Resources and are not considered to materially impact the overall reliability of the dataset.
9.1.4Data Verification Results
The QP’s verification work indicates that:
| ● | QA/QC results show consistent accuracy and precision within accepted industry limits. |
| ● | Duplicate and umpire assay comparisons confirm repeatability and do not indicate systematic bias. |
| ● | CRM recoveries indicate acceptable analytical performance across all laboratories, including McEwen-affiliated facilities (Paragon Advanced Labs and Pangea Laboratories) and independent laboratories (MSALABS, ALS, AGAT, SGS). |
| ● | Survey, collar, and assay data are internally consistent and suitable for Mineral Resource estimation. |
9.1.5QP Opinion on Data Adequacy
The QPs responsible for the respective disciplines are satisfied that:
| ● | Sampling, assay, survey, and QA/QC data used in the Mineral Resource estimate are reliable and of sufficient quality for the purposes of this technical report. |
| ● | Verification procedures support the accuracy and precision of the dataset. |
| ● | Identified limitations are typical of historical datasets and have been appropriately considered in resource classification. |
| ● | Overall, the QPs are satisfied that the data supporting the Mineral Resource estimate are reliable and of sufficient quality to support Mineral Resource estimation in accordance with SEC Regulation S-K 1300. |
9.2Property-Specific Verification
9.2.1Eastern Properties Data Verification
Verification indicates that McEwen drilling data since 2014 are of sufficient quality and integrity, with strong QA/QC performance and consistent survey and collar accuracy.
| Project: 169525666 | 9-2 |
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9 Data Verification
9.2.2Stroud Project Data Verification
Verification work indicates that the historical Stroud drill hole database is sufficiently reliable for use in the current Mineral Resource estimate. Collar locations were validated through RTK re-surveying and transformation from the local mine grid to UTM NAD83, resulting in acceptable spatial agreement.
Assay verification included recovery of historical certificates, re-logging and re-sampling of select holes, and a confirmatory drill program that twinned approximately 15% of historical holes. Independent checks by both the database manager and the QP identified only minor discrepancies (3 of 1,246 assay records), all conservative relative to original certificates.
Overall, drilling, survey, and assay data are considered adequate to support Mineral Resource estimation and geological interpretation.
9.3Geochemical and Water Analysis Verification
9.3.1QP Verification Procedures
For water quality data used in the water balance model, the QP reviewed available datasets and reports provided by McEwen to assess their suitability as geochemical source terms for different areas and rock types across the site. Calculation methods and model outputs, including spreadsheet and GoldSim models, were also reviewed.
The QP reviewed geochemical and water quality data used in the water and solute balance model described in Section 17. These data include site monitoring results (e.g., from the Black Fox East and West stockpiles), as well as laboratory-based static and kinetic testing, including shake flask extraction and humidity cell test results.
The QP evaluated the available data relative to their intended application in defining geochemical source terms for site features and considers the selected datasets appropriate for use in the model. Where available, data provided in project reports were compared with original laboratory analytical results to confirm consistency, including review of kinetic testing datasets.
9.3.2Data Verification Results
The QP considers the available data to be of acceptable quality. In cases where both summarized project report data and laboratory analytical results were available, comparisons indicate consistency between reported values and underlying analytical data.
The QP has determined that a greater degree of uncertainty is associated with the representativeness of specific datasets for application to certain source terms, particularly for the Grey Fox underground mine and associated surface features. This uncertainty does not reflect deficiencies in analytical data quality, but rather limitations in the availability of appropriate analogues to characterize future site-specific conditions. For example, there is uncertainty associated with predicting the quality of water to be pumped from underground workings, due to the absence of directly comparable datasets.
| Project: 169525666 | 9-3 |
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9 Data Verification
Where uncertainty exists in the applicability of specific datasets, the QP considers that conservative assumptions have been applied in the selection of water quality inputs for modeling purposes.
The QP reviewed the water balance methods and key data inputs, including runoff coefficients, catchment areas, precipitation data, and geochemical source terms, and considers them appropriate for the intended level of study. GoldSim is recognized as an industry-standard tool for water and solute mass balance modeling in mining applications.
The QP recommends that, as additional geochemical characterization testing is completed in the future, these data be compared with historical datasets to further refine the selection of representative inputs for for modeling of full-scale waste rock runoff and mine dewatering conditions.
9.3.3QP Opinions on Data Adequacy
The QPs responsible for the respective disciplines are satisfied that:
| ● | Water quality datasets used in development of the water balance model are of acceptable quality. Although there is uncertainty in the applicability of specific datasets to certain geochemical source terms (e.g., identifying appropriate analogues for underground dewatering), conservative assumptions have been applied in assigning water quality inputs. |
9.4Tailings Storage Data Verification
The QP reviewed data used in the development of the tailings storage design and associated cost estimates. The review included geospatial, geotechnical, process, and cost input data, with the objective of assessing their suitability and reliability for the PFS level of study.
9.4.1Source Data
The following primary data sources were reviewed by the QP:
| ● | Topographic and Geospatial Data: |
o | 2025 aerial drone LiDAR data provided by Arcadis for the Stock Mill TMA and surrounding areas. |
o | The 2016 Central Ontario Orthophotography Project (COOP) 2-m digital elevation model (DEM) for areas not covered by the LiDAR survey. |
| ● | Geotechnical Data: |
o | Historical borehole and laboratory test data as referenced in prior design work (Golder 2015), including subsurface conditions relevant to dam foundations and embankment performance. |
| ● | Tailings Production Data: |
o | Historical operating data and projected mill throughput and tailings production rates used to define storage requirements and facility life. |
The QP reviewed these datasets in the context of their application to tailings storage design and considers them appropriate for use in support of the current level of study.
| Project: 169525666 | 9-4 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
9 Data Verification
9.4.2Data Verification Methods
The QP applied the following data verification procedures:
| ● | Topography and Volumes: |
Digital terrain models were cross-referenced against both recent LiDAR data and historical DEM datasets to assess the accuracy of derived dam surface elevations and tailings storage volumes. Comparisons between data sets indicate consistency in overall site geometry. Volumetric estimates were evaluated using industry-standard software tools (e.g., Autodesk Civil 3D) to confirm agreement between conceptual design volumes and actual site topography.
| ● | Geotechnical Conditions: |
Foundation conditions and embankment design parameters were reviewed against available borehole logs and laboratory test results. Where data gaps existed, the QP notes that conservative design values were applied, and that additional investigation is appropriately recommended for subsequent study phases.
| ● | Process and Tailings Data: |
Tailings production rates, physical tailings characteristics, and storage assumptions were reviewed relative to historical site operating data and typical industry benchmarks. The QP evaluated these inputs to confirm that projected tailings volumes and facility life are reasonable and consistent with the proposed mining and processing rates.
| ● | Supplemental Capacity and Site Constraints: |
Available lease boundary mapping was reviewed and compared with aerial imagery to assess land availability for potential future expansion The QP evaluated the consistency between mapped boundaries and physical state conditions to support conclusions regarding expansion potential.
| ● | Tailings Storage Facility Costing: |
Tailings storage facility capital costs were developed as a conceptual estimate using published, auditable benchmarks, including RECLAIM 7.0, escalated via Statistics Canada CPI to 2026 CAD; publicly available government engineering and remedial-action cost estimates, including US Environmental Protection Agency and US Army Corps of Engineers; and selective vendor budgetary quotations. The estimate includes contingency appropriate to a Class 5/4 study.
9.5Water Treatment
Water treatment inputs are based on water chemistry and flow rate data derived from the water balance. Water treatment costs are based on input from a water treatment specialist with experience in the design and specification of water treatment facilities and are supported by historical project pricing for the purchase and installation of vessels, pumps, and industrial metal buildings.
9.6Metallurgical Testing and Analysis
The QP was unable to independently verify the representativeness of all samples used in historical metallurgical testwork programs. A significant portion of the metallurgical testwork was completed by previous property owners and operators, and the documentation available to the QP did not, in all cases,
| Project: 169525666 | 9-5 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
9 Data Verification
include sufficient detail regarding sample selection methodologies, compositing procedures, sample locations, or the rationale used to define metallurgical domains.
Consequently, the QP cannot confirm that the samples tested are fully representative of the range of mineralization and metallurgical variability present within the deposit. The QP has relied upon the available historical records and the results of the metallurgical programs as documented. In the absence of complete sample selection records, it is inferred, based on industry practice, that the individuals responsible for the test programs selected and composited samples were selected and composited in a manner intended to reasonably represent the anticipated processing characteristics of the mineralized material. While the testwork results are considered suitable for the purposes of this study, the uncertainty associated with sample representativeness should be recognized when evaluating the metallurgical performance projections presented herein. Additional variability testwork utilizing samples selected under current QA and documentation protocols is recommended to further validate the metallurgical response of the deposit.
The QP is familiar with the laboratories that conducted the historical metallurgical testwork and understands them to be established facilities with recognized metallurgical testing capabilities. Based on the QP’s industry experience and prior interactions with these laboratories, their testing procedures, analytical methods, and QC practices are considered to be consistent with accepted industry standards for metallurgical investigations.
9.6.1QP Opinions on Data Adequacy
Although the QP was not directly involved in the execution of the historical test programs and has not independently audited the laboratories’ quality management systems, there is no indication from the available documentation or test results that the metallurgical data are unreliable or unsuitable for the purposes of this study.
| Project: 169525666 | 9-6 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
10 Mineral Processing and Metallurgical Testing
10Mineral Processing and Metallurgical Testing
10.1Summary
10.1.1Comminution
Comminution testwork was conducted on Grey Fox drill cores across several test campaigns, and included Steve Morrell Comminution (SMC) testing, Bond Ball Mill Work index (BWi) testing, and grind calibration work. The testwork indicates a requirement of high specific grinding energy. SMC testing yielded drop-weight index (DWi) values of 8 to 10 kWh/m³ and Axb parameter values of 30 to 35, corresponding to the 76th to 89th percentile range of the JKTech SMC database. These results reflect the highly competent nature of the ores tested. The BWi results also confirmed the extremely high energy requirement to grind the ore, with values for the harder composites reaching up to 27 kWh/t (147 Zone) and the softer end (some parts of the underground zones) closer to 18 kWh/t.
With the harder samples being from the 147 Zone, which represents approximately 2/3 of the deposit, it is evident that the average and design hardness values should be skewed towards the harder end of the range of test results. BWi test results were weighted according to ore tonnage distribution by domain. The 85th percentile is 27.1 kWh/t. The highest BWi value (27.1 kWh/t) applies to Domain 31 (147 Zone iron-rich mafic volcanics), which comprises 28.3% of the total orebody (refer to Table 10-1 for domain-specific distributions). Additional variability testing is scheduled for the next phase of the project to gain more granularity at the top end of the hardness curve.
Table 10-1:Orebody Breakdown by Zone and BWi
Domain ID | Tonnage | Proportion% | BWi (kWh/t) |
Domain 10 - Gibson South | 3,506,192 | 20.9 | 18.7(1) |
Domain 11 - Gibson North | 1,770,573 | 10.6 | 19.7(1) |
Domain 20 - Contact Zone | 1,253,925 | 7.5 | 20.7(2) |
Domain 30 – 147 Zone Mafic | 4,763,982 | 28.4 | 25.3(2) |
Domain 31 – 147 Zone Fe-rich mafics | 4,741,755 | 28.3 | 27.1(3) |
Domain 32 - Whiskey Jack | 717,137 | 4.3 | 19.5(4) |
Total Orebody | 16,753,564 | 100 | 23.4 |
Notes:
(1) | Average of three samples tested in 2025. |
(2) | Average of two samples tested in 2014 (XPS Phase 2). |
(3) | Single result of one sample tested in 2014 (XPS Phase 2). |
(4) | Average of two samples tested in 2025. |
| Project: 169525666 | 10-1 |
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10 Mineral Processing and Metallurgical Testing
10.1.2Gravity Testing
Gravity recovery testwork conducted at ALS Metallurgy and XPS (on open pit samples) confirms the presence of coarse free gold, with gravity recoverable gold (GRG) test values ranging between 4% and 32%. Extended gravity recoverable gold (EGRG) tests achieved mass pulls below 0.2% of new feed mass, with high gold grades recovered to a concentrate between 200 g/t and 1,200 g/t Au, confirming the presence of free coarse gold in the samples tested. The underground samples tested in 2025 contained significantly less GRG compared to the open pit samples tested during preceding test programs. For the underground ore, a gravity concentration step is not essential and can be omitted. Inclusion of a gravity recovery step is recommended for treatment of the open pit ores.
10.1.3Flotation
Bulk sulphide flotation has been shown to be highly effective on Grey Fox ore types, especially for the pyritic and high-sulphur ore types. Testing by XPS and SGS on open pit samples yielded gold recoveries ranging from 91% to 97% into an 8% to 12% mass pull primary concentrate, using standard xanthate-type collectors at natural pH. The highest recoveries exceeding 95% were achieved at finer grind sizes (P80 = 60 µm). However, subsequent testwork confirmed that similar recoveries could be achieved at coarser grind sizes (up to P80 = 120 µm). The flotation concentrates produced were primarily pyrite with lower amounts of base metals, amenable to direct cyanidation. A carbon pre-float was ineffective due to the presence of carbonates, although this was not found to have a significant impact on overall flotation performance. Underground mine samples tested in 2025 yielded marginally lower overall recoveries using a flotation flowsheet, with an average gold recovery of 87.2%.
For all samples tested to date, a gravity-flotation flowsheet outperformed a gravity-leach flowsheet by 7% to 14% in terms of overall gold recovery. However, the rougher flotation concentrates produced did not achieve saleable concentrate grades as a standalone product. Further upgrading through additional cleaning stages would be required, but these have not been tested to date.
10.1.4Cyanidation of Flotation Products
Cyanidation of the flotation concentrates resulted in variable gold extraction, dependent on pyrite content and grain size. In general, as-floated concentrates (P₈₀ ~60 µm) yielded gold recoveries via cyanidation of 77% to 82% for the open pit samples. Regrinding of the concentrates to a P₈₀ ~25 µm improved gold extraction by approximately 2% to 4%. No additional benefit was observed by grinding to finer sizes approaching a P₈₀ ~12 µm. This suggests that some of the contained gold in pyrite is either very fine and locked within the pyrite lattice or is in solid solution and therefore not accessible through cyanidation.
For the underground samples, the results were more variable, with cyanidation gold extractions after regrinding ranging between 46% and 95%. The 46% result is considered anomalous, as leaching was not complete by the end of the test. After discounting this result as anomalous, two of the other seven samples yielded extractions on the order of 70%. Therefore, the underground samples underperformed compared to the open pit samples.
| Project: 169525666 | 10-2 |
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10 Mineral Processing and Metallurgical Testing
Cyanidation of flotation tailings consistently yielded high extractions. The open pit samples again outperformed the underground samples, with extractions exceeding 74% and final tailings grades below 0.1 g/t Au achieved. By comparison, the underground samples yielded an average extraction of 72% and an average final tailings grade of 0.19 g/t Au.
A split-leach approach, comprising concentrate and tailings leaching, is supported by the testwork, with the potential to match or exceed whole-ore leach recoveries while decoupling primary grind size, to some extent, from overall recovery, thereby offering potential savings in grinding costs.
10.1.5Whole-Ore Cyanidation
Whole-ore leach testwork was conducted on a range of composite materials and showed a wide range of recoveries tied to head grade and sulphur content. Free-milling ores from the 147 Zone returned gold recoveries of 88% to 94% at moderate grind sizes (P₈₀ of 75 to 100 µm). In contrast, low-grade pyritic ores or those with high S/Au ratios from the Contact Zone (CZ) and Grey Fox South showed reduced recovery, with values on the order of 71% to 80%, even after extending leach durations beyond 24 h.
The open pit samples tested in 2025 exhibited similar variability, ranging from as low as 64% recovery to as high as 92% recovery, with an average of 80%.
Preg-robbing is minimal and appears to correlate with total organic carbon (TOC) levels above 0.5%. The whole-ore cyanidation route is viable for higher-grade, low-sulphur ores, but should be avoided for high-pyrite or low-grade domains due to lower recoveries and high reagent consumption.
10.1.6Cyanide Detoxification
Cyanide (CN) destruction via the SO₂/air process was demonstrated to be effective. In batch and continuous tests conducted on leached slurries from both the 147 Zone and CZ master composites (MCs), Weak Acid Dissociable (WAD) CN levels were reduced from approximately 165 mg/L to <0.1 mg/L using SO₂ doses of 4.0 to 4.8 g/g CNWAD and a copper catalyst at 0.06 to 0.12 g/g CNWAD. The resulting solutions met Ontario Provincial Water Quality Objectives (PWQO) guidelines for cyanide and most metals. Some elevated molybdenum levels were noted in decant solutions, but all other metals remained within acceptable limits. The process is considered robust and scalable.
The underground mine samples from Whiskey Jack and Gibson Zones have not been tested to date but their response to this method of detoxification is expected to be similar. Testing is recommended to confirm this assumption.
10.1.7Sedimentation
Settling tests show that underflow densities of approximately 65% solids (w/w) can be achieved using non-ionic flocculants at dosages on the order of 25 g/t. Dynamic settling tests yielded optimum solids loadings of 0.41 to 0.47 t/m2/h for the 147 Zone and CZ, respectively. Rheology testing confirms manageable yield stresses (27 to 52 Pa at 68% solids), indicating that conventional thickening and deposition strategies are applicable. The sedimentation behavior of the Whiskey Jack and Gibson Zone underground samples was
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not tested. Future sedimentation testwork should include flotation concentrate samples to confirm the sizing of a concentrate thickener for the proposed flowsheet.
10.1.8Environmental
Static geochemical testing, including acid-base accounting, net acid generating, and shake flask extraction (SFE) testing of waste rock and tailings materials, suggests that most samples are non-potentially acid generating (NPAG), with 70% to 78% exceeding the neutralization potential ratio (NPR) >2 threshold. The remainder are considered uncertain and subject to ongoing kinetic testing. Paste pH values for all samples were alkaline (8.5 to 9.6), and sulphur was dominantly present as sulphide. Tailings residues from cyanidation and detoxification were classified as NPAG, with a Neutralizing Potential to Acid Potential (NP:AP) ratio greater than 40. Decant water chemistry met applicable discharge criteria, aside from minor molybdenum exceedances. No environmental testwork was conducted on underground samples as part of the 2025 program.
10.2Introduction
This chapter summarizes all available metallurgical testwork results for the Grey Fox deposit, together with other pertinent information required to support preliminary feasibility and trade-off studies. For the purposes of this report, the testwork programs were grouped as historical programs, referring to programs conducted for previous owners, and recent programs conducted by McEwen. Process design criteria are defined based on these test results and are used as the basis flowsheet development and subsequent equipment sizing for the studies.
10.3Test Work Completed to Date
This section summarizes all completed metallurgical and geochemical testwork available on the Grey Fox deposit. Please refer to Table 10-2, where each document is listed by its name, title, and general theme, excluding any reports that are strictly proposals or quotations for future work.
Table 10-2:Test work Programs
Authoring Entity and Date | Report Title | Scope of Work |
JKTech, Oct. 2012 | SMC Test Report on Three Samples | Comminution parameters for 147, |
| from Grey Fox | breccia, and tuff domains |
SGS Canada, March 27, 2013 | 13327-002 Met Report: A | Gravity, flotation, whole-ore |
| continuation of testwork on samples | leaching, cyanide detox, rheology |
| from Grey Fox | |
SGS Canada, March 27, 2013 | 13327-002 QEMSCAN Report: A | Bulk mineralogy and gold |
| continuation of testwork on samples | deportment |
| from Grey Fox | |
XPS Consulting and Test work | Geometallurgical Definition and | Initial scoping-level gravity and |
Services, Dec. 6, 2013 | Metallurgical Assessment of Grey | cyanidation tests |
| Fox Zones, Phase 1 | |
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Authoring Entity and Date | Report Title | Scope of Work |
XPS Consulting and Test work | Geomet Definition and Metallurgical | Variability testing of multiple 147 |
Services, Feb. 10, 2014 | Assessment of Grey Fox Zones, | Zone and CZ composites |
| Phase 2 | |
XPS Consulting and Test work | Geometallurgical Assessment of | Flotation and leaching of flotation |
Services, Nov. 10, 2014 | Grey Fox Pyritic (Phase 3) and Grey | products. Inclusion of Grey Fox |
| Fox South | South. |
XPS Consulting and Test work | Brigus Grey Fox Phase IV: Leaching | Flotation optimization and carbon |
Services, June 9, 2015 | with Flotation | prefloat analysis |
Golder Associates, March 30, 2016 | Grey Fox Deposit – Interim kinetic | Leach columns and kinetic test |
| geochemistry results update #2 | results over short durations |
ALS Metallurgy, Feb. 11, 2020 | KM6034 –Metallurgical and | Cyanidation leach, grind sensitivity, |
| Environmental Test Work for the | environmental residue |
| Grey Fox Deposit | characterization. Grey Fox 147NE |
| | Composite |
ALS Metallurgy, October 2025 | KM7663 –Metallurgical and | Comprehensive test program for the |
| Environmental Test Work for Grey | previously untested Whiskey Jack |
| Fox Underground Zones | and Gibson Zones |
10.4Historical Metallurgical Testing Results
10.4.12013 SGS Master Composite & Variability Program
The report titled “An Investigation into Continuation of Testwork on Samples from Grey Fox” (SGS Project 13327-002, March 27, 2013) (SGS, 2013) was commissioned to support the ongoing metallurgical characterization of ore from both the 147 Zone and the CZ and included an expanded testwork scope focused on processing and environmental aspects.
10.4.1.1Sample Selection and Compositing Rationale
Two (2) MCs were generated from coarse assay rejects (stage‑crushed to <10 mesh) representing the 147 Zone and CZ ore types. Sub-sampling instructions were provided by EHA Engineering; preparation, splitting and head sampling were completed at SGS. Composite design targeted representative lithologies and gold grade population, while providing ≥10 kg for each downstream test per domain.
10.4.1.2Head Assay
Screened‑metallics fire assay indicates head grades of 3.35 g/t Au for the 147 Zone MC and 4.64 g/t Au for the CZ MC, with >97% of the gold reporting to the -105 µm fraction. There is good agreement between the grades determined through the screened metallics procedure and the direct fire assays. This suggests the absence of a significant nugget effect. This observation is supported by the high proportion of gold in the - 150 mesh fraction.
Multi‑element Inductively Coupled Plasma scans showed low deleterious element levels (Cu ≤0.015%, As <50 ppm), while total carbon occurred mainly as carbonate (~95% of Ct). QEMSCAN analysis identified
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a predominantly quartz–carbonate gangue with 3% to 5% pyrite; visible gold was free‑milling and largely liberated at <75 µm. Key results are summarized in Table 10-3.
Table 10-3:Head Assays for 147 Zone and CZ Master Composites
Master | Screened | Direct Fire | Cu (%) | Ag (g/t) | S (%) | Ct (%) | CO3 (%) |
Composite | Metallics Au | Assay Au | | | | | |
| (g/t) | (g/t) | | | | | |
147 Zone | 3.35 | 3.36 | 0.010 | 1.6 | 1.70 | 2.76 | 9.77 |
CZ | 4.64 | 4.56 | 0.015 | 1.8 | 1.90 | 1.91 | 6.61 |
10.4.1.3Bulk Modal Mineralogy
Modal mineralogy determined by QEMSCAN at a grind of P₈₀ ~150 µm revealed that both MCs were dominated by silicate gangue (>70 vol%), with carbonates constituting the next most abundant group, and sulphides making up only a few percent. Please refer to Figure 10-1. The graphite composite exhibited similar silicate proportions but contained ~4% pyrite and trace graphite.

Figure 10-1: Modal Compositions of 147 Zone, CZ and Graphite Master Composites
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10.4.1.4Grain Size and Liberation Statistics
QEMSCAN particle sectioning across four sieve fractions (+150 µm, –150 µm/+75 µm, –75 µm/+25 µm and –25 µm) showed that:
| ● | Pyrite liberation averaged 70% across the whole feed. Liberation improved markedly with size reduction, reaching ~80% in the –75 µm/+25 µm band and >90% in the –25 µm band for both MCs. Non-liberated pyrite was predominantly intergrown with silicates (hard and soft) with only minor complex locking. |
| ● | Silicate gangue (quartz + feldspars + chlorite/sericite) was inherently well liberated (>90% free or liberated) at all sizes. |
| ● | Carbonate liberation was limited in the coarse fractions, with only ~45% free/liberated above 150 µm. Liberation improved to ~60% in the –75 µm/+25 µm interval and to 85%–90% below 25 µm. Residual locked carbonate was mainly associated with silicates. |
Table 10-4 below summarizes how much of the pyrite (the main sulphide of economic interest) was either free or liberated. Values were calculated from the liberation data tables in the SGS QEMSCAN report [3] for the three composites. These data confirm that a primary grind of P₈₀ = 75 µm is sufficient to expose the majority of gold‑bearing pyrite surfaces, consistent with the >90% Au flotation recoveries obtained in SGS
Tests F7–F8 [2].
Table 10-4:Pyrite Liberation Per Size Range for Three Composites
Size Fraction | 147 Zone MC | CZ MC | Graphite Composite |
Combined | 74.4% | 74.9% | 72.1% |
+150 µm | 58.9% | 51.0% | 36.2% |
-150 µm/+75 µm | 69.6% | 69.2% | 69.4% |
-75 µm/+20 µm | 80.9% | 77.7% | 80.8% |
-20 µm | 91.3% | 92.6% | 95.3% |
10.4.1.5Gravity Recovery
EGRG tests on the 147 Zone MC achieved 28% gold recovery to a Mozley concentrate grading 629 g/t Au at P80 ≈ 91 µm, while a finer grind (P80 ≈ 69 µm) increased recovery to ~32% with concentrate grades exceeding 1,100 g/t Au. The CZ MC yielded ~22% GRG at a similar grind, reflecting a higher proportion of gold hosted in sulphide minerals. Refer to Table 10-5 for detailed results.
Table 10-5:Gravity Recovery for 147 Zone and CZ
Test ID | Ore Type | Grind P80 (µm) | Conc. Mass (%) | Conc. Au (g/t) | Au Recovery (%) |
G 5 | 147 MC | 91 | 0.13 | 629 | 28.0 |
G 8 | 147 MC | 69 | 0.10 | 1 142 | 32.1 |
G 3 | CZ MC | 97 | 0.18 | 511 | 17.2 |
G 9 | CZ MC | 74 | 0.09 | 1 242 | 21.6 |
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The gravity recoveries achieved are marginally below the rule-of-thumb minimum of 25% recovery required during laboratory testing to justify inclusion of a gravity recovery step in the flowsheet.
10.4.1.6Flotation
Sulphide flotation with carbon pre-flotation of gravity tails was conducted using a reagent suite of kerosene, potassium amyl xanthate (PAX), methyl isobutyl carbinol (MIBC), and MaxGold 900 (modified dithiocarbamate). This testing showed gold recoveries exceeding 90% at mass pulls between 10% and 15%, producing concentrates grading 21 g/t to 33 g/t Au.
Combined gravity and flotation recoveries of +93% and +94% were observed for 147 Zone and CZ composites, respectively.
At the time of the flotation tests, only total carbon assays were available, and it was suspected that the carbon was only present in organic or graphitic forms. However, it was later determined that most of the carbon present was in the form of carbonate, which explains the poor performance of the carbon pre-float, which recovered only 1.8% of the contained carbon in tests F-7 and F-8.
Refer to Table 10-6 and Table 10-7 for additional information.
Table 10-6:Flotation Results for 147 Zone and CZ
ID | Product | Wt% | Au (g/t) | TOC (%) | S (%) | Au Dist | C Dist | S Dist |
Test | | | | | | (%) | (%) | (%) |
F-8 (147) | Carbon Pre- | 1.6 | 35.8 | 3.25 | 2.72 | 25.3 | 1.8 | 2.8 |
| Float Conc | | | | | | | |
F-8 (147) | Bulk Ro Conc | 8.2 | 18.1 | 1.96 | 17.4 | 66.3 | 5.8 | 93.6 |
F-8 (147) | Carbon + Ro | 9.8 | 21.0 | 2.17 | 15.0 | 91.5 | 7.6 | 96.4 |
| Conc | | | | | | | |
F-8 (147) | Ro Tail | 90.2 | 0.21 | 2.85 | 0.06 | 8.5 | 92.4 | 3.6 |
F-8 (147) | Head | 100 | 2.24 | 2.78 | 2.78 | 100 | 100 | 100 |
| (Calculated) | | | | | | | |
F-8 (147) | Head (Direct) | | 2.08 | 2.76 | 1.57 | | | |
F-7 (CZ) | Carbon Pre- | 1.7 | 30.0 | 2.13 | 4.13 | 9.9 | 1.8 | 2.8 |
| Float Conc | | | | | | | |
F-7 (CZ) | Bulk Ro Conc | 12.5 | 33.7 | 0.87 | 18.0 | 83.5 | 5.6 | 92.3 |
F-7 (CZ) | Carbon + Ro | 14.2 | 33.3 | 1.02 | 16.4 | 93.4 | 7.5 | 95.7 |
| Conc | | | | | | | |
F-7 (CZ) | Ro Tail | 85.8 | 0.39 | 2.08 | 0.14 | 6.6 | 92.5 | 4.9 |
F-7 (CZ) | Head | 100 | 5.05 | 1.93 | 1.93 | 100 | 100 | 100 |
| (Calculated) | | | | | | | |
F-7 (CZ) | Head (Direct) | | 4.36 | 1.91 | 2.59 | | | |
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Table 10-7:Stage Recoveries after Carbon Pre-flotation Results for 147 and CZ Samples
| 147 Zone | CZ |
Gravity | 28.0 | 17.2 |
Flotation | 91.5 | 93.4 |
Combined | 93.9 | 94.5 |
10.4.1.7Cyanidation of Gravity Tailings
Bottle-roll cyanidation tests were conducted on gravity tailings at 40% (w/w) solids, pH 10.5–11.0 and 0.5 g/L NaCN for 48 h, following a 1-h pre-aeration step. Results are shown in Table 10-8.
Table 10-8:Bottle Roll Cyanidation Results for 147 and CZ MC Samples
Composite | Head Feed | Cyanidation Stage | Overall Au | Residue | NaCN Cons. | CaO Cons. |
| Au (g/t) | Au Extraction (%) | Recov. (%) | Au (g/t) | (kg/t) | (kg/t) |
147 MC | 2.36 | 75 | 83 | 0.58 | 0.51 | 0.97 |
CZ MC | 4.22 | 69 | 76 | 1.29 | 0.55 | 0.88 |
Combined gravity + cyanidation extractions yielded overall gold recoveries of 83% (147 MC) and 76% (CZ MC).
10.4.1.8Detoxification
Leach tails from CN-16 (147 MC) and CN-17 (CZ MC) were subjected to an SO₂/Air–Cu-catalyzed detox process consisting of one (1) batch and three (3) continuous trials for each composite. The retention time for the continuous trials were approximately 60 minutes. Results are summarized as follows:
| ● | 147 Zone MC: Weak-acid-dissociable cyanide (CNWAD) dropped from 169 mg L⁻¹ to ≤ 0.1 mg L⁻¹ in every continuous run. Sulphur dioxide consumption ranged from 4.75 g to 4.34 g SO₂ per gram of CNWAD, with a constant Cu catalyst dose of 0.11 g g⁻¹ CNWAD. |
| ● | CZ MC: CNWAD was similarly reduced from 162 mg L⁻¹ to ≤ 0.1 mg L⁻¹ across all three continuous tests. Sulphur dioxide demand varied between 4.50 g and 3.98 g SO2 per gram of CNWAD. Copper addition started at 0.12 g per gram of CNWAD (CND 2) and was lowered to 0.06 g per gram of CNWAD for trials CND 2-1 and CND 2-2. |
10.4.1.9Sedimentation
Settling and rheology tests were performed on 10 kg lots of the 147 MC and CZ MC, each milled to P₈₀=83 µm. Flocculant optimization showed that a non-ionic polymer (Magnafloc 351) proved optimal at a dosage rate of 15 g/t. Static settling tests were assessed at varying feed rates, after which it was determined that a 10% pulp density produced the best clarity/underflow compromise for both composites. Refer to Table 10-9 for sedimentation test results.
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Table 10-9:Dynamic Solid-Liquid Separation Tests Results
Test No. | Feed Solids | Underflow | Unit Area | Initial Rate |
| (%) | Solids (%) | (m²/t/d) | (m/h) |
5 | 5 | 62 | 0.084 | 0.94 |
6 | 10 | 68 | 0.078 | 0.56 |
7 | 15 | 67 | 0.119 | 0.20 |
8 | 20 | 66 | 0.232 | 0.06 |
Dynamic thickening tests showed that, for the 147 MC, 26 g/t flocculant resulted in 64.5% solids underflow density at 88 m³/m²/d net rise rate, 0.41 t/m³/h solids loading, and 3.6 m³/m²/ h net hydraulic loading. For the CZ MC, at a 20 g/t flocculant dosage, a 65% underflow density was obtained, with net rise rate of 103 m³/m²/d, solids loading of 0.47 t/m³/h, and net hydraulic loading of 4.3 m³/m²/h.
Both thickener underflows exhibited a critical solids density of ~68%. At this density, the 147 Zone MC displayed yield stresses of 41 Pa (unsheared) and 27 Pa (post-shear), while the Contact-Zone MC measured 52 Pa and 30 Pa, respectively. JKTech Comminution Testing – “Final SMC Report for Grey Fox Project” (JKTech Job 12007/P53, 12 October 2012).
10.4.1.10Sample Handling and Density Checks
SMC test data for three (3) Grey Fox composites (147 Zone MC, Breccia, and Tuff) were received by JKTech from SGS Minerals Services on October 12, 2012 and analyzed to generate JKSimMet comminution parameters. The SMC protocol, a drill‑core variant of the JK Drop‑Weight test, provides ore breakage characteristics (A, b, ta, DWi) and derives specific‑energy indices (Mia, Mih, Mic) essential for preliminary comminution circuit design.
The core for all three (3) Grey Fox composites (147 Zone MC, Breccia, and Tuff) was quarter-cut, weighed in air and water, and its density established prior to breakage testing. Average specific gravities determined from the SMC Test were 2.91 for both the Breccia and 147 Zone MCs and 2.71 for the Tuff sample.
10.4.1.11Drop-Weight Index Test Results
The Drop‑Weight Index (Dwi) indicates a consistently hard ore. Axb values corroborate this, with the Breccia sample being the most resistant to impact breakage. Note that lower Axb values indicate a more competent sample and vice versa. The resultant test parameters and obtained indices are shown in Table 10-10.
Table 10-10:JKTech Results
Sample | DWi | Axb | Category | ta | Mia (kWh/t) | Mih (kWh/t) | Mic (kWh/t) |
| (kWh/m³) | | | | | | |
147 Zone | 9.01 | 32.6 | Hard | 0.29 | 22.9 | 18.0 | 9.3 |
Breccia | 9.58 | 30.1 | Hard | 0.27 | 24.0 | 19.1 | 9.9 |
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Sample | DWi | Axb | Category | ta | Mia (kWh/t) | Mih (kWh/t) | Mic (kWh/t) | |
| (kWh/m³) | | | | | | | |
Tuff | 7.82 | 35.3 | Moderately | 0.33 | 21.7 | 16.6 | 8.6 | |
| | | Hard | | | | | |
DWi values plot between the 76th and 89th percentiles of the >11,000‑sample SMC database, underscoring the ore’s high competency, while Axb percentiles are in the 13% to 26% range, meaning 74% to 87% of the ores in the database are softer. Breccia is, as expected, the hardest sample tested. The t10 @1 kWh/t averages 26.9%, which is also in the harder quartile of JKTech data.
High DWi and low Axb dictate a power‑intensive comminution circuit. JKTech correlations indicate that ore with these hardness characteristics typically requires:
| ● | Elevated SAG mill specific energy or the inclusion of a pebble crusher is required to maintain throughput. |
| ● | Potential benefit from high-pressure grinding rolls (HPGR) ball‑mill flowsheets where Mih (~17 to 19 kWh/t) falls below Mia, offering energy savings of ~10% to 15% relative to SAG mill–Pebble Crusher–Ball mill Circuit (SABC) designs. This is offset by a relatively modest throughput and low cost of electricity in Ontario which makes the HPGR option less attractive |
10.4.2Phase 1 Variability Assessment
The Phase 1 metallurgical testwork program was conducted by XPS in 2013 and documented in “Geomet Definition & Metallurgical Assessment of Grey Fox Zones, Phase 1” (Report 5013826.00, dated December 6, 2013) (XPS, 2013) represents the first systematic geometallurgical assessment of the Grey Fox deposit and was conducted to better understand ore variability and its implications for gold recovery across different geological and lithologic domains.
The primary aim of the program was to assess how gold recovery performance varies with geological characteristics—such as lithology, sulphide content, alteration, and depth—by conducting metallurgical and mineralogical testing on a carefully selected suite of composite samples.
The Phase 1 metallurgical testwork program provides critical early-stage insights into ore variability and its implications for gold recovery across the deposit. The 2013 study forms the foundation for defining geometallurgical units and supports the development of a predictive framework for processing behavior, laying the groundwork for optimization in both mine design and processing strategy.
10.4.2.1Variability Sample Matrix
Eight (8) variability composites were selected to benchmark the principal geometallurgical controls at Grey Fox. Selection criteria targeted lithology (147 Zone vs CZ), host unit, and depth (Upper vs Lower horizons) while maintaining a similar head‑grade window (~3 g/t) to isolate textural and sulphide effects. The resulting matrix provides a representative first‑pass dataset on which subsequent phases will be built (Table 10-11).
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Table 10-11: Sample Compositing Matrix
Comp # | Zone | Host Lithology | Horizon | Target Au (g/t) | Au (g/t) |
1 | 147 FW | Variolitic Volcanic (VIV) | Upper | 2.97 | 4.31 |
2 | 147 FW | VIV | Lower | 2.92 | 6.37 |
3 | 147 HW | Mafic Intrusive (MI) | Upper | 3.08 | 2.20 |
4 | 147 HW | MI | Lower | 2.90 | 3.15 |
5 | CZ FW | Sedimentary (SED) | Upper | 2.96 | 3.37 |
6 | CZ FW | SED | Lower | 2.99 | 5.70 |
7 | CZ HW | Mafic Volcanic (MV) | Upper | 2.96 | 2.36 |
8 | CZ HW | MV | Lower | 2.97 | 3.03 |
Note: HW = Hangingwall, FW = Foot Wall
10.4.2.2Head Assay and Mineralogical Correlation
Head assays showed gold grades from 2.20 g/t to 6.37 g/t and sulphur grades from 0.93% to 2.92%. Elevated sulphur (proxy for pyrite) was most pronounced in CZ units and correlates negatively with leach recovery. Composite‑scale QEMSCAN and backscatter electron imaging confirmed that CZ MV samples host finer, pyrite‑locked gold grains, whereas 147 Zone samples contain coarser, partially liberated gold. Typical major‑element chemistry for the eight (8) composites is summarized in Table 10-12.
Table 10-12: Head Assays of Composites
Comp # | Zone | Au (g/t) | S (%) | Fe (%) | Pyrite vol. (%)† |
1 | 147 FW | 4.31 | 1.18 | 10.49 | 2.8 |
2 | 147 FW | 6.37 | 1.47 | 10.28 | 4.1 |
3 | 147 HW | 2.20 | 0.93 | 9.79 | 1.6 |
4 | 147 HW | 3.15 | 1.14 | 9.79 | 2.0 |
5 | CZ FW | 3.37 | 2.12 | 4.33 | 4.6 |
6 | CZ FW | 5.70 | 1.33 | 3.57 | 6.6 |
7 | CZ HW | 2.36 | 1.41 | 7.27 | 4.0 |
8 | CZ HW | 3.03 | 2.92 | 8.46 | 6.6 |
Note: † Pyrite volume derived from modal mineralogy tables (XPS Phase 1 Report Appendices 2).
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10.4.2.3Whole-Ore Cyanidations
Whole-ore cyanidation testing was conducted using a batch (bottle-roll) methodology on all eight variability composites. Test conditions were standardized across all samples to enable direct performance comparison:
| ● | Charge size: 2 kg. |
| ● | Initial pH: 11.0 (adjusted with lime addition). |
| ● | NaCN dosage: 2,500 mg/L (maintained at equilibrium throughout test). |
| ● | Pulp density: 40% solids (w/w). |
| ● | Dissolved oxygen: 8–10 mg/L (maintained by air sparging). |
| ● | Sampling intervals: 2, 4, 6, 24, and 48 h. |
Final gold recovery varied considerably across the composites, ranging from 70% to 93%, and correlated primarily with ore head grade and sulphur content.
Dissolved oxygen levels were maintained within the 8-10 ppm range through air sparging. Sodium cyanide consumption spanned 1.26 kg/t (MV Upper) to 2.45 kg/t (147 FW Lower), as shown in Table 10-13.
Table 10-13: Whole-Ore Cyanidation Results
Comp # | Zone | Au Recovery | NaCN Consumed | Average Au grain size |
| | (%) | (g/t) | (µm) |
1 | 147 FW | 84.8 | 1,859 | 5.6 |
2 | 147 FW | 93.4 | 2,452 | 4.4 |
3 | 147 HW | 86.2 | 1,383 | 3.2 |
4 | 147 HW | 89.3 | 2,081 | 7.3 |
5 | CZ FW | 87.5 | 2,109 | 9.2 |
6 | CZ FW | 92.8 | 1,725 | 31.9 |
7 | CZ HW | 76.6 | 1,258 | 5.4 |
8 | CZ HW | 70.0 | 1,667 | 2.7 |
Kinetic analysis of leach solutions sampled at 2, 4, 6, 24, and 48 h revealed different dissolution kinetic profiles by Zone: 147 Zone composites leached fast, reaching 65% of their ultimate extraction within the first 2 h, whereas CZ ores lagged significantly, with averaged 2-h recoveries of ~41%. These kinetic differences have implications for leach tank sizing: CZ ore required longer residence times to achieve comparable recovery to 147 Zone material at the same grind size.
With the average recovery of 85% after 2 days of leaching, it is evident that the ore body contains significant portions that are mildly refractory.
Gold extraction is chiefly grade‑driven with a secondary penalty from pyrite. 147 Zone composites averaged 88% recovery, whereas CZ composites averaged 81%, primarily due to the poor‑performing MV subgroup.
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Within zones, upper vs lower horizons did not materially affect recovery at this grind size. The data also confirms that higher sulphur grades (>2%) combined with lower gold grades (<4 g/t) generally yields a sub 80% recovery. The two worst performing variability samples (7 and 8) also exhibited below average gold grain sizes, again hinting at some encapsulation of gold within the pyrite matrix. The results suggest that higher grades occur when coarse free gold is present, while lower grades are associated with much finer gold, often locked in sulphides and hence not amenable to cyanidation.
10.4.3Phase 2 Composite Program
The Phase 2 metallurgical testwork program was conducted by XPS and documented in “Geomet Definition & Metallurgical Assessment of Grey Fox Zones, Phase 2” (Report 5013826.00, dated February 10, 2014) (XPS, 2014a). This Phase 2 campaign continued the systematic geometallurgical evaluation of the Grey Fox deposit initiated in Phase 1, with a specific focus on validating and refining metallurgical domains and assessing their predictive value for processing performance.
The results of XPS’s Phase 1 testwork program demonstrated that the four laboratory composites comprising high- and low-grade material from the 147 Zone, and the two principal lithologies from the CZ (MV and SEDS units), are accurate, homogeneous, and representative of the current resource. The testwork further confirmed that these composites provide a suitable and reliable basis for predicting full-scale plant performance.
The main objectives of the Phase 2 program were:
| ● | To confirm and validate the metallurgical behavior of key geometallurgical units through comparative leaching and flotation performance of the four selected composites. |
| ● | To assess the reproducibility and internal variability of leach recoveries and flotation responses, ensuring these units are suitable for metallurgical modeling and process planning. |
| ● | To refine and update Phase 1 conclusions using material from recent drilling, with particular emphasis on head-grade characterization, sulphur and carbon content, and ore hardness. |
| ● | To reaffirm the geometallurgical drivers for processing behavior, namely that Grey Fox remains a coarse-gold, pyrite-hosted deposit where metallurgical response is closely tied to sulphur and carbon variability. This included observations on the influence of carbonaceous content, pyrite deportment, and gold grain size on recovery. |
| ● | To explore the potential for flotation as a recovery route for high-sulphide, low-recovery leach material by quantifying gold recovery into sulphide-rich flotation concentrates. |
In summary, the Phase 2 metallurgical testwork program provides enhanced confidence in the use of the four geometallurgical composites as representative processing units for Grey Fox. By validating composite consistency and updating metallurgical profiles using current drilling, the program confirms that recovery variability is chiefly controlled by sulphide and carbon content. These findings support the development of predictive recovery models and provide a basis for informing plant design decisions.
10.4.3.1Composite Definition and Representativeness
Four (4) geometallurgical composites were prepared from drill core intervals considered representative of the Grey Fox orebody: 147 Zone High Grade (HG), 147 Zone Low Grade (LG), CZ–Massive Volcanic (MV)
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and CZ–Siltstone/Epidote/Diopside Skarn (SEDS). Core was stage‑crushed to –10 mesh, blended and rotary‑split. Triplicate external reference distribution assays confirmed homogeneity with relative standard deviations ≤7% for gold. The resulting head grades bracket the expected resource cut‑off ranges and provide a robust basis for flowsheet selection (Table 10-14).
Table 10-14: Composites Definitions
Composite | Lithology / Zone | Au (g/t) |
147 HG | Quartz feldspar porphyry | 9.49 |
147 LG | Mafic volcanic | 1.83 |
Contact MV | Massive volcanic | 3.91 |
Contact SEDS | Bedded tuffaceous siltstone | 2.96 |
10.4.3.2Head Grade and Mineralogy
Head assay results (as shown in Table 10-15) confirm gold association with pyrite. Arsenic and total carbon remain modest (As <0.02 %, TOC <3%) across all composites. Sulphur in Contact SEDS (3.1 %) is ~60% higher than Contact MV (1.9%), reversing Phase 1 trends and explaining the lower leach response for SEDS. QEMSCAN imagery showed ~90% of gold as ≤10 µm inclusions in pyrite or at pyrite–silicate boundaries, supporting a sulphide flotation flowsheet.
Table 10-15: Composite Head Assays
Composite | Au (g/t) | As (%) | Fe (%) | S (%) | TOC (%) | Remarks |
147 HG | 9.49 | 0.013 | 10.12 | 1.86 | 2.12 | Head grade higher than model; blended later |
147 LG | 1.83 | 0.006 | 10.06 | 1.03 | 1.62 | Provides dilution for 6 g/t blend |
Contact MV | 3.91 | 0.008 | 7.81 | 1.95 | 3.09 | Highest carbon; potential preg robbing |
Contact SEDS | 2.96 | 0.005 | 4.69 | 3.05 | 1.49 | Most pyritic sample |
10.4.3.3Comminution
BBWi values placed Grey Fox ores among the very hardest gold deposits globally (19–26 kWh/t). These results supported a high‑power conventional SAG/ball‑mill circuit or, alternatively, a secondary crush / closed‑circuit ball‑mill configuration should SAG throughput prove limiting. Please refer to Table 10-16 for a summary of results.
Table 10-16: Composite Head Assays
Composite | BWi (kWh/t) | Percentile* | Comment |
147 HG | 25.9 | 99 | Very hard – upper variability limit |
147 LG | 24.6 | 99 | Comparable hardness |
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Composite | BWi (kWh/t) | Percentile* | Comment |
Contact MV | 22.1 | 97 | Slightly softer, very hard |
Contact SEDS | 19.2 | 89 | Hardness advantage |
10.4.3.4Gravity Recovery
Dedicated GRG testing was not repeated in Phase 2; however, rougher flotation concentrates showed gold call factors up to 120% (147 HG), indicating a persistent coarse‑gold/nugget component. Phase 1 testwork suggested 20% to 30% of gold is amenable to gravity; similar performance is inferred here, justifying a gravity circuit ahead of leach or flotation.
10.4.3.5Flotation
Single‑stage rougher flotation was carried out on all four composites at a grind P₈₀ ≈ 60 µm (consistent with the anticipated primary‑mill product), 40 min residence in a 5 L Denver cell, and a reagent suite comprising 110 g/t PAX and 25 g/t MaxGold 900, supported by 40 g/t MIBC frother. Flotation was done using tap water at natural pH of 8. Under these conditions gold recoveries ranged from 92.9% to 96.8% for the 147 Zone composites and 94.3% to 95.7% for the two CZ composites; pyrite recovery exceeded 95% in most cases while mass pull to concentrate ranged between 8% and 12%. Please refer to Table 10-17 for summary of the flotation results.
Table 10-17: Initial Flotation Results
Composite | Au Rec. (%) | FeS₂ Rec. (%) | SiO₂ Rec. (%) | Au Call Factor (%) |
147 Zone HG | 96.8 | 96.0 | 7.8 | 120 |
147 Zone LG | 92.9 | 95.0 | 7.6 | 125 |
Contact MV | 95.7 | 95.0 | 7.8 | 104 |
Contact SEDS | 94.3 | 95.5 | 11.7 | 85 |
Concentrate grades varied between 18 g/t and 105 g/t Au, with the higher values coinciding with the 147 Zone samples that contain a coarse gold component. The elevated “call factors” (>120%) calculated for 147 HG and LG indicate the presence of unassayed liberated gold remaining in the feed, whereas the lower call factor of 85% for Contact SEDS points to a finer gold‑in‑pyrite grain size. Overall, the data confirm that a single reagent recipe and 60 µm grind size can accommodate Grey Fox variability with minimal loss in performance, providing a sound baseline for the forthcoming locked‑cycle and concentrate treatment tests.
10.4.3.6Whole-Ore Cyanidation
Extended bottle‑roll cyanidation tests (sampling at 2, 4, 6, 24 and 48 h) conducted at P₈₀ ≈ 60 µm, 2,500 mg/l NaCN dosage, dissolved oxygen at >8 mg L⁻¹ and a target pH 11.0. Pulp Eh and residual CN⁻ were logged at 2, 8, 24 and 48 h intervals, but only the 24 h and 48 h gold extractions are reported by XPS and shown in Table 10-18.
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Table 10-18: Extended Cyanidation Results
Sample | Head | NaCN | NaCN | Au | Au | Comments |
147 HG | 10.3 | 3.1 | 4.6 | 94.2 | 93.6 | Fast, diffusion limited after 8 h; no preg-robbing or thiocyanate build up |
147 LG | 2.42 | 1.7 | 2.4 | 82.2 | 83.2 | Kinetics governed by finer Au; plateau reached only after ~36 h |
147 Blend A | 7.09 | 1.0 | 1.4 | 90.5 | 93.0 | Confirms near linear grade vs recovery trend; CN efficiency improves at intermediate grade |
147 Blend B | 5.86 | 1.3 | 1.4 | 92.5 | 92.0 | Replicate validates projection at 6 g/t design grade |
Contact MV | 3.87 | 2.1 | 3.2 | 88.0 | 85.7 | Slight Au drop between 24 h & 48 h due to preg robbing by organic carbon (3% TOC) |
Contact SEDS | 3.07 | 1.6 | 2.2 | 70.8 | 70.5 | High sulphide slows dissolution; pre oxidation or finer grind recommended |
Based on the cyanidation results in Table 10-18, the 147 Zone behaved as a classic free‑milling system, with extraction almost linearly proportional to head grade. Blending high‑ and low‑grade material to a ~6 g/t Au feed grade yielded ~90% recovery after 24 h and exceeded 92% at 48 h. Cyanide consumption scaled with sulphide content but stabilised below 1 kg/t at the design grade, indicating that reagent efficiency improved when the excess sulphide surface area of low‑grade ore was diluted with high‑grade feed.
The CZ composited diverged markedly. Contact MV responds well initially (88% in 24 h) but showed a modest regression by 48 h, diagnosed by XPS as preg‑robbing from graphitic carbon that became active once dissolved gold concentrations fell below ~2 mg/L. In contrast, Contact SEDS extraction was inhibited from the outset, with only 71% of gold dissolved after 48 h. This behavior was attributed to the higher pyrite (~3% S) competing for cyanide and passivation of gold surfaces. Pre‑oxidation or finer grinding was therefore required for this domain.
Overall, these results confirmed that a whole‑ore leach flowsheet will be feasible for 147 Zone ore, provided that head grades stay above ~5 g/t (refer to Figure 10-2). For CZ ores, a flotation‑first route appears to be optimal. The blended tests clarified recovery at the reserve grade and will provide input into the recovery algorithms in the Grey Fox economic model.
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Figure 10-2:Head Grade vs Recovery for 147 Zone
10.4.3.7Flotation Tailings Cyanidation
Although flotation tailings were not separately leached in Phase 2, the high (>95 %) pyrite recoveries imply low residual sulphide and a remaining unrecovered gold fraction of only 2%–3%, placing doubt on the efficacy and value of leaching flotation tails.
10.4.42014 Phase 3 Pyritic & South Study
The test program conducted in 2014 represents Phase 3 of metallurgical and geometallurgical investigation into the Grey Fox deposit by XPS for then-owner Brigus Gold. The findings of this testwork were documented in “Geometallurgical Assessment of Grey Fox Pyritic & Grey Fox South” (Report 5014812.00, dated November 10, 2014) (XPS, 2014b). This phase was aimed at advancing the process design by exploring the recovery behavior of both high-sulphur and variable-grade ore types through alternative flowsheet strategies.
The 2014 report documents Phase 3 metallurgical and geometallurgical testwork carried out by XPS on two ore sources from the Grey Fox deposit: a high-sulphur “Contact Zone Pyritic” composite and a suite of variability samples from Grey Fox South. The program combined bulk sulphide flotation, bottle-roll cyanide leaching, QEMSCAN mineralogy, and hardness testing to define geometallurgical units, measure gold deportment in pyrite, and establish how head grade and sulphur content control recovery. Its purpose was to generate the data needed to compare whole-ore leaching against flowsheets that float, regrind, and separately leach sulphide concentrates and tailings, thereby guiding process design for both the pyritic and Grey Fox South ores.
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This Phase 3 report extends the geometallurgical understanding of the Grey Fox deposit by targeting two challenging ore domains—high-sulphur pyritic and variable Grey Fox South ores. The comprehensive approach combining flotation, leaching, mineralogy, and hardness testing delivers the critical data needed to evaluate and compare processing strategies, optimize recovery, and support design decisions for future development phases.
10.4.4.1Sample Classification
Two distinct groups of samples were selected from the Grey Fox deposit to represent the expected variability in ore properties and associated metallurgical performance. One composite specifically represented the high-sulphur, low-grade CZ Pyritic ore, identified as potentially refractory due to its elevated sulphur content. In addition, six variability samples were sourced from the Grey Fox South zone. These samples spanned a range of lithologies including Variolitic Volcanics (VIV), Mafic Volcanics (MV), Mafic Intrusive (MI), and Sedimentary (SEDS) rocks, each reflecting a spectrum of gold and sulphur contents.
These Grey Fox South variability samples were later consolidated into four clearly defined geometallurgical units, facilitating easier interpretation and prediction of metallurgical performance:
| ● | High-grade (HG) ore with Au >4 g/t (Grey Fox South-HG). |
| ● | Low-grade (LG) ore with Au <4 g/t (Grey Fox South-LG). |
| ● | Low-grade, low-pyrite (LGC) ore defined by a S/Au ratio below 0.75 (Grey Fox South-LGC). |
| ● | Low-grade, high-pyrite (LGP) ore defined by a S/Au ratio above 0.75 (Grey Fox South-LGP). |
In parallel with the metallurgical classification, a detailed mineralogical analysis using QEMSCAN was undertaken on all feed samples and specifically on the CZ Pyritic concentrate after flotation, to thoroughly characterize pyrite liberation, gold deportment, and mineral associations impacting cyanide leach recoveries.
10.4.4.2Head Assays
Detailed head assays were conducted to characterize the ore samples prior to metallurgical testing. These assays highlighted the critical influence of sulphur and gold contents on downstream processing and recoveries. The CZ Pyritic composite specifically showed a relatively low gold grade of 1.92 g/t Au coupled with an elevated sulphur content of about 4.0%, resulting in a very high sulphur-to-gold ratio (S/Au ≈ 2.1), indicative of challenging recovery conditions.
The Grey Fox South geometallurgical units demonstrated a diverse set of head assay values, clearly delineating their metallurgical response, as shown in Table 10-19.
Table 10-19:Geomet Units Head Assay
Composite | Gold Grade (Au, g/t) | Sulphur (S,%) | S/Au Ratio |
CZ Pyritic | 1.92 | 4.0 | 2.1 |
Grey Fox South-HG | 5.3 | 1.5 | 0.28 |
Grey Fox South-LG | 0.95 | 1.4 | 1.5 |
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Composite | Gold Grade (Au, g/t) | Sulphur (S,%) | S/Au Ratio |
Grey Fox South-LGC | 3.40 | 1.1 | 0.31 |
Grey Fox South-LGP | 2.99 | 3.9 | 1.3 |
10.4.4.3 | Comminution |
Ore hardness is critical for process design and throughput forecasting. Historical BWi data indicated that ores from the Grey Fox deposit vary from moderately hard to extremely hard. The CZ ores exhibited moderate hardness, with a BWi range from 19 kWh/t to 22 kWh/t. In contrast, the 147 Zone and particularly the VIV-rich ores from Grey Fox South displayed significantly higher hardness values, typically ranging from 24 kWh/t to 27 kWh/t, placing them in the category of very hard ores (Table 10-20).
Table 10-20: BWi Results by Zone
Zone / Lithology | BWi (kWh/t) |
Contact – SEDS-Tuff | 19.2 |
CZ – MV | 22.1 |
147 Zone – VIV + MI (LG) | 24.6 |
147 Zone – VIV + MI (HG) | 25.9 |
147 Zone – VIV + MV Blend | 27.1 |
In the case of Grey Fox South, this zone is largely comprised of VIV hosted ore with marginal amounts of MV and MI hosted ore making up the balance. This indicates that the expected BWi hardness of the Grey Fox South-hosted ore may fall between 24 kWh/t and 27 kWh/t and be considered in the 98th to 99th percentile for hardness.
To evaluate liberation and recovery trade-offs, all metallurgical testwork in this phase used a consistent primary grind size of approximately 60 µm (P₈₀). In addition, pyrite concentrates from flotation were further reground to finer sizes (25 µm and 12 µm) to investigate the impact on gold liberation and the subsequent extraction efficiencies via cyanide leaching.
10.4.4.4Whole-Ore Cyanidations
Whole-ore cyanidation tests involved duplicate 48-h bottle-roll leaches at a controlled pH of about 11 and cyanide concentration of approximately 2,500 ppm NaCN, with 50% solids loading. Both solutions and solids residues were assayed in duplicate, enhancing the reliability of the recovery estimates.
The CZ Pyritic composite achieved only moderate recovery (approximately 79%), indicating a significant proportion of gold being refractory and encapsulated in pyrite minerals. Grey Fox South geometallurgical composites yielded higher recovery rates reflecting the influence of gold grade and sulphur content, with HG achieving about 89%, LG around 73%, LGC around 75%, and LGP approximately 81% recovery, as shown in Table 10-21.
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Table 10-21: Geomet Units Cyanidation Results
Composite | Gold Grade | Sulphur Grade | S/Au Ratio | Averaged Au |
| (g/t) | (%) | | Recovery (%) |
CZ Pyritic | 1.92 | 4.0 | 2.1 | 79.4 |
Grey Fox South-HG | 5.3 | 1.5 | 0.28 | 89.3 |
Grey Fox South-LG | 0.95 | 1.4 | 1.5 | 73.2 |
Grey Fox South-LGC | 3.40 | 1.1 | 0.31 | 75.5 |
Grey Fox South-LGP | 2.99 | 3.9 | 1.3 | 81.3 |
10.4.4.5Rougher Flotation
Rougher flotation tests were performed on 2-kg samples, at a grind size of P₈₀ of about 60 µm to evaluate the recovery of gold-bearing sulphides into a concentrate. The focus of the flotation tests was to determine the effect of pyrite-bearing ore; hence, only the CZ Pyritic composite and Grey Fox South-LGP composites were tested. The CZ Pyritic composite exhibited excellent flotation response, recovering approximately 93% of the gold and 97% of the sulphur into only 14% of the total mass. Similarly, the Grey Fox South-LGP composite showed comparable flotation efficiency, achieving about 95% gold recovery into a concentrate comprising approximately 15% of the total feed mass (Table 10-22).
Table 10-22: Geomet Units Flotation Results
Composite | Mass Pull (%) | Au Recovery (%) | Sulphur Recovery (%) |
CZ Pyritic | 14.0 | 93% | 97% |
Grey Fox South-LGP | 14.6 | 95% | Not reported |
10.4.4.6Flotation Tailings Cyanidation
Flotation tails were cyanide-leached without further regrinding. The tailings from the CZ Pyritic composite were successfully leached to a residual gold content of approximately 0.05 g/t Au. From the initial flotation tail feed (0.18 g/t Au), this represented around 74% recovery. Similarly, for the LGP composite, a gold recovery of 74.3% was achieved (Table 10-23), indicating minimal refractory gold in non-sulphide gangue minerals. Cyanide consumption was approximately 1.2 kg/t but maybe have been inflated due to the use of a very high cyanide concentration during the test. It is expected that cyanide consumption for tailings leaching would be <1 kg/t due to the removal of cyanide-consuming components from the tails.
Table 10-23: Flotation Tailings Cyanidation Results
Sample Type | Flotation Tail Grade | Leach Tails | Au Recovery from |
CZ Pyritic composite | 0.18 | 0.05 | 73.6% |
Grey Fox South-LGP | 0.16 | 0.04 | 74.3% |
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10.4.4.7Flotation Concentrate Cyanidation
Leaching tests on pyrite concentrates indicated limited recovery gains from intensive regrinding. At the as-floated grind size (~60 µm), the CZ Pyritic concentrate yielded about 80% gold recovery. Regrinding the concentrate to a P₈₀ of 25 µm improved recovery only slightly to 83%, while finer grinding to 12 µm provided no further recovery benefit, indicating diminishing returns at finer sizes due to pyrite-locked gold inclusions. The Grey Fox South-LGP composite reflected similar recovery compared to the CZ Pyritic composite (Table 10-24). Cyanide consumption was approximately 5 kg/t of leach feed but again from a very high cyanide concentration in solution.
Table 10-24: Flotation Concentrate Cyanidation Results
Sample Type | Conc Grade Au | Residual Au | Au Recovery from |
CZ Pyritic Composite Concentrate @ 60 µm | 12.6 | 2.59 | 80.2% |
CZ Pyritic Composite Concentrate @ 22 µm | 12.6 | 2.11 | 83.5% |
CZ Pyritic Composite Concentrate @ 12 µm | 12.6 | 2.09 | 82.9% |
Grey Fox South-LGP | 17.06 | 3.26 | 80.9% |
10.4.52015 Phase 4 Leaching-with-Flotation Investigation
The Phase 4 testwork program was completed by XPS and documented in the report titled “Brigus Grey Fox Phase IV: Leaching with Flotation” (Report 4015803.00, dated June 9, 2015) (XPS, 2015). This program was designed to evaluate processing optimization opportunities for Grey Fox South ore: the southernmost HG zone of the deposit. Specifically, Phase 4 targeted optimization opportunities around grind size, flotation, and leaching strategies.
The primary goals of this Phase 4 testwork program were:
| ● | To assess the response of Grey Fox South ore to flotation and leaching at grind sizes coarser than the baseline P₈₀ of 60 µm, with test grind sizes up to 120 µm. This was driven by previous observations of high energy consumption due to ore hardness. |
| ● | To evaluate whether flotation could effectively concentrate gold into a low-mass sulphide product, and if subsequent leaching of this concentrate and its tailings could maintain gold recovery while allowing for coarser primary grinding. |
| ● | To investigate whether a split leach approach (leaching of both flotation concentrate and tailings separately) offered any metallurgical advantages over conventional whole-ore leaching. |
To explore the operational flexibility provided by decoupling recovery from grind size, and assess if energy savings or increased throughput could offset minor losses in gold recovery, especially given the ore’s high hardness characteristics.
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10.4.5.1Sample Selection
A composite sample was prepared from mineralized drill core collected from both the 147 Zone and the CZ at Grey Fox South. The final composite was made from 37 core intervals comprising various lithologies (SED, VIV, MI/MV, FZ) and weighed approximately 40 kg. The expected head grade was 3.0 g/t Au. The assayed composite showed a slightly higher gold grade due to a known nugget effect. Sulphur levels across lithologies ranged from 0.4% to 2.9%. Refer to Table 10-25 for details pertaining to the samples used in this phase of testing.
Table 10-25: XPS Phase 4 Sample Selection
Lithology (Zone) | Core Intervals | Avg. S | Mass Weight | Au Grade |
SED (CZ) | 8 | 1.2 | 8.8 | 3.12 |
VIV (CZ) | 6 | 0.4 | 6.6 | 3.27 |
MI/MV (CZ) | 5 | 2.9 | 5.6 | 3.03 |
FZ (CZ) | 4 | 2.8 | 4.4 | 3.40 |
Subtotal Contact | 23 | 1.8 | 25.4 | 3.19 |
VIV (147) | 6 | 1.0 | 6.6 | 3.09 |
MV (147) | 6 | 1.7 | 6.6 | 2.54 |
MI (147) | 1 | 1.1 | 0.5 | 2.07 |
SED (147) | 1 | 0.5 | 1.1 | 2.62 |
Subtotal (147) | 14 | 1.1 | 14.8 | 2.78 |
Full Composite | 37 | 1.43 | 40.2 | 3.00 |
10.4.5.2Flotation
Flotation tests were conducted on the composite sample using 2 x 2.0 kg charges. Reagents used included 110 g/t PAX and 25 g/t Aero Maxgold 900 promoter, with MIBC frother. Flotation was performed at natural pH over 40 minutes. The aim was to recover gold into a low-mass sulphide concentrate for further treatment. Rougher flotation was performed on multiple grind sizes (P₈₀ of 60 µm, 90 µm, and 120 µm), and consistently achieved a gold recovery of ~94% with a mass pull of ~14%, indicating flotation performance is insensitive to grind over the range tested. Sulphur recovery followed the same trend, as shown in Table 10-26.
Table 10-26: XPS Phase 4 Flotation Results
Primary Grind P₈₀ | Mass Pull to Con. | Au Recovery to | S Recovery to |
60 | 13.8 | 93.6 | 96.7 |
90 | 12.7 | 94.0 | 95.7 |
120 | 14.5 | 93.9 | 95.7 |
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10.4.5.3Whole-Ore Cyanidation
Cyanidation of whole-ore samples was performed at 2,500 ppm CN dosage. This level was maintained throughout the leaching, which included solution collection and analysis after 6, 24 and 48 h of leaching. Leaching performance was evaluated at different grind sizes. The recalculated head grades differed considerably between the tests due to variations in the amount of gold found in solution; however, the duplicate tailings assays showed a clear trend toward higher gold losses as a function of increasing size consistent with plant experience.
As shown in Table 10-27, the tailings gold grade increased from 0.85 g/t Au at 60 μm to 0.97 g/t Au at 120 μm, or 0.12 g/t increase over a 60 μm increase in the P₈₀. This is equivalent to 0.02 g/t Au, or ~0.6% recovery, per 10 μm change in the P₈₀.
Table 10-27: Grind-Cyanidation Results
Primary Grind | Head Grade | Solution Grade | Tails Grade (g/t) | Call Factor | Calculated Au |
60 | 3.56 | 2.70 | 0.85 | 100 | 76.0 |
90 | 3.56 | 5.89 | 0.91 | 191 | 74.2 |
120 | 3.56 | 3.60 | 0.97 | 128 | 72.4 |
It is important to note that the nugget effect became more pronounced with coarser grind sizes, making it difficult to draw definitive conclusions regarding the grind-recovery relationship.
10.4.5.4Flotation Tailings Cyanidation
The flotation tailings, defined as non-sulphide gangue (NSG), were subjected to cyanidation at varying primary grind sizes. Leaching of NSG tails showed that gold recovery was less sensitive to grind size compared to whole-ore leaching. The indicated leach recovery was 73.9% at 60 μm, declining to 63% at 90 μm and 57% at 120 μm (Table 10-28). Expressed as a tailings grade, the final leach tailings rose from 0.10 g/t Au at 60 μm to 0.15 g/t Au at 120 μm, or a 0.05 g/t Au increase over a 60 μm increase in the P₈₀. This is equivalent to about 0.08 g/t Au, or approximately 0.25% recovery, per 10 μm change in the P₈₀. This indicates the presence of fine free gold for which recovery is independent of liberation size.
Table 10-28: Grind vs Flotation Recovery Results
Primary Grind | Flotation Tails | Solution Grade | Tails Grade (g/t) | Call Factor | Assayed Au |
60 | 0.30 | 0.28 | 0.10 | 128 | 73.9 |
90 | 0.36 | 0.22 | 0.13 | 97 | 62.9 |
120 | 0.31 | 0.19 | 0.15 | 108 | 56.7 |
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10.4.5.5Flotation Concentrate Cyanidation
The flotation concentrate (~14% of feed mass) was reground to a P₈₀ of ~35 µm in all cases before cyanidation. In Phase 3 testwork, further regrinding to finer sizes (P₈₀ 25 µm and 15 µm) showed only minor improvements in recovery for finer grinds, and therefore was not repeated. In the Phase 4 program, the focus was on confirming these results under different primary grind sizes. No significant change in flotation concentrate leach recovery was observed with changes in the original grind size of the ore, as indicated in Table 10-29.
Table 10-29: Grind vs Flotation Concentrate Cyanidation Results
Primary Grind | Flotation Conc | Leach Solution | Tails Grade (g/t) | Assayed Au |
60 | 31.3 | 25.6 | 5.78 | 81.9 |
90 | 38.7 | 32.1 | 5.91 | 84.5 |
120 | 25.3 | 20.1 | 5.14 | 79.7 |
10.5Recent Metallurgical Testing Results
10.5.12020 ALS Metallurgy Program KM6034
This program comprised metallurgical and environmental testwork conducted on mineralized material from the 147NE Zone of the Grey Fox deposit as part of McEwen’s ongoing evaluation and process development. The program was carried out by ALS Metallurgy in 2019 and 2020 and was designed to support process design through assessment of gold recovery potential via cyanidation, while also evaluating environmental considerations associated with leach residues. Findings from this testing program were documented in the report titled “Metallurgical & Environmental Testwork for the Grey Fox Deposit,” dated February 11, 2020 (ALS, 2020).
This program used six individual drill core composites and a MC from the 147NE Zone. The testing included bottle-roll cyanidation leach tests, grind size sensitivity analysis, head assay determination, environmental characterization of residues, and deportment analysis of refractory gold. The goal was to determine the cyanide leach amenability of the samples, understand the influence of grind size and reagent consumption on recovery, and gather supporting environmental data for residue management.
This testwork program provided critical information on the cyanidation leach performance of Grey Fox 147NE material, showing how grind size and composite variability influence recovery, reagent consumption, and leach kinetics. It also delivered environmental characterization data to support future permitting and waste management planning, and improved understanding of refractory gold deportment within the deposit. The results will guide process design decisions for gold recovery and support metallurgical modeling efforts for the Grey Fox Project.
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10.5.1.1Master and Variability Samples Compositing Strategy
ALS Metallurgy prepared a robust and methodically constructed composite sampling strategy to characterize the metallurgical behavior of ore samples from the 147NE Zone of the Grey Fox deposit. Samples were received by ALS on two separate dates (November 7 and 22, 2019), comprising 28 individual drill-core intervals of approximately 4 kg each.
From these individual samples, six variability composites (Composite 1 through Composite 6A) were carefully assembled, ensuring representative blending from specified drill-core intervals. Each variability composite aimed to capture unique metallurgical characteristics expected within the 147NE Zone.
This assembly approach enabled an accurate representation of spatial and geological variability, ensuring comprehensive coverage of anticipated ore variability. Individual variability composites ranged from approximately 4.7 kg (Composite 5) to 30.0 kg (Composite 2), allowing for sufficient mass to perform standardized cyanidation tests. MC 1 (totaling 40 kg), blended from equal proportions (8 kg) of Composites 1, 2, 3, 4, and 6A, provided a larger representative bulk sample for detailed grind sensitivity, comminution characterization, environmental testing, and gold deportment studies.
10.5.1.2Head Assays
Head assays conducted on each of the composites (Table 10-30) confirmed gold grades ranging from approximately 2.60 g/t to 8.09 g/t Au, with notable variations observed within duplicate assays, suggesting nuggety gold occurrences. Composite 2 yielded the highest average gold grade (8.09 g/t Au), whereas Composite 1 was the lowest grade sample (2.60 g/t Au). Significant assay variance in Composites 3, 4, and 6A suggested the presence of coarse gold particles, emphasizing the recommendation by ALS to employ screened metallic assays in future to enhance assay reliability and mitigate variability risks in head-grade determination.
Table 10-30: ALS Composite Sample Head Assays
Composite | Duplicate 1 Au (g/t) | Duplicate 2 Au (g/t) | Average Au (g/t) |
1 | 2.72 | 2.48 | 2.60 |
2 | 7.99 | 8.20 | 8.09 |
3 | 8.74 | 5.01 | 6.87 |
4 | 2.34 | 3.59 | 2.96 |
5 | 3.86 | 3.74 | 3.80 |
6A | 5.99 | 4.18 | 5.09 |
Master 1 | 4.49 | 5.15 | 4.82 |
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10.5.1.3Comminution
ALS performed rod-mill grind-calibration tests on every variability composite and on MC 1. Each test used a 2 kg charge, 1 L water and 20 kg mild-steel rods (Mill M2). The mill was stopped at timed intervals and the product screened through ASTM screens to generate full particle-size distributions. While these results are not used for sizing full-scale grinding mills, they do provide indicative information regarding differences in hardness.
The grind-calibration tests reveal a clear range in relative hardness: Composites 2 and MC 1 are the most resistant, needing more than 30 minutes of rod-milling to fall below a 100 µm P₈₀, whereas Composite 5 is the softest, achieving that size in only 22 minutes. This 20%–25% spread in grind time implies proportionally higher specific energy requirements for the harder ore samples—consistent with the very hard BWi of ~25 kWh/t recorded for MC 1. Nonetheless, every composite reached the design grind of ~100 µm within a practical 22-43 minute window. MC 1’s grind-sensitivity profile (157 µm→98 µm→66 µm) supplied the data underpinning subsequent cyanidation optimization. Together, these calibrated grind curves and work-index measurements provide a robust basis for sizing the primary grinding circuit and forecasting power demand across the deposit’s varying ore domains.
10.5.1.4Whole-Ore Cyanidation
Cyanidation leach tests performed at various grind sizes (66 µm, 98 µm, and 157 µm P₈₀) on MC 1 at a pulp density of 33% solids, pH 11 (maintained with lime), and a cyanide concentration of 600 ppm showed robust gold extraction performance between 66 µm (90.2% Au recovery) and 98 µm (91.0% Au recovery), with only a minor decrease observed at the coarser grind size of 157 µm (87.0% Au recovery).
Refer to Table 10-31 for results. Gold leach kinetics were rapid, achieving near-complete extraction within the first 6 h.
Table 10-31: ALS Grind-Whole Ore Cyanidation Results
Test | P80 | Au Extraction | Tail Au | NaCN | Lime | Calc. Head |
1 | 66 | 90.2 | 0.56 | 0.56 | 0.9 | 5.70 |
2 | 98 | 91.0 | 0.57 | 0.57 | 0.8 | 6.33 |
4 | 157 | 87.0 | 0.84 | 0.84 | 0.5 | 6.48 |
These findings indicated limited sensitivity to grinding finer than ~100 µm, providing a metallurgical basis for a design decision at or near 100 µm as a target grind size.
As shown in Table 10-32, leach testing of the variability composites at a standardized grind size (P₈₀ = 100 µm) showed consistently high gold extractions ranging from approximately 85.1% (Composite 3) to 95.8% (Composite 1). Composites with higher gold grades and higher sulphide content (e.g., Composite 2 and Composite 3) tended toward somewhat lower extraction efficiencies and higher cyanide and lime consumptions. This underscores the importance of monitoring sulphide-gold associations to optimize recovery and manage reagent use.
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Table 10-32: ALS Variability Cyanidation Results
Composite | Au Extraction (%) | Tail Au (g/t) | NaCN (kg/t) | Lime (kg/t) | Head Au (g/t) |
1 | 95.8 | 0.21 | 0.2 | 0.5 | 4.94 |
2 | 90.8 | 0.96 | 1.1 | 1.1 | 10.41 |
3 | 85.1 | 1.05 | 1.0 | 1.2 | 7.05 |
4 | 93.0 | 0.22 | 0.4 | 0.5 | 3.15 |
5 | 91.1 | 0.42 | 0.4 | 0.9 | 4.74 |
6A | 91.3 | 0.65 | 1.1 | 1.1 | 7.49 |
10.5.22025 ALS Metallurgy Test Work Program KM7663
10.5.2.1Sample Description and Test Work Objectives
This testwork program, completed in October 2025, focused on samples from the underground zones Whiskey Jack and Gibson. These two zones constitute the bulk of the underground mine resource, whereas most of the previous testing was conducted using samples from the open pit mining zones. The primary objective of the program was to assess the amenability of these underground zones to the flowsheet as proposed for the open pit zones. A secondary objective was to adjust Process design criteria, if necessary, to include this part of the overall orebody.
Eight (8) drill core samples were provided to ALS Metallurgy for testing:
| ● | Samples 1, 2 and 3 from Gibson South. |
| ● | Samples 4, 5 and 6 from Gibson North. |
| ● | Samples 7 and 8 from Whiskey Jack. |
The testwork program consisted of head assays, mineralogy, comminution testing, flotation testing and leaching of flotation products.
10.5.2.2Head Assays
Head assays conducted on each of the underground samples (Table 10-33) show gold grades ranging from approximately 2.05 g/t to 6.28 g/t with an average of 3.8 g/t. The average for this set of samples is well above the life-of-mine (LOM) average which is expected to be closer to 2.5 g/t. This implies that average recovery results may be somewhat elevated.
Table 10-33: Underground Samples Head Assays
Sample ID | Fe (%) | S(t) (%) | TOC (%) | Au (g/t) |
Sample 1 | 2.35 | 0.50 | 0.06 | 2.98 |
Sample 2 | 3.81 | 0.20 | 0.07 | 4.25 |
Sample 3 | 6.75 | 0.84 | 0.05 | 2.05 |
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Sample ID | Fe (%) | S(t) (%) | TOC (%) | Au (g/t) |
Sample 4 | 2.71 | 1.04 | 0.07 | 2.12 |
Sample 5 | 2.49 | 0.41 | 0.05 | 3.88 |
Sample 6 | 2.74 | 0.63 | 0.04 | 6.01 |
Sample 7 | 6.25 | 0.79 | 0.06 | 6.28 |
Sample 8 | 6.55 | 0.45 | 0.06 | 2.72 |
Gold assays were performed using the screen metallics method, whereby a representative sub-sample was screened at 75 µm and the oversize fraction, which may contain coarse particulate gold, was digested to extinction and the solution subsequently analyzed. The more voluminous -75 µm fraction was split into smaller fractions, two of which were analyzed for gold using conventional fire assay. The results of the screen metallics procedure are shown in Table 10-34.
For the three higher-grade samples (2, 6 and 7), the increase in average grade appears to be due to an increase in coarse gold content in the +75 µm size fraction. Comparing the +75 µm and -75 µm split grades indicates that grades are similar when the average grade is below 4 g/t Au; however, for the three higher-grade samples, the grade of the +75 µm fraction is noticeably higher than that of the -75 µm fraction. This assessment is supported by the mass and gold distribution splits, which are similar for the lower-grade samples, but for the three higher-grade samples show gold distributions that are much higher than the corresponding mass split to the +75 µm oversize.
Table 10-34: Screen Metallics Gold Assay
Sample ID | Average Au (g/t) | Size | Au grade (g/t) | Mass% | Gold Distribution (%) |
Sample 1 | 2.98 | >75 µm | 2.14 | 8.0 | 5.7 |
| | <75 µm | 3.05 | 92.0 | 94.3 |
Sample 2 | 4.24 | >75 µm | 5.36 | 7.0 | 8.9 |
| | <75 µm | 4.16 | 93.0 | 91.1 |
Sample 3 | 2.05 | >75 µm | 2.17 | 6.8 | 7.2 |
| | <75 µm | 2.04 | 93.2 | 92.8 |
Sample 4 | 2.12 | >75 µm | 2.07 | 4.9 | 4.8 |
| | <75 µm | 2.12 | 95.1 | 95.2 |
Sample 5 | 3.88 | >75 µm | 2.78 | 5.7 | 4.1 |
| | <75 µm | 3.95 | 94.3 | 95.9 |
Sample 6 | 6.01 | >75 µm | 8.36 | 5.8 | 8.1 |
| | <75 µm | 5.87 | 94.2 | 91.9 |
Sample 7 | 6.28 | >75 µm | 9.04 | 6.0 | 8.7 |
| | <75 µm | 6.10 | 94.0 | 91.3 |
Sample 8 | 2.72 | >75 µm | 1.65 | 7.0 | 4.3 |
| | <75 µm | 2.80 | 93.0 | 95.7 |
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The implication of this difference is that it supports the inclusion of a gravity concentration step in the flowsheet to remove coarse gold as early as possible. This would result in less variable gold grade feed to the downstream processes and would also increase the accuracy of metallurgical accounting.
10.5.2.3Mineralogy
Table 10-35 presents the mineral composition of the samples as determined by QEMSCAN.
Table 10-35: Minerals Composition of the Underground Samples
Minerals | Sample | Sample | Sample | Sample | Sample | Sample | Sample | Sample |
| 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 |
Chalcopyrite | 0.1 | 0.1 | <0.1 | 1.3 | <0.1 | <0.1 | <0.1 | <0.1 |
Bornite | 0.0 | <0.1 | 0.0 | <0.1 | <0.1 | 0.0 | 0.0 | 0.0 |
Chalcocite | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | <0.1 | 0.0 | 0.0 |
Covellite | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | <0.1 | 0.0 | 0.0 |
Tetrahedrite | <0.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
Cuprite/Native Cu | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 |
Other Sulphides | <0.1 | <0.1 | 0.0 | 0.0 | <0.1 | <0.1 | 0.0 | 0.0 |
Pyrite | 0.8 | 0.3 | 1.7 | 1.1 | 0.7 | 1.0 | 1.5 | 0.8 |
Iron Oxides | 0.5 | 2.1 | 0.3 | 0.3 | 0.2 | 0.1 | 0.1 | 0.3 |
Quartz | 8.1 | 7.6 | 1.0 | 4.8 | 35.8 | 34.1 | 33.4 | 37.9 |
Feldspars | 56.4 | 53.2 | 57.9 | 66.3 | 29.9 | 23.5 | 2.3 | 7.7 |
Chlorite | 2.9 | 7.9 | 30.1 | 7.9 | 6.5 | 3.7 | 17.0 | 9.6 |
Muscovite | 10.3 | 6.5 | 4.6 | 9.7 | 14.7 | 15.2 | 4.5 | 8.0 |
Biotite/Phlogopite | 1.4 | 3.0 | 1.7 | 2.1 | 1.5 | 1.7 | 3.2 | 2.2 |
Titanium Minerals | 0.6 | 1.0 | 0.6 | 0.4 | 0.6 | 0.5 | 1.2 | 2.2 |
Apatite | 0.8 | 1.3 | 0.7 | 0.5 | 0.3 | 0.3 | 0.1 | 0.2 |
Calcium Carbonates | 17.5 | 16.2 | 0.8 | 5.0 | 9.0 | 19.2 | 34.6 | 29.9 |
Kaolinite | 0.2 | 0.2 | 0.1 | 0.2 | 0.2 | 0.3 | 0.2 | 0.2 |
Others | 0.5 | 0.7 | 0.5 | 0.4 | 0.6 | 0.4 | 1.8 | 1.0 |
Feldspars, quartz and calcium carbonates are the most abundant minerals and constitute about 75% of the total mass. Chlorite and muscovite are also present in significant quantities. The low composition of kaolinite (0.2%) and absence of other clay minerals indicates that the ore should not pose significant handling challenges. Sulphide minerals contribute only 1.5% to the total mass.
Table 10-36 presents the breakdown of sulphide minerals in these samples.
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Table 10-36: Sulphide Minerals Proportions in the Underground Samples
Sulphide Minerals | Sample | Sample | Sample | Sample | Sample | Sample | Sample | Sample |
Copper Sulphides | 6.6 | 11.5 | 0.9 | 42.4 | 3.1 | 1.0 | 1.4 | 1.5 |
Pyrite | 92.2 | 87.6 | 99.1 | 57.5 | 96.7 | 98.8 | 98.5 | 98.3 |
Molybdenite | 0.1 | 0.2 | 0.0 | 0.0 | <0.1 | 0.0 | 0.0 | 0.0 |
Galena | <0.1 | 0.0 | 0.0 | 0.0 | 0.0 | 0.1 | <0.1 | 0.0 |
Sphalerite | 0.0 | 0.0 | 0.0 | 0.0 | 0.0 | <0.1 | 0.0 | 0.0 |
Other Sulphides | 1.1 | 0.6 | <0.1 | 0.1 | 0.2 | <0.1 | 0.1 | 0.1 |
Pyrite is by far the most abundant sulphide, contributing more than 90% to the total sulphide mass in most of the samples. Minor quantities of copper sulphides are also present. Sample 4 is distinct in that it contains a significant quantity of chalcopyrite (42.4% of the total sulphides). For this sample, elevated cyanide consumption could be expected, and it may also cause adsorption problems because dissolved copper can compete with gold for adsorption sites on activated carbon. When treating this part of the orebody, it may be prudent to blend this chalcopyrite-rich feed with other run-of-mine (ROM) feed. Carbon stripping frequency would also need to be increased to accommodate the negative effects of this mineral.
10.5.2.4Comminution
Eight (8) samples were subjected to BWi testing and results are presented in Table 10-37.
Table 10-37: BWi Results
Sample ID | F₈₀ (µm) | P₈₀ (µm) | Grams/Revolution | BWi (kWh/t) |
Sample 1 | 2308 | 80 | 1.05 | 17.7 |
Sample 2 | 2418 | 77 | 0.89 | 19.7 |
Sample 3 | 2328 | 78 | 0.97 | 18.6 |
Sample 4 | 2345 | 81 | 1.01 | 18.3 |
Sample 5 | 2483 | 76 | 0.82 | 20.8 |
Sample 6 | 2427 | 75 | 0.85 | 20.1 |
Sample 7 | 2349 | 76 | 0.97 | 18.2 |
Sample 8 | 2343 | 75 | 0.83 | 20.7 |
Average | | | | 19.3 |
The closing screen size for all of the BWi tests was 106 µm.
The underground mine samples, with an average BWi of 19.3 kWh/t, are not as hard as the open pit ore samples tested in previous campaigns, which yielded BWi results around 24 kWh/t. These results display a moderate degree of variability which implies that the grinding circuits will not be subjected to excessive
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peaks and troughs with respect to ore feed hardness and should therefore be relatively easy to control and operate.
10.5.2.5Whole-Ore Cyanidation
The eight samples were subjected to whole-ore cyanidations after grinding to a P₈₀ of approximately 80 µm. Results are presented in Table 10-38. Test conditions were as follows:
| ● | Pulp density = 45%w/w solids. |
| ● | Total test duration = 48 h. |
| ● | NaCN concentration = 471 g/m3 (maintained by manual addition of NaCN). |
| ● | pH = 11.0 (maintained manually). |
| ● | Oxygen sparged in headspace of bottle roll. |
Table 10-38: Whole-Ore Cyanidation Results
Sample ID | Au | NaCN | Ca(OH)2 | Residence | Calc Head | Measured | Tails |
Sample 1 | 90.9 | 0.3 | 2.4 | 48 | 3.64 | 2.98 | 0.33 |
Sample 2 | 93.3 | 0.2 | 3.4 | 40 | 5.34 | 4.25 | 0.36 |
Sample 3 | 78.6 | 0.2 | 2.9 | 30 | 2.82 | 2.05 | 0.61 |
Sample 4 | 71.1 | 1.2 | 3.4 | 48 | 2.04 | 2.12 | 0.59 |
Sample 5 | 70.8 | 0.5 | 5.9 | 30 | 4.05 | 3.88 | 1.19 |
Sample 6 | 64.6 | 0.4 | 2.7 | 40 | 6.58 | 6.01 | 2.33 |
Sample 7 | 93.1 | 0.4 | 2.4 | 24 | 6.69 | 6.28 | 0.47 |
Sample 8 | 91.8 | 0.5 | 1.7 | 28 | 3.41 | 2.72 | 0.28 |
Average | 81.8 | 0.46 | 3.10 | 36 | 4.32 | 3.79 | 0.77 |
Whole-ore cyanidation results were similar to that of the open pit samples tested previously with a wide range of gold recoveries ranging from as low as 64.4% to 93.3%. Cyanide consumption rates were reduced compared to the open pit testing with the notable exception of Sample 4, where the abundance of cyanide-soluble copper resulted in a 1.2 kg/t cyanide consumption rate. The samples leached relatively slowly with many still leaching after 40 h of cyanidation.
10.5.2.6Gravity Concentration
The eight samples were subjected to gravity separation tests after grinding to a P₈₀ of approximately 80 µm. Two sets of gravity separation tests were conducted. In the first set, 2-kg sub-samples were used to measure gravity recoveries and grades. In the second set, 10-kg bulk gravity separation tests were conducted primarily to generate gravity tailings for downstream flotation and cyanidation testing. In both cases, a centrifugal concentrator was used as the first stage, followed by panning of the primary
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concentrate to produce an upgraded final concentrate. The two-stage approach is generally considered to produce results that best mimic full-scale operations.
Results are summarized in Table 10-39 and Table 10-40.
Table 10-39: Gravity Concentration Results (2 kg tests)
Sample ID | Mass Pull | Grade | Au Recovery | Calc Head | Measured Head |
Sample 1 | 0.6 | 122 | 19.2 | 3.54 | 2.98 |
Sample 2 | 0.9 | 141 | 26.5 | 4.71 | 4.25 |
Sample 3 | 0.5 | 58.2 | 12.6 | 2.45 | 2.05 |
Sample 4 | 0.6 | 53 | 15.9 | 2.06 | 2.12 |
Sample 5 | 0.5 | 89 | 11.6 | 3.88 | 3.88 |
Sample 6 | 0.6 | 76 | 7.3 | 6.25 | 6.01 |
Sample 7 | 0.8 | 115 | 15.3 | 6.27 | 6.28 |
Sample 8 | 0.7 | 83.1 | 21.3 | 2.72 | 2.72 |
Average | 0.65 | 92.2 | 16.2 | 3.99 | 3.79 |
Table 10-40: Gravity Concentration Results (10 kg bulk tests)
Sample ID | Mass Pull | Grade | Au Recovery | Calc Head | Measured Head |
Sample 1 | 0.16 | 163 | 11.0 | 2.32 | 2.98 |
Sample 2 | 0.19 | 208 | 14.8 | 2.64 | 4.25 |
Sample 3 | 0.19 | 614 | 30.0 | 3.85 | 2.05 |
Sample 4 | 0.18 | 86.2 | 8.7 | 1.76 | 2.12 |
Sample 5 | 0.18 | 256 | 12.2 | 3.74 | 3.88 |
Sample 6 | 0.18 | 220 | 6.9 | 5.78 | 6.01 |
Sample 7 | 0.22 | 115 | 4.2 | 5.90 | 6.28 |
Sample 8 | 0.20 | 83.1 | 6.8 | 2.43 | 2.72 |
Average | 0.19 | 218.2 | 11.8 | 3.55 | 3.79 |
Comparing the results for the 2-kg and 10-kg charges, the mass pull to concentrate was lower for the bulk test, which is attributed to differences in equipment operation. The lower mass pull is more representative of what would be expected in a full-scale plant. As a result of the lower mass pull, the resulting concentrate exhibited, on average, higher grades and a decrease in gold recovery to the gravity concentrate.
No meaningful correlations were observed between head grade and either recovery or gravity concentrate grade. The occurrence of GRG appears to be random and unrelated to grade variations. For these underground zones, gravity recoveries are noticeably lower than those recorded during earlier test programs for open pit samples. The average gravity recovery for the underground zones was approximately
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12%, compared to 25% recorded for the open pit zones. At these lower levels, a gravity recovery unit operation would likely not be included in the flowsheet for the full-scale plant.
Given that the mine plan has the underground zones being mined first, followed by the open pit later, there is an opportunity to defer capital expenditure by delaying the installation of the gravity circuit until the start of open pit mining.
10.5.2.7Cyanidation of Gravity Tails
A 2 kg sub-sample of the tailings produced from the bulk gravity separation tests (Table 10-39) was subjected to standard bottle-roll cyanidation. Cyanidation conditions were consistent with those used for the whole-ore cyanidation tests. Results are summarized in Table 10-41.
Stage gold recovery during cyanidation is reported as the percentage of gold extracted from the gravity tailings sample into solution. Overall gold recoveries, inclusive of both the preceding gravity step and subsequent cyanidation of the gravity tailings, are also presented. Overall recovery was calculated using both solution gold analysis by AA spectrometry and solids gold analysis by fire assay.
Good agreement was observed between recovery values calculated from solution and solids analyses, providing confidence in the accuracy of the test and analytical procedures used by the laboratory.
Table 10-41: Cyanidation of Gravity Tails Results
Sample ID | Au Stage | NaCN | Lime | Residence | Overall Recovery% | Overall Recovery% |
Sample 1 | 76.4 | 0.23 | 0.64 | 24 | 79.0 | 79.5 |
Sample 2 | 89.6 | 0.28 | 0.85 | 24 | 91.1 | 92.0 |
Sample 3 | 89.2 | 0.19 | 0.82 | 24 | 92.4 | 85.9 |
Sample 4 | 69.3 | 1.04 | 0.54 | 48 | 72.0 | 75.0 |
Sample 5 | 65.4 | 0.19 | 0.82 | 48 | 69.6 | 69.8 |
Sample 6 | 63.2 | 0.24 | 0.98 | 30 | 65.7 | 65.2 |
Sample 7 | 90.7 | 0.28 | 0.91 | 24 | 91.1 | 90.6 |
Sample 8 | 77.9 | 0.44 | 1.20 | 32 | 79.4 | 76.5 |
Average | 77.7 | 0.36 | 0.85 | 31.8 | 80.0 | 79.3 |
Comparing these results with the whole-ore cyanidation tests shows that overall recoveries were similar, with average recoveries of 80.7% for the whole-ore cyanidation tests compared to 79.7% for the gravity plus cyanidation route. This indicates that the addition of a gravity step does not necessarily improve overall gold extraction when sufficient time was allowed for coarse gold dissolution in whole-ore leach testing.
Comparison of minimum required residence times indicates that the gravity tailings leached faster than the whole-ore samples. This implies that a residence time of approximately 32 h will be sufficient for leaching of gravity tailings, whereas the same residence time may result in incomplete dissolution of coarse gold if the
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gravity step is omitted. Alternatively, a whole-ore cyanidation flowsheet would require more leach volume to achieve the same gold extraction as a gravity-leach flowsheet.
Measured reagent consumptions also differed between two routes, with gravity-leach cyanidation requiring less cyanide (0.36 kg/t vs 0.46 kg/t) and substantially less lime (0.85 kg/t vs 3.1 kg/t). These results indicate that a significant portion of the reagent consumers reported to the gravity concentrate. It is possible that the reagent consumption may be the same after intensive cyanidation of the gravity concentrate; however, there is potential to reduce reagent costs if intensive cyanidation incorporates a pre-oxygenation step, whereby cyanide-soluble sulphides may be oxidized to sulphate. The oxidation of reagent consumers was not tested in this test program but should be considered in future test programs if a gravity-plus-leach flowsheet is pursued.
10.5.2.8Rougher Flotation of Gravity Tails
A 2 kg sub-sample of the same bulk gravity tailings used for the cyanidation tests was subjected to rougher flotation testwork using the following conditions:
| ● | Denver flotation cell (4.4 L). |
| ● | Natural pH ranging from 8.3 to 8.6. |
| ● | Total duration of 8 minutes with sampling at 2-minute intervals. |
| ● | PAX additions ranging from 40 to 70 g/t (depending on visual observation of the froth). |
| ● | MIBC additions ranging from 44 to 60 g/t (visual observation of froth). |
Table 10-42 summarizes the results. All values in the table refer to the head grade (i.e., rougher floatation recovery represents the percentage of gold reporting to the rougher concentrate relative to the head sample, rather than the gravity tailings sample. The mass pull, similarly, is based expressed relative to the original ROM sample mass and does not represent a stage recovery from the previous step.
Table 10-42: Rougher Flotation of Gravity Tails Results
Sample ID | Gravity | Gravity Au | Rougher | Rougher Float | Overall Au | Overall Sulphur |
Sample 1 | 0.16 | 11.0 | 6.8 | 77.4 | 88.4 | 94.6 |
Sample 2 | 0.19 | 14.9 | 4.4 | 74.8 | 89.7 | 92.3 |
Sample 3 | 0.19 | 30.0 | 4.7 | 59.3 | 89.3 | 91.0 |
Sample 4 | 0.18 | 8.7 | 10.3 | 78.9 | 87.6 | 95.9 |
Sample 5 | 0.16 | 12.3 | 5.9 | 73.9 | 86.2 | 88.3 |
Sample 6 | 0.18 | 6.9 | 7.1 | 72.0 | 78.9 | 89.0 |
Sample 7 | 1.10 | 1.3 | 5.2 | 84.8 | 86.1 | 92.8 |
Sample 8 | 1.10 | 3.3 | 4.0 | 82.1 | 85.4 | 89.6 |
Average | 0.41 | 11.1 | 6.1 | 75.4 | 86.5 | 91.7 |
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Comparison with results previously reported indicates that the rougher concentrate mass pull of 6.1% for these underground samples is lower than the average of 12% recorded for the open pit samples tested previously. This difference may be partly due to the shorter 8 minute total duration compared to 40 minutes for the open pit samples. However, evaluation of the incremental mass recoveries it is evident that very little additional mass or sulphide recovery is expected after 8 minutes.
Overall gold and sulphur recoveries for the underground samples, at 86.5% and 91.7%, respectively, were also lower than the corresponding recoveries of 93% and 95% reported for the open pit samples. The implication is that both cyanidation and flotation achieved lower overall gold recoveries for the underground samples relative to the open pit material.
10.5.2.9Whole-Ore Rougher Flotation
A 2 kg sub-sample of the original as-received samples was subjected to rougher flotation testwork after grinding to 80% passing 90 µm. The purpose of this set of tests was to evaluate whether the omission of an upstream gravity concentration step had any effect on flotation performance. The same conditions were employed as for the flotation test on gravity tailings.
Table 10-43 summarizes the results for the set of whole-ore rougher flotation tests.
Table 10-43: Whole-ore Rougher Flotation
Sample ID | Mass pull (%) | Gold Recovery (%) | Sulphur Recovery (%) |
Sample 1 | 4.8 | 89.7 | 93.0 |
Sample 2 | 4.7 | 89.6 | 87.6 |
Sample 3 | 6.7 | 91.0 | 96.7 |
Sample 4 | 11.6 | 88.7 | 84.9 |
Sample 5 | 6.3 | 88.4 | 88.9 |
Sample 6 | 8.2 | 79.4 | 89.8 |
Sample 7 | 5.6 | 88.8 | 89.8 |
Sample 8 | 3.9 | 88.1 | 86.3 |
Average | 6.5 | 88.0 | 89.6 |
Comparison of these results with the previous set of tests that included a gravity step indicates that the overall gold recoveries were marginally higher (88.0% vs 86.5%). However, given that recoveries were calculated from gold analyses of the gravity concentrate, which represents a small mass at a much higher grade, the observed difference is likely within the margin of error. The absence of a significant decrease in performance suggests that the gravity step is not an essential component of the overall flowsheet.
Samples were analyzed at 2 minute floatation intervals to assess kinetics. Figure 10-3 shows the averaged curve for all eight samples combined.
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Figure 10-3: Rougher Flotation Kinetics for Whole-Ore Samples
Flotation kinetics were fast, with most of the recoverable gold reporting into the concentrate within the first 2 minutes. Recovery then slowed significantly but continued at a steady rate over the remainder of the 8-minute test duration. It appears that extending the test time beyond 8 minutes would likely have resulted in gold recoveries exceeding 90%. Given that previous test campaigns on open pit samples achieved approximately 93% but with 40 minutes of flotation time, it is likely that the shorter duration of the underground sample tests was a primary factor contributing to the lower recoveries achieved.
Figure 10-4 shows a comparison of the overall gold recoveries achieved through cyanidation versus flotation for all eight samples. For both cyanidation and flotation routes, the average results of the tests with and without gravity separation were used. The graph shows that the flotation route yielded less variable and, on average, superior results compared to cyanidation. The average recovery for the eight samples combined was 87.2% through flotation, compared to 80.2% through cyanidation. While the recoveries are marginally lower than for open pit samples, mostly due to shorter float times, the underground samples nevertheless exhibited good amenability to flotation.
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Figure 10-4:Overall Recoveries through Cyanidation versus Flotation for Underground Samples
10.5.2.10Cyanidation of Rougher Tails
The rougher flotation tailings produced during the previous set of tests were subjected to bottle-roll cyanidations using the standard conditions as listed in Section 10.5.2.5. Results are tabulated in Table 10-44.
Note that the gold stage recoveries represent the average of recoveries calculated from the solution analysis by AA spectroscopy and from the fire assays of the tailings residues. The results show that approximately 72% of the gold contained in the rougher tails was extracted through cyanidation. Given that the rougher tails contain approximately 12% of the ROM feed gold, the downstream cyanidation of the rougher tails contributes approximately 8.6% to the overall gold recovery.
Table 10-44: Cyanidation of Rougher Flotation Tails
Sample ID | Au Stage | Calc Feed | Tails grade | NaCN | Lime | Residence |
Sample 1 | 77.7 | 0.39 | 0.09 | 0.50 | 0.7 | 24 |
Sample 2 | 76.5 | 0.54 | 0.13 | 0.42 | 0.69 | 48 |
Sample 3 | 80.1 | 0.34 | 0.07 | 0.16 | 0.67 | 48 |
Sample 4 | 68.3 | 0.25 | 0.08 | 0.39 | 0.63 | 48 |
Sample 5 | 52.9 | 0.46 | 0.22 | 0.40 | 0.81 | 24 |
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Sample ID | Au Stage | Calc Feed | Tails grade | NaCN | Lime | Residence |
Sample 6 | 55.7 | 1.53 | 0.68 | 0.83 | 1.05 | 24 |
Sample 7 | 78.4 | 0.87 | 0.19 | 0.39 | 1.13 | 24 |
Sample 8 | 85.7 | 0.49 | 0.07 | 0.46 | 0.75 | 48 |
Average | 71.9 | 0.61 | 0.19 | 0.44 | 0.80 | 36 |
Cyanide and lime consumptions were similar to those recorded during the gravity tailings series of tests. Four of the samples exhibited slower leach kinetics, with a significant amount of leaching continuing into the second day. This behavior is unexpected because leaching from silicates is usually fast and complete within 24 h.
Another unexpected result was the tailings grade of 0.68 g/t Au recorded for Sample 6. It is possible that the gold in this sample was not liberated, which is consistent with the low flotation recovery observed for this sample. No follow-up testing was conducted on this material. It is therefore recommended that a similar sample be collected for future testing and that its products be subjected to a diagnostic procedure to determine the cause of its lower recovery.
10.5.2.11Cyanidation of Rougher Concentrate
Rougher flotation concentrates produced during the previous set of rougher flotation tests were ground to 80% passing 14 µm and then subjected to cyanidation. Regrinding of flotation concentrates allowed additional liberation and gold recovery during previous test campaigns for open pit samples. The purpose of this set of rougher concentrate cyanidations was to assess if the same holds true for the underground samples. The same set of standardized cyanidation conditions were used for this set of tests.
Results are tabulated in Table 10-45.
Table 10-45: Cyanidation of Rougher Flotation Concentrate
Sample ID | Au Stage | Calc Feed | Tails grade | NaCN | Lime | Required |
Sample 1 | 93.0 | 47.4 | 3.33 | 2.90 | 2.40 | 24 |
Sample 2 | 94.0 | 69.9 | 4.19 | 2.40 | 2.50 | 24 |
Sample 3 | 82.1 | 33.6 | 6.03 | 1.30 | 1.70 | 30 |
Sample 4 | 45.8 | 14.1 | 7.63 | 5.70 | 0.70 | 48 |
Sample 5 | 69.7 | 45.4 | 13.75 | 0.80 | 2.30 | 40 |
Sample 6 | 70.2 | 54.7 | 16.3 | 0.50 | 0.20 | 16 |
Sample 7 | 95.1 | 80.3 | 3.94 | 0.50 | 2.20 | 24 |
Sample 8 | 94.2 | 46.6 | 2.72 | 0.80 | 1.40 | 18 |
Average | 80.5 | 49.0 | 7.24 | 1.86 | 1.68 | 28 |
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Samples 1, 2, 7 and 8 yielded stage gold recoveries exceeding 90%. However, the other four samples all yielded lower than expected recoveries, with some as low as 45.8% (Sample 4). This sample contained a large amount of cyanide soluble copper so it is possible that cyanide deficiency may have been partly responsible for the result (even though the cyanide was measured and replenished at timed intervals). The results suggest that it would be worthwhile to explore the possible application of the Albion process (which could destroy the sulphide matrix in an atmospheric oxidation step ahead of cyanidation).
Cyanide consumption was skewed by the 5.7 kg/t outlier recorded for Sample 4. Both cyanide and lime consumptions were highly variable as can be expected from concentrates.
Leach kinetics were, in most cases, faster than expected. The only sample requiring more than 40 h of leaching was Sample 4 which may, again, be due to insufficient cyanide.
10.5.2.12Combining the Results for the Float-Regrind-Leach Flowsheet
In this section, results from the entire underground test campaign were combined to estimate overall gold recovery for the float-regrind-leach flowsheet. Table 10-46 summarizes the results and illustrates the distribution of gold among the various products generated, including gravity concentrate, flotation concentrate, and leach solutions following leaching of the flotation tails and concentrate, respectively. The final two columns in Table 10-46 compare the overall recovery achieved using the flotation-based flowsheet with recovery obtained without the flotation step, using whole-ore cyanidation only.
The comparison shows that the addition of the flotation-regrind steps adds significant value to the flowsheet in terms of increased gold recoveries. Sample 4 is the only exception with the very low recovery of 54.4% being significantly lower than the 72.6% achieved for the leaching only flowsheet. This result for sample 4 is believed to be anomalous and due to cyanide deficiency and insufficient leach time during the cyanidation of the rougher concentrate. Flotation followed by regrinding will liberate more gold hence the expectation is that the result must be either the same or better when adding these additional steps. A significant decrease in recovery is not possible hence the observed result can be ignored as an anomaly. In the last two rows the averages are calculated first with sample 4 included then when excluding Sample 4 data. With sample 4 excluded the overall recovery for the flotation-regrind flowsheet is 86.1% which is significantly better than the 81.2% achieved without flotation. This outcome supports the decision to add the flotation step into the full-scale plant flowsheet.
It should be noted that the average recovery achieved for the underground samples with the float-regrind flowsheet is about 2% lower than what was previously achieved for the open pit samples. This difference is even more pronounced (about 5%) for the simpler flowsheet which excludes the flotation-regrind steps.
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Table 10-46: Cyanidation of Rougher Flotation Concentrate
Sample ID | Gold Distribution (% of head feed) | Overall Au Recovery (%) | ||||
Gravity | Flotation | Tails Leach | Conc. Leach | With Float + | Without Float | |
Sample 1 | 15.1 | 77.4 | 5.8 | 72.0 | 92.9 | 84.6 |
Sample 2 | 20.7 | 74.8 | 3.5 | 70.3 | 94.4 | 92.0 |
Sample 3 | 21.3 | 59.3 | 15.5 | 48.7 | 85.5 | 81.8 |
Sample 4 | 12.3 | 78.9 | 6.0 | 36.1 | 54.4 | 72.6 |
Sample 5 | 11.9 | 73.9 | 7.5 | 51.5 | 70.9 | 69.9 |
Sample 6 | 7.1 | 72.0 | 11.6 | 50.5 | 69.3 | 64.2 |
Sample 7 | 9.8 | 84.8 | 4.3 | 80.6 | 94.7 | 91.8 |
Sample 8 | 14.1 | 82.1 | 3.3 | 77.3 | 94.7 | 84.3 |
Average | 14.0 | 75.4 | 7.2 | 60.9 | 82.1 | 80.1 |
Avg excl. | 14.3 | 74.9 | 7.4 | 64.4 | 86.1 | 81.2 |
10.6Process Design Criteria Derived from Test Results
The following Process design criteria (Table 10-47) consolidates all operating and design parameters that can be directly referenced to the Grey Fox metallurgical test programs (2013 to 2025). Values were extracted from MC, variability and bulk tests undertaken to date. Parameters are grouped by unit operation—mineralogy/head grade, comminution, gravity, flotation, cyanidation (whole ore, tails and concentrate), detoxification, and solid-liquid separation.
All reagent dosages are stated as consumption on a dry-solids basis (kg/t); residence times and grind sizes are those that achieved target metallurgical performance in the lab.
A flowsheet incorporating flotation followed by regrinding of the flotation concentrate yielded higher gold recoveries for some of the samples tested to date and should be the preferred route for any greenfield development. However, the existing Stock Mill flowsheet does not include flotation. Retrofitting flotation and regrinding into the existing mill flowsheet and layout would be costly and operationally disruptive. Additionally, the remaining Stock Main and West ore is not expected to benefit from flotation and represents approximately half of the total tonnage projected to be treated through the Stock Mill with Grey Fox material. Consequently, the existing whole-ore cyanidation flowsheet at the Stock Mill will be adopted, unchanged, for Grey Fox ore treatment.
These criteria are intended as a baseline for mechanical and mass-balance design for the trade-off and PFS studies.
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Table 10-47: Process Design Criteria
Area | Parameter | Design Criterion / Typical Range | Notes / Basis |
Mineralogy and | Gold head grade (Au) | Nominal = 3.8 g/t | Test work Samples Typical Range = 3 – 5 g/t |
| Total sulphur (S) | 1.5%–2.0% | Dominated by pyrite; rises to ≈ 3% S in high-sulphide SEDS domains. Needs to be assessed with further variability testing. |
| Gangue minerals | Quartz-carbonate host; | Carbonate buffering limits acid |
| | CO₂ 7%–10%; SG ≈ 2.9 t/m³ | generation; density used for all volumetric throughputs. |
Comminution | BBWi | Nominal = 23 kWh/t; | Suggest a high-power SABC or HPGR- ball-mill circuit. |
| SMC parameters | DWi = 9.0–9.6 kWh/m³; | Confirms competent, impact-resistant ore. |
| Rock Density | 2.91 t/m³ (ore) | Used for equipment sizing and |
| | | mass/volume conversions. |
Whole-Ore Leach | Grind P₈₀ | P₈₀ = 75 µm | Diminishing returns < 100 µm. Unliberated gold appears to be fine. |
| Au Recovery | 64%-95% (Avg 84% for open pit zones and average 88% for the underground samples) | Average recovery for underground zones excludes anomalous results from the Gibson North zone. |
| Pre-aeration conditions | 1 h at 40% w/w solids, pH 10.5–11 (for open pit, not used for underground tests) | |
| Leach time | 36h | Tests range was 26 to 48 h |
| NaCN dosage | 1.1 kg/t for open pit samples; 0.46 kg/t for underground | MC & variability tests – KM6034 report. Important to note underground tests were done at lower cyanide levels. |
| Lime (CaO) | 1.2 kg/t (with pre- aeration) but >2 without (underground tests were without) | To hold pH ~11 |
Detoxification | Method | SO₂/Air + Cu catalyst | |
| CN-WAD start and end conc | 165 mg/t to 0.1 mg/l | |
| Residence | 180 min | Batch-tested |
Sedimentation | Thickener underflow density | 65% solids | |
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Area | Parameter | Design Criterion / | Notes / Basis |
| Unit area | 88 and 103 m³/m²/day net rise rate | 147 Zone and CZ |
| | 0.41 to 0.47 t/m2/h solids loading | 147 Zone and CZ |
| | 3.6 m³/m²/ h net hydraulic loading | 147 Zone |
| Flocculant | 15–25 g/t Magnafloc 351 (non-ionic) | |
10.7Recovery Model
The Grey Fox deposit comprises a combination of free milling gold and gold intricately associated with pyrite (semi-refractory). Recovery is generally positively correlated to liberation and negatively correlated to sulphur grade. With a limited volume of distinct variability samples tested to date it is not appropriate to attempt to define a predictive model at this juncture. Consequently, only averaged recoveries will be used for the PFS.
Whole-ore cyanidation results for the Gibson North Zone yielded unexpectedly low recoveries into the leach solutions. Upon investigation, it was observed that the selected intercepts had unusually high concentrations of graphite, phyllosilicate, and galena. It is possible that the poor recoveries could be attributed to re-adsorption of leached gold, surface coatings, or physical encapsulation of liberated gold. For the purposes of the PFS, these results were excluded from the estimation of average recovery for the combined underground zones.
Dissolved gold losses and losses to carbon fines are expected to be constant and independent of grade. A well-run carbon in pulp (CIP) adsorption circuit should maintain dissolved gold losses below 0.01 mg/L. At a solid-to-liquid ratio of roughly 1:1, this equates to a constant efficiency loss of 0.01 g/t. Gold losses to carbon fines are negligible by comparison.
The resultant recovery model for the Grey Fox underground deposit can therefore be formulated as follows:
Gold Recovery (%) = 87.8 - (1 / Head Grade)
Where 87.8 represents the average extraction achieved through cyanidation, and the second term represents dissolved gold losses as a function of head grade (g/t).
Opportunities to improve the overall recovery will be explored during future testwork programs. Adding a flotation step followed by fine grinding and leaching of flotation products has shown some promise. Adding an oxidation step after fine grinding to destroy the sulphide host matrix will also be explored.
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10.8Deleterious Elements
The current flowsheet will produce doré bars; therefore, no penalties are anticipated. Mineralogical testing showed that the ore does not contain significant quantities of arsenic, while head-grade analysis showed that mercury levels are not significant.
10.9Interpretation and Conclusions
Cyanidation, with or without gravity concentration, yielded mixed results, with some samples registering recoveries exceeding 94%, while a significant proportion of samples tested registered recoveries below 90%. Based on the testwork results, the average recovery with this type of flowsheet is estimated at approximately 87% for the underground zones. Additional testing is required to improve the accuracy of the recovery estimate.
Given the hardness of the samples tested, a SABC comminution circuit is recommended.
10.10Recommendation for Future Work
Historical testwork provides sufficient information on the Grey Fox deposit to support a PFS. However, beyond the PFS stage, and contingent upon the consideration of an optimized flowsheet that is not processing Grey Fox ore at the Stock Mill, several information gaps and opportunities remain, including the following:
· | The effects of pre-oxygenation, oxygen sparging, and the addition of chemical oxidants (e.g., PbNO3) on cyanide consumption have not been investigated. |
· | For fine grinding, vendor-specified fine-grinding tests are required, as Bond’s Fourth Law is not valid below a grind size of approximately 50 µm. This recommendation applies only to a flowsheet that contains a fine-grinding or regrinding step. |
· | Carbon adsorption testing, including assessment of the effects of carbon fouling by flotation reagents. |
· | The addition of a cleaning stage after the initial bulk flotation step should be tested, as this could reduce the costs for downstream processing of the concentrate. Of particular interest would be to assess the leach efficiency of the cleaner tails if they are rejected to tailings rather than recycled. Cleaner flotation should be tested both with and without regrinding. Producing a saleable flotation concentrate could result in an overall recovery above 90% if the cleaner tails are also amenable to cyanidation. |
· | Specific testing to assess the presence of preg-robbers. |
· | Sedimentation and rheology of the flotation concentrate have not been tested. |
· | Intensive cyanidation of gravity concentrate should be tested. |
· | Filtration of tailings could be considered, as this would provide information should paste backfill ever be considered. While this is not currently the case, it may be prudent to generate this information. |
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· | Water chemistry and the effects of recirculating process water need to be determined. Test work to date was conducted using neutral-pH tap water. The effects of flotation reagents, lime, and NaCN recirculating through the plant process water system must therefore be investigated. |
· | Testing of the Albion Process to evaluate the potential for overall recoveries exceeding 95%. Test work performed to date indicates that remaining unrecovered gold is locked within sulphides, which may be liberated if subjected to the full Albion Process. |
· | Locked-cycle testing should be undertaken if cleaner flotation is considered. |
· | Dilution testing to assess amenability to the use of Jameson flotation cells. |
While the current metallurgical and geochemical testwork programs have provided useful baseline data, it is important to note that the testing has predominantly been conducted on master or composite samples rather than on discrete variability samples. As such, the spatial and lithological variability across the deposit has not been thoroughly evaluated. Further investigation is warranted to assess the geometallurgical variability across the resource, particularly in relation to lithological domains, alteration styles, and sulphide content, and how these factors align with the mine plan and processing schedule. A structured variability testing program—incorporating both metallurgical and geochemical analyses on domain-specific intervals from representative boreholes—is recommended to ensure process performance assumptions remain valid across the full LOM.
Specific areas that should be confirmed through variability testing include:
· | Whole-ore cyanidation leach performance, especially in relation to sulphur content and Au/S ratios. |
· | GRG response across different lithologies and head grades. |
· | Flotation response and variability in sulphide recovery rates across domains. |
· | Cyanidation of flotation concentrates and tailings to quantify recovery contributions and assess leach kinetics. |
· | Variability in reagent consumption (cyanide, lime, flotation reagents) as a function of mineralogy. |
· | Confirmation of preg-robbing potential associated with variable carbonaceous content and its deportment. |
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11Mineral Resource Estimates
11.1Approach
The 2026 Grey Fox Pre-Feasibility Study, and thus the more in depth engineering and economic aspects of this TRS, are based on the mineral resources defined at Grey Fox. In addition, the report also includes Resource Model updates for the following deposits which also occur on the broader Fox Complex Project areas:
· | Black Fox |
· | Froome |
· | Stroud |
· | Stock West and Main |
· | Stock East |
· | Davidson-Tisdale |
Two employees of McEwen are the QPs for all resource estimates in this report and have calculated the Mineral Resource estimates for Grey Fox, Black Fox, Froome, Stroud, Stock West and Main, Stock East and Davidson-Tisdale. The Resource Models were prepared and/or updated using Datamine Studio RM estimation software, with lithological modeling prepared using Leapfrog Geo software. Geostatistics were analyzed using Datamine’s Snowden Supervisor software module. To demonstrate the reasonable prospects for eventual economic extraction (RPEEE), all deposits were evaluated using Datamine’s Mineable Shape Optimizer (MSO) extension.
In general the methodology is as follows:
· | Compilation of the Resource Database and Data Validation |
· | Exploratory Data Analysis |
· | Geological Modeling |
· | Compositing of Sample Data |
· | Geostatistics and Block Estimation |
· | Model Validation |
· | Resource Classification |
· | Reasonable Prospects for Eventual Economic Extraction |
· | Mineral Resource Statement |
· | Factors That Could Affect Mineral Resource Estimates |
11.2Resource Estimation
The accuracy of resource (and later reserve) estimates is, in part, a function of the quality and quantity of available data and of geological interpretation (and later engineering) and judgment. Given the data available at the time this report was prepared, the estimates presented herein are considered reasonable. However, they should be accepted with the understanding that additional data and analysis available subsequent to the date of the estimates may necessitate revision. These revisions may be material.
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11.3Grey Fox
11.3.1Mineral Resource Database
The close-out date for the Mineral Resource database was 11 July 2025. A total of 23 drill holes were excluded from the drill database because they are geotechnical or metallurgical holes and were never assayed for gold. The database now consists of 1,659 core drill holes totalling 619,504 m of drill core and 322,665 m of sampled core. Unsampled intervals were considered barren and assigned a background gold grade of 0.0005 g/t or one quarter of the assay laboratory’s lower detection limit.
Drilling campaigns at Grey Fox have taken place since 2021 with 29 new holes in 2021, 14 new holes in 2022, 21 new holes in 2023, ramping up to 126 holes in 2024 and 65 holes in 2025. These holes were primarily drilled in the Gibson, 147, South and Whiskey Jack zones. Logging and assay results continue to indicate strong continuity in Whiskey Jack and an increase in confidence in the model. Drilling in the Gibson zone resulted in the modeling of additional C-veins, expanding resources to the North, as well as the validation of previously modeled C-veins. Drilling in the South and 147 Zone resulted in validation of previously modeled C-veins, intersecting them at optimal angles.
On importing the drill hole database from the central SQL database to Datamine Studio software in preparation for resource estimation, sample data were checked for missing and overlapping intervals in the assay and survey tables, and collar locations checked against the LiDAR topography surface.
11.3.2Geological Modeling
11.3.2.1Lithology
A lithology model was constructed to capture the seven key deposit lithologies as shown in Figure 11-1. The primary deposit area is bounded in the east by ultramafic metavolcanics and in the west by chlorite-talc schist ultramafic metavolcanics. Each are separated from the main deposit area by regional faults and deformation zones. The western portion of the deposit is hosted in a metasedimentary unit intruded by a brecciated syenitic- to dioritic-feldspar porphyry intrusion. The metasedimentary unit has an angular unconformity contact with an assemblage of metavolcanic mafic rocks in the east. There is a prominent diabase dyke (believed to be post mineralization) running through the assemblage sub-parallel to the unconformable sediment-mafic contact. The mafic metavolcanic units can be described as massive/pillowed, or variolitic textured and have been separated in the model based on those primary textures.
A 3D surface of the bedrock/overburden contact was generated from the drill holes and used to constrain the upper extent of mineralization.
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Source: (McEwen, 2025)
Figure 11-1: Plan View of the Grey Fox Project Lithology Model
11.3.2.2Mineralized Zones
The Grey Fox deposit area is subdivided into six mineralized zones differing in host lithology. The zones include the Contact, 147, 147NE, Gibson and South Zone with the northern most mineralized lens of the Contact Zone area named the Whiskey Jack Zone (Figure 11-2). The mineralization is further categorized into six domains based on mineralization style, orientation, grade population, and host lithologies.
The mineralization wireframes were created by geologically interpreting the structures controlling mineralization, guided by structural data and gold grades. These were then explicitly modelled creating closed volumes around the defining drill hole intercepts at an approximate cut-off grade of 0.5 g/t Au.
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Source: (McEwen, 2025)
Figure 11-2: Plan View of the Grey Fox Project Mineralized Zones and Domains
A description of each mineralized zone is summarized in Table 11-1.
Veins hosted in the syenite and sediments form the local Domains 10 and 11; Domain 10 has a lower grade population, and an orientation that strikes Southwest and forms the Gibson Main; Domain 11 has a slightly higher grade population, strikes Southwest and forms the Gibson North. Veins hosted in the mafic intrusive and volcanic rocks form Domain 30. The veins hosted in the variolitic units appear to be a continuation or subset of the veins in the surrounding mafic rocks and form Domain 31. Due to their physical continuity with Domain 30, but having a slight grade population difference, Domain 31 veins were estimated using a soft boundary contact with veins of Domain 30.
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Table 11-1: Grey Fox Mineralized Domains
Domain | | Description |
10 | | Southwest trending, steeply northwest dipping quartz veins and breccias hosted in sediments and the Gibson syenite intrusive (70° dip @ 280° dip direction) |
11 | | Southwest trending, steep northwest dipping quartz veins and breccias hosted in sediments and the syenite Gibson intrusive (80° dip @ 310° dip direction). This is a new domain, separated from Domain 10, due to a change in lens orientation and indicated by geostatistical data. |
20 | | North-south trending unconformity contact between mafic rocks and sedimentary rocks. Outcrop is steeply east dipping (75° dip @ 80° dip direction), at the northern extent and at depth the zone rolls over to a steep westerly dip (75° dip @ 250° dip direction) |
30 | | Southwest trending, steeply northwest dipping quartz veins and breccias hosted in mafic volcanic flows and mafic intrusive rocks (65° dip @ 310° dip direction) |
31 | | Southwest trending, steeply northwest dipping quartz veins and breccias hosted in dominantly iron-rich variolitic textured mafic rocks (65° dip @ 310° dip direction) |
32 | | East trending sub-vertical to steep south dipping quartz breccia veins hosted in mafic volcanic and intrusive rocks (75° dip @ 175° dip direction) |
11.3.2.3Background Envelope
A background envelope (Domain 100) of approximately 25 m was constructed around all mineralized domains to capture mineralized samples outside the mineralized domains and to estimate adjacent dilution.
11.3.3Composites
More than 70% of the assays have a sample length of 1 m. The modal composite length of 1 m was applied to samples within the mineralized zones which generated composites close to 1 m with a minimum composite length of 0.3 m. A modal composite length of 4 m was applied to samples within the background envelope (dilution) based on the parent cell size of the block model.
11.3.1Capping
The impact of high-grade outlier populations was analyzed using histograms, log probability plots, mean and variance, and cumulative metal plots. Results are presented in Table 11-2 for each mineralized domain with metal removed ranging from 4.6% in Domain 11 and 27.4% in Domain 20.
Table 11-2: Grey Fox – Metal Removed by Capping Composites
Domain | | Raw Composites | | Capped | | Capped Composites | | No. | | Metal | ||||
| | Mean (g/t) | | CV | | Grade (g/t) | | Mean (g/t) | | CV | | Capped | | Removed (%) |
10 | | 1.60 | | 3.67 | | 27 | | 1.47 | | 1.98 | | 29 | | 8.5 |
11 | | 1.99 | | 2.37 | | 27 | | 1.90 | | 2.06 | | 17 | | 4.6 |
20 | | 2.23 | | 10.02 | | 34 | | 1.62 | | 2.39 | | 19 | | 27.4 |
30 | | 1.65 | | 23.53 | | 87 | | 1.23 | | 3.94 | | 20 | | 25.4 |
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Domain | | Raw Composites | | Capped | | Capped Composites | | No. | | Metal | ||||
| | Mean (g/t) | | CV | | Grade (g/t) | | Mean (g/t) | | CV | | Capped | | Removed (%) |
31 | | 2.02 | | 8.58 | | 70 | | 1.76 | | 2.95 | | 27 | | 13.0 |
32 | | 4.22 | | 2.41 | | 48 | | 3.93 | | 2.06 | | 16 | | 6.8 |
100 | | 0.10 | | 19.07 | | 10 | | 0.09 | | 4.65 | | 115 | | 13.8 |
11.3.2Density
There are 14,459 density samples contained in the Mineral Resource database. Currently, one in twenty assay samples are selected for density analysis by the assay laboratory. A study of all density data was conducted to determine an average density value for each of the host lithology units. Blocks were assigned the average density per unit as listed in Table 11-3.
Table 11-3: Grey Fox – Density Values by Lithology
Lithology | No. of Samples | Avg. Density |
Ankerite Altered Ultramafic Volcanics (AUV) | 17 | 2.82 |
Fuchsite Altered Ultramafic Volcanics (CGR) | 98 | 2.89 |
Diabase (DIA) | 49 | 2.94 |
Mafic Volcanics (AMV, PMV, MV, MI, MR) | 3580 | 2.90 |
Quartz Veins (QV, QBX) | 55 | 2.86 |
Sediments (SED, GR) | 719 | 2.76 |
Felsic Intrusives (SYN, FI, FP) | 1660 | 2.76 |
Ultramafic Volcanics (UMV,UV,CUV,TUV) | 488 | 2.83 |
Variolitic Mafic Volcanics (VIV) | 4902 | 2.86 |
All Lithologies Combined | 11568 | 2.85 |
* 14,459 Total samples. Lowest 5 and highest 5 values removed from evaluation as outliers | | |
* Density measurements belonging to minor, unmodeled lithologies removed from density calculation. | | |
*Overburden given a specific gravity of 2.0 | | |
11.3.3Variography
The spatial distribution (continuity) of gold within each mineralized zone was evaluated using variograms.
Primary directions of the variograms were modeled based on observed mineralization orientations. These orientations were then examined statistically to ensure they represented the best possible fit with the variography. The stability of the variograms was evaluated by varying the direction specification and comparing the resulting experimental variograms. Variograms were modelled with two spherical structures, three rotations to match the strike, dip and plunge of the mineralized zone. Nugget effects range from 10% in Domain 30 and 32 to 20% in Domain 10, 11, 20, and 31.
11.3.4Grade Estimation
A block size of 4 m x 4 m x 4 m was selected based on drill hole spacing, composite length, the geometry of the modelled mineralized zones, and anticipated mining methods. Sub-cells down to 0.5 m x 0.5 m x 0.5 m
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were used to better reflect the shape and volume of the mineralized domains. No rotation was applied to the block model.
Ordinary kriging was used to estimate the blocks within the mineralized domains using a four-pass approach, although estimated blocks within only the fourth search neighborhood are not classified. Search neighborhoods are based on variography, with the range doubling from search pass 1 to search pass 2, multiplying by 2.5 from search pass 2 to search pass 3 and doubling from 3 to 4. Datamine’s dynamic anisotropy function was implemented due to the anisotropic nature and widths of the mineralized domains.
Data selection for mineralized domains in passes one and two used a minimum of nine and a maximum of 16 composites from at least three drill holes to estimate a given block. Data selection for mineralized domains in pass three and four used a minimum of five and a maximum of 12 composites from at least two drill holes to estimate a given block. Blocks within the background envelope were estimated using inverse distance to the power of three with its ellipsoid guided by the general lithology contact orientation determined through variography. Any blocks that were not estimated in one of the three passes were assigned a background gold value of one quarter of detection limit, or 0.0005 g/t.
The search parameters are presented in Table 11-4 below.
Table 11-4: Grey Fox Estimation Search Parameters
Domain | Orientation Rotation | | Search Volume 1 | Search Volume 2 | Search Volume 3 | Search Volume 4 Distances | | | | ||||||||||
Z | X | Z | | X(Stri ke) | Y(Dip) | Z(Perp) | X(Stri ke) | Y(Dip) | Z(Perp) | X(Stri ke) | Y(Dip) | Z(Perp) | X(Stri ke) | Y(Dip) | Z(Perp) | Min | Max | Max Composites | |
| Dynamic Anisotropic Search Volume | | | | | | | | | | | | | | | | | ||
10 | | | 120 | | 17 | 13 | 9 | 34 | 26 | 18 | 85 | 65 | 45 | 170 | 130 | 90 | | Search Vol 1&2 | |
11 | | | 150 | | 11 | 15 | 12 | 22 | 30 | 24 | 55 | 75 | 60 | 110 | 150 | 120 | 9 | 16 | 4 |
20 | | | 90 | | 17 | 28 | 6 | 34 | 56 | 12 | 85 | 140 | 30 | 170 | 280 | 60 | |||
| Dip Direction | Dip | | | | | | | | | | | | | | | | | |
30 | | | 90 | | 19 | 11 | 14 | 38 | 22 | 28 | 95 | 55 | 70 | 190 | 110 | 140 | | Search Vol 3&4 | |
31 | | | 80 | | 11 | 10 | 6 | 22 | 20 | 12 | 55 | 50 | 30 | 110 | 100 | 60 | 5 | 12 | 4 |
32 | | | 100 | | 13 | 7 | 2 | 26 | 14 | 4 | 65 | 35 | 10 | 130 | 70 | 20 | |||
100 | -170 | 80 | 150 | | 39 | 54 | 32 | 78 | 108 | 64 | | | | | | | 5 | 12 | 4 |
11.3.1Model Validation
The estimated block model was validated by visually comparing drill hole data with block grades and by reviewing swath plots to determine whether any local bias exists. Figure 11-3 shows a section view looking east for the Whiskey Jack Zone, and Figure 11-4 shows a section view looking northeast for Gibson Zone North, both comparing block grades with drill hole data using ±25 m clipping. These analyses indicate that the block model reasonably reflects the assay sample data, with only minor local bias in areas of sparse data.
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Source: (McEwen, 2025)
Note: Looking east, ±25 m clipping
Figure 11-3: Section Comparing Block Grades vs Drill Hole Data, Whiskey Jack, Grey Fox Model
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Source: (McEwen, 2025)
Note: Looking northeast, ±25 m clipping
Figure 11-4: Section Comparing Block Grades vs Drill Hole Data, Gibson Zone N, Grey Fox Model
11.3.2Confidence Classification
The QP is confident that the Grey Fox mineralization model honours the current informing data contained within the geological database. The sample locations and assay data are considered reliable and of sufficient quality to support Mineral Resource evaluation. The Mineral Resource model is constrained within mineralized domains based on lithological, structural and grade criteria and has been developed using core drilling completed on an irregular grid with drill hole spacing ranging from approximately 5 m and 50 m. The controls on the distribution of gold mineralization are well understood, and confidence in geological continuity is considered reasonable.
Classification criteria consider confidence in the continuity of mineralization, average distance to informing samples (weighted on distance), and continuity of drill hole spacing. The following classification criteria were applied:
· | Indicated: Assigned to those continuous blocks within the mineralized domains and within a weighted average informing sample distance of 40 m. The estimates had to be informed by, and the sample spacing had to be continuous between, three or more drill holes and estimated within the first three search passes. |
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· | Inferred: Assigned to those continuous blocks within the mineralized domains informed by at least two drill holes and within a weighted average informing sample distance of 60 m and estimated within the first three search passes. |
Blocks within the mineralized zones not meeting the above criteria were not classified. Blocks within the background envelope were not classified.
11.3.3Reasonable Prospects for Eventual Economic Extraction
For a Mineral Resource to be reported, the QP must determine that RPEEE has been established.
Due to the narrow-vein nature, geometry, and location of the Grey Fox mineralization, the QP considers the deposit to be amenable to underground mining methods. A cut-off grade of 1.35 g/t Au was determined using the cost and input parameters presented in Table 11-5, based on recent quotations and benchmarked against comparable projects.
Table 11-5: Grey Fox Mineral Resource Cut-off Grade Parameters
Parameter | Unit | Value |
Mining Cost | $US/t | 67.72 |
G&A Cost | $US/t | 16.60 |
Milling Cost | $US/t | 30.77 |
Transport Cost | $US/oz | 1.52 |
Payable Gold | % | 99.95 |
Dilution | % | 15 |
Gold Price | $US/oz | 3,000 |
Exchange Rate (US$/C$) | - | 1.35 |
Royalty (NSR) | % | * |
Mill Recovery | % | 90 |
Note: *Royalty is variable from 0.15% NSR to 3% NSR, with a calculated cut-off grade varying from 1.33 g/t to 1.37 g/t, ultimately a rounded 1.35 g/t cut-off grade was used for all of Grey Fox.
Reasonable prospects for eventual economic extraction were derived from potentially mineable shapes developed using Datamine’s Mineable Shape Optimizer function. A stope size of 12 m vertical height by 6 m wide along strike by a minimum 3 m wide across strike was adopted. This size was benchmarked against mined stopes at the nearby Black Fox underground mine. Sub stopes were developed at half height and half width along strike (6 m x 3 m) to account for local anisotropy of the grade continuity. Stopes with a width less than 3 m across strike were not considered potentially economical and excluded. Stope shapes were developed using the economic cut-off-grade of 1.35 g/t Au. All classified blocks were analyzed by the mineable shape optimizer with resulting stopes shown in Figure 11-5.
All classified blocks were flagged by the potentially mineable shapes including those below the 1.35 g/t Au cut-off grade, this is known as “must take material” and as a combined mineable shape they meet the
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necessary parameters, including the cut-off grade. Isolated, discontinuous stope shapes were not considered economic and were therefore removed and not included in the Mineral Resource Statement.

Source: (McEwen, 2025)
Figure 11-5: Plan View of the Potentially Mineable Stope Shapes at Grey Fox
Figure 11-6 presents the experimental grade–tonnage sensitivities at various cut-off grades. The sensitivities were generated using raw block grades and include both Indicated and Inferred classified blocks. Sensitivities include all classified blocks, not only those meeting RPEEE. These results are provided for comparative purposes only, to illustrate the potential effect of applying different cut-off grades on tonnage and grade. Sensitivity cases do not represent Mineral Resources and should not be interpreted as such.
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Source: (McEwen, 2026)
Note: Sensitivities use raw block grades and include Indicated and Inferred blocks. These results are for comparison only and do not represent Mineral Resources.
Figure 11-6:Experimental Grade‑Tonnage Sensitivities at Various Cut‑Off Grades
11.3.4Mineral Resource Statement
Table 11-6 summarizes the Grey Fox Mineral Resource estimate, assuming underground stoping methods. The Mineral Resource estimate is limited to those parts of the gold mineralization for which the QP has determined RPEEE through underground stope extraction.
This Mineral Resource statement is reported exclusive of Mineral Reserves (Section 12). Mineral Resources were estimated after applying the RPEEE criteria and removing material classified as Mineral Reserves.
Table 11-6: Grey Fox Mineral Resource Statement, April 2, 2026, exclusive of Reserves
Classification | Tonnes (kt) | Au Grade (g/t) | Contained Au (koz) |
Indicated | 9,681 | 2.25 | 701 |
Inferred | 4,696 | 2.57 | 388 |
Notes:
· | Data cut-off date for the Mineral Resource estimate is July 11, 2025. The QP for the estimate is Mr. Carson Cybolsky, P.Geo, an employee of McEwen. |
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· | Mineral Resources are reported using Item 1300 of Regulation S-K. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. |
· | Resources are reported exclusive of the reserves reported in Section 12. |
· | Mineral Resources are reported above an economic cut-off grade of 1.35 g/t gold assuming underground extraction methods and based on a mining cost of $67.72/t, process cost of $30.77/t, G&A cost of $16.60/t, metallurgical recovery of 90%, variable royalty NSR from 0.15% to 3.0%, dilution of 15% and gold price of US$3,000/oz. |
· | Figures may not sum due to rounding. |
Table 11-7 summarizes the Grey Fox resource as inclusive of Reserves reported in Section 12.
Table 11-7: Grey Fox Mineral Resource Statement, April 2, 2026, inclusive of Reserves
Classification | Tonnes, kt | Au Grade, g/t | Contained Au, koz |
Indicated | 18,819 | 3.28 | 1,986 |
Inferred | 5,056 | 2.69 | 438 |
Notes:
· | Data cut-off date for the Mineral Resource estimate is 11 July 2025. The QP for the estimate is Mr Carson Cybolsky, P.Geo, an employee of McEwen. |
· | Mineral Resources are reported using Item 1300 of Regulation S-K. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. |
· | Indicated resources are reported inclusive of the reserves reported in Section 12. |
· | Mineral Resources are reported above an economic cut-off grade of 1.35 g/t gold assuming underground extraction methods and based on a mining cost of $67.72/t, process cost of $30.77/t, G&A cost of $16.60/t, metallurgical recovery of 90%, variable royalty NSR from 0.15% to 3.0%, dilution of 15% and gold price of US$3,000/oz. |
· | Figures may not sum due to rounding. |
11.3.5Factors That Could Affect the Mineral Resource Estimate
Factors that may affect the Grey Fox Mineral Resource estimate include:
· | Changes in the local geological interpretations and assumptions used to generate the estimation domains. |
· | Changes in mineralization and geological geometry and continuity of mineralized zones. |
· | Changes in assumptions of mineralization and grade continuity. |
· | Changes in the treatment of high-grade gold values. |
· | Changes in the grade interpolation methods and estimation parameter assumptions. |
· | Changes in the confidence assumptions and methods used in the mineral resource classification. |
· | Changes in the density and the methods used in the density assignments. |
· | Changes in metal price and exchange rates and other economic assumptions used in the cut-off grade determination. |
· | Changes in input and design parameter assumptions that pertain to the underground mining constraints. |
· | Changes to assumptions as to the continued ability to access the mine site, retain mineral and surface rights titles, maintain the operation within environmental and other regulatory permits, and maintain the social license to operate. |
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No other environmental, permitting, legal, title, taxation, socioeconomic, marketing, political or other relevant factors are known to the QP that would materially affect the estimation of Mineral Resources that are not discussed in this report.
11.4Stroud
11.4.1Mineral Resource Database
In March 2026, McEwen Inc. developed the initial Stroud mineral resource model. This model incorporates historic drilling results with follow up drilling completed by McEwen from the late 2025 and Q1 2026 confirmation drill campaign. The resource database includes 149 historic holes drilled from 1974 to 2007 as well as 31 holes drilled in Q4 2025 and Q1 2026 to confirm the mineralization described and captured in the historic database. The current drill hole database was closed on March 26, 2026 and consists of 180 holes, comprised of 36,486 m of drill core and 27,201 intervals (25,932 m) assayed for gold.
11.4.2Geological Modeling
The Stroud deposit occurs proximal to the Hislop fault, mostly within sheared, altered mafic metavolcanic rocks, but also within felsic intrusives, and to a lesser extent metasediments, volcanic tuffs and ultramafic intrusives. These units, along with the mineralization, are crosscut by younger diabase dykes. The mineralization was explicitly modelled by members of the McEwen Exploration team and the QP using Datamine Studio. Wireframes were snapped to drill intercepts, using approximately 0.5 g/t as a general cut-off for mineralization. Core logs, photos, assays, and previously modeled wireframes were used as a guide to orient the wireframes. The mineralization was divided into three domains based on geostatistics, geology, and geographic areas. All three domains show similar geology in that they are predominantly composed of altered (sericite, carbonate, +/-hematite) metavolcanic mafics within a shear zone:
· | Domain 10, historically the “Main Zone,” is composed of sheared, stacked veins within altered mafic metavolcanics, and also contains felsic porphyries and metasediments. This domain strikes at ~135° with a variable dip of ~35°-60°. |
· | Domain 20, historically the “Creek Zone,” is composed of sheared, stacked veins within altered mafic metavolcanic, and also contains felsic porphyries. This domain strikes at ~130° with a ~65° dip. |
· | Domain 30, historically the “Creek Zone Extension,” is composed of sheared, stacked veins within altered mafic metavolcanics, and also contains felsic porphyries. This domain has a more variable orientation with the strike at ~135°-150° with a ~55° dip. |
A longitudinal view of the different domains present at Stroud are shown in Figure 11-7.
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Source: (McEwen, 2026)
Figure 11-7: Longitudinal View of the Mineralized Domains at Stroud (looking NE)
11.4.3Composites
Over 97% of all samples have core lengths between 0.5 m and 1.5 m. The modal composite length of 1 m was applied to samples within the mineralized zones which generated composites close to 1 m with a minimum composite length of 0.3 m and a maximum of 1.5 m. A composite length of 3 m was applied to samples within the background envelope (dilution) based on the parent cell size of the block model.
11.4.4Capping
The impact of high-grade outlier populations was analyzed using histograms, log probability plots, mean and variance, and cumulative metal plots. Results are presented in Table 11-8 for each mineralized domain, with metal removed ranging from 4.2% in Domain 30, to 18.4% in Domain 20. The capping values derived from this analysis were applied to drill hole sample composites.
Table 11-8: Stroud – Metal Removed by Capping Composites
Domain | | Raw Composites | | Capped | | Capped Composites | | No. | | Metal | ||||
| | Mean (g/t) | | CV | | Grade (g/t) | | Mean (g/t) | | CV | | Capped | | Removed (%) |
10 | | 2.56 | | 2.21 | | 27.0 | | 2.40 | | 1.85 | | 16 | | 6.4 |
20 | | 2.63 | | 4.54 | | 25.0 | | 2.14 | | 1.32 | | 3 | | 18.4 |
30 | | 2.45 | | 1.12 | | 8.5 | | 2.35 | | 1.04 | | 6 | | 4.2 |
Note: CV = coefficient of variation
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11.4.5Density
As no certified density measurements are in the historical data base, a value of 2.65 g/cm3, reported in previous estimation reports is considered as representative for the mineralized rock types and used in all tonnage calculations. As density measurements are taken from further additional drilling, this will be reevaluated and combined with the lithological model. This default value of 2.65 g/cm3 is considered adequate for Inferred classification but represents a potential source of uncertainty. Further testwork is underway and a density study will be conducted to create and refine the density model.
11.4.6Variography
The spatial distribution (continuity) of gold within each mineralized domain was evaluated using variograms.
Primary directions of the variograms were modelled based on observed mineralization orientations. The stability of the variograms were evaluated by varying the direction and comparing the resulting experimental variograms. The developed variograms displayed two spherical structures and three rotations to match the strike, dip and plunge of the modelled mineralization. Nugget effects are 20% for all Domains. Variography and Kriging Neighborhood Analysis were conducted on Datamine’s Supervisor software and were used to calculate search ellipse dimensions.
11.4.7Grade Estimation
A block size of 3 m x 3 m x 3 m was selected based on drill hole spacing, composite length, the geometry of the modelled mineralized zones, and anticipated mining methods. Sub-cells down to 0.5 m x 0.5 m x 0.5 m were used to better reflect the shape and volume of the mineralized domains. No rotation was applied to the block model.
Ordinary kriging was used to estimate the blocks within the mineralized domains using a three-pass approach. Search neighborhoods are based on variography with ranges doubling in length with each pass. Datamine’s dynamic anisotropy function was implemented due to the anisotropic nature and widths of the mineralized domains. This function aligns the search ellipse with the local dip and dip direction with the plunge defined as per the variography direction.
Data selection for all mineralized domains remained the same for all passes using a minimum of nine and a maximum of 16 composites from at least three drill holes to estimate a given block in the first three search passes. Data selection for the fourth search pass used a minimum of five and a maximum of 12 composites from at least two drill holes to estimate a given block, ultimately no blocks within the fourth search pass were classified.
Blocks within the background dilution envelope were estimated using ordinary kriging with its ellipsoid guided by dimensions determined through variography without the use of dynamic anisotropy. Any blocks that were not estimated in one of the four passes were assigned a background gold value of ¼ of detection limit, or 0.0005 g/t.
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11.4.8Model Validation
The estimated block model was validated by visually comparing the drill holes with the block grades (Figure 11-8 and Figure 11-9), with swath plots to determine whether any statistical local bias exists, and a nearest neighbor estimate versus the kriged estimate to determine if any global bias exists. A histogram comparison of the estimated grades versus the composite grades was also used to investigate grade smoothing. These analyses indicate the block model acceptably reflects the assay sample data with only minor local bias in areas of sparse data. There is a minor amount of local smoothing of the higher grades; however, the grade distribution of the samples is reasonably reproduced by the estimate.

Source: (McEwen, 2026)
Figure 11-8: Plan View of Blocks and Informing Drill Holes at Stroud, Domains 20 &10
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Source: (McEwen, 2026)
Note: Looking east (550515E); ±15 m clipping
Figure 11-9: Vertical Section of Estimated Blocks and Informing Drill Holes in Domain 20 at Stroud
11.4.9Classification
The QP is confident that the Stroud mineralization model honours the current informing data from the geological database. The location of the samples and the assay data are sufficiently reliable to support Mineral Resource evaluation. The Mineral Resource model is constrained by mineralized domains based on lithological, structural and grade criteria and is modelled from core holes drilled on an irregular grid. The controls on the distribution of the gold mineralization are understood, and the confidence in geological continuity is reasonable.
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Classification criteria considers the confidence in the continuity of mineralization, average distance to informing samples, distance to the closest informing sample and continuity of drill hole spacing. The following classification criteria were defined:
· | Measured: No blocks were assigned the measured category. The QP requires the geological model and grade interpolation to be validated with either 10 m spaced definition drilling or physical mapping from surface or underground to assign a measured classification. |
· | Indicated: Until more robust data validation on historical data can be performed and density data can be confirmed, no blocks were assigned to the indicated category. |
· | Inferred: Assigned to those continuous blocks within the mineralized domains, informed by three or more drill holes, less than 30 m to the nearest sample, and within an average drill hole spacing of 50 m. |
11.4.10Reasonable Prospects for Eventual Economic Extraction
For a Mineral Resource to be reported, the QP must determine that RPEEE has been established.
Due to the narrow-vein nature, geometry, and location of the Stroud mineralization, the QP considers the deposit to be amenable to underground mining methods. A cut-off grade of 1.35 g/t Au was determined considering the costs and input parameters (Table 11-9) benchmarked with similar projects, in particular the nearby Grey Fox deposit.
Table 11-9: Stroud Mineral Resource Cut-off Grade Parameters
Parameter | Unit | Value |
Mining Cost | $US/t | 67.72 |
G&A Cost | $US/t | 16.60 |
Milling Cost | $US/t | 30.77 |
Transport Cost | $US/oz | 1.52 |
Payable Gold | % | 99.95 |
Dilution | % | 15 |
Gold Price | $US/oz | 3,000 |
Exchange Rate (US$/C$) | - | 1.35 |
Royalty (NSR) | % | 0 |
Mill Recovery | % | 90 |
RPEEEs were derived from potentially mineable shapes developed using Datamine’s Mineable Shape Optimizer function. A stope size of 12 m vertical height by 6 m wide along strike by a minimum 3 m wide across strike was adopted. This size was benchmarked against mined stopes at the nearby Black Fox underground mine. Sub stopes were developed at half height and half width along strike (6 m x 3 m) to account for local anisotropy of the grade continuity. Stopes with a width less than 3 m across strike were not considered potentially economical and excluded. Stope shapes were developed using the economic cut-off-grade of 1.35 g/t Au. All classified blocks were analyzed by the mineable shape optimizer with resulting stopes shown in Figure 11-10. All classified blocks were flagged by the potentially mineable
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shapes including those below the 1.35 g/t Au cut-off grade, this is known as “must take material” and as a combined mineable shape they meet the necessary parameters, including the cut-off grade.
Isolated, discontinuous stope shapes were not considered economic, and were therefore removed and not included in the Mineral Resource Statement.

Source: (McEwen, 2026)
Figure 11-10: Long Section NE View of the Generated Stroud MSO Shapes
Figure 11-11 presents the experimental grade–tonnage sensitivities at various cut-off grades. The sensitivities were generated using raw block grades and include all classified blocks, not only those meeting RPEEE. These results are provided for comparative purposes only, to illustrate the potential effect of applying different cut-off grades on tonnage and grade. Sensitivity cases do not represent Mineral Resources and should not be interpreted as such.
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Source: (McEwen, 2026)
Note: Sensitivities use raw cut-off grades and include all Inferred blocks. This is for comparison to show what potential effect a change in cut-off grade would have and does not represent Mineral Resources.
Figure 11-11:Experimental Sensitivities at Various Cut-Off Grades
11.4.11Mineral Resource Statement
Table 11-10 summarizes the Mineral Resource estimates for Stroud, assuming underground stoping methods, reported in accordance with the 2014 CIM Definition Standards (2014). The Mineral Resource was limited to those parts of the gold mineralization for which there are reasonable prospects for eventual economic extraction via underground stope extraction.
Table 11-10: Stroud Mineral Resource Statement, March 26, 2026
Classification | Tonnes, kt | Au Grade, g/t | Contained Au, koz |
Indicated | 0 | 0.00 | 0 |
Inferred | 1,866 | 2.80 | 168 |
Note:
· | Effective date of the Mineral Resource estimate is March 26, 2026. The QP for the estimate is Mr. Carson Cybolsky, P.Geo, an employee of McEwen. |
· | Mineral Resources are reported using Item 1300 of Regulation S-K. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. |
· | Mineral Resources are reported above an economic cut-off grade of 1.35 g/t gold assuming underground extraction methods and based on a mining cost of $67.72/t, process cost of $30.77/t, G&A cost of $16.60/t, metallurgical recovery of 90%, dilution of 15% and gold price of US$3,000/oz. |
· | Figures may not sum due to rounding. |
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11.4.12Factors That Could Affect the Mineral Resource Estimate
Factors that may affect the Stroud Mineral Resource estimate include:
· | Changes in the local geological interpretations and assumptions used to generate the estimation domains. |
· | Changes in mineralization and geological geometry and continuity of mineralized zones. |
· | Changes in assumptions of mineralization and grade continuity. |
· | Changes in the treatment of high-grade gold values. |
· | Changes in the grade interpolation methods and estimation parameter assumptions. |
· | Changes in the confidence assumptions and methods used in the mineral resource classification |
· | Changes in the density and the methods used in the density assignments. |
· | Changes in metal price and exchange rates and other economic assumptions used in the cut-off grade determination. |
· | Changes in input and design parameter assumptions that pertain to the underground mining constraints. |
· | Changes to assumptions as to the continued ability to access the mine site, retain mineral and surface rights titles, maintain the operation within environmental and other regulatory permits, and maintain the social license to operate. |
No other environmental, permitting, legal, title, taxation, socioeconomic, marketing, political or other relevant factors are known to the QP that would materially affect the estimation of Mineral Resources that are not discussed in this report.
11.5Black Fox
11.5.1Mineral Resource Database
The close-out date for the Mineral Resource database is 31 December 2025 and consists of the following:
· | 7,731 core drill holes totalling 1,097,798 m of drill core and 438,200.1 m of sampled core (144 drill holes were excluded from the drill hole database, primarily due to low confidence in their locations). |
· | 13,332 strings of chip samples totalling 52,295.3 m from development headings were sampled for a total of 56,884 assays. |
Unsampled intervals were considered barren and were assigned a background gold grade of 0.0005 g/t, or one-quarter of the assay laboratory’s lower detection limit.
On importing the drill hole database from the central SQL database to Datamine Studio software in preparation for resource estimation, sample data were checked for the following:
· | Missing, duplicated and overlapping intervals in the assay and lithology tables. |
· | Missing and overlapping intervals in the survey table. |
· | Visually checking collar locations in 3D against mine excavations and surface topography. |
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11.5.2Geological Modeling
11.5.2.1Mineralized Domains
Gold mineralization at Black Fox occurs in several different geological settings within the main Ankerite Alteration envelope. The mineralization occurs within both ultramafic and mafic volcanic rock types within the outer boundaries of the PDDZ. The mineralization and alteration envelopes are primarily parallel/subparallel and adjacent to the regional A1 fault. The lenses of the mineralization have been developed within the main lithological and alteration units and primarily occur in vein arrays, shear veins, and replacement zones within the interleaved mafic and ultramafic host rocks.
The mineralized lenses were interpreted and explicitly modelled considering structural and lithological controls, and a grade threshold of approximately 0.5 g/t Au to demonstrate mineralized continuity. The mineralized lenses were divided into nine mineralized domains (Figure 11-12) based primarily on mineralization style, grade population statistics and primary host lithologies.

Source: (McEwen, 2025)
Figure 11-12: Long Section Looking North of Black Fox Mineralized Domains
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11.5.2.2Background Envelope
A background envelope (Domain 100) representing a low-grade alteration package surrounding the mineralization, was constructed around all mineralized domains to capture mineralized samples outside the mineralized domains and to estimate adjacent dilution.
11.5.3Composites
A large percentage of the assays within the mineralized domains have a sample length of 1 m. The modal composite length of 1 m was applied to all samples (drill hole and chip) in the database. This generated composites close to 1 m with a minimum composite length of 0.3 m.
11.5.4Capping
The impact of high-grade outlier populations was analyzed using histograms, log probability plots, mean and variance analysis, and cumulative metal plots. Results are presented in Table 11-11 for each mineralized domain, with metal removed ranging from 0.6% in Domain 6, to 45.9% in Domain 2. Capping was warranted on all mineralized domains except for Domain 5. The capping values derived from this analysis were applied to both drill hole and chip sample composites.
Table 11-11: Black Fox – Metal Removed by Capping Composites
Domain | | Raw Composites | | Capped | | Capped Composites | | No. | | Metal | ||||
| | Mean (g/t) | | CV | | Grade (g/t) | | Mean (g/t) | | CV | | Capped | | Removed (%) |
1 | | 3.86 | | 4.00 | | 52.0 | | 3.53 | | 2.05 | | 70 | | 8.4 |
1.1 | | 2.14 | | 4.45 | | 20.0 | | 1.64 | | 1.99 | | 40 | | 23.3 |
2 | | 6.43 | | 6.45 | | 28.0 | | 3.48 | | 2.00 | | 522 | | 45.9 |
2.1 | | 8.83 | | 3.46 | | 140.0 | | 7.86 | | 2.73 | | 38 | | 11.0 |
2.2 | | 2.58 | | 4.57 | | 16.5 | | 1.63 | | 2.00 | | 19 | | 36.9 |
3 | | 4.37 | | 5.53 | | 30.0 | | 2.93 | | 2.11 | | 259 | | 32.9 |
4 | | 1.99 | | 3.63 | | 29.0 | | 1.73 | | 2.03 | | 40 | | 13.3 |
5 | | 1.46 | | 1.42 | | - | | 1.46 | | 1.42 | | - | | - |
6 | | 0.90 | | 2.20 | | 33.0 | | 0.90 | | 2.09 | | 3 | | 0.6 |
100 (background) | | 0.26 | | 28.5 | | 15.0 | | 0.16 | | 5.44 | | 681 | | 36.1 |
100 (background) | | 0.26 | | 28.5 | | 30.0 | | 0.18 | | 6.95 | | 313 | | 28.5 |
Note: CV = coefficient of variation
11.5.5Density
A constant density value of 2.84 g/cm3 was applied to all material. This value has been used in previous estimates and for production tracking. This value has been validated by analyzing the average value of 150 specific gravity measurements, which are restricted to samples within mineralized domains, and taken from drill hole samples since 2018.
| Project: 169525666 | 11-24 |
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11.5.6Variography
The spatial distribution (continuity) of gold within each mineralized domain was evaluated using variograms. Primary directions of the variograms were modelled based on field observations and interpreted mineralization orientations. The stability of the variograms were evaluated by varying the direction and comparing the resulting experimental variograms. The developed variograms displayed two spherical structures and three rotations to match the strike, dip and plunge of the modelled mineralization. Nugget effects range from 21% in Domain 6 to 33% in Domains 2 and 3.
11.5.7Grade Estimation
A block size of 3 m x 3 m x 3 m was selected based on drill hole spacing, composite length, the geometry of the modelled mineralized zones, and anticipated mining methods. Sub-cells down to 0.5 m x 0.5 m x 0.5 m were used to better reflect the shape and volume of the mineralized domains. No rotation was applied to the block model.
Ordinary kriging was used to estimate the blocks within the mineralized domains using a three-pass approach with increasing search neighborhoods with each pass. Datamine’s dynamic anisotropy function was implemented due to the anisotropic nature and widths of the mineralized domains. This function aligns the search ellipse with the local dip and dip direction of the mineralization, with the plunge component defined as per the variography direction.
Data selection for mineralized domains remained the same for the first and second passes using a minimum of 7 and a maximum of 15 composites from at least three drill holes to estimate a given block. The third pass reduced the minimum requirement to four composites from at least two drill holes. The search parameters are presented in Table 11-12.
Table 11-12: Black Fox Estimation Search Parameters
Domain | Orientation Rotation | Search Volume 1 Distances | Search Volume 2 Distances | Search Volume 3 Distances | Number of samples used to estimate | |||||||||||
| Z | X | Z | X(Stri ke) | Y(Dip) | Z(Perp) | X(Stri ke) | Y(Dip) | Z(Perp) | X(Stri ke) | Y(Dip) | Z(Perp) | Search Pass | Min | Max | Max Composites |
| Dynamic Anisotropic Search Volume | | | | | | | | | | | | | | ||
1 | | | 160 | 13 | 19 | 4 | 39 | 57 | 12 | 52 | 76 | 16 | | | | |
1.1 | | | 110 | 31 | 15 | 4 | 93 | 45 | 12 | 124 | 60 | 16 | 1 | 7 | 15 | 3 |
2 | | | 180 | 18 | 7 | 8 | 54 | 21 | 24 | 72 | 28 | 32 | | | | |
2.1 | | | 90 | 7 | 4 | 2 | 21 | 12 | 6 | 28 | 16 | 8 | 2 | 7 | 15 | 3 |
2.2 | Dip Direction | Dip | -150 | 9 | 5 | 2 | 27 | 15 | 6 | 36 | 20 | 8 | | | | |
3 | | | 150 | 4 | 3 | 2 | 12 | 9 | 6 | 16 | 12 | 8 | 3 | 4 | 15 | 3 |
4 | | | -130 | 12 | 12 | 5 | 36 | 36 | 15 | 48 | 48 | 20 | | | | |
5 | | | -150 | 16 | 13 | 3 | 48 | 39 | 9 | 64 | 52 | 12 | | | | |
6 | | | -150 | 10 | 15 | 14 | 30 | 45 | 42 | 40 | 60 | 56 | | | | |
100 0 run | 170 | 60 | 130 | 5 | 5 | 5 | | | | | | | 1 | 1 | 12 | 3 |
100 Main Run | 170 | 60 | 130 | 50 | 50 | 10 | 100 | 100 | 20 | 250 | 250 | 50 | 1, 2 | 4 | 18 | 3 |
Blocks within the background envelope (Domain 100) were estimated using inverse distance to the power of three with its ellipsoid guided by the deposit’s general mineralized orientation. An initial estimation pass focused on estimating areas where high-grade composites were not captured in the mineralized domains. This estimation pass used composites capped at 15 g/t gold with a tight isometric search ellipse to limit the number of blocks estimated to one or two in each direction. Three subsequent passes using composites capped at 30 g/t were made with increasing search ranges and any blocks not estimated were assigned a background gold value of one-quarter of the detection limit, or 0.0005 g/t.
| Project: 169525666 | 11-25 |
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11.5.8Model Validation
In validating the estimated block model, nearest neighbor and inverse distance models were constructed. The nearest neighbor model produces a theoretically globally unbiased estimate of the average value when no cut-off grade is applied and is a good basis for checking the performance of different estimation methods.
The estimated block model was validated by visual inspection, with swath plots to determine whether any local bias exists, and with local and global reconciliations using randomly selected stopes in mined out areas.
Results of the validation show the estimated model acceptably reflects the sample data and past production results.
11.5.9Confidence Classification
The QP is confident that the Black Fox mineralization model honours the current informing data from the geological database. The location of the samples and the assay data are sufficiently reliable to support Mineral Resource evaluation. The Mineral Resource model is constrained by mineralized domains based on lithological, structural and grade criteria and is modelled from core holes drilled on an irregular grid. The controls on the distribution of the gold mineralization are understood, and the confidence in geological continuity is reasonable.
Block classification scenarios were analyzed using a combination of criteria, including confidence in the mineralization’s continuity, drill spacing, sample spacing (in the form of average distance to informing samples - weighted on kriging weights), and the number of drill holes used to estimate. The QP considers the average distance at approximately one-third the modelled variogram (10 m) to adequately represent the local mineralization grades considering the amount of informing data used in the estimate. The QP also considers the estimated grades, using a search distance equal to the average full sill ranges of the modelled variograms (30 m), to adequately represent the global mineralization grades.
The following classification criteria were defined:
· | Measured: Assigned to those continuous blocks within the mineralized domains, estimated within 10 m of informing composites from at least three drill holes. |
· | Indicated: Assigned to those continuous blocks within the mineralized domains, estimated within 10 m of informing composites from at least two drill holes. |
· | Inferred: Assigned to those continuous blocks within the mineralized domains estimated within 30 m of informing composites from at least two drill holes. |
Blocks within the mineralized zones not meeting the above criteria were not classified. Blocks within the background envelope were not classified.
11.5.10Reasonable Prospects for Eventual Economic Extraction
For a Mineral Resource to be reported, the QP must determine that RPEEE has been established.
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Due to the narrow vein nature, geometry, and location of the Black Fox mineralization, the QP considers the deposit to be amenable to underground mining methods. A cut-off grade of 1.35 g/t Au was determined considering the costs and input parameters (Table 11-13) based on recent quotations and benchmarked with similar projects.
Table 11-13: Black Fox Mineral Resource Cut-off Grade Parameters
Parameter | Unit | Value |
Mining Cost | $US/t | 62.66 |
G&A Cost | $US/t | 20.49 |
Milling Cost | $US/t | 32.21 |
Transport Cost | $US/oz | 1.52 |
Payable Gold | % | 99.95 |
Dilution | % | 15 |
Gold Price | $US/oz | 3,000 |
Exchange Rate (US$/C$) | - | 1.35 |
Royalty (NSR) | $US/t | 7.20 |
Mill Recovery | % | 95 |
RPEEEs were derived from calculating potentially mineable shapes developed using Datamine’s MSO function. A stope size of 12 m vertical height by 6 m wide, along strike by a minimum 3 m wide across strike was adopted. Sub stopes were developed at half height and half width along strike (6 m x 3 m) to account for local anisotropy of the grade continuity. Stope shapes were developed using the economic cut-off-grade of 1.35g/t Au. All classified blocks were analyzed by the mineable shape optimizer.
Isolated, discontinuous stope shapes were not considered economic and were therefore removed and not included in the Mineral Resource Statement. Mineralization below the 300 m level is not considered economic at this time due to the lack of accessibility and the current condition of workings at the deeper levels. All blocks beneath the 300 m level are coded as such and are not included in the Mineral Resource Statement.
Figure 11-13 presents the experimental grade–tonnage sensitivities at various cut-off grades. The sensitivities were generated using raw block grades and include Measured, Indicated and Inferred blocks. Sensitivities include all classified blocks, not only those meeting RPEEE. These results are provided for comparative purposes only, to illustrate the potential effect of applying different cut-off grades on tonnage and grade. Sensitivity cases do not represent Mineral Resources and should not be interpreted as such.
| Project: 169525666 | 11-27 |
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Source: (McEwen, 2026)
Note: Sensitivities use raw block grades and include Measured, Indicated and Inferred blocks. These results are for comparison only and do not represent Mineral Resources.
Figure 11-13:Experimental Grade‑Tonnage Sensitivities at Various Cut‑Off Grades
11.5.11Mineral Resource Statement
Table 11-14 summarizes the Mineral Resource estimates for Black Fox, assuming underground stoping methods, reported in accordance with the 2014 CIM Definition Standards (2014). The Mineral Resource was limited to those parts of the gold mineralization for which there are reasonable prospects for eventual economic extraction via underground stope extraction.
Table 11-14: Black Fox Mineral Resource Statement, December 31, 2025
Classification | Tonnes (kt) | Au Grade (g/t) | Contained Au (koz) |
Measured | 244 | 3.59 | 28 |
Indicated | 141 | 3.54 | 16 |
Total Measured + Indicated | 385 | 3.57 | 44 |
Inferred | 385 | 2.90 | 36 |
Note:
· | Effective date of the Mineral Resource estimate is 31 December 2025. The QP for the estimate is Mr. Carson Cybolsky, P.Geo, an employee of McEwen. |
· | Mineral Resources are reported using Item 1300 of Regulation S-K. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. |
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· | Mineral Resources are reported above an economic cut-off grade 1.35 g/t gold assuming underground extraction methods and based on a mining cost of $62.66/t, process cost of $32.21/t, G&A cost of $20.49/t, metallurgical recovery of 95%, dilution of 15% and gold price of US$3,000/oz. |
· | Figures may not sum due to rounding. |
· | Informing sample database cut-off date is 2 October 2024. Mining depletion date up to and including 31 December 2025. |
11.5.12Factors That Could Affect the Mineral Resource Estimate
Factors that may affect the Black Fox Mineral Resource estimate include:
· | Changes in the local geological interpretations and assumptions used to generate the estimation domains |
· | Changes in mineralization and geological geometry and continuity of mineralized zones |
· | Changes in assumptions of mineralization and grade continuity |
· | Changes in the treatment of high-grade gold values |
· | Changes in the grade interpolation methods and estimation parameter assumptions |
· | Changes in the confidence assumptions used in the resource classification |
· | Density assignment |
· | Changes in metal price and exchange rates and other economic assumptions used in the cut-off grade determination |
· | Changes in input and design parameter assumptions that pertain to the underground mining constraints |
· | Changes to assumptions as to the continued ability to access the mine site, retain mineral and surface rights titles, maintain the operation within environmental and other regulatory permits, and maintain the social license to operate. |
No other environmental, permitting, legal, title, taxation, socioeconomic, marketing, political or other relevant factors are known to the QP that would materially affect the estimation of Mineral Resources that are not discussed in this Technical Report Summary.
11.6Froome
11.6.1Mineral Resource Database
The close-out date for the Mineral Resource database was 31 December 2025 and consisted of 1,112 core drill holes totalling 221,479 m of drill core and 128,304 m of sampled core. The database also includes 1,599 strings of chip samples totalling 9,196 gold assays values from 8,617 m of underground development. Unsampled intervals were considered barren and assigned a background gold grade of 0.0005 g/t, or one-quarter of the assay laboratory’s lower detection limit.
On importing the drill hole and chip databases from the central SQL databases to Datamine Studio software in preparation for resource estimation, sample data were checked for missing and overlapping intervals in the assay, lithology and survey tables, and density values inspected to ensure no erroneous entries were present.
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Underground grade control drilling has continued since the close-out date for the Mineral Resource database in areas of proposed mining. Small local geological interpretations have been improved in these areas; however, no material difference is indicated by the results.
11.6.2Geological Modeling
11.6.2.1Mineralized Domains
The Froome project area is subdivided into four mineralized domains. There are two grade populations hosted primarily in metasediments and two grade populations hosted in FW mafic and ultramafic metavolcanics. All mineralized domains were created using explicit wireframing techniques around static drill holes. Figure 11-14 shows the location of the mineralized domains.
Domain 300 is comprised of the relatively higher gold grade population hosted in metasediments. A low grade mineralized mafic intrusive dyke (domain 300-MI) running through the core of Domain 300 was modelled separately to reduce the smearing of low-grade samples into the surrounding sediments and also to restrict high-grade samples in the surrounding sediments from the mafic dyke. No major structures were noted as gold mineralization is hosted within disseminated sulphide mineralization. However, grade trends were analyzed and planes representing those trends were created.

Source: (McEwen, 2025)
Figure 11-14:East-West Long Sectional View of Froome Project Mineralized Domains
Domain 301 is disseminated through the metasediments, primarily along the north (FW) contact and consists of a lower gold grade population.
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Both domains 500 and 501 are hosted primarily in the mafic and ultramafic metavolcanics in the FW of the metasediment unit. The mineralization of these domains is hosted in fault-filled quartz carbonate veins and breccias typical of Archean lode gold vein structures along the PDDZ. Statistical analysis of the gold grades within the mineralized lenses that make up these domains suggests there are two populations of gold grade. Domain 501 has a higher probability of containing higher-grade mineralization.
Average structural planes through the FW domain lenses were created to determine each lens anisotropy. The bedrock/overburden contact was generated from the drill holes and used to constrain the extent of mineralization.
11.6.2.1.1Background Envelope
A background envelope (Domain 400) was constructed around all mineralized domains to capture mineralized samples outside the mineralized domains and to estimate adjacent dilution.
11.6.3Composites
More than 50% of the assays within the mineralized domains have a sample length of 1 m. The modal composite length of 1 m was applied to all samples in the database. This generated composites close to 1 m with a minimum composite length of 0.3 m and a maximum of 1.5 m.
11.6.4Capping
The impact of high-grade outlier populations was analyzed using histograms, log probability plots, mean and variance, and cumulative metal plots. Results are presented in Table 11-15 with metal removed ranging from 0.4% in Domain 300 to 27.7% in Domain 500.
Table 11-15: Froome – Metal Removed by Capping Composites
Domain | Raw Composites | Capped | Capped Composites | No. | Metal | ||
| Mean (g/t) | CV | Grade (g/t) | Mean (g/t) | CV | Capped | Removed (%) |
300 | 3.19 | 1.07 | 19.0 | 3.17 | 1.05 | 21 | 0.4 |
300-MI | 2.7 | 1.11 | 8.5 | 2.55 | 0.99 | 55 | 5.4 |
301 | 1.23 | 1.64 | 10.0 | 1.19 | 1.44 | 43 | 3.5 |
500 | 2.1 | 7.3 | 19.0 | 1.52 | 1.58 | 7 | 27.7 |
501 | 2.03 | 5.72 | 45.0 | 1.74 | 2.73 | 17 | 14.3 |
400 | 0.07 | 3.56 | 2.3 | 0.06 | 2.61 | 92 | 4.5 |
Note: CV = coefficient of variation
| Project: 169525666 | 11-31 |
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11.6.5Density
A bulk density analysis was completed for the previous resource update (dated 31 December 2024) and is still considered valid. In that resource update there were 2,973 density samples used in the Froome Mineral Resource bulk density analysis. Density samples were measured on NQ sized core with lengths between 10 and 15 cm, using the Archimedes’ Principle method. A study of all the density data in the resource database was conducted and used to determine an average density value for each of the modelled domains. The average densities for each domain are presented in Table 11-16 and applied to the blocks contained within.
Table 11-16: Froome – Density Values by Mineralized Domain
Domain | Density (g/cm3) |
300 | 2.76 |
301 | 2.76 |
500 | 2.85 |
501 | 2.85 |
400 | 2.81 |
11.6.6Variography
The spatial distribution (continuity) of gold within each mineralized domain was evaluated using variograms.
Primary directions of the variograms were modelled based on observed mineralization orientations. The stability of the variograms were evaluated by varying the direction and comparing the resulting experimental variograms. The developed variograms displayed two spherical structures and three rotations to match the strike, dip and plunge of the modelled mineralization. Nugget effects range from 0% in Domain 500, and 300-MI to 23% in Domain 301.
11.6.7Grade Estimation
A block size of 3 m x 3 m x 3 m was selected based on drill hole spacing, composite length, the geometry of the modelled mineralized zones, and anticipated mining methods. Sub-cells down to 0.5 m x 0.5 m x 0.5 m were used to better reflect the shape and volume of the mineralized domains. No rotation was applied to the block model.
Ordinary kriging was used to estimate the blocks within the mineralized domains using a three-pass approach. Search neighborhoods are based on variography with ranges doubling in length with each pass. Datamine’s dynamic anisotropy function was implemented due to the anisotropic nature and widths of the mineralized domains. This function aligns the search ellipse with the local dip and dip direction with the plunge defined as per the variography direction.
Data selection for mineralized domains 300, 300-MI & 301 remained the same for all passes using a minimum of seven and a maximum of 15 composites from at least three drill holes to estimate a given block. Data selection for mineralized domains 500 & 501 used a minimum of 5 and a maximum of 15
| Project: 169525666 | 11-32 |
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composites from at least two drill holes to estimate a given block. Blocks within Domains 300-MI and 400 were estimated using ordinary kriging with its ellipsoid guided by the general lithology contact orientation determined through variography without the use of dynamic anisotropy. Any blocks that were not estimated in one of the three passes were assigned a background gold value of one quarter of the detection limit, or 0.0005 g/t.
Estimation search parameters are presented in Table 11-17 below.
Table 11-17: Froome Estimation Search Parameters
Domain | Orientation Rotation | Search Volume 1 | Search Volume 2 | Search Volume 3 | Search Volume 4 Distances | Number of samples used to Estimate | ||||||||||||||
Z | X | Z | X(Stri ke) | Y(Dip) | Z(Perp) | X(Stri ke) | Y(Dip) | Z(Perp) | X(Stri ke) | Y(Dip) | Z(Perp) | X(Stri ke) | Y(Dip) | Z(Perp) | Mi n | Ma x | Ma x | |||
| Dynamic Anisotropy | | | | | | | | | | | | | | | | | |||
300 | | 90 | 15 | 10 | 2.5 | 30 | 20 | 5 | 60 | 40 | 10 | 300 | 300 | 50 | 7 | 15 | | |||
301 | TRDIPDIR | TIRDIP | 90 | 7 | 10.5 | 4 | 14 | 21 | 8 | 28 | 42 | 16 | 300 | 300 | 50 | | | 3 | ||
500 | | 130 | 7.5 | 4 | 2.5 | 15 | 8 | 5 | 30 | 16 | 10 | 300 | 300 | 50 | 5 | 15 | | |||
501 | | 80 | 6.5 | 3.5 | 3 | 13 | 7 | 6 | 26 | 14 | 12 | 300 | 300 | 50 | | | | |||
| Z | X | Z | | | | | | | | | | | | | | ||||
300-mi | -170 | 75 | 110 | 2.5 | 9 | 1 | 5 | 18 | 2 | 10 | 36 | 4 | 7 | 15 | 3 | |||||
400 0 Run | 0 | 0 | 70 | 5 | 5 | 3 | | | | | | | 1 | 12 | 3 | |||||
400 Background | 0 | 0 | 70 | 20 | 18 | 18 | 40 | 36 | 36 | 60 | 54 | 54 | 7 | 15 | 3 | |||||
11.6.8Model Validation
The estimated block model was validated by visually comparing the drill holes with the block grades (Figure 11-15 and Figure 11-16), with swath plots to determine whether any statistical local bias exists, a nearest neighbor estimate versus the kriged estimate to determine if any global bias exists, and a local stope reconciliation. A histogram comparison of the estimated grades versus the composite grades was also used to investigate grade smoothing. These analyses indicate the block model acceptably reflects the assay sample data with only minor local bias in areas of sparse data. There is a minor amount of local smoothing of the higher grades; however, the grade distribution of the samples is reasonably reproduced by the estimate.

Source: (McEwen, 2025)
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Note: 10 m clipping, looking east
Figure 11-15: Section View Comparing Block Grades with Drill Hole Data in Froome Domain 501

Source: (McEwen, 2025)
Note: Zoomed in on Froome West Domain 501, 10 m clipping.
Figure 11-16:Plan View at Elevation 9840 Comparing Block Grades with Drill Hole Data
11.6.9Confidence Classification
The QP is confident that the Froome mineralization model honours the current informing data from the geological database. The location of the samples and the assay data are sufficiently reliable to support Mineral Resource evaluation. The Mineral Resource model is constrained by mineralized domains based on lithological, structural and grade criteria and is modelled from underground mapping and core holes drilled on an irregular grid, with an average spacing between drill holes of 10 and 30 m. The controls on the distribution of the gold mineralization are understood, and the confidence in geological continuity is reasonable.
For Domains 300 and 301, classification criteria considers the confidence in the continuity of mineralization, distance to the closest informing sample, and average drill hole spacing based on the three closest drill holes. The following classification criteria were defined:
· | Measured: Assigned to those continuous blocks within the mineralized Domains 300 and 301, informed by three or more drill holes, less than 7 m to the nearest drill hole, and within an average drill hole spacing of 10 m |
· | Indicated: Assigned to those continuous blocks within the mineralized Domains 300 and 301, informed by three or more drill holes, less than 15 m to the nearest drill hole, and within an average drill hole spacing of 25 m |
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· | Inferred: Assigned to those continuous blocks within the mineralized Domains 300 and 301, informed by three or more drill holes, less than 20 m to the nearest drill hole, and within an average drill hole spacing of 40 m. |
The geological nature of the gold mineralization in Domains 500 and 501 exhibits higher variability in grade then other domains and therefore was assigned a stricter classification criteria. The following classification criteria were defined:
· | Measured: Due to lower confidence, no blocks in these domains were assigned to the measured classification (the QP requires an area with 10m spaced drilling or visual mapping to confirm the geological model before considering the measured category). |
· | Indicated: Assigned to those continuous blocks within the mineralized Domains 500 and 501, informed by three or more drill holes, less than 10 m to the nearest drill hole, and within an average drill hole spacing of 25 m. |
· | Inferred: Assigned to those continuous blocks within the mineralized Domains 500 and 501, informed by two or more drill holes, less than 20 m to the nearest drill hole, and within an average drill hole spacing of 40 m. |
Blocks within the mineralized domains not meeting the above criteria were not classified. Blocks within the background envelope were not classified.
11.6.10Reasonable Prospects for Eventual Economic Extraction
For a Mineral Resource to be reported, the QP must determine that RPEEE has been established.
Due to the geometry and location of the Froome mineralization, the QP considers the deposit to be amenable to underground mining methods. A cut-off grade of 1.35 g/t Au was determined considering the costs and input parameters (Table 11-18) based on current rates and costs and benchmarked with similar projects.
Table 11-18: Froome Mineral Resource Cut-off Grade Parameters
Parameter | Unit | Value |
Mining Cost | $US/t | 62.66 |
G&A Cost | $US/t | 16.07 |
Milling Cost | $US/t | 32.21 |
Transport Cost | $US/oz | 1.52 |
Payable Gold | % | 99.95 |
Dilution | % | 15 |
Gold Price | $US/oz | 3,000 |
Exchange Rate (US$/C$) | - | 1.35 |
Royalty (NSR) | $US/t | 7.20 |
Mill Recovery | % | 89.5 |
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Reasonable prospects for eventual economic extraction were derived from potentially mineable shapes developed using Datamine’s MSO function. A stope size of 12 m vertical height by 6 m wide along strike by a minimum 3 m wide across strike was adopted. This size is consistent with current mining methods and was benchmarked against mined stopes at the nearby Black Fox underground mine. Sub stopes were developed at half height and half width along strike (6 m x 3 m) to account for local anisotropy of the grade continuity. Stopes with a width less than 3 m across strike were not considered RPEEE. Stope shapes were developed using the economic cut-off-grade of 1.35 g/t Au. All classified blocks were analyzed by the MSO with resulting stopes shown in Figure 11-17.
All classified blocks were flagged by the potentially mineable shapes including those below the 1.35 g/t Au cut-off grade, this is known as “must take material” and as a combined mineable shape they meet the necessary parameters, including the cut-off grade. Isolated, discontinuous stope shapes were not considered economic, and were therefore removed and not included in the Mineral Resource Statement.

Source: (McEwen, 2025)
Figure 11-17:Long Section Looking North of Potentially Mineable Stope Shapes at Froome
Figure 11-18 presents the experimental grade–tonnage sensitivities at various cut-off grades. The sensitivities were generated using raw block grades and include Measured, Indicated and Inferred blocks. Sensitivities include all classified blocks, not only those meeting RPEEE. These results are provided for comparative purposes only, to illustrate the potential effect of applying different cut-off grades on tonnage and grade. Sensitivity cases do not represent Mineral Resources and should not be interpreted as such.
| Project: 169525666 | 11-36 |
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Source: (McEwen, 2026)
Note: Sensitivities use raw block grades and include Measured, Indicated and Inferred blocks. These results are for comparison only and do not represent Mineral Resources.
Figure 11-18:Experimental Grade‑Tonnage Sensitivities at Various Cut‑Off Grades
11.6.11Mineral Resource Statement
Table 11-19 summarizes the Mineral Resource estimates for Froome, assuming underground stoping methods, reported in accordance with the 2014 CIM Definition Standards (2014). The Mineral Resource was limited to those parts of the gold mineralization for which there are reasonable prospects for eventual economic extraction via underground stope extraction.
Table 11-19: Froome Mineral Resource Statement, December 31, 2025
Classification | Tonnes (kt) | Au Grade (g/t) | Contained Au (koz) |
Measured | 212 | 2.45 | 17 |
Indicated | 440 | 2.94 | 42 |
Total Measured + Indicated | 651 | 2.78 | 58 |
Inferred | 302 | 2.93 | 28 |
Notes:
· | Effective date of the Mineral Resource estimate is December 31, 2025. The QP for the estimate is Mr. Carson Cybolsky, P.Geo, an employee of McEwen. |
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· | Mineral Resources are reported using Item 1300 of Regulation S-K. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. |
· | Mineral Resources are reported above an economic cut-off grade of 1.35 g/t Au assuming underground extraction methods and based on a mining cost of $62.66/t, process cost of $32.21/t, G&A cost of $16.07/t, metallurgical recovery of 89.5%, dilution of 15% and gold price of US$3,000/oz. |
· | Figures may not sum due to rounding. |
· | Informing sample database cut-off and mining depletion date is December 31, 2025. |
11.6.12Factors That Could Affect the Mineral Resource Estimate
Factors that may affect the Froome Mineral Resource estimate include:
· | Changes in the local geological interpretations and assumptions used to generate the estimation domains |
· | Changes in mineralization and geological geometry and continuity of mineralized zones |
· | Changes in assumptions of mineralization and grade continuity |
· | Changes in the grade interpolation methods and estimation parameter assumptions |
· | Changes in the confidence assumptions used in the resource classification |
· | Density assignments |
· | Changes in metal price and exchange rates and other economic assumptions used in the cut-off grade determination |
· | Changes in input and design parameter assumptions that pertain to the underground mining constraints |
· | Changes to assumptions as to the continued ability to access the mine site, retain mineral and surface rights titles, maintain the operation within environmental and other regulatory permits, and maintain the social license to operate. |
No other environmental, permitting, legal, title, taxation, socioeconomic, marketing, political or other relevant factors are known to the QP that would materially affect the estimation of Mineral Resources that are not discussed in this Report.
11.7Stock Property – West and Main Zone
11.7.1Mineral Resource Database
The close-out date for the Mineral Resource database is October 23, 2023 and consists of 567 core drill holes totalling 241,163.70 m of drill core and 73,148 intervals assayed for gold. Unsampled intervals were considered barren and assigned a background gold grade based on ¼ of the assay laboratory’s lower detection limit.
There has been only limited drilling activity at the property since the database close-out. Logging and assay results of the new data indicate the geological and mineralization model reported here continues to be valid. As new data arrives in future drilling campaigns, the estimation methods and parameters will be refined, which will affect the Mineral Resources dynamically.
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On importing the drill hole database from the central SQL database to Datamine Studio software in preparation for resource estimation, sample data were checked for missing and overlapping intervals in the assay and survey tables, and collar locations checked against the LiDAR topography surface.
Mining as-builds and remnant shapes were up-to-date as of December 31, 2025 and used to deplete the model.
11.7.2Geological Modeling
11.7.2.1Lithology
A lithology model was developed implicitly to capture the eight key deposit lithologies and the overburden as shown in Figure 11-19.
Using the logged lithology, an overburden volume was modeled to the top of the bedrock and was used to cap the lithology wireframes.

Source: (McEwen, 2023)
Figure 11-19: Isometric View of the Stock Project Lithology Model
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11.7.2.2Mineralized Domains
The Stock West and Main deposit contain five main zones of mineralization shown in Figure 11-20 and described below:
· | Domain 10 is a shear zone, hosted in highly altered ultramafic rocks. Coincident with the most intense mineralization within Domain 10 is the primary alteration carbonate mineral, fuchsite. Disseminated gold mineralization occurs in en-echelon quartz veins, quartz stockwork and matrix material. Domain 10 trends east-northeast and dips moderately to steeply southeast. |
· | Domains 10.2 and 10.3 form a mineralized zone near the Stock Portal, composed of conjugate sets of crosscutting quartz veins in fuchsite altered ultramafics; 10.2 veins are sub-horizontal; 10.3 veins form sub-vertical, north-south striking lenses. |
· | Domain 20 is a lower grade zone located in the HW of Domain 10 and is hosted primarily in a bleached altered mafic volcanic unit trending east-northeast and dipping moderately to steeply southeast. |
· | Domain 30 is generally HW to both Domain 10 and Domain 20, and hosted primarily in felsic porphyry and intrusive units, as well as mineralized mafic metavolcanic units. |
Mineralized lenses were interpreted (usually following a threshold grade of 0.5 g/t), flagged in the drill hole file and modeled using Datamine’s implicit Vein Modeling module with a minimum thickness of 0.5 m.

Source: (McEwen, 2023)
Note: Looking NNW
Figure 11-20:Long view of Stock West and Main Mineralized Zones and Background Envelope
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11.7.2.2.1Background Envelope
A background envelope (Domain 200) was constructed around the mineralized domains to capture mineralized samples outside the mineralized domains and to estimate adjacent dilution (Figure 11-20). It is approximately a 50m buffer around mineralized lenses, constructed from strings using sections spaced every 50m.
11.7.3Composites
More than 50% of the assays have a sample length of 1 m. The modal composite length of 1 m was applied to samples within the modeled domains which generated composites close to 1 m with a minimum composite length of 0.3 m.
11.7.4Capping
The impact of high-grade outlier populations was analyzed using histograms, log probability plots, mean and variance, and cumulative metal plots. Results are presented in Table 11-20 for each domain with metal removed ranging from 6.7% in Domain 10 to 51.3% in Domain 10.3.
Table 11-20: Stock West & Main – Metal Removed by Capping Composites
Domain | Raw Composites | Capped | Capped Composites | No. | Metal | ||
| Mean (g/t) | CV | Grade (g/t) | Mean (g/t) | CV | Capped | Removed (%) |
10 | 1.38 | 4.07 | 20.0 | 1.29 | 2.01 | 30 | 6.7 |
10.2 | 2.96 | 5.64 | 15.0 | 1.62 | 1.94 | 27 | 45.1 |
10.3 | 4.27 | 5.65 | 15.0 | 2.08 | 1.69 | 22 | 51.3 |
20 | 0.80 | 3.31 | 13.0 | 0.71 | 1.99 | 24 | 10.9 |
30 | 0.86 | 2.12 | 7.0 | 0.78 | 1.57 | 9 | 9.3 |
200 | 0.07 | 20.77 | 2.4 | 0.05 | 4.02 | 262 | 28.4 |
Note: CV = coefficient of variation
11.7.5Density
There are 2,124 density samples contained in the Mineral Resource database. Currently, one sample every 20 is collected by the assay laboratory for density analysis in the sample stream submitted for gold assay analysis. A study of all density data was conducted to determine an average density value for each of the host lithology units. Outliers were identified and removed resulting in the average density values listed in Table 11-21.
The block model was flagged by the major lithology wireframes and average densities were applied to the blocks accordingly. Any blocks outside the modelled lithologies were assigned overall average density value of 2.83 g/cm3. Blocks above the bedrock and below the topography were flagged as overburden and assigned a density of 2.0 g/cm3.
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Table 11-21: Stock West & Main – Density Values by Lithology
Lithology | | | | No. of Samples | Avg. Density |
Bleached Mafic Volcanics | | (AMV, BMV) | | 298 | 2.83 |
Fuchsite Altered Ultramafic Volcanics | | (CGR) | | 287 | 2.89 |
Diabase | | (DIA) | | 11 | 2.89 |
Felsic Intrusive | | (AFP, FP, FI, II, QFP) | | 251 | 2.70 |
Mafic Volcanics | | (MV, PMV) | | 129 | 2.84 |
Sediments | | (SED) | | 63 | 2.76 |
Ankerite Altered Ultramafic Volcanics | | (AUV, CGY) | | 532 | 2.86 |
Ultramafic Volcanics | | (TUV, CUV, UMV, UV) | | 244 | 2.84 |
All Lithologies Combined | | | | 1815 | 2.83 |
* 2124 Total samples. Lowest 5 and highest 5 values removed from evaluation as outliers | | | | ||
* Density measurements belonging to minor, unmodeled lithologies removed from density calculation. | | | | ||
* overburden given a specific gravity of 2.00 | | | | ||
11.7.6Variography
The spatial distribution (continuity) of gold within each mineralized domain was evaluated using variograms.
Primary directions of the variograms were modelled based on observed mineralization and structural orientations. These orientations were then examined statistically to ensure they represented the best possible fit with the variography. The stability of the variograms was evaluated by varying the direction specification and comparing the resulting experimental variograms. Variograms were modelled with spherical structures and two or three rotations to match the strike, dip and plunge of the mineralized zone. Nugget effects are 20% in all Domains.
11.7.7Grade Estimation
A block size of 3 m x 3 m x 3 m was selected based on drill hole spacing, composite length, the geometry of the modelled mineralized zones, and anticipated mining methods. Sub-cells down to 0.5 m x 0.5 m x 0.5 m were used to better reflect the shape and volume of the mineralized domains. No rotation was applied to the block model.
Ordinary kriging was used to estimate the blocks within the mineralized domains using a four-pass approach. For Domain 10, search neighborhoods are based on variography with ranges doubling in length for passes two and three with the maximum search length in pass four equal to one and one half the range of the maximum variogram structure. For Domains 10.2, 10.3, 20 and 30, search neighborhoods are based on variography with ranges doubling in length for all search ranges.
Data selection for mineralized domains remained the same for the first three passes using a minimum of 7 and a maximum of 15 composites from at least 3 drill holes to estimate a given block. These restrictions were reduced to a minimum of 4 composites from at least 2 drill holes to estimate a block in the fourth pass.
Blocks within the background envelope were estimated using inverse distance to the power of three with its ellipsoid guided by the general lithology contact orientation determined through variography. An initial estimation pass focused on estimating areas where high-grade composites were not captured in the
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mineralized domains. This estimation pass used uncapped composites with a tight search ellipse to limit the number of blocks estimated to one or two in each direction. Three subsequent passes were made with increasing search ranges and any blocks not estimated were assigned a background gold value of a one-quarter of detection limit, or 0.0005 g/t.
11.7.8Model Validation
In validating the estimated block model, a nearest neighbor model was constructed. This model mimics a declustered data set and was generated using 3 m capped composites (block dimension) following the same search ellipse as the ordinary kriged estimate.
The estimated block model was validated by visual inspection, comparing the global statistics of the estimated model with the nearest neighbor model, and with swath plots to determine whether any local bias exists.
Inspecting drill holes with block estimates in section (Figure 11-21) and plan (Figure 11-22) confirms gold grades of the model follow the grades of the informing samples.
Swath plots indicate the mean grades of the estimates follow the mean grades of the declustered informing samples relatively well with small local biases in areas with less informing sample data.
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Source: (McEwen, 2025)
Note: Includes MSO outlines and planned development, ±25 m clipping
Figure 11-21:Section View Comparing Block Grades in Domains 10 and 20 with Drill Hole Data
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Source: (McEwen, 2025)
Note: ± 20 m clipping, -100 m elevation, includes MSO outlines
Figure 11-22:Plan View Comparing Block Grades with Drill Hole Data
Block estimates were checked for global bias by comparing the average grade (at a zero g/t cut-off) of the estimated model with that obtained from nearest neighbor estimates. The QP considers the estimate to be globally unbiased if the comparison is within a ±5% tolerance. The global bias check was made on the classified Mineral Resource resulting in less than a 5% difference showing no global bias exists.
11.7.9Confidence Classification
The QP is confident that the Stock West & Main mineralization models honour the current informing data from the geological database. The location of the samples and the assay data are sufficiently reliable to support Mineral Resource evaluation. The Mineral Resource model is constrained by mineralized domains based on lithological, structural and grade criteria and is modelled from core holes drilled on an irregular grid, with a spacing between 15 m and 35 m. The controls on the distribution of the gold mineralization are understood, and the confidence in geological continuity is reasonable.
Classification criteria considers the confidence in the continuity of mineralization, average distance to the closest three drill holes, distance to the nearest drill hole, and search neighborhood. The following classification criteria were defined:
· | Indicated: assigned to those continuous blocks within mineralized domains 10, 10.2, 10.3, and 20, informed by three or more drill holes, within the first three search neighborhoods, less than 15 m to the nearest drill hole, and an average drill spacing less than 25 m. |
· | Inferred: assigned to those continuous blocks within the mineralized domains and within the first three search neighborhoods, informed by at least three drill holes, and an average drill spacing less than 40 m. Also assigned to those continuous blocks within the mineralized domains and within the |
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fourth search neighborhood, informed by at least three drill holes, less than 12.5 m to the nearest drill hole, and within an average drill spacing less than 40 m.
For Domain 30, lenses are small and discontinuous, it was concluded that more data is needed to increase the confidence therefore the classification for this domain was forced as inferred; any material that might have been classified as indicated using the above criteria was classified as inferred.
Blocks within the mineralized domains not meeting the above criteria were not classified. Blocks within the background envelope were not classified.
11.7.10Reasonable Prospects for Eventual Economic Extraction
For a Mineral Resource to be reported, the QP must determine that RPEEE has been established.
Due to the geological nature, geometry, and location of the Stock West mineralization, the QP considers the deposit to be amenable to underground mining methods. A cut-off grade of 1.30 g/t Au was determined considering the costs and input parameters (Table 11-22) based on recent quotations and benchmarked with similar projects.
Table 11-22: Stock West and Main Mineral Resource Cut-off Grade Parameters
Parameter | Unit | Value |
Mining Cost | $US/t | 62.66 |
G&A Cost | $US/t | 20.49 |
Milling Cost | $US/t | 32.21 |
Transport Cost | $US/oz | 1.52 |
Payable Gold | % | 99.95 |
Dilution | % | 15 |
Gold Price | $US/oz | 3,000 |
Exchange Rate (US$/C$) | - | 1.35 |
Royalty (NSR) | % | * |
Mill Recovery | % | 93 |
Note: *Franco Nevada retains a 1.0% NSR Royalty on a portion of Stock Main, calculated cut-off grade for that zone is 1.30g/t vs 1.29g/t for the remainder of the deposit, ultimately a rounded 1.30 g/t cut-off grade was used for all of Stock.
Reasonable prospects for eventual economic extraction were derived from potentially mineable shapes developed using Datamine’s Mineable Shape Optimizer function. A stope size of 12 m vertical height by 6 m wide along strike by a minimum 3 m wide across strike was adopted. This size was benchmarked against mined stopes at the nearby Black Fox underground mine. Sub stopes were developed at half height and half width along strike (6 m x 3 m) to account for local anisotropy of the grade continuity. Stopes with a width less than 3 m across strike were not considered potentially economical and excluded. Stope shapes were developed using the economic cut-off-grade of 1.30 g/t Au. All classified blocks were analyzed by the mineable shape optimizer with resulting stopes shown in Figure 11-23.
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All classified blocks were flagged by the potentially mineable shapes including those below the 1.30 g/t Au cut-off grade that were included in the MSO shapes calculated at the economic cut-off grade. This can be considered as internal dilution or “must-take” material. Isolated, discontinuous stope shapes were not considered economic, and were therefore removed and not included in the Mineral Resource Statement.

Source: (McEwen, 2026)
Note: Looking north
Figure 11-23:Long Section View of the Potentially Mineable Stope Shapes at Stock West & Main
Figure 11-24 presents the experimental grade–tonnage sensitivities at various cut-off grades. The sensitivities were generated using raw block grades and include both Indicated and Inferred classified blocks. Sensitivities include all classified blocks, not only those meeting RPEEE. These results are provided for comparative purposes only, to illustrate the potential effect of applying different cut-off grades on tonnage and grade. Sensitivity cases do not represent Mineral Resources and should not be interpreted as such.
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Source: (McEwen, 2026)
Note: Sensitivities use raw block grades and include Indicated and Inferred blocks. These results are for comparison only and do not represent Mineral Resources.
Figure 11-24:Experimental grade‑tonnage sensitivities at Various Cut‑Off Grades
11.7.11Mineral Resource Statement
Table 11-23 summarizes the Mineral Resource estimates for Stock West and Main, assuming underground stoping methods. The Mineral Resource was limited to those parts of the gold mineralization for which there are RPEEEs via underground stope extraction.
Table 11-23: Stock Project - West & Main Mineral Resource Statement, December 31, 2025
Classification | Tonnes (kt) | Au Grade (g/t) | Contained Au (koz) |
Indicated | 3,179 | 2.63 | 268 |
Inferred | 2,468 | 2.31 | 184 |
Notes:
· | Effective date of the Mineral Resource estimate is December 31, 2025. Drill hole database cut-off date is October 23, 2023 and the effective depletion date is December 31, 2025. The QP for the estimate is Mr. Carson Cybolsky, P.Geo, an employee of McEwen. |
· | Mineral Resources are reported using Item 1300 of Regulation S-K. Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. |
· | Mineral Resources are reported above an economic cut-off grade of 1.30 g/t gold assuming underground extraction methods and based on a mining cost of $62.66/t, process cost of $32.21/t, G&A cost of $20.49/t, metallurgical recovery of 93%, dilution of 15% and gold price of US$3,000/oz. |
· | Figures may not sum due to rounding. |
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11.7.12Factors That Could Affect the Mineral Resource Estimate
Factors that may affect the Stock West and Main Mineral Resource estimate include:
· | Changes in the local geological interpretations and assumptions used to generate the estimation domains |
· | Changes in mineralization and geological geometry and continuity of mineralized zones |
· | Changes in assumptions of mineralization and grade continuity |
· | Changes in the treatment of high-grade gold values |
· | Changes in the grade interpolation methods and estimation parameter assumptions |
· | Changes in the confidence assumptions and methods used in the mineral resource classification |
· | Changes in the density and the methods used in the density assignments |
· | Changes in metal price and exchange rates and other economic assumptions used in the cut-off grade determination |
· | Changes in input and design parameter assumptions that pertain to the underground mining constraints |
· | Changes to assumptions as to the continued ability to access the mine site, retain mineral and surface rights titles, maintain the operation within environmental and other regulatory permits, and maintain the social license to operate. |
No other environmental, permitting, legal, title, taxation, socioeconomic, marketing, political or other relevant factors are known to the QP that would materially affect the estimation of Mineral Resources that are not discussed in this Technical Report Summary.
11.8Stock Project – East Zone
11.8.1Mineral Resource Database
The Stock Project East Zone has been tested by diamond drilling over a cumulative strike length of approximately 1,100 m and down to a vertical depth of about 500 m. The close-out date for the Mineral Resource database is May 20, 2024 and consists of 257 surface diamond drill holes. The average drill hole spacing in the best drilled areas of the deposit is about 20 m; the spacing in the more poorly drilled areas is between 100 m and 150 m.
Mining as-builds and remnant shapes were up-to-date as of December 31, 2025 and used to deplete the model.
11.8.2Geological Modeling
11.8.2.1Lithology
A lithology model was developed implicitly to capture the 10 key deposit lithologies and the overburden as shown in Figure 11-25.
Using the logged lithology, an overburden volume was modeled to the top of the bedrock and was used to cap the lithology wireframes.
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Source: (McEwen, 2024)
Figure 11-25:Isometric View of the Stock Project East Zone Lithology Model
11.8.2.2Mineralized Domains
Gold mineralization in the Stock East deposit occurs primarily in a quartz breccia (QBX) and generally follows the bleached/altered mafic volcanic lithological unit (BMV). Mineralization is bounded on the footwall by the interpreted Night Hawk Break regional fault structure. The Night Hawk Break is a splay off the regional Porcupine Destor fault zone.
Mineralized veins were interpreted (usually following a threshold grade of 0.5 g/t), flagged in the drill hole file and modeled using Datamine’s implicit Vein Modeling module with a minimum thickness of 0.5 m.
11.8.2.2.1Background Envelope
A background envelope (Domain 100) was constructed around the BMV Domain (Domain 1) to capture mineralized samples outside the mineralized domains and to estimate adjacent dilution. It is approximately a 50 m buffer around mineralized lenses, constructed from strings using sections spaced every 50 m.
The modelled domains for Stock’s East zone are shown in Figure 11-26.
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11.8.3Composites
A composite length of 1 m was selected based on the mode of the sample lengths. Any residual length was distributed equally to the 1 m composites to ensure that the entire length of each drill intersection within a domain was utilized. The rationale behind adopting a standard sample length of 1 m within zones perceived to be geologically similar was to maintain resolution in terms of the gold grade distribution. That resolution is maintained by adopting 1 m as the composite length.

Source: (McEwen, 2024)
Figure 11-26:Long View of Stock East Zone Showing Modelled Domains 1 & 100 (Background)
11.8.4Capping
Grade capping was conducted using population histograms and probability/log-probability plots to limit the influence of outlier values within each domain. Results are presented in Table 11-24 for each domain with 13.2% metal removed from the BMV Domain 1.
Table 11-24: Stock East – Metal Removed by Capping Composites
Domain | Raw Composites | Capped | Capped Composites | No. | Metal | ||
| Mean (g/t) | CV | Grade (g/t) | Mean (g/t) | CV | Capped | Removed (%) |
1 | 1.45 | 3.97 | 13.5 | 1.26 | 1.41 | 28 | 13.2 |
100 | 0.05 | 5.44 | 2.4 | 0.05 | 3.22 | 28 | 6.1 |
Note: CV = coefficient of variation
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11.8.5Density
There are 1,445 density samples contained in the Mineral Resource database for Stock’s East Zone. A study of all density data was conducted to determine an average density value for each of the host lithology units. Outliers were identified and removed resulting in the average density values listed in Table 11-25.
The block model was flagged by the major lithology wireframes and average densities were applied to the blocks accordingly. Any blocks outside the modelled lithologies were assigned the overall average density value of 2.80 g/cm3. Blocks above the bedrock and below the topography were flagged as overburden and assigned a density of 2.0 g/cm3.
Table 11-25: Stock Project – East Zone Density Averages for Host Lithologies
Lithology |
| | No. of Samples | Avg. Density |
Altered Ultramafic Volcanics | | AUV | 55 | 2.81 |
Bleached Mafic Volcanics | | BMV, AMV | 557 | 2.86 |
Fuchsite Altered Ultramafic Volcalics | | CGR | 35 | 2.88 |
Diabase | | DIA | 15 | 2.87 |
Felsic Porphyry | | FP, FI | 365 | 2.68 |
Mafic Volcanics | | MV, PMV | 329 | 2.82 |
Quartz Breccia | | QBX, QV | 11 | 2.77 |
Sediments | | SED | 14 | 2.74 |
Talc-Chlorite Altered Ultramafics | | TUV | 64 | 2.79 |
All Lithologies Combined | | | 1445 | 2.80 |
* 1445 Total samples. Lowest 3 and highest 3 values removed from evaluation as outliers (2 BMV, 1 MV, 2 AUV, and 1 TUV).
* overburden given a specific gravity of 2.0
* Intermediate Intrusives (II) given a specific gravity of 2.80 (avg density)
* Gabbro (GAB) given a specific gravity of 2.80 (avg density)
11.8.6Variography
The spatial distribution (continuity) of gold within each modeled domain was evaluated using variograms.
Precision in spatial analysis/variography is directly proportional to the quality of the sampling pattern. Due to the moderate- to steeply-dipping nature of the Stock East deposit, some of the drill holes from surface intersect the mineralization at oblique angles while some are at the desired right angles, culminating in a mixture of orientations. Thus, variography results are not perfectly representative of the spatial continuity/distribution patterns of the mineralization. Experimental variograms were modeled with two spherical structures and with a dip and strike. Nugget effects are 20% in the BMV domain and 0% in the background envelope.
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11.8.7Grade Estimation
A block size of 3 m x 3 m x 3 m was selected after comparing the kriging efficiency and slope of regression for various block sizes. The selected block size is supported by the average drill hole spacing of 20 to 30 m in well drilled areas of the deposit. Sub-cells down to 1 m x 1 m x 1 m were used to better reflect the shape and volume of the mineralized domains. No rotation was applied to the block model.
Ordinary kriging was used to estimate the blocks within the modelled domains using a four-pass approach. Search neighborhoods are based on variography with ranges doubling in length for the first three search ranges, with the fourth search range having a distance of 1.5x that of the third search range. The range of the third search range is based on the range of the second variogram structure.
Data selection for modeled domains require 11 composites from three drill holes to be estimated in passes 1 through 3. The fourth pass requires a minimum of 6 composites and a maximum of 18 from at least two drill holes.
11.8.8Model Validation
In validating the estimated block model, nearest neighbor and inverse distance cubed models were constructed. The nearest neighbor model mimics a declustered data set and was generated using 3 m composites.
The estimated block model was validated by visually comparing the drill holes with the block grades, and with swath plots to determine whether any local bias exists.
Inspecting drill holes with block estimates in section and plan confirms gold grades of the model follow the grades of the informing samples.
Swath plots indicate the mean grades of the estimates follow the mean grades of the declustered informing samples relatively well with small local biases in areas with less informing sample data.
11.8.9Confidence Classification
Classification criteria consider the confidence in the continuity of mineralization, average distance to informing samples (weighted on distance), and continuity of sample spacing. No material has been classified as a Measured Mineral Resource. The following classification criteria were defined:
· | Indicated: assigned to those contiguous blocks within the mineralized domain, within the first three search neighborhoods, informed by between 11 and 18 composites from three or more drill holes, less than 15 m to the nearest drill hole, and an average drill spacing less than 25 m. |
· | Inferred: assigned to those contiguous blocks within the mineralized domain, and within the first three search neighborhoods, informed by between 11 and 18 composites from at least three drill holes, and an average drill spacing less than 40 m. Also assigned to those continuous blocks within the mineralized domains and within the fourth search neighborhood, informed by between 6 and 18 composites from at least three drill holes, less than 12.5 m to the nearest drill hole, and within an average drill spacing less than 40 m. |
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11.8.10Reasonable Prospects for Eventual Economic Extraction
For a Mineral Resource to be reported, the QP must determine that RPEEE has been established.
The Stock East deposit area is proximal to the existing plant/mill infrastructure, and in the QP’s opinion, the small size of the deposit does not justify relocating the processing facilities to allow for extraction via an open pit. Thus, it seems more feasible to mine the deposit using underground mining methods. A cut-off grade of 1.30 g/t Au was determined considering the costs and input parameters summarized in Table 11-26.
Table 11-26: Stock East Mineral Resource Cut-off Grade Parameters
Parameter | Unit | Value |
Mining Cost | $US/t | 62.66 |
G&A Cost | $US/t | 20.49 |
Milling Cost | $US/t | 32.21 |
Transport Cost | $US/oz | 1.52 |
Payable Gold | % | 99.95 |
Dilution | % | 15 |
Gold Price | $US/oz | 3,000 |
Exchange Rate (US$/C$) | - | 1.35 |
Royalty (NSR) | % | 0 |
Mill Recovery | % | 93 |
RPEEEs were derived from potentially mineable shapes developed using Datamine’s MSO function. A stope size of 12 m vertical height by 6 m wide along strike by a minimum 3 m wide across strike was adopted. This size was benchmarked against mined stopes at the nearby Black Fox and Froome underground mines. Sub stopes were developed at half height and half width along strike (6 m x 3 m) to account for local anisotropy of the grade continuity. It should be noted that different stope dimensions will yield different resources at the same cut-off grade. Isolated, discontinuous stope shapes were not considered economic, and were therefore removed and not included in the Mineral Resource Statement.
Figure 11-27 presents the experimental grade–tonnage sensitivities at various cut-off grades. The sensitivities were generated using raw block grades and include both Indicated and Inferred classified blocks. Sensitivities include all classified blocks, not only those meeting RPEEE. These results are provided for comparative purposes only, to illustrate the potential effect of applying different cut-off grades on tonnage and grade. Sensitivity cases do not represent Mineral Resources and should not be interpreted as such.
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Source: (McEwen, 2024)
Note: Sensitivities use raw block grades and include Indicated and Inferred blocks. These results are for comparison only and do not represent Mineral Resources.
Figure 11-27:Experimental Grade‑Tonnage Sensitivities at Various Cut‑Off Grades
11.8.11Mineral Resource Statement
Table 11-27 summarizes the Mineral Resource estimates for Stock East, assuming underground stoping methods. The Mineral Resource was limited to those parts of the gold mineralization for which there are RPEEEs via underground stope extraction.
Table 11-27: Stock Project – East Zone Mineral Resource Statement, December 31, 2025
Classification | Tonnes (kt) | Au Grade (g/t) | Contained Au (koz) |
Indicated | 1,790 | 2.12 | 122 |
Inferred | 1,350 | 2.02 | 87 |
Notes:
· | Effective date of the Mineral Resource estimate is December 31, 2025. Drill hole database cut-off date is May 20, 2024 and the effective depletion date is December 31, 2025. The QP for the estimate is Mr. Carson Cybolsky, P.Geo, an employee of McEwen. |
· | Mineral Resources are reported using Item 1300 of Regulation S-K and in accordance with the CIM Best Practice Guidelines (2019). Mineral Resources that are not Mineral Reserves do not have demonstrated economic viability. |
· | Mineral Resources are reported above an economic cut-off grade of 1.30 g/t gold assuming underground extraction methods and based on a mining cost of $62.66/t, process cost of $32.21/t, G&A cost of $20.49/t, metallurgical recovery of 93%, and gold price of US$3,000/oz. |
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· | Mineral Resources include the ‘must take’ minor material below cut-off grade which is interlocked with masses of blocks above the cut-off grade within the mineable shape optimizer stopes. |
· | Figures may not sum due to rounding. |
11.8.12Factors That Could Affect the Mineral Resource Estimate
Factors that may affect the Stock Project – East Zone Mineral Resource estimate include:
· | Changes in the local geological interpretations and assumptions used to generate the estimation domains |
· | Changes in mineralization and geological geometry and continuity of mineralized zones |
· | Changes in assumptions of mineralization and grade continuity |
· | Changes in the treatment of high-grade gold values |
· | Changes in the grade interpolation methods and estimation parameter assumptions |
· | Changes in the confidence assumptions and methods used in the mineral resource classification |
· | Changes in the density and the methods used in the density assignments |
· | Changes in metal price and exchange rates and other economic assumptions used in the cut-off grade determination |
· | Changes in input and design parameter assumptions that pertain to the underground mining constraints |
· | Changes to assumptions as to the continued ability to access the mine site, retain mineral and surface rights titles, maintain the operation within environmental and other regulatory permits, and maintain the social license to operate. |
No other environmental, permitting, legal, title, taxation, socioeconomic, marketing, political or other relevant factors are known to the QP that would materially affect the estimation of Mineral Resources that are not discussed in this Report.
11.9Davidson-Tisdale
In May 2017, SRK prepared and completed an internal Mineral Resource Estimate for the Davidson-Tisdale gold deposit under a commission by Lexam. After the acquisition of Lexam by McEwen, SRK was again commissioned to prepare a Mineral Resource statement for the 2021 IA for Davidson-Tisdale using updated economic parameters. In April 2026, McEwen (as QP) updated the Mineral Resource statement for Davidson-Tisdale using updated economic parameters. No additional resource drilling has been completed at Davidson-Tisdale recently, and the existing 2017 resource model was used as a basis for reporting purposes.
11.9.1Mineral Resource Database
The resource database comprises primarily samples from surface and underground core drilling. The database comprises 691 drill holes with a total length of 80,026 m. The total number of samples with gold assays is 24,162 (26,665 m). The database also includes 80,847 m of lithological, structural and alteration logging.
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Six level plans were digitised and used as well as the existing geological and structural maps to guide mineral resource modeling.
On importing the drill hole database to Datamine Studio and Leapfrog software several validation steps were performed and any errors revealed were corrected.
11.9.2Geological Modeling
11.9.2.1Mineralized Areas
Gold mineralization at Davidson-Tisdale belongs to the class of structurally controlled Archean lode gold deposits. The mineralization is associated with the quartz vein zones whose distribution and orientation generally corresponds with the structure of the faults.
Two main areas of mineralization were modelled. The north area comprises the most abundant and high-grade mineralization with a general strike of 060° and a dip of 30 to 50° northwest. Mineralization in the north area also has strike lengths up to 300 m and widths up to 20 m. The south area is lower grade, but with good continuity, an eastern strike of 060° and a dip of 10 to 20° north. Mineralization in the south area has strike lengths up to 700 m and widths up to 25 m.
11.9.2.1.1North Area
Three zones of mineralization were modelled within the north area: Zones A, B and C. The B Zone was split into Zones B1 and B2 by the Main fault.
A combination of lithological, alteration, structural and grade criteria were used to define the resource domains. The lithological criteria included the presence of foliation, shearing and quartz veins. The grade threshold was chosen as 0.4 g/t Au. The intervals were prioritized based on the satisfaction of one or more criteria as follows:
· | High priority intervals – lithological + grade criteria |
· | Medium priority intervals – only grade criteria |
· | Low priority intervals – only lithological criteria. |
The low priority intervals were used only to maintain the continuity of the mineralized zone and used with adjacent high and medium priority intervals.
Considering the good general continuity, but high variability on a smaller scale, the mineralized zone wireframes were modelled in two steps:
· | Generation of the external general wireframe manually containing some internal barren intervals within it (Figure 11-28). |
· | Generation of the internal wireframe within the external contour with semi-automatic wireframing (Figure 11-29) algorithms which excludes the barren intervals and follows the general trend of the mineralized zone. This wireframe was used to constrain grade estimation. |
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Source: (prepared by SRK, 2021; reissued by McEwen, 2026)
Note: A Zone – purple, B Zone – orange, C Zone – yellow
Figure 11-28:Isometric View of the Davidson-Tisdale North Area, External Contours
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Source: (prepared by SRK, 2021; reissued by McEwen, 2026)
Note: A Zone – purple, B Zone – orange, C Zone – yellow
Figure 11-29:Isometric View of the Davidson-Tisdale North Area, Internal Contours
11.9.2.1.1South Area
South Area wireframe (S Zone) was modelled based on quartz veins lithological criteria only. The S Zone is described as having very good continuity, but relatively low grades so no internal wireframe was constructed (Figure 11-30).
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Source: (prepared by SRK, 2021; reissued by McEwen, 2026)
Figure 11-30:Isometric View Looking South of the S Zone Wireframe
11.9.3Composites
Most of the analytical samples within the mineralized areas were collected at 0.5 m and 1 m intervals. A modal composite length of approximately 1 m was applied to all the data, generating composites as close to 1 m as possible, while creating residual intervals of up to 0.5 m in length.
11.9.4Capping
The impact of high-grade outlier populations was examined on composite data using log probability plots and cumulative statistics separately for all mineralized areas. A capping value of 110 g/t was applied for the B Zone and 100 g/t for the C and S Zones. No capping was used for the A Zone. Results are presented in Table 11-28 for each zone with metal removed, ranging from 6% in C Zone to 29% in B Zone.
Table 11-28: Davidson-Tisdale – Metal Removed by Capping Composites
Domain | | Raw Composites | | Capped | | Capped Composites | | No. | | Metal Removed | ||||
| | Mean (g/t) | | CV | | Grade (g/t) | | Mean (g/t) | | CV | | Capped | | (%) |
| | | | | | North Zone | | | | | | | ||
A Zone | | 5.54 | | 1.61 | | - | | 5.54 | | 1.61 | | - | | - |
B1+B2 Zone | | 5.59 | | 6.40 | | 110 | | 3.99 | | 3.16 | | 16 | | 29 |
C Zone | | 4.56 | | 3.44 | | 100 | | 4.29 | | 3.12 | | 5 | | 6 |
| | | | | | South Zone | | | | | | | ||
S Zone | | 1.71 | | 7.33 | | 100 | | 1.45 | | 6.01 | | 5 | | 15 |
Note: CV = coefficient of variation
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11.9.5Density
In 2012, a total of 55 core samples were taken and analyzed at AGAT (Altman et al., 2014). The average bulk density of 2.87 g/cm3 of the 55 samples was applied to this resource estimate for Zones A, B and C.
For Zone S, a more conservative density value of 2.70 g/cm3 was used on Lexam’s recommendation.
11.9.6Variography
The spatial distribution of gold in the North and South areas was evaluated using variograms and correlograms.
Variograms/correlograms were modelled using two spherical structures and three rotations to match the strike, dip and plunge of the modelled mineralization. Nugget effects are 40% for both areas.
11.9.7Grade Estimation
The criteria used in the selection of block size included the drill hole spacing, composite length, the geometry of the modelled zone, and the anticipated mining method. A block size of 5 m x 5 m x 5 m was selected. Sub-cells were used allowing a resolution of 0.5 m x 0.5 m x 0.5 m to better reflect the shape of the mineralized area. No rotation was applied to the block model.
Ordinary kriging was used to estimate the blocks within the mineralized zones using a three -pass approach in the North Area and four passes in the South Area. An initial pass in the S Zone focused on estimating areas where there were high-grade composite values. Capped composites with a tight isotropic search ellipse were used to limit the number of blocks estimated to one or two in each direction. Subsequent passes were made with composites capped to 10 g/t gold to minimize smearing of high-grade outliers in lower grade areas and increasing search ranges based on the variogram ranges. Datamine’s dynamic anisotropy function was implemented due to the anisotropic nature and widths of the mineralized zones.
Data selection for mineralized zones varied for each pass requiring a minimum number of composites between seven and four and a maximum number of composites between 10 and 16 for passes 1 to 3. Estimated blocks required at least three holes in pass 1, and two holes in pass 2 and 3.
11.9.8Model Validation
The block model was validated by visual comparison of informing sample data with resource blocks data (on plan and section, see Figure 11-31) and with swath plots (section by section) comparing the ordinary kriged blocks with the informing composite data.
The results of the validation show that the block model acceptably reflects the assay sample data. The deviations between the averages on swath plots appear within the areas of the low data density and within the S Zone where more restrictive capping was applied.
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Source: (prepared by SRK 2021; reissued by McEwen 2026)
Note: East-West at Y=9,920
Figure 11-31:Cross-Section Comparing B Zone Estimated Blocks and Composite Data
11.9.9Confidence Classification
Industry best practices suggest that classification should consider the confidence in the geological continuity of the mineralized structures, the quality and quantity of exploration data supporting the estimates, and the geostatistical confidence in the tonnage and grade estimates. Appropriate classification criteria should aim at integrating these concepts to delineate regular areas at similar resource classification as well as the continuity of the deposit at the reporting cut-off grade.
The QP is satisfied that the mineralization model honours the current informing data from the geological database. The location of the samples and the assay data are sufficiently reliable to support resource evaluation and do not present a risk that should be considered for block classification. The Mineral Resource model is constrained by mineralized zones based on lithological, structural and grade criteria and is modelled from drill holes on a somewhat irregular grid, with a spacing between 5 m and 40 m.
The QP considers the drill spacing to be sufficient to assume reasonable continuity of the gold mineralization. Accordingly, block estimates were classified using a combination of criteria, including confidence in the mineralization’s continuity, drilling spacing and estimation results. The following classification criteria were defined:
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· | Measured: Assigned to those continuous blocks located within Zones B and C of the North Area and informed by the data from at least three drill holes within a 15 m buffer. The wireframe surface, which limits and smooths the Measured category, was also developed. |
· | Indicated: Assigned to those continuous blocks informed by the data from at least three drill holes within one search radius (one variogram range). The wireframe surface, which limits and smooths the Indicated category, was also developed. |
· | Inferred: Assigned to all remaining blocks. |
11.9.10Reasonable Prospects for Eventual Economic Extraction
In accordance with the CIM Definition Standards on Mineral Resources and Reserves (CIM Definition Standards, 2014), the Mineral Resource statement must demonstrate RPEEE.
The requirement for RPEEE generally implies that the quantity and grade estimates meet certain economic thresholds and that the Mineral Resources are reported at an appropriate cut-off grade considering extraction scenarios and processing recoveries. The QP considers the mineralization is amenable to underground extraction. A cutoff grade of 1.30 g/t Au was determined considering the cost and input parameters summarized in Table 11-29.
The MSO algorithm within Datamine Studio RM software package was used to evaluate the profitability of each resource block based on its value (Figure 11-32). All classified blocks were flagged by the potentially mineable shapes including those below the 1.30 g/t Au cut-off grade. Isolated, discontinuous stope shapes were not considered economic and were therefore removed and not included in the Mineral Resource Statement.
Table 11-29: Davidson-Tisdale Optimization Parameters
Parameter | Unit | Value |
Mining Cost | $US/t | 67.72 |
G&A Cost | $US/t | 16.60 |
Milling Cost | $US/t | 30.77 |
Transport Cost | $US/oz | 1.52 |
Payable Gold | % | 99 |
Dilution | % | 15 |
Gold Price | $US/oz | 3,000 |
Exchange Rate (US$/C$) | - | 1.35 |
Mill Recovery | % | 92 |
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Source: (McEwen, 2026)
Note: MSO shapes = green, Block model above1.30 g/t Au cut-off grade = grey
Figure 11-32:Plan View, Davidson-Tisdale MSO Shapes, Blocks >1.30 g/t Au
Figure 11-33 presents the experimental grade–tonnage sensitivities at various cut-off grades. The sensitivities were generated using raw block grades and include Measured, Indicated and Inferred classified blocks. Sensitivities include all classified blocks, not only those meeting RPEEE. These results are provided for comparative purposes only, to illustrate the potential effect of applying different cut-off grades on tonnage and grade. Sensitivity cases do not represent Mineral Resources and should not be interpreted as such.
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Source: (McEwen, 2026)
Note: Sensitivities use raw block grades and include Indicated and Inferred blocks. These results are for comparison only and do not represent Mineral Resources.
Figure 11-33:Experimental Grade-Tonnage Sensitivities at Various Cut-off Grades
11.9.11Mineral Resource Statement
Table 11-30 summarizes the Mineral Resource estimates for Davidson-Tisdale assuming underground stoping mining methods, reported in accordance with the CIM Definition Standards on Mineral Resources and Reserves (2014). The Mineral Resource was limited to those parts of the gold mineralization for which there are RPEEEs via underground mining methods.
Table 11-30: Davidson-Tisdale Mineral Resource Statement April 9, 2026
Classification | Tonnes (kt) | Au Grade (g/t) | Contained Au (koz) |
Measured | 198 | 6.44 | 41 |
Indicated | 95 | 5.80 | 18 |
Total Measured + Indicated | 294 | 6.23 | 59 |
Inferred | 200 | 3.44 | 22 |
Notes:
· | Effective date of the Mineral Resource estimate is 9 April 2026. The QP for the estimate is Mr. Luke Willis, P.Geo, an employee of McEwen. |
· | Mineral Resources are reported according to Item 1300 of Regulation S-K. Mineral Resources are not Mineral Reserves and do not have demonstrated economic viability. |
· | Mineral Resources are reported above an economic cut-off grade of 1.30 g/t gold assuming underground extraction methods and based on a mining cost of $67.72/t, process cost of $30.77/t, G&A cost of $16.60/t, metallurgical recovery of 92%, dilution of 15% and gold price of US$3,000/oz. |
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| ● | Figures may not sum due to rounding. |
11.9.12Factors That Could Affect the Mineral Resource Estimate
Factors that could materially affect the Mineral Resource Estimate results include:
· | Any new drilling and sampling information that potentially extend the mineralization zones down dip and along the strike. |
· | Metallurgical testwork results might affect the recovery assumptions of the gold and other metals. |
· | Changing gold prices may alter the mine optimization results. |
· | Changes in the local geological interpretations and assumptions used to generate the estimation domains |
· | Changes in mineralization and geological geometry and continuity of mineralized zones |
· | Changes in assumptions of mineralization and grade continuity |
· | Changes in the treatment of high-grade gold values |
· | Changes in the grade interpolation methods and estimation parameter assumptions |
· | Changes in the confidence assumptions and methods used in the mineral resource classification |
· | Changes in the density and the methods used in the density assignments |
· | Changes in metal price and exchange rates and other economic assumptions used in the cut-off grade determination |
· | Changes in input and design parameter assumptions that pertain to the underground mining constraints |
· | Changes to assumptions as to the continued ability to access the mine site, retain mineral and surface rights titles, maintain the operation within environmental and other regulatory permits, and maintain the social license to operate. |
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12Mineral Reserve Estimates
12.1Forward-Looking Statement
The accuracy of the Mineral Reserve estimate depends, in part, on the quality and quantity of available data, geological interpretations, and professional judgment. Based on the data available at the time of preparation of this Technical Report Summary, the Mineral Reserve estimate presented herein is considered reasonable. However, these should be accepted with the understanding that additional data or analyses obtained subsequent to the date of the estimate may necessitate revision, and such revisions may be material. There is no guarantee that all or any part of the estimated mineral reserve will be recoverable. Estimates of mineralization and other technical information presented herein have been prepared in accordance with SEC Regulation S-K 1300 requirements and are based on information available to the QPs at the time of preparation of this Technical Report Summary.
12.2Risks
The Mineral Reserve estimate has been prepared using definitions and categories applicable under SEC Regulation S-K 1300.
Factors that could materially affect the Mineral Reserve estimate include, but are not limited to, the following.
| ● | Commodity price assumptions. |
| ● | Changes in interpretations of mineralization geometry and continuity of mineralization zones. |
| ● | The presence of unrecognized fault structures that could affect mine design, ground control costs, and/or ore dilution. |
| ● | Changes to geotechnical/geomechanical, hydrogeological, and metallurgical recovery assumptions. |
| ● | Input parameters used to assess dilution and recoveries. |
| ● | Assumptions that all required permits to operate can be obtained. |
| ● | Assumptions regarding social, permitting, and environmental conditions. |
| ● | Infill and/or definition diamond drilling. |
The QP has reviewed the risks, opportunities, conclusions, and recommendations presented in this Technical Report Summary and is not aware of any conditions that would put the Mineral Reserve estimate at a high-risk level.
12.3Mineral Reserve Estimate
12.3.1Underground Mineral Reserve Estimation
The Grey Fox Mineral Reserve estimate, prepared by Stantec on March 27, 2026, is based on Indicated Mineral Resources identified in the block model provided by McEwen (rm_gf_1p5_0725_streamlined.dm, issued on September 10, 2025). All Mineral Resource material in the block model that was not classified as Measured or Indicated was removed prior to use. Table 12-1 outlines the estimated Mineral Reserve.
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Table 12-1:Mineral Reserve Estimate, March 27, 2026
Classification | Ore Tonnes (t) | Au (g/t) | Gold Ounces (Oz) |
Proven | 0 | 0.00 | 0 |
Probable | 9,405,829 | 3.24 | 980,303 |
Total Reserve | 9,405,829 | 3.24 | 980,303 |
Notes:
| ● | The Mineral Reserves for this project have been defined, classified, and reported by the Qualified Person (QP) in strict accordance with the U.S. Securities and Exchange Commission (SEC) Regulation S-K 1300 mining property disclosure requirements (17 CFR § 229.1300) |
| ● | Mineral reserve includes longitudinal stopes, overhand cut-and-fill stoping, ore development, as well as marginal longitudinal stopes, and marginal development all factored with external dilution (including host waste rock and estimated backfill tonnes) and mining recovery. |
| ● | Longitudinal stopes were estimated at an undiluted cut-off value of 2.40 g/t. |
| ● | Marginal longitudinal stopes were estimated at an undiluted cut-off value of 2.00 g/t. |
| ● | Cut-and-fill stopes were estimated at an undiluted cut-off value of 2.70 g/t. |
| ● | A minimum mining width of 3.0 m was applied for all stoping. |
| ● | Total dilution is 46.5%, consisting of 11.6% external dilution and 34.9% internal dilution. |
| ● | Total mineable recovery is 91.2%. |
| ● | Some numbers may not sum due to rounding. |
Table 12-2 presents the Mineral Reserve estimate, categorized by mining method.
Table 12-2:Mineral Reserve Estimate by Mining Method
Mining Method | Ore Tonnes (t) | Au (g/t) | Gold Ounces (Oz) |
Longitudinal Longhole Stoping | 6,812,141 | 3.55 | 777,042 |
Marginal Longitudinal Longhole Stoping | 910,806 | 1.85 | 54,090 |
Cut-and-Fill Stoping | 117,984 | 3.94 | 14,959 |
Development Ore | 1,564,899 | 2.67 | 134,212 |
Total Reserve | 9,405,829 | 3.24 | 980,303 |
Table 12-3 presents the Mineral Reserve estimate, categorized by mining zones.
Table 12-3:Mineral Reserve Estimate by Zone
Zone | Ore Tonnes (t) | Au (g/t) | Gold Ounces (Oz) |
Whiskey Jack | 692,256 | 4.37 | 97,165 |
Remaining Grey Fox North | 4,997,799 | 2.95 | 473,751 |
Grey Fox South (147 and South) | 3,715,774 | 3.43 | 409,387 |
Total Reserve | 9,405,829 | 3.24 | 980,303 |
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12.3.2Cut-off Grade
The Grey Fox mineral resource is gold. The cut-off grade will be based on the gold grade field (AU_C) within the block model, expressed in grams per tonne (g/t). To determine a mineral reserve for Grey Fox, a preliminary cut-off grade was estimated prior to preparing the mine design. The cost parameters used to estimate the cut-off grade were provided by McEwen in September 2025. The mining cost for cut-and-fill was estimated using data from McEwen’s Black Fox and Froome deposits, as well as other benchmarks. The surface trucking cost was estimated from the provided mining cost.
The marginal cut-off grades for longhole stoping exclude sustaining capital costs. A processing-and-trucking-only cut-off grade was used to evaluate ore development, with other costs considered sunk, as the development would be required as waste regardless. Final cut-off grade values were rounded up to the nearest tenth of a gram.
Table 12-4 presents the gold revenue assumptions, modifiers, and unit costs used in the cut-off grade calculation. Table 12-5 presents the resulting cut-off grade calculations, adjusted for mill recovery and estimated mining dilution.
For longhole stoping, the mill feed cut-off grade is 2.1 g/t, with a marginal mill feed cut-off grade of 1.7 g/t. The undiluted target stope shape cut-off grade is 2.4 g/t, with a marginal undiluted target stope shape cut-off grade of 2.0 g/t.
For cut-and-fill mining, the mill feed cut-off grade is 2.4 g/t. The undiluted target stope shape cut-off grade is 2.7 g/t.
For development material, the mill feed cut-off grade is 0.5 g/t. The undiluted target development cut-off grade is also 0.5 g/t.
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Table 12-4:Gold Revenue Assumptions, Modifiers, Unit Costs Used in cut-off grade Calculations
Item | Value | Unit |
Gold Revenue & Modifiers | | |
Gold Price | 2,200 | $USD/oz |
Refining Cost | 0.55 | $USD/oz |
Transport and Insurance | 2.05 | $USD/oz |
Excess Liability | 0.92 | $USD/oz |
Payable Gold | 99.95 | % |
Penalties | 0.00 | % |
Royalties | 2.50-3.00 | % |
Revenue per Ounce after fees and royalties | 2,140.54 | $USD/oz |
Revenue per Gram after fees and royalties | 68.82 | $USD/g |
Unit Costs | | |
Mine Operating Cost (Longhole) | $62.72 | $USD/t |
Mine Operating Cost (Cut-and-Fill) | $83.03 | $USD/t |
Surface Trucking Cost | $5.00 | $USD/t |
Mill Operating Cost (Processing) | $23.43 | $USD/t |
General and Administration Operating Costs | $16.60 | $USD/t |
Sustaining Capital Cost (including reclamation and exploration) | $20.91 | $USD/t |
Table 12-5:Cut-off Grade Calculations
Cut-off Grade | Longhole | Marginal | Cut-and-Fill | Ore | | |
| | Longhole | | Development | | |
Item | Value | Value | Value | Value | Unit | |
Total Cost per Tonne | 128.65 | 107.75 | 148.97 | 28.43 | $USD/t | |
Grams Gold per Total Cost | 1.87 | 1.57 | 2.16 | 0.41 | g/t | |
Mill Recovery | 90 | 90 | 90 | 90 | % | |
Mill Feed Cut-off Grade | 2.1 | 1.7 | 2.4 | 0.5 | g/t | |
Estimated Mining Dilution | 15 | 15 | 10 | 10 | % | |
Undiluted Cut-off Grade | 2.4 | 2.0 | 2.7 | 0.5 | g/t | |
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12.3.2.1Consideration of Marginal Cut-off Grade and Low-Grade Material
Marginal material is below the planned break-even cut-off value but can still be processed economically. Marginal stoping occurs where gaps between stopes, in planned stoping sequences can be filled by stopes mined at a lower cut-off grade. The cut-off grade calculation for marginal stoping excludes sustaining capital and infrastructure costs, as this stoping occurs in areas where development is already planned for break-even stoping and the associated development costs are therefore considered sunk.
Ore development material is generated typically in operating crosscuts and sill development. It can be stockpiled separately on a per-round basis as low-grade material and used to fill gaps in the mill schedule without displacing higher-grade material.
12.3.3Modifying Factors
Modifying factors include dilution and mining recovery, both of which were applied in the estimation of Mineral Reserve. The following sub-sections describe these modifying factors and the application to the mine design.
12.3.3.1Internal Dilution
Internal dilution comprises of low-grade material and/or waste rock contained within the stope shape or development shape that will be mined along with the mineralized resource. This internal dilution is included within the mining shapes and reported as part of the reserve. Internal dilution will be defined as material below the mining method’s cut-off grade as determined by the block model. Where no grade is assigned in the block model, the grade will be assumed to be 0.0 g/t.
Stoping-only internal dilution is estimated to be 35.3%, while overall internal dilution, including development, is estimated at 34.9%.
12.3.3.2External Dilution and Backfill Dilution
External dilution includes low-grade material, waste rock, and/or backfill from the HW, FW, and/or end walls that will overbreak into the stope and be mined with the stope resource. External dilution will be calculated during the mine scheduling process, and the methodology is presented in Table 12-6.
Stope-only external dilution is estimated at 14.2%, of which stope backfill dilution accounts for 0.7%. Overall external dilution, including development, is estimated at 11.6%, with stope backfill dilution accounting for 0.5% of the total.
Table 12-6:Stope Dilution Methodology
Dilution Source | Methodology | |
External Dilution | Equivalent Linear Overbreak and Sloughage | |
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Dilution Source | Methodology | |
| Dilution grade 0.0 g/t | |
Backfill Dilution | 0.3 m of overbreak for each exposed adjacent surface at Stope End Walls (Ribs). Dilution grade 0.0 g/t | |
12.3.3.3Mining Recovery
A mining recovery factor has been applied to all stopes to account for losses incurred during the stoping process. These losses reflect material that is not recovered during extraction of blasted ore. Mining losses from longhole stopes were estimated based on the mining method and average stope size. Factors influencing mining losses include mucking line of sight, depth of sight, possible hang-ups on the footwall, and blast-related complications, especially with up-hole stopes. In some instances, rib pillars may also be required for up-hole stopes, as these stopes cannot be backfilled, and these losses are accounted for in the recovery factors. The mining recovery factors are summarized in Table 12-7.
Stope-only mining recovery is estimated at 89.5%, while overall mining recovery, including development, is estimated at 91.2%.
Table 12-7:Mining Recovery Factors
Ore Source | Mining Recovery Factor |
Longitudinal Longhole Stope | 95% |
Up-hole only Stope (<20 m high) | 75% |
Up-hole only Stope (20 to 30 m high) | 65% |
Cut-and-Fill Stope | 98% |
Ore Development* | 100% |
Note: * Assumed unrecovered ore development tonnes are expected to be recovered during stoping.
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13Mining Methods
Grey Fox will be a combination of two underground operations accessed from two separate portals: Grey Fox North, to be excavated from the existing Gibson Ramp and Portal, which includes the Whiskey Jack, Gibson, Contact, and 147NE zones, and Grey Fox South, which includes the 147 and South zones. The zones are portrayed in Figure 13-1.
The Fox Complex is a group of gold properties in Ontario extending eastward from Timmins along Provincial Highway 101. Located 11 km east of Matheson is the Eastern Fox Complex, which include Black Fox open pit mine and the Froome underground mine. Grey Fox is located approximately 3 km southeast of the Black Fox Mine which is approximately 9 km east of Matheson in Hislop Township. Access to the site is via Tamarack Road off Highway 101 East.

Figure 13-1:Grey Fox Mine Zones in Plan View with Google Maps Surface
These zones will be mined using a longitudinal retreat longhole mining method supplemented with overhand cut-and-fill mining. Ore will be hauled on surface to the existing Stock Mill at McEwen’s Stock Property as part of a “hub and spoke” asset strategy for the McEwen Assets along Highway 101.
Project Period development will initiate at the existing Grey Fox North portal in August 2027 where the existing Gibson ramp will be rehabilitated and expanded to 4.0 m W x 4.3 m H approximately 75 m down the ramp. From the Gibson ramp, a new 4.0 m W x 4.3 m H ramp will be excavated northwards towards
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Whiskey Jack which will begin mining at a target of 650 t/d. The existing Gibson ramp will be rehabilitated to approximately 130 m in length total concurrent with development towards Whiskey Jack.
The Whiskey Jack Zone has 9 levels, split into two blocks, at 30 m vertical intervals (except the upper two levels which are 25 m). Figure13-2 presents a longitudinal projection of the Whiskey Jack Zone.

Figure 13-2:Whiskey Jack Zone looking South
In August 2028, as capital development comes to completion in Whiskey Jack, a second, new 4.0 m W x 4.3 m H ramp will be excavated southwards from the existing Gibson ramp towards the remaining Grey Fox North zones (Gibson, Contact, and 147NE). In January 2030, there will be multiple mining fronts in the Grey Fox North first mining block to support a target of 1,500 t/d marking the end of the project period and beginning of the operating period.
The remaining Grey Fox North has a total of 17 levels at 25 m vertical intervals and will be split into four blocks. Figure 13-3 presents a longitudinal projection of Grey Fox North excluding the Whiskey Jack Zone. The mine life of Grey Fox North will be approximately 14.5 years, including an initial ramp up period of approximately 2.5 years.
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Figure 13-3:Grey Fox North looking North
As mining at Grey Fox North progresses into the second mining block, in April 2033, Grey Fox South underground development commences to establish the infrastructure for the first mining block in preparation for the first Grey Fox South stoping in January 2035. In January 2035, Grey Fox South mining will proceed concurrently with Grey Fox North at a target of 2,700 t/d until 2040, when the ramp down period starts until December 2041.
The Grey Fox South has 12 levels at 25 m intervals and will be split into three blocks. The mine life of Grey Fox South will be approximately 8.5 years, including an initial ramp up period of 1.5 years. Figure 13-4 presents a longitudinal projection of Grey Fox South.
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Figure 13-4:Grey Fox South Looking North
To achieve these phased production targets, the mine plan includes production from multiple mining blocks, with multiple stopes available per block. The aforementioned overall production profile and tonnage targets are expected to be complimentary with production from other assets, notably the stock mine, in maximizing the throughput of the Stock Mill.
Conventional trackless mining equipment will be used for the lateral development required to access the zones. Longhole stopes will be drilled using a combination of ITH (primarily for slot drilling) and top hammer longhole drills, blasted using ANFO with some packaged emulsion explosives, and mucked using conventional LHD vehicles. Ore will be hauled to a primary crusher on surface using trucks and waste rock will be hauled either to a surface waste dump or to an active production level for use as stope backfill.
Mine dewatering will be achieved using a multi-level dirty water system. Main sump and pump stations for Grey Fox North will be located on the ramp at 40 Level, 145 and 265 Levels in the Whiskey Jack Zone, and on the 140, 265, 365, and 465 Levels in the Gibson Zone. An additional sump will be placed at the portal entrance to collect surface run-off water that enters the mine via the ramp or portal. For Grey Fox South, main sump and pump stations will be located on the 140, 240, and 340 Levels. A network of borehole sumps and level sumps feed to these main sumps. All sumps will collect any groundwater and any service water used during mining activities. The main sumps are staged up to the next main sump in that zone to surface. Any residual solids in the sumps will be mucked using an LHD and placed into a nearby stope for disposal.
The stopes will be backfilled with a combination of cemented rock fill and unconsolidated rock fill to reduce the use of cement while still minimizing backfill dilution in adjacent stopes. For uppers stopes, backfilling is
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not planned and rib pillars may be left in place during mining to support the voids. A cement slurry will be hopper fed from surface through boreholes to an underground slurry receiving station. The slurry receiving station will be used to distribute the slurry to each level, and spray bars will be used to add the slurry to waste rock in LHD buckets for placement in open stopes. When possible, waste rock will be sourced directly from active development underground.
Design criteria and parameters specific to each aspect of the mining method are presented in subsequent sections. The following were considered when determining the criteria and parameters during the mine design process:
| ● | Health and safety for the workers, local communities, and the environment |
| ● | Develop and design the mine to achieve regulatory approvals |
| ● | Achieve buy-in from local stakeholders |
| ● | Company standards and specifications (or industry best practices where company standards and specifications were not available) |
| ● | Prevention through design concepts |
| ● | Minimizing risk to production |
| ● | Use of proven industry technology, equipment, and processes |
| ● | Operational flexibility |
| ● | Minimizing operating costs |
| ● | Mineral resource recovery (extraction rate) |
13.1Geomechanical
13.1.1Geology
Grey Fox is characterized by complex geology featuring stacked epithermal gold veins, with similarities to other major Canadian Shield gold deposits. Individual vein lens lengths are most commonly 200 m to 300 m long in strike, and the total deposit exists along an approximate 750 m in strike length. The typical thickness HW to FW is 2 m to 10 m. The deposit typically extends from surface to approximately 300 m deep below ground surface (BGS) from the current topography at the Grey Fox North portal, the maximum depth BGS is approximately 800 m, for indicated material in the Gibson Zone.
13.1.2Data
The 2025 drill core logging records provided Rock Quality Designation (RQD) data for Grey Fox, where RQD is generally regarded as excellent with a majority of measured RQD, weighted by core run length, exceeding 90% (Figure 13-5). Data indicates the first quartile of the cumulative RQD distribution is approximately 88%, and the median and third quartiles are closer to 95%. The first quartile RQD value is used for geotechnical design in this study, for 75% reliability.
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Figure 13-5:Grey Fox Length-Weighted and Cumulative RQD Distribution
Grey Fox 2025 drill core samples were selected and brought to Queen’s University for rock strength testing, including unconfined compressive strength (UCS), intact elastic modulus (Ei), Poisson’s Ratio (γ), and specific gravity (Gs).
Additional data for rock mass characterization is provided by previous geotechnical studies for the nearby Froome project pre-scoping studies, by Mine Design Engineering (MDEng) and Golder Associates. Froome data is assumed applicable to Grey Fox due to proximity and geologic similarity.
Grey Fox 2025 oriented drill core logging records provide structural orientation data of discrete and systemic geologic structure.
The regional strike of the deposit is N44°W and the dip is 72.8°SW (azimuth 136° Right Hand Rule). The mine plan proposed stope dimensions are 20 m length along the deposit strike with a vertical height or sublevel standoff of 25 m and a width of 5 m. Backs on the drill/extraction levels are flat and end walls are vertical. Stope FW and HW dips are 63° for Whiskey Jack and 60° for the remainder of the Grey Fox deposit.
Core logging and testing data were used for Q-System rock mass classification. The rock mass quality Q is the product of the rock mass inherent strength and applied stress:
Q = (RQD / Jn) x (Jr / Ja) x (Jw / SRF)
The joint property Jn is the joint density and RQD / Jn is a measure of block size. Grey Fox 2025 oriented core logging is summarized (Figure 13-6) and indicates two main joint sets plus random joint orientations,
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so Jn = 6. The critical joint 197°/65° is identified and plotted in relation to mineralized orientations at Grey Fox.

Figure 13-6:Grey Fox Joint Orientations and Critical Joint
Joint surface roughness is Jr, and joint alteration is Ja. The ratio Jr / Ja is a measure of joint surface strength and stiffness. Golder Associate’s core logging for the 2017 pre-scoping studies indicate Jr / Ja is typically 1.
The joint water factor Jw represents hydraulic pressure due to rates of water flow within the rock mass and the strength reduction factor SRF accounts for loosening of the rock mass at excavation boundaries during and after mining, due to stress, strength, and elasticity of the rock. The modified rock mass quality Q’ considers inherent (logged) properties of the rock mass only and isolated from the impacts of stress, where the terms Jw and SRF drop out:
Q’ = (RQD / Jn) x (Jr / Ja)
13.1.3Analysis and Results
Stability analysis of open stopes and arrays of adjacent open stopes follows the Modified (Mathews-Potvin) Stability Graph Method. This method considers the inherent competence of the rock mass due to joint frequency, orientations, and properties, represented by the modified stability number N’. Stability is determined by plotting the excavation’s face hydraulic radius versus N’ and evaluated in terms of where the excavation face’s hydraulic radius versus N’ plots in relation to the empirically derived graph stability curves.
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Hydraulic Radius (HR) is a shape factor representing the exposure of the excavation face, such as the back, end walls, or FW/HW, for individual stopes or arrays of adjacent open stopes. HR is defined as the area to perimeter ratio of the exposed face.
Base stope geometries for Grey Fox are longitudinal 20 m long stopes following the strike of the deposit, minimum 3 m horizontal width and 25-30 m vertical sublevels. The approximate FW/HW dip angles are 63° for Whiskey Jack and 60° for the remainder of Grey Fox. Stope backs are assumed horizontal, and end walls vertical (Table 13-1).
Table 13-1: Grey Fox Stope HR
Zone | HW and FW | Back | End Walls |
Whiskey Jack | 5.8 | 1.3 | 1.4 |
Remainder of Grey Fox | 5.9 | 1.3 | 1.4 |
N’ is based on Q’ combined with terms representing stress acting on the rock mass (A), joint orientation relative to the excavation surface (B), and gravity adjustment due to excavation geometry (C):
N’ = Q’ x A x B x C
Combining a 25th percentile (75% reliability) RQD of 88% (90% “typical”) with Jn = 6 and Jr / Ja =1, Q’ of the rock mass is 14.67.
To estimate A, it is assumed in-situ ground stress is due to gravity self-loading, and vertical stress σv is the product of rock/overburden Gs and depth BGS. The average Gs is 2.75 and the maximum (worst case in terms of stress) depth of each zone’s indicated material is approximately 300 m BGS for Whiskey Jack, and 800 m BGS for the remainder of Grey Fox. The stress ratio κ defines horizontal stress σh and is a function of Ei and depth BGS:
κ = σh:σv = 0.25 + 7 x Ei x (0.001+1/depth(m))
Due to the resolution of σh and σv stress trajectories around excavation boundaries, stress magnitudes acting directly at the stope faces are determined by applying a methodology to estimate stress magnitudes at open stope boundaries. These stresses along with intact UCS of the rock are used to determine A (Figure 13-7 and Table 13-2).
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Figure 13-7: | Rock stress factor “A” |
Table 13-2: | Grey Fox “A” factors |
| UCSavg | Depth | κ | σv (MPa) | σh (MPa) | Asidewall | Aback | Aendwall |
| (MPa) | (m) | | | | | | |
Whiskey Jack | 118.48 | 300 | 1.26 | 8.1 | 10.2 | 1.00 | 0.44 | 1.00 |
Remaining Grey Fox | 118.48 | 800 | 0.78 | 21.6 | 16.8 | 1.00 | 0.18 | 1.00 |
The factor “B” is determined by identifying the critical joint, which is most likely to impact the stability of an exposed stope face, then measuring the angle α between the critical joint orientation and the stope face orientation (Figure 13-8). The most critical stope face is the HW, which is typically parallel to mineralization for longitudinal stoping methods.
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Figure 13-8:Joint Orientation Factor “B”
Factor “C” is the gravity adjustment factor, which depends on the likely failure mechanism at each stope face. Kinematic analysis identifies the failure mechanism is statistically most likely to impact stope faces, based on the orientations in relation to critical geologic structure, and is based on cumulative kinematic failure probability of each failure mechanism. Kinematic analysis of critical joint 197°/65°, versus stope face orientations, indicate gravity failure is the most likely mechanism of each stope face. The HW is presumed parallel to mineralization dip. For Whiskey Jack (63° dip), C is 5.28 and for the remaining Grey Fox (60° dip), C is 5.0 (Figure 13-9).
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Figure 13-9:Gravity Adjustment Factor “C”
Stope design HW/FW, back, and end wall HR are plotted with respective N’ of the HW/FW, backs, and end walls on the stability graph for Whiskey Jack (Figure 13-10) and remaining Grey Fox (Figure 13-11), indicating at which exposed HR ground support is required or where stopes must be expediently backfilled. For the proposed stope dimensions and deposit dip, stope faces are regarded as “stable-unsupported.” Up to six open longitudinal stopes, adjacent along strike, are possible at Whiskey Jack, and for the deeper Grey Fox deposit (e.g., accounting for deepest stoping in Grey Fox), before the HW/FW is regarded as “transitional-unsupported,” where HW support or very expedient stope cycling and dilution tolerance are required.
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Figure 13-10:Whiskey Jack Stability Graph
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Figure 13-11:Remainder of Grey Fox Stability Graph
13.1.4Waste Pillar Stability
Mineralization, particularly at Whiskey Jack, places recoverable grades of the deposit along the FW/HW closer to the host rock contact, with lesser grades in the center. This may result in stoping along two parallel headings along strike, with lower grade “waste” material left in situ between each heading, resulting in a “waste pillar.” A required waste pillar thickness Wp at increasing depth BGS is calculated, to maintain a pillar factor of safety Fs of 1.3.
The proposed waste pillar thickness for the mine design is 3 m minimum required pillar thicknesses at increasing depth, maintaining a 1.3 Fs, are determined using Lunder-Pakalnis pillar strength methods:
PS = (K x UCS) x (C1 + C2 x kappa)
Where PS is the pillar strength in MPa, intact rock strength UCS is in MPa, and K, C1, and C2 are empirical constants from a case history database and equal to 0.44, 0.68, and 0.52 respectively. The average pillar confinement Cpav is a function of pillar geometry and is used to determine kappa:
Cpav = 0.46 x {log[(Wp / H)+0.75]}1.4/(Wp / H)
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kappa = tan{arcos[(1-Cpav)/(1+Cpav)]}
Where Wp and the pillar height H are in metres. A geometric correction factor σɵc accounts for the effects of pillar inclination ɵ, since pillars are not vertical but governed by the dip of the deposit:
σɵc = (1-sinɸ)/(1-sin(ɸ-arctan(tan(ɵ/(2(1+γ))))))
Where ɸ is the internal friction angle of an intact rock sample and γ is Poisson’s Ratio. Inclined PS is generally less than that of vertical pillars since shear strength has a greater role in the overall PS.
Backfill reinforces adjacent pillars through the “arching” effect, where backfill, as it settles, exerts a normal force on pillars which translates to frictional forces, along the backfill/pillar contact surface, providing additional pillar support. The vertical and horizontal components of pillar stress reduction due to arching are functions of cemented rock fill material properties and volume:
σvh = (ρbfB’/2Kbf tanδ’) x {1 – exp(-2 Kbf D/B’tanδ’)}
σhh = Kbf σvh
Kbf = 1 – sinɸbf
δ ≈ (2/3) x ɸbf
Where:
σvh = vertical stress component of the arching effect (MPa)
σhh = horizontal stress component of the arching effect (MPa)
Kbf = horizontal to vertical stress ratio of the backfill
ɸbf = backfill internal friction angle, assumed 30°
δ’ = effective friction angle between the pillar and the backfill
B’ = stope width (m)
D = depth below ground surface (m)
ρbf = backfill density, assumed 1.95 t/m3 = 0.01911 MN/m3
The analysis assumes that the stope on the FW side of the deposit is mined first, so “B” is the width of the stope on the FW side. If mining and backfilling the HW side first, the waste pillar support must be considered, particularly at lower elevations.
For inclined pillars, pillar stress reductions due to arching are calculated based on arching components σvh and σhh in relation to the deposit dip angle (or pillar inclination), and the total stress reduction due to arching is assumed intermediate to σvh and σhh, with frictional support coplanar to the pillar surface.
The pillar Fs is expressed as a ratio of PS to total pillar stress:
Fs = PS/(σind – σred)
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Where the induced pillar stress σind is the product of the rock supported rock unit weight and the pillar’s tributary area, concentrated on the pillar area, and σred are pillar stress reductions due to counteracting backfill frictional support from arching.
Required Wp at increasing depths BGS, at Fs = 1.3, are presented for Whiskey Jack (Figure 13-12) and the rest of Grey Fox (Figure 13-13). The maximum depth of mineral resource at Whiskey Jack is approximately 300 m BGS, and 800 m BGS at Gibson. At these depths, a 3 m Wp is possible at Whiskey Jack, the main area of concern. For the remaining Grey Fox, 3 m for Wp is possible up to 375 m BGS, though at greater depths the pillars must be supported to maintain a 3 m Wp at Fs = 1.3, particularly if mining along the HW side first.
Cable bolts installed in a fan pattern into the waste pillar, from one of the ore drives at drilling or mucking levels, may provide the necessary waste pillar support.
Additional arching pillar support from backfill is negligible at Grey Fox. The stope geometries dictate low backfill volume, generating insufficient normal and frictional forces due to arching against the pillars to provide any additional support.

Figure 13-12:Wp versus depth BGS, Whiskey Jack
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Figure 13-13: Wp versus depth BGS, Remainder of Grey Fox
13.1.5Sill Pillar
A proposed 4 vertical metre thick sill pillar is evaluated for stability, between stoping areas at Grey Fox. Limit equilibrium methods described by Hoek are used. The sill pillar factor of safety Fs,sil is expressed as:
Fs,sill = (2/ρ) ([τxz/y] + [τyz/x]
Where ρ is the rock density constituting the sill pillar. Figure 13-14 illustrates sill pillar dimensions, resisting shear forces (τxz and τyz), and normal in-situ stresses (σx and σy).
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Source: (Hoek, 1989)
Figure 13-14: Sill Pillar Dimensions, Resisting Stress and Normal Stress Vectors
Resisting shear stresses are assumed equal in the xz and yz planes (τxz = τyz = τ), and are defined by the rock mass Unconfined Compressive Strength UCSrm, the rock mass angle of internal friction ɸrm (32.678°, and the Hoek-Brown parameter m:
τ = ([cotɸrm - cosɸrm] m UCS) / 8
Where:
ɸrm = arctan(1/((4hxzcos²θxz) - 1)0.5)
θxz = (1/3)(90°+arctan(1/((hxz³-1)0.5))
hxz = 1+ (16(mσh + s UCS)/(3 m² UCS)
m = mi ∙ exp([GSI - 100] / 14)
s = exp([GSI - 100] / [9 - 3D])
Assume:
GSI = 9 ln(Q’) + 44 where RQD is assumed 88%, Jn is 6, an Jr / Ja is 1
mi = 19.0 for quartz/quartz-carbonate veins
The disturbance factor D is zero, assuming good blasting practice.
Due to high rock strength properties in the mineralized zone and the narrowness of the stope designs, frictional forces supporting a small sill pillar are much greater than the weight of the pillar and a 4 m surcharge of cemented rock fill on top of the sill pillar, resulting in elevated Fs, sill for Grey Fox. Sill pillars are evaluated for 3 m horizontal widths versus 20 m length on strike, then for 9 m horizontal widths for scenarios where a 3 m waste pillar between two parallel stopes is mined.
The waste rock or ore sill pillar could be eliminated entirely, with sill construction by placement of cemented rock fill with a higher cement content into an empty stope. A cemented rock fill pilot program consisting of
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mixing and testing trial cemented rock fill batches will identify cemented rock fill batch specifications for creating a cemented rock fill sill which may be safely mined underneath.
13.1.6Backfill
Backfill will consist of cemented rock fill or unconsolidated rock fill. Due to relatively small stope sizes and backfill volumes, very limited arching support is anticipated so cemented rock fill and rock fill are expected to behave similarly for taking weight from the waste pillars. One disadvantage with rock fill is it will run if a waste pillar fails.
For twin stopes where the interim waste pillar Wp is 3 m, cemented rock fill is placed on the HW side if this side is mined first, with rock fill on FW side of the waste pillar. If the FW side is mined first, rock fill may be placed on both sides of the waste pillar. Refer to Figure 13-31.
A cemented rock fill pilot program consisting of mixing and testing trial cemented rock fill batches will identify cemented rock fill batch specifications which satisfy general and specialized strength requirements. For the cemented rock fill strength, Mitchell’s Method is used to identify strength requirements based on cemented rock fill vertical exposure, then cement contents are determined based on strength testing trial batches of cemented rock fill at different strength contents and adjusting the cement content to get to the target strength identified by Mitchell’s Method.
13.1.7Crown Pillar
The crown pillar provides ground surface stability over an underground mine. Crown pillar stability analysis considers open stopes or other large underground voids, in proximity to the surface. An appropriate crown pillar thickness determination is based on ground conditions, crown pillar geometry, purpose/expectancy, and risk tolerance.
The Carter Method for scaled span analysis is the application of a scaling factor to the proposed design dimensions to account for geometric influences and ground conditions and applied to sizing / modifying the design span. This method assumes a caving or unraveling failure mechanism, with design geometry and rock parameters as input to determine reliability of pillar integrity at decreasing thickness and increasing span due to mining. Caving is an appropriate assumption since it takes weathering of the bedrock near the surface into account. The method assumes backfilling is not used underground.
The critical span Sc is the maximum self-supporting span due to rock mass conditions:
Sc = 3.3 (Q0.43) x sinh0.0016 (Q)
Where Q is the product of Q’ and (Jw/SRF), Jw is assumed 1.0 (dry), and SRF of the rock is a function of k, UCS, and crown pillar thickness or depth in metres BGS:
SRF = 0.244(depth/UCS)1.322 + 0.176(UCS/depth)1.413
The Scaled Span Cs is the product of the design span and a scaling factor accounting for geometric influences and ground conditions:
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Cs = S {Gs / [T (1+SR) ∙ (1 - 0.4cosɵcp)]}0.5”
S = crown pillar design span (m)
ɵcp = orientation of the crown pillar-wall interface (assumed equal to deposit dip)
T = crown pillar thickness (m)
SR = span ratio = S/L
L = crown pillar strike length (m)
The Probability of Failure (PF,crown) of the crown pillar is a function of the crown pillar Factor of Safety
(FS,crown):
PF,crown = 1 – erf [(2.9 FS,crown - 1) / 4]
FS,crown = Sc / Cs
With PF,crown and the equivalent FS,crown of the crown pillar known, the crown pillar may be assigned to a risk class which provides additional guidance on the expected service life of the crown pillar, accessibility and level of concern post-mine closure, and degree of stability monitoring. Table 13-3 presents Carter’s Crown Pillar Acceptable Risk Exposure Guidelines.
Table 13-3: Crown Pillar Acceptable Risk Exposure Guidelines

The crown pillar consists of approximately 31 m of rock from the back of the Whiskey Jack 65 Level top cut to the bedrock/soil overburden contact, then 22 m of overburden to the surface. The soil overburden is assumed glacial till. Rock is assumed to have a minimum RQD of 10%. At less than 10%, particle sizes are at a scale that the laws of soil mechanics apply. Assuming a worst-case scenario, soils may be represented with a Q value equal to zero. For the rock, Q is the product of Q’ (=15 at 88% RQD for 75% reliability) and strength reductions due to hydraulic stress, rock strength, and depth (=Jw / SRF), where Jw is assumed 1.0
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for dry conditions or negligible inflows. The rock Gs is 2.75 and the glacial till Gs is assumed 2.6, and the crown pillar Gs and Q at increasing total thickness are a weighted average of the glacial till and rock components, with Fs,crown (Figure13-15) and Pf,crown (Figure 13-16) calculated at increasing total thickness, for a 9 m W x 60 m L crown pillar footprint, or three sets of 20 m long parallel stopes with the central barrier pillar removed and mined along strike.

Figure 13-15: Fs,crown at increasing Total Thickness
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Figure 13-16: PF,crown at increasing Total Thickness
Surface elevation directly over the Whiskey Jack 65 Level is 288 m above sea level, and the total crown pillar thickness is 53 m, consisting of 22 m overburden and 31 m rock, given a 5 m vertical top cut at 65 Level. At this total thickness, Fs,crown is 5.22 and Pf,crown is virtually 0%. This classifies the crown pillar as Class G, with a very long-term to permanent service life, minimal post-closure stability concerns, and no anticipated monitoring requirements.
13.1.8Ground Support Standards
First-pass pattern (primary) support for Grey Fox consists of 1.5 m long #6 grouted rebar bolts, on a 1.5 m “dice” pattern, where the nearest distance of the patterned bolts to the “5-spot” bolt is 1 m. The bolts pin 3.3 m x 1.8 m welded wire mesh sheets to the ribs and back for “skin” support. The welded wire mesh sheets are 6-gauge, 10 cm aperture wire mesh sheets, overlapping 3 “squares.” Shotcrete and heavy support may be added, to be determined by encountered ground conditions. Long (secondary) support is added in the back at slashes and intersections (Table 13-4 and Table 13-5). Support classes are defined by the rock mass quality Q or equivalent Rock Mass Rating (RMR, = 9lnQ + 44).
Bolting typically does not extend below the survey reference line (approximately 1.5 m to 1.8 m above the floor) to protect mobile equipment from tire damage. Galvanized bolts and welded wire mesh are recommended for ramp and level development, and non-galvanized for development in ore.
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Table 13-4: Ground Support Standards, Ramp and Level Development
Support | criteria: | criteria: | Bolting and Mesh | Shotcrete | Steel Sets |
RA | I - Very good rock | 4.3 m high x 4 m wide | 1.5 m long #6 grouted rebar on 1.5 m | None | None |
RB | II - Good rock | ||||
RC | III - Fair rock RMR: | 5 cm to 10 cm across the | |||
RD | IV - Poor rock | 10 cm to 15 cm across | 3.7 m PM24 inflatable | ||
RE | V - Very poor rock | 15 cm minimum across | Medium to heavy steel | ||
RF | VI - Intersections, | 4.3 m high x (4.0 m to 8.0 m) | 1.5 m long #6 grouted rebar on 1.5 m | Where required based on | Avoid placing slashes and |
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Table 13-5: Ground Support Standards, Ore Development
Support | criteria: | criteria: | Bolting and Mesh | Long Support | Notes |
SA | I - Very good rock | 5.0 m high x 4.5 m wide | 1.5 m long #6 grouted rebar on 1.5 m | None | N/A |
SB | II - Good rock | ||||
SC | III - Fair rock RMR: | 3.7 m PM24 coated | |||
SD* | IV - Poor rock | Minimum length 6.1 m | Reduce stope size or select | ||
SE | V - Very poor rock | N/A | Stoping not possible, select | ||
At 75% reliability in design, 75% of mine development may be in Classes RC/SC or better (blocky to massive), based on a 25th RQD percentile of 88%, Jn = 6, Jr / Ja and Jw assumed 1.0, and SRF assumed 2.5 for competent, mainly massive rock under low stress and near the surface.
Support requirements are not anticipated for stope HW’s at the majority of Grey Fox. At depth greater than 375 m BGS, waste pillar support may be needed to maintain a 3 m horizontal waste pillar. This may consist of variable length cable bolts, connectable premium inflatable bolts, or connectable hollow bar injectable resin bolts, installed in a fan pattern from the drilling or mucking levels.
13.2 Hydrogeological Considerations
A hydrogeological model was prepared in 2021 by Wood. An updated model was prepared in 2025 by WSP. The memo describes modifications made to the previously developed (Wood, 2021) site groundwater flow model to accommodate the updated mine plan and presents results of new predictive simulations of potential groundwater inflows and impacts to the shallow groundwater flow system from mine dewatering. At the time the model was updated, an open pit was planned for the Grey Fox Project. For this technical report the open pit was eliminated as an option. The following section summarizes the hydrogeological model updates assuming the open pit was still in the plan, although it has been assumed the underground inflows will not be impacted by eliminating the open pit.
13.2.1Model Predicted Seepage Rates
The model predicted groundwater inflow rate to the open pit/underground mine workings (UMWs) for the Base Case model input parameters is 930 m3/d, which represents an increase of 260 m3/d relative to the 2022 model predictions. Model simulation results presented in 2021 indicated that the model predicted
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groundwater seepage rates were most sensitive to changes in the assumed properties of the glacial till unit (sensitivity variant 3, Wood, 2021) and also to the bedrock hydraulic conductivity (sensitivity variant 6, Wood, 2021). To provide upper estimates on the predicted groundwater seepage rate into the open pit/UMW’s for the current model, these sensitivity variants were also run for the current model build. Model predicted groundwater seepage rates for these runs are presented below in Table 13-6.
Table 13-6: Predicted Groundwater Seepage into Open Pit and Underground Mine Workings
Predicted Groundwater Seepage Rate (m3/d) | ||
Model Variant | 2022 Model Predicted Seepage rate into | 2025 Model Update Predicted Seepage |
Base Case | 670 | 930 |
Till k x3 | 735 | 1,000 |
Bedrock k x3 | 1,500 | 1,700 |
13.2.2Model Limitations
Limitations associated with the development and application of this numerical groundwater model for this Project site include:
| ● | Steady-state conditions: The groundwater was simulated assuming steady-state (i.e., long-term, constant) conditions, which represents the long-term dewatering rate after the initial drawdown period. It is expected that short-term dewatering rates during the initial drawdown period and seasonal inflows following the spring freshet will be greater than the long-term rate as storage is released from the surrounding overburden. |
| ● | Data Gaps: Several assumptions were made during model development due to the site-specific data availability: |
o | Equivalent Porous Media: This approach was implanted which is deemed sufficient for characterizing the overall groundwater flow regime at the scale of this analysis. Local faults may be indicated by a bedrock low that passes northwest through the proposed underground workings to the Pike River; however, as there is a considerable thickness of overburden sediments above the bedrock low even where it passes under the river, the prospect of significant groundwater and surface water interaction appears to be low. |
o | Pike River: The riverbed is assumed to be located within the glaciolacustrine deposits across most of the model domain, except at a few locations where bedrock outcrops have been noted from the available surficial geological mapping. Bedrock outcrops along the Pike River may act as “windows” which allow greater hydraulic connection between the bedrock and surficial water features. Presence/absence of bedrock outcrops along the Pike River, within the predicted Zone of Influence is recommended. |
o | Average annual conditions: The model simulates average annual conditions, and not seasonal conditions. Seasonal variations in stream flows, which may result in small tributaries being dry during late summer and late winter conditions, will not be captured by the model. |
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13.2.3Conclusions
The calibrated 3D groundwater flow model developed for the Grey Fox 2022 model build was modified with the updated open pit mine plan and then used in predictive mode to provide new estimates of groundwater seepage inflow rate to the previously proposed open pit and underground mine workings as well as the Zone of Influence relating from mine dewatering and to estimate changes in groundwater-surface water interaction near the mine site. This open pit model was used as a conservative proxy for the drawdown of results for this underground only mining method across a similar footprint.
For the Base Case model input parameters the simulation results indicate the simulated groundwater inflow rate into the fully developed open pit and underground mine workings is 930 m3/d and the Zone of Influence is predicted to extend approximately 2,800 m from the center of the previously proposed open pit to the south and 1,300 m to the north, east and west of the mine site, which are limited by the presence of Pike River. Model sensitivity results indicate that the long-term groundwater seepage rates into the open pit and UMW’s may be 1,700 m3/d. The model results indicated that the Pike River and the three tributaries near the mine site experience an overall reduction in baseflow contribution, with the baseflow reduction to the Pike River constituting approximately 1.3% of the 7Q20 value for the Pike River.
For the Grey Fox Project, the assumed underground inflows are an average of 670 m3/d and a peak of 1500 m3/day per portal. It is recommended to update the model to reflect the current proposed Grey Fox Project mine plan, excluding the previously planned open pit and its influence on the model.
13.3Mine Design and Mining Methods
13.3.1Supporting Assumptions and Background Data
13.3.1.1 Design Codes, Regulations, and Standards
The health and safety of workers will be at the forefront of the mine design. The design will consider industry best practices and will comply with safety codes and regulations.
The following practices and codes will be followed:
| ● | Minimize risk to worker health and safety, including prevention through design concepts. |
| ● | Minimize the impact to the environment and local communities. |
| ● | Occupational Health and Safety Act, R.R.O. 1990, Regulation 854, Mines and Mining Plants. |
| ● | Minimize risk to production. Use proven industry technology, equipment, and processes suitable for worker skill sets. |
13.3.1.2 Units of Measure
The SI system will be used except where specifically indicated otherwise.
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13.3.1.3 Rock Densities
The ore and waste rock densities are included in the resource model. For calculations where data is not directly taken from the model, average in-situ and blasted densities will be used and are presented in Table 13-7.
Table 13-7: Rock Densities
Zone | In-situ Density | Swell Factor (broken) | Broken Density |
Gibson | 2.76 t/m3 | 40% | 1.97 t/m3 |
All other Zones | 2.88 t/m3 | 40% | 2.06 t/m3 |
13.3.2Development
13.3.2.1 Overbreak and Design Allowance
Overbreak and design allowance factors will be applied to the neat quantities from the design solids. Overbreak accounts for the excavation area exceeding the planned dimensions. The design allowance accounts for development that will be required but will not be included in the details of the mine design (intersection slashes, safety bays, etc.). Table 13-8 lists design factors that will be applied to the neat quantities.
Table 13-8: Development Allowances
Item | Allowance |
Design Allowance | |
Ramp and lateral capital development | 10% |
Lateral operating development | 0% |
Raise development | 5% |
Overbreak Allowance | |
Ramp and lateral development in waste | 10% |
Lateral development in ore | 0% |
Raisebored raises | 0% |
Other raises | 10% |
13.3.2.2 Lateral Development
Lateral development includes ramp and level development. The development equipment will include:
| ● | Drill – 2 boom electric hydraulic jumbo |
| ● | Blast – mobile explosives loader |
| ● | Muck – 7-t class LHD |
| ● | Ground Support – mechanized bolter |
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| ● | Truck Haul – 20-t class underground haul truck |
The drift profiles will have a flat back with 1 m arch corners.
13.3.2.2.1Mine Access
The primary access to Grey Fox North will be excavated from the existing Gibson portal and ramp, which will be rehabilitated and expanded to 4.0 m W x 4.3 m H with the portal boxcut to suit, to be known as the Grey Fox North portal, hereafter. Two separate access ramps for Whiskey Jack and the remaining Grey Fox North (Gibson, Contact, and 147NE zones) will be developed from the existing Gibson Ramp. A separate portal will be developed for Grey Fox South with a single access ramp throughout.
The design criteria for the ramps are summarized in Table 13-9.
Table 13-9: Ramp Design Criteria
Item | Criteria |
Profile | 4.0 m W x 4.3 m H to accommodate: |
| Maximum 6 m/s ventilation velocity |
| a 1.1 m (42”) diameter or twin 0.91 m (36”) diameter, semi-rigid ventilation ducting during |
| development |
| 150 mm roadbed ballast |
| 20 t Haul Truck |
| Service water and dewatering pipes |
| Compressed air pipe |
| Electrical and communications cables |
Gradient | Maximum 17% |
Turning Radius | Minimum 20.0 m |
Remuck Bays | Distance between Remuck Bays: 150 m |
| Dimensions: 4.0 m W x 5.0 m H x 15.0 m L |
Truck Loadouts | Distance between Truck Loadouts: 150 m (with remucks) |
| Dimensions: Take Down Back in ramp 4.0 m W x 5.0 m H x 8.0 m L at the remuck area |
Safety Bays | 1.5 m W x 2.0 m H x 0.6 m L, spaced minimum 30 m apart |
13.3.2.2.2Typical Level Development
Levels will be named according to their depth from surface (surface assumed at 295 m elevation). In practice, level development will be at 1% to 2% gradient as required for water drainage but will be designed at 0% gradient for the PFS. Unless otherwise stated, drift size will be 4.0 m W x 4.3 m H with 1 m arch corners for capital development and 3.5 m W x 4.0 m H with 1m arch corners for operating development. Development excavations will target a 4:1 pillar to excavation ratio with a minimum of 3:1 where required. Capital development will be designed in waste rock outside of the mineralization where possible to avoid sterilizing potential future stoping. The criteria for typical level development are summarized in Table 13-10.
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Table 13-10: Typical Level Development Drift Profiles and Criteria
Drift Description | Criteria |
Level Access | 4.0 m W × 4.3 m H |
Ventilation Access | 4.0 m W × 4.3 m H |
Remucks | 4.0 m W × 5.0 m H x 15 m L |
Stope Access | 4.0 m W × 4.3 m H |
Stope Sills | 3.0 m - 5.0 m W x 4.0 m H |
Backfill Access | 4.0 m W × 5.0 m H x 15/25 m L |
Electrical Cut-out | 5.0 m W × 4.3 m H x 10/20 m L |
Sump | 4.0 m W × 4.3 m H x 10 m L, max. Gradient -20% |
Explosive Storage | 7.0 m W x 4.3 m H x 20 m L |
Detonator Storage | 5.0 m W x 4.3 m H x 10 m L |
Underground Workshop | 6.5 m W x 4.3 m H x 44 m L |
Satellite Fuel Bay | 5.0 m W x 4.3 m H x 23 m L |
Wash Bay | 5.0 m W × 4.3 m H x 20 m L |
Permanent Refuge Station (12-person) | 4.0 m W × 4.3 m H x 18 m L |
Levels will be developed every 30 vertical metres in the Whiskey Jack Zone (except the first two levels are 25 m). Whiskey Jack Zone is relatively small and uniform throughout. Figure 13-17 presents the Whiskey Jack Zone typical level development.
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Figure 13-17: Typical Level Development Whiskey Jack Zone 115 Level
The remaining levels in Grey Fox North and Grey Fox South will be developed every 25 m. These zones are more spread out and will have more variance in development level-to-level.
Figure 13-18 presents the typical level development in the second block of Grey Fox North excluding Whiskey Jack Zone. Figure 13-19 presents the typical level development in the first block of Grey Fox South.
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Figure 13-18: Typical Level Development Grey Fox North Zone Block 2 165 Level
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Figure 13-19: Typical Level Development Grey Fox South Block 1 115 Level
13.3.2.2.3Lateral Development Quantities
All lateral development quantities are expressed in equivalent lateral metres to the dimensions as per below:
| ● | Existing Gibson Ramp Capital – Rehabilitation and Expansion to 4.0 m W x 4.3 m H |
| ● | Capital Development – 4.0 m W x 4.3 m H |
| ● | Whiskey Jack Operating Development – 4.0 m W x 4.0 m H |
| ● | Remaining Operating Development – 3.5 m W x 4.0 m H |
The lateral development quantities include cut-and-fill stope access but not cut-and-fill stoping. The lateral development quantities are present in Table 13-11.
Table 13-11: Lateral Development Quantities
Item | Grey Fox North | Grey Fox South | Total |
Capital – Existing Gibson Expansion and Rehabilitation | 156 | - | 156 |
Capital – Ramp and Ramp Remucks | 5,791 | 2,686 | 8,477 |
Capital – Level and Infrastructure Development | 8,668 | 4,485 | 13.153 |
Operating – Stope Access and Sill Development | 40,532 | 26,310 | 66,842 |
Total | 55,147 | 33,481 | 88,628 |
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13.3.2.3 Vertical Development and Quantities
Vertical development assumptions are summarized in Table 13-12.
Table 13-12: Vertical Development
Raise Type | Raise Size | Dip | Excavation Method |
Ventilation Raise | 2.7 m - 3.5 m square | Vertical (to Surface) | Alimak |
Ventilation Raise | 2.7 m - 3.5 m square | minimum 60° | Drop Raise |
Dedicated Escapeway Raise | 1.2 m diameter | minimum 60° | Raisebore |
The vertical development quantities are present in Table 13-13.
Table 13-13: Vertical Development Quantities
Item | Grey Fox North (m) | Grey Fox South (m) | Total (m) |
Escapeway Raise - Raisebore | 604 | 249 | 853 |
Ventilation Raises - Alimak | 211 | 127 | 338 |
Ventilation Raises - Drop Raise | 1,115 | 482 | 1,597 |
Total | 1,930 | 858 | 2,788 |
13.3.3Primary Development and Intersection Ground Support
The primary ground support for lateral excavations is summarized in Table 13-14.
Table 13-14: Primary Ground Support
Excavation Surface | Bolt | Screen |
Back (<5m span) | 1.5 m long #6 rebar bolts | #6 Gauge Screen |
| 1.5 m x 1.5 m dice pattern | |
Back (5-7m span) | 1.8 - 2.4 m long #6 rebar bolts | #6 Gauge Screen |
| 1.2 m x 1.2 m dice pattern | |
Walls | 1.5 m long split sets | #6 Gauge Screen |
| 1.5 m x 1.5 m dice pattern | Down walls from back to within 2.1 m of |
The larger spans at intersections will require secondary ground support. The intersection ground support is summarized in Table 13-15.
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Table 13-15: Intersection Ground Support
Rock Type | Support |
Good Ground (spans > 7 m) | Center 9 cables - 3.65 m long spin cable 1.5 m spacing |
13.3.4Production Stoping
For production mining, longitudinal longhole stoping and overhand cut-and-fill methods will be used.
Longhole stoping requires developing mining levels to access the stopes and facilitate drilling, blasting, and extraction of the material. Once extraction of material within a stope is completed, the stope will be filled with a combination of cemented rock fill or unconsolidated rock fill as required. Longhole is a non-entry mining method (I.e., during mining, personnel will be prohibited from entering the open portion of a stope). Material from within the stope will be mucked remotely using LHDs to reduce worker exposure to potential ground hazards.
The longhole stoping equipment will include:
| ● | Drill - Slot Drill Rig (with V30 Reamer) and Production Drill Rig |
| ● | Blast - Explosive Loader |
| ● | Muck - 10 t class LHD |
| ● | Fill - 10 or 7 t class LHD |
Cut-and-fill requires dividing targeted mineral resource into stacked development drifts. The bottom most drift will be extracted first followed by the next drift above once the previous lower drift is filled with cemented rock fill. The final cut will not require any filing. The cut-and-fill mining method follows the same principles as conventional lateral development otherwise. The cut-and-fill equipment will be the same equipment used for development. Table 13-16 presents the recovered ore tonnes by mining method. Most of the mineral resource will be extracted via the longitudinal longhole method.
Table 13-16: Ore Tonnes by Mining Method
Mining Method | Grey Fox North | Grey Fox South | Total | |
| ||||
| ||||
Longitudinal Longhole | 4,713651 | 3,009,295 | 7,722,946 | |
Cut and Fill | 55,165 | 62,819 | 117,984 | |
Development | 921,239 | 643,660 | 1,564,899 | |
Total | 5,690,055 | 3,715,774 | 9,405,829 | |
13.3.4.1 Mining Blocks
To achieve the planned production rate and allow flexibility in the schedule, production will be required concurrently from multiple fronts. To achieve this, and limit congestion, the mine will be split into mining blocks, and where possible the infrastructure will be grouped by mining block. The mining block divisions
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attempt to minimize the occurrence of mining under backfill, and the divisions are not strictly from one level to the next but change per ore lens based on the local geometry. Each mining block will use a bottom-up approach where possible.
The main vertical mining blocks are as follows and presented in Figure 13-20, Figure 13-21, and Figure 13-22 for the Whiskey Jack Zone, the remaining Grey Fox North, and Grey Fox South, respectively:
| ● | Whiskey Jack Zone Mining Block 1: 145 Level to 65 Level |
| ● | Whiskey Jack Zone Mining Block 2: 295 Level to 145 Level |
| ● | Grey Fox North Mining Block 1: 140 Level to 40 Level |
| ● | Grey Fox North Mining Block 2: 265 Level to 140 Level |
| ● | Grey Fox North Mining Block 3: 365 Level to 265 Level |
| ● | Grey Fox North Mining Block 4: 465 Level to 365 Level |
| ● | Grey Fox South Mining Block 1: 140 Level to 40 Level |
| ● | Grey Fox South Mining Block 2: 240 Level to 140 Level |
| ● | Grey Fox South Mining Block 3: 340 Level to 240 Level |

Figure 13-20: Whiskey Jack Zone Mining Blocks Looking South
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Figure 13-21: Remaining Grey Fox North Mining Blocks Looking North

Figure 13-22: Grey Fox South Mining Blocks Looking North
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13.3.5Longhole and Cut-and-Fill Stoping Design
Longitudinal longhole stoping will be the primary recovery method. Some stopes will be mined with up-holes only when a drill overcut is not suitable or unavailable. Where suitable, shorter length sub-stopes are merged with adjacent stopes not exceeding 40 m. The longhole stope design criteria are summarized in Table 13-17.
Table 13-17: Longhole Stope Design Criteria
Description | Whiskey Jack | All Other | Range | |
| ||||
| ||||
Level Interval (floor to floor) | 30 m | 25 m | 25 to 30 m | |
Stope Length (along strike) | 20 m | 25 m | 10 to 40 m | |
Stope Width (HW to FW) | 5.0 m | 3.5 m | Minimum 3.0 m | |
Stope Footwall dip | 70o | 70o | Minimum 45o | |
Minimum Pillar Width from filled stopes (between | Minimum 3 m <300 m below surface, 6 m otherwise | | ||
Minimum Pillar Width from unfilled uphole stopes | Minimum 10 m <300 m below surface, 15 m | | ||
Overhand cut-and-fill will be used to supplement the longhole stopes with up to 5 m H cuts. The cut-and-fill stope design criteria are presented in Table 13-18.
Table 13-18: Cut-and-Fill Stope Design Criteria
Description | Base | Range |
Cut Width (HW to FW) | 3.0 m | 3.0 to 5.0 m |
Cut Height (floor to floor) | 5.0 m | 3.0 to 5.0 m |
Number of Cuts per Sequence | 2 | 1 to 3 |
13.3.5.1 Stope Sequencing
Stopes will be sequenced to minimize equipment interaction between stopes and maintain overall ground stability. Constraints will be placed on the sequence when two stopes share an access (e.g., the drill horizon for one stope and mucking horizon for the stope above) such that activities do not occur concurrently. In the cases of multiple lenses, there will be a preference to mine the footwall stope prior to the hanging wall stope for ground control purposes. Where possible, up-hole stopes will be sequenced last as these will not be backfilled.
The longitudinal (L) stopes will be sequenced using a bottom-up retreat approach back to an access. Stopes in a longitudinal sequence are dependent on the stopes adjacent and below. Stopes are accessed via a center access (Figure 13-23) or an access on one of the strike ends (Figure 13-24).
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Cut-and-fill stopes will be mined overhand (bottom-up) where multiple cuts are mined in sequence via one attack ramp.

Figure 13-23: Typical Longitudinal Stope Sequence with Center Access (Long Section View)

Figure 13-24: Typical Longitudinal Stope Sequence with End Access (Long Section View)
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13.4 Productivities
13.4.1Annual Working Days and Shift Schedule
The annual working days and shift schedule are listed in Table 13-19.
Table 13-19: Working Days and Shift Schedule
Item | Value |
Days per Year | 360 |
Project Period Shift Schedule | 2 × 12 hours |
Operating Period Shift Schedule | 2 × 10 hours |
13.4.2Effective Hours
The underground operations will consist of two 12-hour shifts per day, seven days per week for contractor personnel and two 10-hour shifts per day, seven days a week for the McEwen personnel. Time worked during these shifts is expected to fall into one of two categories: effective or non-effective.
Non-effective time may result from necessary parts of the job (e.g., travel to the workplace, equipment refueling, and shift safety meetings) during which workers are not actively conducting mining work.
The effective time calculation presented in Table 13-20 represents the available time underground that a worker will be able to complete tasks.
Table 13-20: Effective Time Calculations
Item | Zone | | | | | Unit |
| Priority | Whiskey | Remaining | Whiskey | Remaining | |
| Ramp | Jack | Grey Fox | Jack | Grey Fox | |
Personnel | Contractor | Contractor | Contractor | McEwen | McEwen | |
Shifts per Day | 2 | 2 | 2 | 2 | 2 | shift/day |
Work Week | 7 | 7 | 7 | 7 | 7 | days |
Planned Hours per Shift | 12 | 12 | 12 | 10 | 10 | hour/shift |
Planned Minutes per Shift | 720 | 720 | 720 | 600 | 600 | min/shift |
Rotation | 7 on / 7 off | 7 on / 7 off | 7 on / 7 off | 7 on / 7 off | 7 on / 7 off | day |
Non-Productive Activities | ||||||
Shift Line-up | 15.0 | 15.0 | 15.0 | 15.0 | 15.0 | min/shift |
Daily Safety Toolbox Huddle | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | min/shift |
Monthly Safety Meeting | 2.1 | 2.1 | 2.1 | 2.1 | 2.1 | min/shift |
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Item | Zone | | | | | Unit |
Transportation to Work Area | 14.8 | 19.4 | 18.9 | 19.4 | 18.9 | min/shift |
Field Level Risk Assessment / | 10.0 | 10.0 | 10.0 | 10.0 | 10.0 | min/shift |
Equipment Servicing/Refuelling | 15.0 | 15.0 | 15.0 | 15.0 | 15.0 | min/shift |
Break 1 | 0.0 | 0.0 | 0.0 | 15.0 | 15.0 | min/shift |
Lunch | 0.0 | 30.0 | 30.0 | 30.0 | 30.0 | min/shift |
Break 2 | 0.0 | 0.0 | 0.0 | 15.0 | 15.0 | min/shift |
Supervisory/Survey/Engineering | 15.0 | 15.0 | 15.0 | 15.0 | 15.0 | min/shift |
Transportation from Work Area | 15.5 | 24.1 | 23.1 | 24.1 | 23.1 | min/shift |
Miscellaneous Delays | 5.0 | 5.0 | 5.0 | 5.0 | 5.0 | min/shift |
Blast Delays | 20.0 | 30.0 | 30.0 | 5.0 | 5.0 | min/shift |
Total Non-Productive Time per Shift | 117.4 | 170.6 | 169.1 | 175.6 | 174.1 | min/shift |
Total Effective time per shift | 10.04 | 9.16 | 9.18 | 7.07 | 7.10 | hours |
13.4.3Labor
The majority of the underground development and construction will be completed by McEwen personnel. Contractors will be mostly utilized for the initial year of development activities, underground infrastructure construction and maintenance and replaced by McEwen personnel where required. Contactors will also be used for ongoing Alimak raising and raise bored escapeways throughout the LOM.
The underground labor will peak at 327 personnel on-site payroll. The total underground related labor (peak) by year is presented in Table 13-21.
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Table 13-21: Total On-site Labor
Labor Type | 2027 | 2028 | 2029 | 2030 | 2031 | 2032 | 2033 | 2034 | 2035 | 2036 | 2037 | 2038 | 2039 | 2040 | 2041 |
Contractor | | | | | | | | | | | | | | | |
Integrated Project | 16 | 17 | 17 | 1 | | | | | | | | | | | |
Mine | | 1 | 1 | 1 | 1 | 1 | | | | | | | | | |
Mine Operations | 26 | 50 | | | | | | | | | | | | | |
Mine | 20 | 30 | | | | | | | | | | | | | |
McEwen | | | | | | | | | | | | | | | |
Integrated Project | 25 | 29 | 29 | 2 | | | | | | | | | | | |
Mine | | 5 | 5 | 29 | 31 | 33 | 38 | 38 | 40 | 39 | 39 | 38 | 35 | 26 | 15 |
Mine Operations | 4 | 27 | 85 | 97 | 109 | 113 | 147 | 177 | 209 | 205 | 209 | 215 | 207 | 185 | 37 |
Mine | 2 | 28 | 40 | 50 | 52 | 52 | 60 | 70 | 78 | 78 | 74 | 74 | 73 | 64 | 20 |
Total On-Site | 93 | 187 | 177 | 180 | 193 | 199 | 245 | 285 | 327 | 322 | 322 | 327 | 315 | 275 | 72 |
Note: Numbers may not sum due to rounding.
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13.4.4Lateral Development
The lateral development advance rates were divided into the components of the drill-blast-muck-bolt cycle and estimated from first principles. Advance rates were developed for single and multiple heading scenarios. The rates reflect the advance each drill jumbo crew and its associated gear will achieve over extended periods of operation. The rates reflect long-term averages and include an efficiency allowance. The efficiency allowance accounts for interferences from other activities and conflicting priorities that occur during the operating period.
The priority ramp development rate is estimated with all breaks or interruptions to affect secondary headings and blast at will practices shall be employed before production begins. It is only used while establishing the main ramp and initial levels of the Whiskey Jack Zone with contractors in the first year of development.
The Gibson Ramp rehabilitation will be handled within the first year of development with only contractors on site. Different ore development rates were estimated for the Whiskey Jack Zone as there is generally wider development. The estimated development productivities used in the schedule are summarized in Table13-22.
Table 13-22: Lateral Development Productivity
Item | | | | | Unit |
Personnel | Contractor | Contractor | McEwen | McEwen | |
Development Type | Single Heading | Multi-Heading | Single Heading | Multi-Heading | |
Priority Ramp Development | 6.8 | 9.1 | N/A | N/A | m/d |
Gibson Ramp Rehabilitation | 8.2 | 13.5 | N/A | N/A | m/d |
Ramp Development | 5.5 | 9.1 | 4.2 | 7.0 | m/d |
Lateral Waste Development | 5.4 | 8.9 | 4.2 | 6.9 | m/d |
Ore Development Whiskey Jack | 5.7 | 9.4 | 4.4 | 7.3 | m/d |
Ore Development | 6.1 | 10.1 | 4.7 | 7.8 | m/d |
The time for each element of the development cycle (4.0 m average round length) for a 4.0 m W × 4.3 m H ramp heading is presented in Table 13-23.
Table 13-23: Development Cycle for the Ramp (4.0 m W × 4.3 m H)
Item | Value | Unit |
Drill | 2.9 | hours |
Load/Blast | 1.2 | hours |
Muck | 2.1 | hours |
Ground Support | 3.4 | hours |
Services Install (Critical Path) | 0.2 | hours |
Total Cycle Time | 9.8 | hours |
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13.4.1Vertical Development
The vertical development advance rate using the drop raise method includes setup and teardown, pilot and reaming of a V30 762mm (30”), and drilling and blasting of the raise. All drop raise activities will be completed by McEwen personnel. Table 13-24 presents drop raise productivities.
Table 13-24: Drop Raise Development Productivity
Drop Raise Dimensions | Rate | Unit |
3.1 m x 3.1 m | 1.8 | m/d |
2.7 m x 2.7 m | 2.2 | m/d |
The vertical development advance rate using the raise boring method includes setup and teardown, pilot hole drilling, and reaming of the raise. The only planned raisebore development is for the dedicated escapeways. All raisebore activities will be completed by a contractor. Table 13-25 presents the raise bore productivity.
Table 13-25: Raise Bore Development Productivity
Raise Bore Dimensions | Rate | Unit |
1.1 m (42”) Diameter | 6.3 | m/d |
The vertical development advance rate using the Alimak method includes drilling, blasting, mucking, bolting, and installation of rails. Set-up and teardown are a single lag of 10 days in schedule. The 3.5 m x 3.5 m raises will require two passes. All Alimak raise activities will be completed by a contractor.
The raise development rates are summarized in Table 13-26.
Table 13-26: Alimak Raise Development Productivity
Alimak Raise Dimensions | Rate | Unit |
2.7 m x 2.7 m | 3.6 | m/d |
3.1 m x 3.1 m | 3.2 | m/d |
3.5 m x 3.5 m | 1.9 | m/d |
13.4.2Stope Productivity
Stope production rates were divided into the components of the drill-blast-muck and backfill cycle and estimated from first principles. Stope cycles were estimated for the average longitudinal stope sizes. The cycle includes slot raise drilling, production drilling, blasting, mucking, and backfill. Slot raise drilling will be performed by a drill rig equipped with a V30 762 mm (30”) reamer bit and includes a pilot hole and reaming. Production drilling utilizes 89 mm (3.5 in) holes. All stoping activities are to be completed by McEwen personnel. The stope productivities are summarized in Table 13-27.
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Table 13-27: Longhole Stope Productivities
Item | Whiskey Jack | All Other Zones | Unit |
Slot Raise | 3.5 | 4.0 | m/d |
Production Drilling | 129 | 148 | m/d |
Blasting | 2 | 2 | days |
Mucking (including loading trucks) | 493 | 463 | t/d |
Backfilling | 571 | 432 | t/d |
Average Stope Size | 8,100 | 5,300 | t |
Average Total Tonnes per Day | 167 | 141 | t/d |
Average Total Tonnes per Day Excluding | 210 | 189 | t/d |
The stope average cycle times are summarized in Table 13-28.
Table 13-28: Longhole Stope Average Cycle Times
Item | Whiskey Jack | All Other Zones | Unit |
Slot Raise | 8 | 6 | days |
Production Drilling | 12 | 9 | days |
Blasting | 2 | 2 | days |
Mucking (including loading trucks) | 17 | 12 | days |
Backfilling | 10 | 10 | days |
Average Stope Size | 8,100 | 5,300 | t |
Average Cycle Time | 49 | 38 | days |
Average Cycle Time Excluding Backfill | 39 | 28 | days |
13.5 Mine Production Schedule
13.5.1Underground Development Scheduling
All mine development and production scheduling has been prepared using Deswik scheduling software. The schedule is interactively linked to the 3D mine model. All development and production scheduled is based on dependencies linked within the mine model. All data are contained within the mine model and schedule.
The primary development focus will be the ramp to Whiskey Jack Zone and establish the ventilation system. Whiskey Jack is the first focus for production as it is of the highest-grade resource and requires less development per ore tonne. On each level, priority will be to establish the sump, electrical cut-out, and ventilation access followed by the rest of the infrastructure while ore development will be planned as late as possible without delaying stoping activities. The total lateral development is separated into Capital and Operating and summarized annually in Table 13-29, and Figure 13-25 presents a graph of this data
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Table 13-29: Summary of Annual Lateral Development Metres Profile
Development Type | 2027 | 2028 | 2029 | 2030 | 2031 | 2032 | 2033 | 2034 | 2035 | 2036 | 2037 | 2038 | 2039 | 2040 | 2041 |
Operating Lateral | 14 | 2,095 | 3,725 | 5,124 | 3,943 | 4,871 | 4,813 | 8,938 | 10,383 | 4,048 | 6,452 | 5,629 | 6,075 | 730 | - |
Capital Lateral | 1,417 | 3,756 | 1,294 | 94 | 1,387 | 441 | 2,954 | 1,843 | 172 | 3,245 | 1,501 | 2,380 | 1,178 | 125 | - |
Total Lateral | 1,431 | 5,851 | 5,020 | 5,218 | 5,330 | 5,313 | 7,767 | 10,781 | 10,555 | 7,293 | 7,953 | 8,009 | 7,253 | 855 | - |

Figure 13-25: Annual Lateral Development Metres Profile
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13.5.2Underground Production Scheduling
The focus at Grey Fox will be to extract the higher-grade Whiskey Jack Zone first. Mining will then ramp-up to 1,500 t/d with the rest of Grey Fox North and then to 2,700 t/d with the addition of Grey Fox South in 2035. The process plant is located on McEwen’s Stock Property. The overall production profile and tonnage targets aforementioned are expected to be complimentary with production from other assets, notably the Stock mine, in maximizing the throughput of the Stock Mill. This is part of a “hub and spoke” asset strategy for the McEwen Assets along Highway 101.
13.5.1Production Profile
Table 13-30 and Figure 13-26 present the LOM production tonnes and profile.
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Table 13-30:Summary of Production Profile by Mining Method
Ore Type | 2027 | 2028 | 2029 | 2030 | 2031 | 2032 | 2033 | 2034 | 2035 | 2036 | 2037 | 2038 | 2039 | 2040 | 2041 |
Stoping Ore | - | 63,378 | 230,630 | 375,495 | 385,333 | 399,603 | 407,400 | 297,073 | 652,813 | 761,885 | 674,422 | 731,355 | 773,894 | 731,689 | 327,171 |
Tonnes | |||||||||||||||
Development | - | 65,079 | 85,918 | 111,472 | 90,869 | 122,508 | 104,410 | 196,130 | 238,568 | 82,550 | 178,309 | 135,939 | 135,207 | 17,941 | - |
Ore Tonnes | |||||||||||||||
Cut and Fill | - | 8,083 | 10,082 | 3,995 | 2,048 | 8,444 | 5,058 | 3,552 | 19,758 | 28,920 | 9,765 | 1,137 | 15,101 | 2,041 | - |
Ore Tonnes | |||||||||||||||
Marginal | | | | | | | | | | | | | | | |
Stoping Ore | - | - | 27,534 | 38,266 | 83,375 | 27,826 | 43,532 | 52,901 | 72,357 | 108,139 | 121,820 | 119,798 | 50,124 | 95,471 | 69,661 |
Tonnes | | | | | | | | | | | | | | | |
Total Ore | - | 136,540 | 354,164 | 529,227 | 561,625 | 558,380 | 560,400 | 549,657 | 983,496 | 981,494 | 984,316 | 988,229 | 974,325 | 847,143 | 396,832 |
Tonnes | |||||||||||||||
Average t/d | - | 374 | 970 | 1,450 | 1,539 | 1,530 | 1,535 | 1,506 | 2,695 | 2,689 | 2,697 | 2,707 | 2,669 | 2,321 | 1,087 |

Figure 13-26:Production Profile by Mining Method
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13.6 | Blasting |
13.6.1Development
Development rounds will be loaded using a mechanical explosives loader. ANFO products will be used for all primary development blasting. Specialty blasting such as lifters will be performed with package emulsion products as required.
13.6.2Stoping
ANFO and packaged emulsion products will be used for all longitudinal stope blasting. Non-electronic detonators will be used to control blast timing.
Cut-and-fill stoping will be loaded using a mechanical explosives loader. ANFO products will be used for all cut-and-fill blasting.
13.7 | Mobile Equipment Selection |
Grey Fox will be developed using a high degree of automated equipment. The main production equipment will be capable of remote operation. Mobile equipment was selected that will be appropriate for the mining methods and to support the production rate.
Equipment fleet costs and performance are supported by information from the original equipment manufacturers (OEMs) and only commercially available products were considered. The mine development contractor will use and maintain equipment provided by McEwen and will return the equipment to McEwen in proper working condition. The Alimak and raise boring raising equipment is excluded from the equipment lists as they will be provided by contractors.
Key elements considered in the ultimate equipment selection included:
· | Mine design |
· | Mining methods |
· | Productivities |
· | Fleet standardization of key components |
· | Maintainability |
· | Economics |
The diesel equipment fleet includes the main development and production gear as well as auxiliary gear to support operations.
The makes and models in the following equipment lists were used for pricing estimates at this time, similar equipment could be used.
Table 13-31 presents the complete equipment list including type, function, make, model, and total peak units for Grey Fox North.
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Table 13-31:Grey Fox North Underground Mobile Equipment List
| | |
Equipment Type | Primary Function | Units |
10 t LHD | Transferring muck from draw point to remuck or remuck to truck. | 5 |
7 t LHD | Transferring muck from development headings or raise undercuts to remuck or remuck to truck or to open stopes. | 2 |
20 t Truck | Transport material to surface or remuck | 6 |
2-Boom Jumbo | Development drilling and face ground support installation | 2 |
Mechanized Bolter | Ground support installation | 3 |
Explosive Loader | Development and production explosive loading | 1 |
Scissor Lift | Construction support | 2 |
Production Drill Rig | Production drilling, miscellaneous boreholes | 2 |
Slot Drill Rig | Stope Slot Production Drilling, Drop Raises, miscellaneous boreholes | 2 |
Forklift/Tractor | Material Handling | 3 |
Boom Truck | Material Handling and Transport | 2 |
Motor Grader | Ramp maintenance | 1 |
Small Personnel Carrier | Crew / personnel transportation | 3 |
Small Carrier (Mech/Elec) | Maintenance personnel access to equipment outside of the shop | 2 |
Fuel and Lubrication Truck | Provide fuel and lubricants to production equipment | 1 |
Table 13-32 presents the complete equipment list including type, function, make, model, and total peak units for Grey Fox South.
Table 13-32:Grey Fox South Underground Mobile Equipment List
Equipment Type | Primary Function | Units |
10 t LHD | Transferring muck from draw point to remuck or remuck to truck. | 5 |
7 t LHD | Transferring muck from development headings or raise undercuts to remuck or remuck to truck or to open stopes. | 2 |
20 t Truck | Transport material to surface or remuck | 6 |
2-Boom Jumbo | Development drilling and face ground support installation | 2 |
Mechanized Bolter | Ground support installation | 3 |
Explosive Loader | Development and Production explosive loading | 1 |
Scissor Lift | Construction support | 2 |
Production Drill Rig | Production drilling, miscellaneous boreholes | 3 |
Slot Drill Rig | Stope Slot Production Drilling, Drop Raises, miscellaneous boreholes | 2 |
Forklift/Tractor | Material Handling | 3 |
Boom Truck | Material Handling and Transport | 2 |
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Equipment Type | Primary Function | Units |
Motor Grader | Ramp maintenance | 1 |
Small Personnel Carrier | Crew / personnel transportation | 3 |
Small Carrier (Mech/Elec) | Maintenance personnel access to equipment outside of the shop | 2 |
Fuel and Lubrication Truck | Provide fuel and lubricants to production equipment | 1 |
For Grey Fox North, beginning in August 2027, a single crew will advance the main ramp down to Whiskey Jack and establish the fresh air ventilation. Once flow through ventilation is established in January 2028, a second development crew will be introduced. This second crew will remain until January 2036, and the remainder of mine life will require only one crew to support mining operations.
For Grey Fox South, beginning April 2033, a single crew will advance the main ramp to establish the flow through ventilation. Once established in October 2033, a second development crew will be introduced. This second crew will remain until January 2040, and the remainder of mine life will require only one crew to support mining operations.
Each development crew will have a two-boom drill jumbo for face drilling and installing ground support, access to a shared ANFO loader for development headings, a 7-t LHD to muck the face and load trucks, and a scissor lift for installing services. The development crew will be supported by the haulage truck fleet.
Vertical development will be a combination of drop raises, Alimak raises and raise boring. Drop raising will be completed using the slot drill unit as required. Alimak and escapeway raise boring will be completed by contractors providing the equipment as required.
Production will be largely completed by longitudinal longhole mining. Longhole ITH and top hammer drills will be used to drill the blastholes, the blastholes will be loaded using a shared explosive loader, and an LHD will muck the stope to the nearest remuck or to a waiting truck.
The fleet for each of Grey Fox North and Grey Fox South includes three mechanical bolters for cable bolt drilling and other secondary ground support installation when required.
For loading and transport, Grey Fox North and Grey Fox South, each include up to six haulage trucks with one unit being shared during peak production years for a total of 11 units. These will be accompanied by up to five 10-t LHDs for stoping, for Grey Fox North and Grey Fox South, with one unit being shared between them for a total of nine units.
There will be a peak of 37 and 38 pieces of equipment operating in Grey Fox North and Grey Fox South, respectively. This results in an overall peak of 68 total pieces of equipment operating on site, as some units are shared or permanently transferred between the two ramp networks.
The number of jumbos used for the overall peak (3) is different then the jumbo peak (4), as the overall peak does not coincide jumbo peak. There are six shared or transferred units which are one LHD, one truck, one mechanical bolter, one grader, one fuel truck, and one slot drill rig.
The mobile equipment fleet operating each year is summarized in Table 13-33.
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Table 13-33:Total Operating Equipment by Year for Grey Fox Site
Equipment Type | 2027 | 2028 | 2029 | 2030 | 2031 | 2032 | 2033 | 2034 | 2035 | 2036 | 2037 | 2038 | 2039 | 2040 | 2041 |
10-t LHD | 0 | 1 | 3 | 5 | 5 | 5 | 5 | 5 | 9 | 9 | 9 | 9 | 9 | 9 | 2 |
7-t LHD | 1 | 2 | 2 | 2 | 2 | 2 | 3 | 4 | 4 | 4 | 4 | 4 | 4 | 3 | 1 |
20-t Truck | 1 | 3 | 3 | 4 | 4 | 5 | 7 | 8 | 9 | 10 | 11 | 11 | 11 | 11 | 4 |
2-Boom Jumbo | 1 | 2 | 2 | 2 | 2 | 2 | 3 | 4 | 4 | 3 | 3 | 3 | 3 | 2 | 0 |
Mechanized Bolter | 2 | 3 | 3 | 3 | 3 | 3 | 5 | 5 | 5 | 5 | 5 | 5 | 5 | 4 | 0 |
Explosive Loader | 1 | 1 | 1 | 1 | 1 | 1 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 | 2 |
Scissor Lift | 1 | 2 | 2 | 2 | 2 | 2 | 3 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 1 |
Production Drill Rig | 0 | 1 | 2 | 2 | 2 | 2 | 2 | 3 | 4 | 4 | 5 | 5 | 5 | 5 | 2 |
Slot Drill Rig | 0 | 1 | 1 | 1 | 2 | 2 | 2 | 3 | 3 | 3 | 3 | 3 | 3 | 3 | 2 |
Forklift/Tractor | 1 | 3 | 3 | 3 | 3 | 3 | 4 | 6 | 6 | 6 | 6 | 6 | 6 | 5 | 2 |
Boom Truck | 0 | 2 | 2 | 2 | 2 | 2 | 2 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 1 |
Motor Grader | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
Small Personnel Carrier | 1 | 3 | 3 | 3 | 3 | 3 | 4 | 6 | 6 | 6 | 6 | 6 | 6 | 6 | 3 |
Small Carrier (Mech/Elec) | 0 | 2 | 2 | 2 | 2 | 2 | 2 | 4 | 4 | 4 | 4 | 4 | 4 | 4 | 1 |
Fuel and Lubrication | 0 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 | 1 |
Total | 9 | 28 | 31 | 34 | 35 | 36 | 46 | 60 | 66 | 66 | 68 | 68 | 68 | 64 | 23 |
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Equipment operating hours have been estimated from first principles. The requirement for equipment specific to development or production will fluctuate with changes to annual throughput, while some equipment will operate at a certain rate regardless of the tonnage or metres being developed.
A mobile equipment rebuilds and replacements schedule was developed based on the operating hours required and the available equipment. These rebuilds and replacements are determined by the life of the engine on the units. The total number of rebuild and replacement quantities are presented in Table 13-34.
Table 13-34:Total Number of Rebuilds and Replacements by Equipment Type
| | |
Equipment Type | Rebuilds | Replacements |
10 t LHD | 14 | 7 |
7 t LHD | 6 | 5 |
20 t Truck | 12 | 5 |
2-Boom Jumbo | 0 | 0 |
Mechanized Bolter | 0 | 0 |
Explosive Loader | 1 | 1 |
Scissor Lift | 3 | 2 |
Production Drill Rig | 0 | 0 |
Slot Drill Rig | 0 | 0 |
Forklift/Tractor | 6 | 3 |
Boom Truck | 4 | 2 |
Motor Grader | 1 | 1 |
Small Personnel Carrier | 3 | 0 |
Small Carrier (Mech/Elec) | 2 | 0 |
Fuel and Lubrication Truck | 1 | 0 |
Total | 53 | 26 |
13.8 | Ventilation |
The underground mine ventilation system is designed to be a “push-pull” system, with fans at the top of the fresh air raise and at the portals pushing fresh air into the mine and fans at the top of the return air raise pulling exhaust and contaminated air out of the mine. Heaters will be operated as required on surface at the fresh air raise in conjunction with the fresh air fans to prevent freezing in winter.
The intake ventilation fans will have a maximum design capacity of 50 m3/s each with parallel fans providing up to 250m3/s of intake air at the intake raise and portal, and the exhaust fans will provide 250 m3/s at each exhaust fan station to support development and production activities for the LOM. This ventilation capacity is based on the requirement to provide airflow for diesel particulate matter dilution, dust control, and to maintain adequate airflow through all active areas.
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13.8.1Airflow Requirements
To determine the ventilation requirements for the operating equipment at Grey Fox North and Grey Fox South, full production activities were considered with Whiskey Jack and Gibson/Contact/147NE evaluated separately due to a difference in the mobile fleet requirements and therefore the ventilation requirement in those zones.
A utilization factor was applied to estimate the operating engine power for each type of equipment, and to estimate the ventilation required (0.063 m3/s of ventilation air was provided for each kW of engine power operating). The full production ventilation required for Whiskey Jack, Grey Fox North, and Grey Fox South are provided in Table 13-35, Table 13-36, and Table 13-37, respectively. This is calculated to be 131 m3/s for Whiskey Jack, and ~237 m3/s for each of the Grey Fox North and Grey Fox South. With identical ventilation infrastructure assumed, due to the similar ventilation requirements.
Table 13-35:Whiskey Jack Full Production Ventilation Required
Equipment Type | Units | Utilization | Engine | Vent |
10 t LHD | 2 | 80% | 202 | 20 |
7 t LHD | 2 | 80% | 117 | 12 |
20 t Truck | 2 | 80% | 242 | 24 |
2-Boom Jumbo | 2 | 15% | 120 | 2 |
Mechanized Bolter | 3 | 15% | 119 | 3 |
Explosive Loader | 1 | 40% | 99 | 2 |
Scissor Lift | 2 | 40% | 110 | 6 |
Production Drill Rig | 2 | 15% | 80 | 2 |
Slot Drill Rig | 1 | 15% | 100 | 1 |
Forklift/Tractor | 3 | 40% | 74 | 6 |
Boom Truck | 2 | 40% | 110 | 6 |
Motor Grader | 1 | 40% | 97 | 2 |
Fuel and Lubrication Truck | 1 | 80% | 110 | 6 |
Small Personnel Carrier | 3 | 40% | 74 | 6 |
Small Carrier (Mech/Elec) | 2 | 40% | 74 | 4 |
Sub-Total Equipment | | | | 101 |
Leakage / Contingency | | 30% | | 30 |
Total Vent Requirements | 29 | | | 131 |
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Table 13-36:Grey Fox North Full Production Ventilation Required
Equipment Type | Units | Utilization | Engine | Vent |
10 t LHD | 5 | 80% | 202 | 51 |
7 t LHD | 2 | 80% | 117 | 12 |
20 t Truck | 6 | 80% | 242 | 73 |
2-Boom Jumbo | 2 | 15% | 120 | 2 |
Mechanized Bolter | 3 | 15% | 119 | 3 |
Explosive Loader | 1 | 40% | 99 | 2 |
Scissor Lift | 2 | 40% | 110 | 6 |
Production Drill Rig | 2 | 15% | 80 | 2 |
Slot Drill Rig | 2 | 15% | 100 | 2 |
Forklift/Tractor | 3 | 40% | 74 | 6 |
Boom Truck | 2 | 40% | 110 | 6 |
Motor Grader | 1 | 40% | 97 | 2 |
Fuel and Lubrication Truck | 1 | 80% | 110 | 6 |
Small Personnel Carrier | 3 | 40% | 74 | 6 |
Small Carrier (Mech/Elec) | 2 | 40% | 74 | 4 |
Sub-Total Equipment Ventilation | | | | 181 |
Leakage / Contingency | | 30% | | 54 |
Total Vent Requirements | 37 | | | 236 |
Table 13-37:Grey Fox South Full Production Ventilation Required
Equipment Type | Units | Utilization | Engine | Vent |
10 t LHD | 5 | 80% | 202 | 51 |
7 t LHD | 2 | 80% | 117 | 12 |
20 t Truck | 6 | 80% | 242 | 73 |
2-Boom Jumbo | 2 | 15% | 120 | 2 |
Mechanized Bolter | 3 | 15% | 119 | 3 |
Explosive Loader | 1 | 40% | 99 | 2 |
Scissor Lift | 2 | 40% | 110 | 6 |
Production Drill Rig | 3 | 15% | 80 | 3 |
Slot Drill Rig | 2 | 15% | 100 | 2 |
Forklift/Tractor | 3 | 40% | 74 | 6 |
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Equipment Type | Units | Utilization | Engine | Vent |
Boom Truck | 2 | 40% | 110 | 6 |
Motor Grader | 1 | 40% | 97 | 2 |
Fuel and Lubrication Truck | 1 | 80% | 110 | 6 |
Small Personnel Carrier | 3 | 40% | 74 | 6 |
Small Carrier (Mech/Elec) | 2 | 40% | 74 | 4 |
Sub-Total Equipment Ventilation | | | | 182 |
Leakage / Contingency | | 30% | | 55 |
Total Vent Requirements | 38 | | | 237 |
13.8.2Overall Ventilation
13.8.2.1Stage 1: Initial Development
The initial development for Whiskey Jack (Grey Fox North) and Grey Fox South from the respective portals will be supported with twin semi-rigid 0.9 m (36 ft) oval ducting from surface, until the first raise is established. Two development fans in series will be installed in each duct to support approximately 700 m of development (with the second series fan required at the midway mark). Each fan is rated at 112 kW (150 HP) and will provide 47 m3/s at the length to the first fresh air raise. To prevent freezing in the winter months, a rental 11 MMBTU/h heater will be installed at the portal, with the twin fans/ducts installed downstream of the heater. This heater will be maintained through the LOM. A schematic outlining the ventilation system for the initial ramp development at Whiskey Jack is presented in Figure 13-27.

Figure 13-27:Ventilation Schematic Initial Ramp Development
Once the first fresh air ventilation raise is established at Whiskey Jack, the existing 20 MMBTU/hr heater from Froome will be relocated to the top of the raise along with 2 x 112 kW (150 HP) intake fans pushing a
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maximum of 100 m3/s to support production and development activities. This will allow for flow through ventilation to be established, with fresh air through the raises and return air through the ramp. A schematic of this stage is provided in Figure 13-28.

Figure 13-28:Whiskey Jack Initial Flowthrough Ventilation Established
Production development fans will be installed in the fresh air bulkheads, with the duct running to the headings providing ventilation air to support the production activities.
13.8.2.1Stage 2: Transition from Whiskey Jack to Gibson
The full production ventilation system for Whiskey Jack features a second raise, for exhaust, to maintain velocity limits in the ramp and to aid in smoke clearance after blasting. The exhaust fan installed on surface on top of the exhaust raise will be a single 373 kW (500 HP) fan. Once the exhaust fan is commissioned, a second heater identical to the one installed in Stage 1 will be installed in parallel at the surface intake raise collar, with an additional two 112 kW fans.
Similar to the previous stage, bulkheads will be installed on each production level and production fans will be installed in the bulkheads to support the production activities. A schematic of the ventilation system is provided in Figure 13-29.
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Figure 13-29:Whiskey Jack Full Production Ventilation System
This stage also indicates the exhaust raise at Gibson is established to provide flow through ventilation, with the development to the raise supported by the flowthrough ventilation in the ramp. For the exhaust raise, fans identical to the Whiskey Jack exhaust fan will be installed at Gibson, with the fan from Whiskey Jack being relocated to Gibson as production in Whiskey Jack is complete.
13.8.2.2Stage 3: Life of Mine
Once production in Whiskey Jack is complete, the ramp to Whiskey Jack will be dedicated to transfer the fresh air to Gibson. The exhaust fan at Whiskey Jack, as previously noted will be moved at the Gibson exhaust raise, and Gibson will operate with 3 x 373 kW (500 HP) fans at its peak. A 10 MMBTU heater with a 112 kW (150 HP) intake fan will be installed at the ramp to provide additional intake ventilation with the heater air ducted to the portal entrance. Bulkheads and regulators will be used to push air to the bottom of Gibson. Production fans will be ducted from the closest flowthrough location on the level.
A similar ventilation system is planned for Grey Fox South, with two raises: one for fresh air and the other for exhaust air with initial development until the first raise is established and supported by the portal development fans/heaters. A schematic of the ventilation system for Gibson and Grey Fox South is outlined in Figure 13-30.
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Figure 13-30:Grey Fox North and Grey Fox South at Full Production Ventilation System
13.8.3Ventilation Infrastructure
13.8.3.1 Main Fans
The main fan motor power requirements were estimated from the ventilation model and system capabilities that are summarized in Table 13-38. These are to be verified by the vendor. The exhaust fans are to be equipped with variable frequency drives (VFDs) and will be installed as a single fan for Whiskey Jack and in a trifurcated arrangement at Gibson/Grey Fox South. The intake fans will be installed in parallel, downstream of the heaters, with ducting to the raise house which will allow for access to the secondary escapeway. All main fans are to be a four-fan arrangement and equipped with dampers to prevent re-circulation in the event of one or more fans not being in operation.
Table 13-38:Main Fan Ventilation Requirements
Location | Installation | Type | No. Fans | Airflow per | Collar Total | Estimated |
Whiskey Jack | Surface | Intake | 4 (at raise) | 50 | 1,050 | 112 |
Whiskey Jack | Surface | Intake | 1 (at portal) | 50 | 1,050 | 112 |
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Location | Installation | Type | No. Fans | Airflow per | Collar Total | Estimated |
Whiskey Jack | Surface | Exhaust | 1 | 130 | 685 | 373 |
Gibson | Surface | Exhaust | 3* | 92 | 2,600 | 373 |
Grey Fox South | Surface | Intake | 4 (at raise) | 50 | 1,050 | 112 |
Grey Fox South | Surface | Intake | 1 (at portal) | 50 | 1,050 | 112 |
Grey Fox South | Surface | Exhaust | 3 | 92 | 2,600 | 373 |
Note: * The second of three fans will be relocated from Whiskey Jack.
13.8.3.1Auxiliary Ventilation
The auxiliary fan systems were sized to provide sufficient airflow taking into consideration mobile equipment use and minimum velocity thresholds. Table 13-39 outlines the fans’ requirements for the development and production auxiliary ventilation based on the development and production activities in the mining schedule.
Table 13-39:Auxiliary Fan Ventilation Requirements
Description | Quantity | Airflow per | Fan Total | Estimated | Fan Size |
Development Fans | 8 | 25 | 2,500 | 112 | 1.07 (42”) |
Production Fans (Short Levels) | 10 | 19 | 1,900 | 75 | 0.91 (36”) |
Production Fans (Long Levels) | 20 | 19 | 2,900 | 112 | 0.91 (36”) |
Short development or production headings less than 300 m long will use flexible ducting (or layflat), while longer development or production headings will use semi-rigid PVC ducting.
13.8.3.2Ventilation Controls
Ventilation controls will be used to control the flow throughout the mine, to optimize the ventilation system performance, and reduce health and safety risks from recirculation and air short circuiting. These controls will primarily include bulkheads (including bulkheads with doors) and drop-board regulators.
Bulkheads will be used to isolate areas of the mine to prevent short-circuiting, and several types of bulkheads are planned to be utilized. Installations such as plain bulkhead with fan inserts, drop-board regulator bulkheads, and a mobile access/personnel door will be used.
For the ventilation emergency alert system, ethyl mercaptan is planned to be used as a stench gas; this will be used together with R134a as a propellant to form a gas and then introduced into the ventilation stream. The system will be located at the portal intakes and other strategic locations to ensure timely warning to all personnel in remote working areas. It will have redundancy injection and a cylinder package complete with enclosures, and the system will be sized to a capacity suitable for the air flow intake and required concentrations through the mine workings.
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13.9 Ore and Waste Handling System
The ore and waste handling system will use truck haulage consisting of up to six 20-t trucks to be loaded at designated remucks at both Grey Fox North and Grey Fox South. One truck will be shared for a total of 11 units. These will be loaded with up to five 10-t LHDs and two 7-t LHDs in each of Grey Fox North and Grey Fox South. Waste will be stockpiled on surface during initial development. During production, waste will be deposited into the stopes along with the surface stockpile and supplemented with waste rock from McEwen’s Black Fox site.
13.10 Mine Dewatering
The underground dewatering facilities at Grey Fox North and Grey Fox South are designed to receive water from two sources: groundwater seepage and underground operations. The planned backfill activities will not require flush water, nor will there be any decant water from backfill.
Groundwater seepage will contribute approximately 62.5 m3/h to each mine. While it is likely that most of this water will report to the upper levels of the mine, for the purposes of designing the mine dewatering infrastructure, it was assumed that this flow could report at depth. Service water from operations which includes drilling, dust control, washing equipment, etc. will produce an average of 19.6 m3/h of water. Water will be directed to the sumps located in the underground mine workings for a total combined average rate of 82.1 m3/h as presented in Table 13-40. Daily volumes will vary depending on the level of activities, mining sequence, etc.
Table 13-40:Estimate Water Source Flows
Mine Source | Average Flow (m3/h) |
Groundwater | 62.5 |
Service Water | 20 |
Backfill Flush/ Decant | 0 |
Total | 82 |
For each mine, a target pumping rate of 136 m3/h (600 gpm, 2,270 L/min) was selected taking into consideration the average flowrates, peak flows, and a reasonable water velocity in the pipe to maintain solids in suspension during pumping.
The dewatering system will be a cascading design that includes borehole sumps, “pocket” or “hole in the wall” sumps and decline sumps. Borehole sumps will collect and drain water to the next level below, offering no storage capacity and not equipped with a pump. The hole in wall sumps will be short decline sumps with minimal storage capacity and equipped with a single 22 to 37 kW (30 to 50 HP) submersible pump which will deliver water to another sump on the same level, or to the next level above. The decline sumps will be the major pumping stations, offering some water storage capacity (nominal 35 m3 of live capacity, depending on pump selection), and equipped with operating and standby 112 kW (150 HP) submersible pumps accessed via steel walkway and monorail/trolley,
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At Grey Fox North, main pump stations (decline sumps) will be located on 465, 365, 265, and 140 Levels in Gibson and 265 and 145 Levels in Whiskey Jack. Hole in the wall sumps will be located 315 and 215 Levels in Gibson, 295 Level in Whiskey Jack, and one located inside the portal to capture immediate ground water. Borehole sumps will be located on all other mining levels; some levels may have more than one borehole sump, depending on strike length and mine layout. Ultimately, all water will report through the main decline sump located on 115 Level and be pumped to the holding pond on surface.
At Grey Fox South, main pump stations will be located on 340, 240, 140, and 40 Levels. The uppermost main station (40 Level) will pump water to the portal and overland (approximately 2,000 m) to the collection pond on surface. Borehole sumps will be used on other mine levels to drain water to the next main station. There will also be a small sump located inside the portal to capture immediate groundwater.
13.11Backfill Distribution
The stopes will be backfilled with a combination of unconsolidated rock fill plus cemented rock fill to prevent backfill dilution in subsequent stopes while also minimizing the use of cement.
Primary method will be cemented or uncemented rock fill.
1. | Slurry delivery - Slurry will be mixed on surface in a hopper and distributed underground via borehole to an underground receiving station. |
2. | Waste Rock Mixing for cemented rock fill – The underground receiving station will be connected to a pump and spray curtain. An LHD will drive under the curtain with a load of waste rock and slurry will be sprayed over the rock. The slurry loading cutout on the levels will be developed slightly down gradient to collect any spillage. |
3. | Stope Placement – The LHD will tram and dump the cemented rock fill into the stope. |
The backfill placement is presented in Figure 13-31.
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Figure 13-31: Backfill Placement
The cemented rock fill against future stope placed first, uncemented rock fill placed second, and cemented mucking floor placed last. If stopes were being mined below there will need to be complete coverage of cemented backfill on the floor. If stopes are not being mined adjacent to or above the stope it could be filled completely with uncemented rock fill. If stopes were being mined above but not adjacent a cemented mucking floor will still be required. If stopes are not planned above a cemented muck floor will not be required. The cure time used to work on top of cemented rock fill will be 7 days and to blast a stope adjacent to cemented rock fill a 21-day cure time will be required.
The amount of cemented rock fill used in a stope compared to uncemented rock fill is summarized Table 13-41. The annual fill schedule is presented in Table 13-42.
Table 13-41:Cemented Rock Fill Backfill Factors
Stope Description | Cemented Rock Backfill % |
Longhole Stope with Stope Adjacent and/or Below and Above | 65% |
Longhole Stope with Stope Adjacent Only | 55% |
Longhole Stope with Stope Above Only | 10% |
Longhole Stope with No Stope above, below or adjacent | 0% |
Uphole Stope | 0% |
Cut and Fill Stope | 100% |
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Table 13-42:Underground Backfill Schedule
Year | Waste | Fill Required - | Development | Surface Waste | Additional Waste |
2027 | 71,581 | 0 | 0 | 0 | 0 |
2028 | 238,009 | 45,415 | 45,415 | 0 | 0 |
2029 | 147,150 | 189,588 | 147,150 | 42,438 | 0 |
2030 | 110,303 | 297,440 | 110,303 | 187,137 | 0 |
2031 | 156,252 | 322,485 | 156,252 | 34,600 | 131,633 |
2032 | 101,199 | 304,097 | 101,199 | 0 | 202,898 |
2033 | 265,146 | 329,126 | 265,146 | 0 | 63,980 |
2034 | 291,467 | 259,530 | 259,530 | 0 | 0 |
2035 | 209,397 | 495,057 | 209,397 | 31,937 | 253,723 |
2036 | 270,102 | 569,525 | 270,102 | 0 | 299,423 |
2037 | 166,025 | 535,390 | 166,025 | 0 | 369,365 |
2038 | 226,084 | 511,162 | 226,084 | 0 | 285,078 |
2039 | 185,047 | 462,944 | 185,047 | 0 | 277,897 |
2040 | 18,344 | 490,223 | 18,344 | 0 | 471,879 |
2041 | 0 | 176,497 | 0 | 0 | 176,497 |
Total | 2,456,106 | 4,988,479 | 2,159,994 | 296,112 | 2,532,373 |
13.12 | General Underground Infrastructure |
There are numerous underground facilities proposed for the Grey Fox Project. The facilities are described in this section, the total quantities of facility is presented in Table 13-43.
Table 13-43:Underground Infrastructure Matrix
Item | | Qty |
| Wash Bay | 2 |
| Fuel and Lube Storage | 5 |
Underground Facilities | Satellite Garage | 5 |
| Detonator Storage | 7 |
| Explosive Storage | 7 |
| Refuge Station/Lunchroom (permanent - 12 person) | 4 |
Refuge Station | Refuge Station (portable - 12 Person) | 8 |
| Latrine | 12 |
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Item | | Qty |
Power | Typical Electrical Room Type 1 | 12 |
Typical Electrical Room Type 2 | 27 | |
| ||
| Slurry Surface Hopper | 3 |
Rockfill | Slurry Distribution Station | 5 |
| Slurry Receiving Station | 28 |
| Hole in Wall Sump (with Pump) | 8 |
Mine Water | Borehole Sump/ Slash | 31 |
Decline Sump | 11 | |
| ||
| Pressure Regulating Valve Station | 21 |
13.12.1Personnel and Material Movement
All personnel and materials will be transferred to and from the underground workings via a mine ramp.
During full mine production an additional means of emergency egress from the mine will be a ladder system located in the fresh air raise to surface of each mine exiting through an airlock in the fan ducting on surface. A series of dedicated internal escapeways will lead to this emergency egress through both mines. For Grey Fox North, personnel will have to travel across 65 Level in the Gibson Zone and down the Whiskey Jack Ramp to the fresh air raise.
13.12.1.1Personnel Movement
Personnel carriers will be used to move workers between surface and the underground workplaces at the start and end of each shift. Workers that operate mobile equipment will park in a designated area (in some cases on surface) at the end of each shift.
13.12.1.2Material Movement
Consumable materials, equipment, and maintenance parts will be delivered to designated underground storage locations via the mine ramp using boom trucks.
13.12.2Refuge Stations
Refuge stations will be located throughout the mine in the fresh air circuit, and the vertical interval between stations will not exceed 100 m. To achieve this a refuge station will be placed every third level at a minimum. Therefore, every working level will have access to a refuge either on that level or up/down a single vertical level.
The refuge stations will serve the development, production, maintenance, and construction crews working in the area. Portable refuge stations will primarily be used and will be moved when areas of the mine cease production. Permanent Refuge Stations will accompany the underground maintenance shops except in the
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Whiskey Jack Zone and serve dual purpose as lunchrooms. A latrine or portable sanitary system will be provided near each refuge station location.
13.12.2.1Permanent Refuge Stations
Permanent refuge stations will be used primarily as an employee lunchroom but are designed for use during emergency situations located on the same levels as the underground workshops except in the Whiskey Jack Zone. Whiskey Jack will not have a permanent refuge station due to its relatively short production life.
Each refuge station will be constructed with materials that have at least a one-hour fire resistance rating, and will be equipped with the following:
· | Boot and hand-washing facilities for use prior to entering the refuge station |
· | Racks to hang outer work gear prior to entering the refuge station |
· | Thirty-six hours of potable water and bottled respirable air |
· | Emergency food |
· | Lights |
· | First aid supplies |
· | Sanitation facilities |
· | Service water line |
· | Suitable firefighting equipment |
· | Sufficient seating for each worker |
· | Multiple means of communication with the surface |
· | A double door that creates an air lock when closed |
· | Means of tight sealing the door to prevent gases from entering |
13.12.2.2Portable Refuge Stations
Portable refuge stations will be strategically purchased throughout the LOM. As mine development and production advances into new mining areas, these portable refuge stations will be placed in appropriate existing cutouts. As mining ceases in areas the stations will be moved to alternate locations.
13.12.3Explosives and Detonators Storage Facilities
Underground storage magazines for explosives, detonators, and blasting accessories will be located on the 90 Level in the Whiskey Jack Zone, 140, 265, and 390 Levels in the Gibson Zone, and 140 and 240 Levels in Grey Fox South. These will be set a safe distance from the underground infrastructure and work areas. There will be separate magazines for explosives and detonators.
Explosive products used for development and production mining will be securely handled and stored in the magazines, including ANFO, packaged emulsion explosives, and detonators.
All explosives will be stored, stacked, and labeled to facilitate a first-in / first-out inventory control system. Each magazine will be designed with a locking gate. The location of the explosive or detonator facility will be at least 25 m from the main travel way.
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Explosive and detonator materials will be transported via truck from the surface via the ramp to the underground magazines. Special trucks operated by trained and authorized individuals will be used to transport explosive materials from the underground magazines to the workplace.
13.12.4Maintenance Shop
The main workshop for the mine will be located on surface and mobile equipment will be driven up ramp for maintenance and repair. Underground workshops will be constructed on the 175 Level in the Whiskey Jack Zone, 140 and 315 Levels in the Gibson Zone, and 140 and 240 Levels in Grey Fox South.
These underground workshops will be used for minor repairs and maintenance to supplement the main workshop on surface. The underground workshops will be a single-bay facility that can service up to two pieces of mobile equipment.
13.12.5Fuel and Lubricants
The underground mine will have a fuel and lube storage accompanying each of the underground workshops on 175 Level in the Whiskey Jack Zone, 140 and 315 Levels in the Gibson Zone, and 140 and 240 levels in Grey Fox South. A fuel and lube truck will be the primary delivery vehicle.
Fuel bladders will be transported via truck from surface via the mine ramp to the fuel bays. Lubricants will be transported in bladders and pails via truck from surface via the mine ramp to the lube storage bays.
A fire door will be installed at the entrance to the fuel and lubricant bay. This door will close in the event of a fire to prevent any potential fires and noxious gases from spreading into the mine. Fire detection and suppression equipment that interfaces with the mine’s emergency alarm system will be included in the fuel and lubricant storage bays. All mobile equipment will have onboard fire suppression systems.
13.13General Underground Services
13.13.1Compressed Air
Permanent compressors will be located in a building on surface at each portal for Grey Fox North and Grey Fox South to provide compressed air for the mine development and operating phases. Each compressor house will have three compressors installed, with two normally operating and the third typically on standby, but occasionally able to provide additional capacity if required.
Compressed air will be used by the drills (production and jumbos), bolters, face pumps, miscellaneous hand tools, garage facilities, Alimaks, and a source of emergency air for the refuge stations. Compressed air usage underground was estimated as approximately 1.1 m3/s or 2,350 cubic feet per minute (cfm), with peak flows of approximately 1.4 m3/s (3,000 cfm).
The compressors are sized to deliver nominally 0.7 m3/s (1,500 cfm) each, with motor size of 220 to 260 kW (300 to 350 HP), final flow and related motor size will depend on the compressor manufacturer’s standard offerings. An air receiver will be located at each compressor plant. At each mine, a DN150 (6” diameter)
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pipe will be installed from the air receiver to the portal and in the ramp. Branches to the mine levels will be DN100 (4” diameter) pipe.
13.13.2Service Water
Service water will be required for use in exploration, development, production drilling, dust control, washing floors and equipment, preparing shotcrete and concrete mixes, fire protection, and other miscellaneous processes. The underground water distribution system will be supplied from a surface holding pond (the same holding pond to which the underground mine dewatering pumps report).
Pumps will be installed in a pumphouse near the surface holding pond to provide service water to each underground mine. The pumps will use variable frequency drives and/or a pressure tank to maintain pressure and flow under varying conditions. Table 13-44 outlines the primary service water usage underground at each mine (common fleets, quantities, and usage profiles at each).
Table 13-44:Service Water required by Equipment Type
Equipment | Qty | Water | Utilization | Operating | Total | Peak | |
| |||||||
| |||||||
| |||||||
| |||||||
2-Boom Jumbo | 2 | 200 | 50% | 7.5 | 90,000 | 400 | |
Mechanized Bolter | 3 | 100 | 15% | 7.5 | 20,250 | 300 | |
Production Drill Rig | 3 | 49 | 80% | 7.5 | 53,352 | 148 | |
Slot Drill Rig | 1 | 35 | 80% | 4.0 | 6,739 | 35 | |
Dust Control | 4 | 30 | 5% | 2.0 | 720 | 120 | |
Handheld Drill | 4 | 28 | 25% | 6.0 | 10,080 | 112 | |
Diamond Drill | 1 | 130 | 50% | 8.5 | 33,150 | 130 | |
Subtotal | | | | | 214,291 | 1,245 | |
Allowance – leaks, misc. | 10% | | | | 21,429 | 125 | |
| | | | Average | 327 | | |
| |||||||
| |||||||
| | | | Peak (L/min) | | 1,370 | |
At each mine, the average flow is estimated to be 327 L/min, with peaks to 1,370 L/min. The distribution pipe will be sized to deliver peak flows. A DN150 (6 in diameter) pipe will be installed in each main ramp with smaller branches on each level. Pressure reducing stations will be installed every second level to maintain the pressure suitable for use.
13.13.3Potable Water
Potable water will be delivered underground via large plastic bottles. Potable water will be provided in underground workshops, permanent refuge stations, and dedicated bottle filling stations.
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Personnel must fill appropriate water containers on surface or at a designated bottle filling station and carry a water supply to the work areas.
13.13.4Fire Water
Underground fire-related services are required to meet National Fire Protection Association requirements including fire water, fire detection and suppression systems, and dedicated reservoirs.
Fire water must be available for underground fire suppression, hose reels, and sprinkler systems.
Fire detection and suppression systems will interface with the emergency alarm system and will be included in areas at high risk of fires. These areas include the underground workshops. Individual operating systems, such self-contained fuel and lube units and hydraulic power units, will be equipped with integral fire-suppression and will not require fire water.
Dedicated reservoirs will be excavated a level above the underground workshops, approximately 12 m long to contain sufficient volumes of water to provide sufficient water for the fire suppression requirements.
13.14Underground Electrical and Power Distribution
The power distribution system for Grey Fox North will be four feeders from the surface substation to the Grey Fox North portal and down the ramp. Power will be distributed from the ramp electrical room via the ramp to the levels. Power will be distributed throughout the mines via ramp and boreholes, maximizing the use of boreholes wherever possible to reduce the cable lengths and voltage drop. Power feeders will also alternate powering levels in Gibson to provide redundancy.
The power distribution system for Grey Fox South will be four feeders from the surface substation to the Grey Fox South portal and down the ramp. Power will be distributed from the 40 Level electrical room via ramp and boreholes, maximizing the use of boreholes wherever possible to reduce the cable lengths and voltage drop. Power feeders will also alternate powering levels in the to provide redundancy.
13.14.1Underground Electrical Distribution
Power for the Grey Fox North mine will be provided via four 5 kV feeders. Feeders will land in the ramp electrical room. On the secondary side of the switchgear, one feeder will provide power to Whiskey Jack and four feeders will provide power to the remaining Grey Fox South areas to support mining activities, as well as development, underground infrastructure, dewatering and ventilation.
Power for the Grey Fox South mine will be provided via four 5 kV feeders. Feeders will land in the 40 Level electrical room, then distribute to support mining activities, as well as development, underground infrastructure, dewatering and ventilation.
The main ventilation fans for both mines are powered on the surface from separate feeders from the surface substation.
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The power distribution system is designed to have a main (Type 1) electrical room every three to four levels to provide power to three to four smaller (Type 2) electrical rooms. From the electrical room on each level, 5 kV power will be fed to development and production equipment, while a 600 V power distribution panel or splitter will feed power to infrastructure facilities (ventilation, dewatering, shops, etc.).
Boreholes will be used to route both 5 kV and 600 V power between levels to minimize voltage drop and to protect cabling.
Figure 13-32 presents the underground power distribution system and the locations of the types of electrical rooms.
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Figure 13-32:Underground Power Distribution Routing
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Figure 13-33 presents the layout of a typical Type 1 electrical room. Type 1 electrical rooms will consist of metal enclosed switchgear, underground substation or a mine power center, 600 V power distribution panel or splitters, lighting transformer and panel, remote I/O cabinet (as required), network cabinet and medium and/or low voltage junction boxes (as required).

Figure 13-33:Type 1 Electrical Room Layout
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Figure 13-34 presents the layout of a typical Type 2 electrical room. Type 2 electrical rooms will consist of a 600 V power distribution panel or splitters, lighting transformer and panel, remote I/O cabinet (as required), network cabinet and medium and/or low voltage junction boxes (as required). The Type 2 electrical rooms are designed to have the space for an underground substation (a mine power center) for mine development purposes.

Figure 13-34:Type 2 Electrical Room Layout
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13.14.2Load List and Schedule for Mining Facilities
Table 13-45 provides a load summary by area for underground and surface mining facilities, while
Table 13-46 and Table 13-47 provide power schedules broken down by quarter and by year, respectively.
Table 13-45: Grey Fox Mining Load Summary (for peak year – 2038)
Area | Demand Load (kVA) | % of Total |
Surface Infrastructure | 1,091 | 5% |
Surface Dewatering | 590 | 3% |
Surface Ventilation | 4,295 | 21% |
Surface Compressors | 1,746 | 9% |
Underground Mining Equipment | 926 | 5% |
Underground Infrastructure | 3,921 | 19% |
Underground Dewatering | 2,362 | 11% |
Underground Ventilation | 5,658 | 27% |
Total | 20,589 | |
Table 13-46:Power Schedule by Quarter
| 2027 | 2028 | ||||||
| Q1 | Q2 | Q3 | Q4 | Q1 | Q2 | Q3 | Q4 |
Load (kVA) | 0 | 0 | 2,118 | 2,825 | 5,008 | 7,496 | 8,029 | 8,446 |
Table 13-47:Power Schedule by Year
| 2029 | 2030 | 2031 | 2032 | 2033 | 2034 | 2035 | 2036 | 2037 | 2038 | 2039 | 2040 | 2041 |
Load | 9,751 | 9,891 | 10,689 | 10,916 | 15,489 | 18,124 | 19,645 | 19,975 | 20,117 | 20,589 | 20,135 | 18,958 | 17,670 |
13.15Underground Communication and IT
The underground communication between levels will be routed using a combination of ramp, drift and/or boreholes (for fiber optic and analog telephone systems) to minimize cable lengths or routed in the ramps (Leaky Feeder system) to ensure coverage to every underground area. Communication cables installed in boreholes will be kept separate from power cables.
The following systems are planned as part of the underground communication and IT package:
· | Fibre optic network |
· | Underground wireless network (5G) |
· | Leaky feeder system (radio) |
· | Analog telephone |
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13.15.1Fibre Optic Network
The underground fiber optic network will be used for transmitting information for business networks, process control networks, and other dedicated systems (as required). The design for the fiber optic network will be a star topology, with the backbone connecting all underground Type 1 network cabinets, located in each electrical room.
13.15.2Underground Wireless Network (5G)
The underground wireless network will be 5G using dedicated fibers from the fiber optic backbone to connect hardware throughout the mine. The 5G network will be the primary communication system underground to be used with telephones, tablets, and other peripheral devices. The 5G network will also be used for data collection (e.g., mobile equipment telemetry, equipment/personnel tracking), and tele-remote operation.
13.15.3Leaky Feeder System (Radio Communication)
The leaky feeder system will be the primary method of communication in the ramp during development activities until the fiber optic backbone and 5G system is installed. The system’s head end will be in the surface substation, and it will be connected to the local network cabinet.
Underground, the leaky feeder system will be routed along the main ramp and will split into the main level access drift of each level.
13.15.4Analog Telephone
Analog telephones will be used for underground communications and will be in each electrical room and refuge station.
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14 Processing and Recovery Methods
14 | Processing and Recovery Methods |
The Project involves the processing of Grey Fox underground material through the existing Stock Mill. Ore is sourced from underground mining operations only, crushed to -120 mm at the Grey Fox portals using a new modular jaw crushing plant, and then trucked to stockpiles at the Stock Mill. The crushing plant at Grey Fox and the trucking of crushed rock to the Stock Mill operates for 8 hours daily during daylight hours only.
Primary crushed material is loaded from stockpiles at the Stock Mill through the existing load-in to the two-stage crushing circuit. The -12 mm product from the crushing circuit is stored in the fine ore bin and is nominally 80% passing approximately 8 mm. Finely crushed ore is reclaimed from the fine ore bin and fed to the existing two-stage grinding circuit, which comprises a primary ball mill followed by two parallel ball mills. Ore is ground to a P80 of 75 µm and then pumped to the existing thickener for densification ahead of treatment in the existing leach- carbon-in-leach (CIL) circuit.
The existing 3-t elution circuit and smelting operation are used to produce dorè bars. Tailings are deposited in the existing Stock Mill tailings management facility.
Metallurgical testwork demonstrated variable ore characteristics, with whole-ore cyanidation recoveries ranging from 70% to 95%, with an average of approximately 88%. Mineralogical analysis confirmed that gold is primarily associated with pyrite.
Testwork also indicated that flotation followed by fine grinding of the flotation concentrate could improve overall recoveries for certain portions of the orebody. However, retrofitting flotation and regrinding into the existing Stock Mill flowsheet would be costly and operationally disruptive and was therefore not considered economical. As a result, the existing whole-ore cyanidation flowsheet was adopted unchanged for the Project.
Comminution testing indicated a hard and competent ore requiring significant grinding energy. Consequently, the installed grinding power available at the Stock Mill represents the primary processing bottleneck and determines the overall achievable throughput.
The process flowsheet incorporates the following main unit operations:
· | Primary crushing (at Grey Fox) |
· | Transportation to Stock Mill |
· | Secondary and tertiary crushing |
· | Two-stage grinding and classification |
· | Densification |
· | Cyanidation |
· | Recovery of gold onto activated carbon |
· | Elution, electrowinning and smelting to produce doré |
Detailed descriptions of each unit operation are provided in Section 14.3.
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14.1 | Process Flowsheet |
The Grey Fox process flowsheet was developed based on metallurgical testwork results and industry best practice guidelines. The proposed flowsheet, as shown in Figure 14-1 below, incorporates crushing, grinding, and cyanidation stages tailored to the ore characteristics determined during testwork.

Figure 14-1:Block Flow Diagram for the Treatment of Grey Fox Ore
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14.2 | Process Design Criteria |
Table 14-1 below summarises the key design criteria for the treatment of Grey Fox ore from underground mining operations through the existing Stock Mill. Note that the “Nominal” and “Design” cases refer to the average (50th percentile) and design (85th percentile) ore hardnesses, respectively. The expected average throughput for each case reflects the maximum throughput at which the installed grinding equipment can deliver the targeted grind size of 80% passing 75 µm.
Table 14-1: Process Design Criteria
Description | Units | Nominal | Design |
General: | | | |
Expected throughput | t/d | 1,470 | 1,123 |
ROM Feed Grade | g Au/t | 3.42 | 3.42 |
Gold Extraction (Overall) | % | 88 | 88 |
ROM Feed Specific Gravity | | 2.91 | 2.91 |
JKTech Axb Parameter (50th and 85th Percentiles) | | 33 | 30 |
Bond Ball Mill Work Index (50th and 85th Percentiles) | kWh/t | 23.2 | 27.2 |
Primary Crushing: | | | |
Primary Crushing Section Utilization | % | 33.3 | 33.3 |
ROM Feed Grizzly Square Aperture | mm | 350 | 350 |
Primary Crushed Product P80 | mm | 100 | 100 |
Moisture | % | 3.0 | 3.0 |
Throughput Rate | tph | 183.8 | 140.4 |
Secondary and Tertiary Crushing: | | | |
Sec and Tertiary Crushing Section Utilization | % | 70 | 70 |
Tertiary Crushing Circuit Product P80 | mm | 7.3 | 7.3 |
Throughput Rate | tph | 87.5 | 66.8 |
Grinding: | | | |
Grinding Section Utilization | % | 92 | 92 |
Throughput Rate | tph | 66.6 | 50.9 |
Grinding Section Product P80 | µm | 75 | 75 |
Total power available (3 motors’ nameplate) | kW | 2,034 | 2,034 |
Total pinion power available (after 8% losses) | kW | 1,871 | 1,871 |
Total pinion power required | kW | 1,871 | 1,871 |
Leaching and Adsorption: | | | |
NaCN consumption (Testwork) | kg/t | 0.42 | 0.42 |
Hydrated Lime Consumption (Testwork) | kg/t | 2.35 | 2.35 |
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Description | Units | Nominal | Design |
Number of large Leach tanks | # | 2 | 2 |
Number of CIL tanks used for leaching | # | 2 | 2 |
Number of CIL tanks used as CIL tanks | # | 4 | 4 |
Slurry Residence Time Required | h | 34 | 34 |
Slurry Residence Time Provided | h | 45 | 57 |
Targeted Solution Tails Concentration | mg/L | 0.01 | 0.01 |
Carbon Concentration | g/L | 10 | 10 |
Loaded Carbon Grade | g/t | 3,700 | 3,700 |
Eluted Carbon Grade | g/t | 100 | 100 |
Cyanide Detoxification: | | | |
Total Residence Time Required | h | 2.5 | 2.5 |
SO2: WAD requirement | kg/kg | 4.6 | 4.6 |
Cu: WAD requirement | kg/kg | 0.1 | 0.1 |
CIL terminal WAD CN | ppm | 100 | 100 |
Reclaim Return Solution WAD CN conc. | ppm | 50 | 50 |
Target WAD CN concentration | ppm | 0.1 | 0.1 |
Elution and Regeneration: | | | |
Available carbon batch size | t | 3 | 3 |
Expected number of strips (calculated) | per week | 2.5 | 1.9 |
Max Strips per Day | # | 2 | 2 |
Carbon regeneration kiln energy | kWh/kg | 2 | 2 |
Elution heater benchmarked energy cons. | kW/t carbon | 230 | 230 |
Carbon regeneration kiln run time | h/d | 20 | 20 |
Note: WAD CN = Weak Acid Dissociable cyanide
14.3 | Process Description |
14.3.1Crushing
The proposed Grey Fox underground material will be processed through the existing Stock Mill facility at an average rate of 536,550 dry tonnes per year (1,470 t/d), with a ROM ore head grade of 3.42 g/t Au. When treating ore blocks of above-average hardness, the average throughput is expected to decrease to as low as 1,123 t/d at the 85th percentile of hardness.
The primary crushing section at the Grey Fox site is staffed for 12 h/d but operates for 8 h/d. This operating schedule avoids nighttime transportation of ore and allows 4 h/d for delays and maintenance. Ore is fed to a modular primary crushing plant consisting of a ROM feed bin, a vibrating grizzly feeder, a fixed rockbreaker, a C106 jaw crusher, and a crushed product conveyor. Crushed rock is loaded by front-end loader onto road
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trucks and transported to the Stock Mill, where it is dumped onto stockpiles. This primary crushing front end consists of new equipment that has been specifically purchased for the Project. All subsequent processing is conducted through the existing facilities at the Stock Mill, as described below.
Primary crushed ore is reclaimed from stockpiles by front-end loader and fed into the load-in bin. The material is conveyed via a dedicated conveyor to an open-circuit Sandvik CH430 secondary cone crusher. Secondary crushed product (-40 mm) is conveyed by two conveyors to a double-deck banana screen measuring 6.1 m in length by 2.05 m in width. Screen oversize (+10 mm) reports to a Metso Nordberg HP300 tertiary cone crusher. Screen undersize (-10 mm) is conveyed to the fine ore bin. Tertiary crushed product is recycled via the screen feed conveyor back to the banana screen. The fine ore bin has a capacity of 1,360 tonnes, providing approximately one day of surge capacity between the three-stage crushing front end and the downstream grinding circuit.
14.3.2Grinding
Two reclaim belt feeders extract finely crushed ore from the fine ore bin and discharge onto the primary ball mill feed conveyor.
The primary ball mill has a diameter of 3.66 m and an effective grinding length (EGL) of 5.49 m and is driven by a 1,250 kW motor. The mill discharges into a dedicated cyclone feed pumpbox, from which slurry is pumped to a dedicated 4-way cyclopack fitted with 380 mm diameter hydrocyclones. Cyclone underflow returns to the primary ball mill feed chute, while cyclone overflow reports to the secondary grinding cyclone feed pumpbox.
The primary ball mill circuit product is subjected to further grinding in two parallel ball mills, designated as Secondary Ball Mill #1 and Secondary Ball Mill #2. The two secondary ball mills are similarly sized but not identical. Secondary Ball Mill #1 has a diameter of 2.89 m and an EGL of 3.66 m, while Secondary Ball Mill #2 has a diameter of 2.74 m and an EGL of 3.48 m. These mills are driven by 448 kW and 336 kW motors, respectively.
The secondary ball mills operate in closed circuit with a common secondary grinding cyclone cluster, which ensures that coarse particles are returned to the mills, while fine slurry proceeds to downstream processing. The cyclone cluster consists of six ports, with three 250 mm diameter cyclones in operation, two installed standbys, and one blanked port.
Cyclone overflow is directed to a trash screen to remove wood chips, plastics, and similar foreign objects. Screen underflow flows by gravity to the thickener feed pumpbox, from which it is pumped to the 19.8 m diameter high-rate thickener. Cyclone underflow is split into two streams that recycle back to the feed chutes of the two secondary ball mills.
14.3.3Sedimentation, Leaching and Carbon-In-Leach
Flocculant is added at a rate of approximately 15 g/t solids to promote settling and clarification in the thickener. Thickener underflow, at a density of approximately 50% w/w solids, is pumped to the first of two leach tanks, while thickener overflow flows by gravity to the process water storage tank for re-use.
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Sodium cyanide and lime are added to extract gold from the finely ground ore. Most of the sodium cyanide and lime, approximately 0.42 kg/t NaCN and 2.35 kg/t lime, are added into the first leach tank. The two large leach tanks have a live capacity of 1,166 m3 each, providing approximately 27 h of leach residence time at the nominal throughput rate. Additional lime and cyanide are added downstream to maintain a minimum level of free cyanide concentration and to ensure the slurry pH remains above a minimum of 10.7. Compressed air is bubbled through all leach and CIL tanks to provide oxygen for the oxidation reactions occurring during cyanidation.
Slurry from the second leach tank flows by gravity to the six CIL tanks (277 m3 live capacity each). The first two tanks operate as leach tanks only, with no carbon addition. The remaining four tanks are equipped with carbon advance pumps and carbon retention screens, allowing them to operate as CIL tanks.
The combined residence time for the two leach tanks and six CIL tanks is 45 h, which exceeds the required residence time of 34 h by a significant margin.
Activated carbon is added to the four CIL tanks to adsorb dissolved gold to a target solution concentration of approximately 0.01 mg/L. A minimum carbon concentration of 10 g/L is maintained in the four CIL tanks to limit the amount of pumping required to move 1.24 t/d of carbon. At this advancement rate, the loaded carbon has a grade of approximately 3,700 g/t Au.
A carbon safety screen is installed as a final safeguard against gold loss. This vibrating screen intercepts any gold-bearing carbon that may pass through the carbon retention screen or broken carbon particles, preventing loss of gold to the tailings management facility.
14.3.4Acid-Washing, Elution and Regeneration
Loaded carbon, extracted from the first CIL tank, is stripped using the pressure Zadra process in 3-t batches. With the 3-t circuit and an expected gold loading of 3,700 g/t, approximately 2.5 strips per week would be required under nominal operating conditions. This is again well below the typical industry practice, which generally ranges from 5 to 6 strips per week.
Following washing on the loaded carbon screen, the washed carbon flows by gravity from the screen to the acid wash column, where it is contacted with dilute nitric acid at a concentration of 3% w/w. The purpose of the acid wash step is to remove any calcite buildup from the carbon in preparation for the subsequent elution step. The acid wash cycle employs sequential soak and rinse steps, using 0.60 bed volumes of dilute acid followed by rinsing with two bed volumes of clean water. The total acid wash cycle duration is typically 10 h.
Following acid washing and neutralization, the carbon is transferred to the elution column. The elution cycle lasts approximately 15 h and includes carbon transfer from the acid wash, solution preheating, elution, carbon cooling, and transfer from the elution column to regeneration. The resultant loaded solution (eluate) is processed by electrowinning to produce a gold sludge for smelting.
Stripped carbon from the elution process is first dewatered on a screen and then flows by gravity into a storage bin, from which it is fed at a controlled rate into the regeneration kiln.
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Carbon regeneration is performed in a horizontal, electrically heated kiln with a minimum power rating of 143 kW and a capacity of 100 kg/h. The kiln operates at temperatures ranging from 650°C to 700°C. Reactivated carbon discharges into a quench tank, with the discharge pipe terminating below the water surface to prevent combustion of the carbon. From the quench tank, regenerated carbon is pumped to a horizontal vibrating sizing screen for removal of carbon fines before being returned to the adsorption circuit.
14.3.5Smelting
The pregnant solution (gold-rich eluate) is collected in a dedicated pregnant solution tank and pumped to two operating electrowinning cells. Each electrowinning cell contains 30 stainless steel cathodes onto which gold is plated. Once loaded, the metals sludge is dislodged from the cathodes using a high-pressure washer and then dewatered using a small pressure filter. The filtered sludge is dried in an oven and smelted in a furnace to produce doré bars.
On average, approximately one smelt is required per week. The furnace has significant spare capacity to accommodate short-term grade peaks.
14.3.6Tailings Detoxification and Disposal
CIP tailings are directed through the carbon safety screen to a tailings pumpbox, from which they are pumped to the tailings management facility. A dam lift is planned for the 2026-2027 period to expand tailings management facility capacity as required for continued deposition. Supernatant solution is reclaimed and returned to the Stock Mill to replenish the process water system. Prior to reuse or discharge, the reclaimed solution is treated in dedicated detoxification tanks to destroy residual CNWAD.
Chemical oxidation using the SO2/air process is employed to convert cyanide into environmentally safe compounds. Sodium metabisulphite is used as the sulphur dioxide source, while hydrated lime is added to neutralize acid generated during the detoxification reactions. Air is bubbled through the tanks to supply oxygen for the oxidation process.
14.3.7Reagent Systems
Reagents used in the process plant include hydrated lime, sodium cyanide (NaCN), activated carbon, caustic soda (NaOH), nitric acid (HNO3), flocculant, smelting fluxes (borax, silica sand, and nitre), antiscalant, copper sulphate (CuSO4), and sulphur dioxide (SO2).
Reagent mixing is carried out in a dedicated area of the plant specifically designed with appropriate safety features, including air extraction systems and bunded containment equipped with dedicated sump pumps. Reagents are typically prepared in batches. Once mixed, each batch is transferred from the mixing tank to a storage tank, from which it is delivered to end-use points at controlled rates. Dosing is generally achieved using positive displacement pumps to ensure accuracy and consistency.
One of the decommissioned CIP tanks is used for hydrated lime mixing.
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14.3.8Water Services
Reclaimed water is recovered from the tailings management facility supernatant pond and is detoxified prior to being returned to replenish the Stock Mill process water inventory. Due to the hardness of the Grey Fox ore, throughput is reduced and all water services are therefore operated at reduced capacity.
14.3.9Air Services
Existing compressors are used to supply compressed air for leaching and detoxification aeration, as well as for operation of filter presses and all pneumatic equipment.
14.4 Conclusions
Due to the hardness of the Grey Fox ore, the Stock Mill will continue to operate at a reduced throughput relative to its current capacity. This provides the benefit of longer cyanidation residence time, which has been shown to be required for some of the samples tested.
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15Infrastructure
The Grey Fox infrastructure (Figure 15-1) will include ore and waste stockpiles, primary crushing facility, water collection ponds, two underground portals (North and South Portals) with associated ventilation plants, and supporting buildings including administration and dry facilities, gatehouse, compressor facilities, and maintenance shop.
Site access is provided via Tamarack Road, a public road connected to Ontario Highway 101 near the town of Matheson. Ore produced at the site will be trucked via Highway 101 to the Stock Mill, located approximately 34 km west. Electrical power will be supplied through a tie-in to the existing grid infrastructure along Tamarack Road.

Figure 15-1: Grey Fox Site Plan
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15.1 Existing Infrastructure
The Grey Fox Project is located approximately 3 km south of the Black Fox site, which includes the currently operating Froome underground mine. As a result, the Project can leverage selected existing infrastructure at the Black Fox site to support early development and construction activities at Grey Fox (Figure 15-2).
Facilities that can be used to support early works include:
| ● | 27.6 kV Grid Electricity |
| ● | Security office and parking |
| ● | Office and dry facilities |
| ● | Surface maintenance shop |
| ● | Fuel storage tanks |
| ● | Water collection pond |
| ● | Clean waste rock stockpiles |
| ● | Available capacity within existing overburden stockpiles |
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Figure 15-2: Grey Fox and Existing Black Fox Site Plan
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15.2 Project Site Preparation
The Grey Fox site layout is presented in Figure 15-1. The site is designed to be compact and centralized around the two mine portals. Prior to construction, a significant portion of the site, particularly around the Grey Fox North Portal and areas north of the river designated for the office and dry area, will be cleared and grubbed. Soil and organics will be stockpiled for future surface reclamation. The remainder of the site will be cleared prior to the development of the Grey Fox South Portal and related surface facilities.
Contractor and mine laydown areas will be established and utilized for site establishment activities. The existing maintenance shop at the Black Fox site will be used for early equipment commissioning and maintenance until the Grey Fox surface maintenance shop is constructed.
Clearing and grubbing activities will include disposal of brush, roots, and stumps. Cutting and disposal of trees have already been completed. The area surrounding the Grey Fox North Portal will be roughly graded prior to construction.
15.2.1Soil Storage
Topsoil removed from the site will be stored in the designated soil storage area for reclamation at Black Fox site. The actual volume of stripped topsoil stored for reclamation will be determined with a complete site investigation and geotechnical assessment.
15.3 Project Access
15.3.1Mine Road
The existing gravel road, Tamarack Road, provides access south of Highway 101 and will be used for transportation of mine personnel and general supplies, as well as for hauling ore to the Stock Mill (Figure 15-3). The road is in good condition and will require minimal maintenance. An existing bridge crossing the Pike River is located approximately 2.5 km south of Highway 101 and will require a field inspection prior to commencement of underground construction to confirm suitability for its intended use without restriction. McEwen Inc. has begun discussions with the Township of Black River-Matheson regarding the care and custody of this infrastructure.
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Source: (Google Earth 2026; Site Visit 2025)
Figure 15-3: Grey Fox Site Access Road
15.3.2Highway 101
Traffic on public Highway 101, including the segment near the Tamarack Road intersection and the town of Matheson, is under the jurisdiction of the Government of Ontario and is maintained accordingly, including winter snow removal. New turn-in and turn-out lanes, along with road lighting, are recommended at the intersection of Tamarack Road and Highway 101 to improve visibility and safety, given the anticipated increase in traffic movements during nighttime operations.
15.3.3Existing Tamarack Road Bridge
The Tamarack Road Bridge is a 42 m long single-span, 30° skewed steel plate girder structure with a cast-in-place concrete deck supported on elastomeric bearings. It carries a single lane of two-way traffic.
Using the Canadian Highway Bridge Design Code (CSA S6:19), Section 14, a desktop assessment was completed of the bridge superstructure under permanent loads, including steel, deck and barriers, and asphalt wearing surface. Transitory loads were assessed as well, including normal traffic loading (CL1, CL2, CL3 625 Ontario truck and lane loads) and permit bulk mining trucks, including CAT777G, CAT773G, CAT745C, and CAT770.
Assessment results indicate the steel girders have adequate capacity for both normal traffic loading and the assessed permit bulk mining vehicles; however, the existing concrete deck does not. Load posting is not
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recommended for normal traffic, provided the bridge continues to exhibit no signs of distress. Annual visual inspections are advised to confirm ongoing deck performance.
To enable mining operations involving heavier vehicles in a future mining scenario, deck strengthening would be required. Options include bonded fibre reinforced polymer sheets applied to the deck surface, or partial-depth deck replacement with modern stainless-steel reinforcement and steel traffic barriers, which would provide sufficient capacity for CAT745C and CAT770 vehicles or equivalent. Full-depth deck replacement and thickening, using either cast-in-place or precast panels, would be required to accommodate larger CAT777G and CAT773G trucks, as well as CAT745C and CAT770 vehicles.
If deck replacement proceeds, ancillary rehabilitation works should also be integrated, including replacement or elimination of expansion joints, assessment of elastomeric bearings for condition and capacity, development of a bearing replacement strategy if needed, and upgrading of approach slabs to accommodate heavier mining loads.
Further hydrotechnical and geotechnical investigations are needed to confirm the capacity and performance of the bridge substructure.
15.3.4Mine Service Roads and Site Parking
A light vehicle parking lot will be located adjacent to the administration and dry complex. The parking area will be located inside the gatehouse perimeter and separated from haul truck traffic. The parking lot will be equipped with receptacles for engine block heaters.
15.4 Buildings and Ancillary Items
15.4.1Temporary Construction Facilities
Mobilization, demobilization, temporary construction facilities, and selected mobile equipment required during the construction phase will be contractor supplied. McEwen will provide underground mobile equipment, power, and water.
15.4.2Surface Maintenance Shop
The surface maintenance shop will be designed to maintain the underground and surface fleet, and will be housed in a pre-engineered building measuring 22 m wide x 30 m long x 12 m high. The building will be complete with metal cladding, insulation, HVAC, and snow guards. The ground floor will contain four (4) bays with overhead doors designed to accommodate mining mobile equipment. The remaining ground floor area will include an electrical bay, tool rooms, welding stations, vehicle wash area, and warehouse space for spare parts.
A 10-tonne crane will be installed above the vehicle maintenance bays.
The pre‑engineered building will be installed on a concrete perimeter wall with footings under each structural column. The foundation will be backfilled and compacted on both the interior and exterior of the building. The slab-on-grade, which will be sloped in the maintenance area, is designed to contain and direct
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spills toward in-ground sumps equipped with pumps. The wash area will be isolated by low curb walls and will include dedicated in-floor sump pumps fitted with an oil and water separator.
A layout of the truck shop and warehouse are presented in Figure 15-4.

Figure 15-4: Surface Maintenance Shop – Section View
15.4.3Warehouse
Two warehouses will be installed for Grey Fox, one near the administration office and mine dry, and a second installed near the surface maintenance shop. The warehouses will be new manufactured fabric buildings, each approximately 20 m wide x 25 m long, and will be equipped with power and HVAC.
Figure 15-5 provides an example of a typical warehouse.
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Figure 15-5: Example of Typical Warehouse
15.4.4Administration Office and Mine Dry
15.4.4.1 Mine Dry
The mine dry will be a single-story, prefabricated building composed of multiple connected trailers. Separate female and male dry areas will be provided and sized to accommodate approximately 350 workers. The trailers will be fitted with lockers, washrooms, and shower facilities.
15.4.4.2 Administration Office
The administration office will consist of multiple prefabricated building trailers set on cribbing foundations and combined to form a single complex. The facility will include office and cubicle spaces, two meeting rooms, training room, storage areas, washrooms, and a kitchen and lunchroom. A mine rescue office will be incorporated into the administration office.
The Mine Dry and Administration Office will come furnished with the following:
| ● | HVAC units and internal ducting |
| ● | Interior finishes including flooring, painting, lighting and emergency lighting, internal partition walls, and interior and exterior doors and glazing |
| ● | Fire detection and protection systems |
| ● | Internal plumbing and water filtration systems |
| ● | Electrical and communications wiring |
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15.4.5Security/Reception
A security gatehouse will be located at the entrance to the mine site and will control access to and from the site. All personnel, including operations staff, management, and visitors will be required to report to security prior to accessing the site.
A first aid office will be incorporated into the mine dry complex.
15.4.6Fuel Storage and Distribution
Fuel storage and distribution facilities will be located adjacent to the security/reception and near the surface maintenance shop. The facility near the security/reception will store gasoline and diesel, while the facility near the maintenance shop will store diesel and low-sulphur diesel.
Storage and dispensing equipment for low-sulphur diesel will be constructed for use by underground mobile equipment. Low-sulphur diesel will be delivered to site via tanker trucks. The storage facility will be equipped with a high-flow pump to fill the service truck used to refuel underground mobile equipment.
Storage and dispensing equipment for gasoline and regular diesel will be constructed for use by surface generators, water pumps, and mobile surface equipment.
15.4.7Waste Disposal
Site waste including plastic, paper, cardboard, food scraps, and rubber will be collected and stored in a designated garbage disposal area. Waste will be removed on a set schedule and transported offsite for disposal.
Hazardous materials such as spent oil, batteries, paint, compressed gas cylinders, and corrosive products will be managed and disposed of in accordance with McEwen’s Standard Operating Procedures. McEwen’s Health and Safety Department will ensure that appropriate signage, safety data sheets, and standard operating procedures are available and kept current for all hazardous materials used on site.
Hazardous materials will be transported to and from the site by qualified contractors.
15.4.8Mine Laydown Area
Mine laydown areas will be constructed of compacted granular material. A laydown area will be located near the administration office and mine dry complex. Additional laydown areas will be constructed near the North Portal and will serve as the construction staging area during the surface infrastructure and portal construction phases.
15.4.9Concrete/Shotcrete Receiving Stations
Multiple concrete / shotcrete receiving station will be constructed for the Grey Fox Project. The receiving stations will be located near the Whiskey Jack ventilation raises, near the Gibson Return Air Fan and near the Grey Fox South ventilation raises.
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Concrete/shotcrete will be delivered to site as wet ready-mix.
The receiving stations will include the following:
| ● | a cased borehole from surface to the initial production level at each station |
| ● | weatherproof enclosure |
| ● | borehole inserts on surface |
| ● | receiving hopper |
| ● | washout and pumping equipment and |
| ● | related electrical, automation and IT equipment. |
The underground receiving stations are defined in Section 13.10
15.4.10 Surface Pumphouse
A surface pumphouse will be located adjacent to the surface collection pond.
The pumphouse will be equipped with a pumping system to deliver recycled service water to Grey Fox North and Grey Fox South portals. The system will consist of both operating and standby pumps equipped with variable speed drives.
The pumphouse will also include an operating pump and standby pump to deliver excess water to the Black Fox site holding pond for treatment.
15.5 Ventilation Collars
The Grey Fox Project will include multiple ventilation collars: two near the Whiskey Jack deposit, one at the existing Gibson portal, and two in the South Portal area.
Geotechnical assessments at Whiskey Jack indicate that the permanent vent raise collars intersect unconsolidated soils above bedrock. To mitigate this risk and ensure safe, stable access, vertical collars will be constructed. This approach will require crane mobilization and preparation of a properly compacted subgrade.
Each collar will have a finished inside diameter of 4.3 m and extend approximately 30 m below grade. Construction will proceed in controlled 2 m lifts using formed concrete sections with 400 mm wall thickness. Each lift will incorporate a reinforced rebar mat with dowels extending into the subsequent pour. Following curing, material beneath each section will be excavated, allowing the collar to be advanced incrementally to the next elevation. This method will continue until bedrock is reached.
At bedrock, perimeter anchors will be installed to secure the structure, followed by a socket pour to control groundwater ingress. If required, supplementary well drilling may be implemented to manage groundwater conditions. Upon completion and final curing, the vertical development contractor will break into the collar to commence raise excavation.
The remaining collars are located in areas with minimal overburden. These will be constructed by removing overburden, installing a concrete pad, and completing raise excavation from underground using an Alimak
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system in a two-pass sequence. All raises will maintain the same finished diameter for consistency across the project.
15.6 Power Distribution
The initial power distribution system for the Grey Fox surface substation will be supplied from an existing 27.6 kV distribution line located on the eastern side of Tamarack Road. The final power configuration will require updates to the overall incoming utilities, to be finalized by McEwen. In both cases, a 27.6 kV tap will feed a new 35 kV disconnect switch and two 27.6 kV to 4.16 kV transformers located outside the substation. From the substation, 4.16 kV and 600 V power will be distributed to the remainder of the Grey Fox site through new switchgear.
To distribute power to the various surface facilities, 5 kV and 1 kV cables will be buried in trenches and routed where required. This is intended to minimize the risk of encounters with overhead power lines. The substation switchgear will provide 4.16 kV power to the ventilation facilities, compressor houses, administration office, crusher, pumphouse, and the portals for Grey Fox North and Grey Fox South.
The remaining surface facilities will be supplied with 600 V power via a 4.16 kV to 600 V transformer and 600 V power distribution panel located inside either the substation, administration office, or the Grey Fox South compressor house. Figure 15-6 illustrates the surface routing of buried electrical cables.

Figure 15-6: Surface Routing of Buried Cables
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In the event of a utility outage, the generator located at the substation will provide sufficient power for all critical surface infrastructure, including ventilation systems and compressor house. The generator will be configured in a main-tie-main-tie-main arrangement with the two 27.6 kV to 4.16 kV transformers.
15.7 Communications and IT
Communication between surface facilities will be routed using buried conduits to ensure coverage to every area of the surface site. Communication cables installed in conduit will be kept separate from power cables.
The following systems are part of the planned surface communication and IT package:
| ● | Fibre optic network |
| ● | Radio communications |
For surface facilities, communication infrastructure will be installed in each building using either Type 1 or Type 2 network cabinets. Servers and core network switches will be located within the administration office.
15.7.1Fibre Optic Network
The surface fibre optic network will be used for transmitting information for business networks, process control networks, and other dedicated systems as required, including fire alarm and power management systems.
The fibre optic network will connect with the 5G network infrastructure through network cabinets and will support systems such as tele-remote equipment operation and wireless network access. It will also connect to VoIP phones, which will be installed in surface facilities, as required.
15.7.2Radio Communications
To allow for site-wide radio communications, repeater units will be installed throughout the Grey Fox site. These repeaters will have an overlapping radius and communicate with the existing Black Fox radio system. Figure 15-7 outlines the radio repeater locations across the Grey Fox site to achieve site-wide surface radio communication.
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Figure 15-7: Locations of Radio Repeaters at the Grey Fox Site
15.8 Ore and Waste Rock Management
Separate ore and waste pads will be established between the Grey Fox North and South portals and will be constructed of compacted granular material.
A primary crusher with a stacking conveyor will be located on the ore pad. ROM ore will be trucked from either the North or South Portal and deposited near the primary crusher. A loader will be used to feed the crusher. Once crushed, the ore will be loaded into surface haulage trucks and hauled to the Stock Mill for processing.
The waste pad will be designed to accommodate approximately 300,000 tonnes of waste at peak accumulation prior to the start of underground production. Once production commences, stopes will be backfilled with ROM waste, and supplemented as required with material reclaimed from the surface waste stockpile. Waste rock from the Black Fox site will also be hauled to the Grey Fox waste stockpile as backfill demand exceeds the waste produced from Grey Fox underground operations.
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15.9 Water Management
The water management plan for the Grey Fox site is to collect and store on-site contact water and then transfer that contact water to the Black Fox mine for treatment and discharge. To reduce the mine water inventory, non-contact runoff at Grey Fox will be diverted using perimeter berms, allowing runoff to drain naturally offsite. Existing watersheds within the Grey Fox site include tributaries that drain to the Pike River, which bisects the Grey Fox property boundary west to east.
Two water management ponds will be constructed at Grey Fox to contain contact water from the existing 1:100-year annual exceedance probability (AEP) storm event. Each pond will have an emergency spillway sized to attenuate the 1:100-year AEP storm with climate change while maintaining a minimum freeboard of 0.5 m. The ponds will target a minimum length-to-width ratio of 2:1 to reduce short-circuiting. The Grey Fox holding pond will have a permanent pool to promote settling and provide extended detention and storage of settled material.
Contact water collection ditches will drain by gravity where practicable to reduce pumping requirements. In areas where gravity drainage to a sedimentation pond is not feasible due to site topography or stockpile geometry, excavated sumps and pumps will be installed to direct water to the water management ponds. Electric pumps will be used in areas where electrical service is available, with diesel pumps used elsewhere as required. Water discharged from excavated sumps will be released into the same perimeter ditch further downstream once gravity drainage toward a pond or closest downstream sump resumes.
The conceptual water management arrangement is provided in Figure 15-8 and detailed in Section 15.9 below.
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Source: (Stantec 2026)
Figure 15-8: Grey Fox Conceptual Water Management General Arrangement
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15.9.1Water Management Overview
Contact water management will be required for the waste rock stockpile and ore stockpile areas, dewatering from the underground workings, and areas where fuel storage or handling occurs, including the north fuel depot, laydown area, North and South Portal areas, and fuel depot. A minimum 15 m setback from watercourses and waterbodies will be maintained to limit potential interactions with the natural environment.
Runoff and seepage generated from the Project will be managed through a stockpile collection pond and a holding pond. The stockpile collection pond will receive contact water from the waste rock stockpile and South Portal area, and will be designed to convey collected water to the Grey Fox holding pond, with drawdown occurring over an estimated period of five days following the 1:100 AEP, 24-hour precipitation event.
The Grey Fox holding pond will be designed to receive direct runoff from the ore stockpile, North Portal area, south fuel depot, and laydown area, in addition to pumped inflows from underground dewatering and the stockpile pond. The Grey Fox holding pond will also serve as a source of water for underground service water requirements and surface site needs, such as dust suppression.
The Grey Fox holding pond will function as a throughput pond and pumping station for Project infrastructure located south of the Pike River, conveying water via pipeline at a maximum rate of approximately 130 L/s to the Black Fox water management system for treatment. The holding pond will be sized to manage inflows associated with the 1:100 AEP, 24-hour precipitation event, with discharge occurring over an estimated period of five days.
Water collected from the administration fuel depot located north of the Pike River will be managed separately and conveyed to the main discharge pipeline at an approximate rate of 0.5 L/s for transfer to the Black Fox site for treatment.
15.9.2Water Balance
A site-wide water balance was completed to estimate the quantity of mine site contact water expected to be managed during the operational phase of the Project to support water management design and feasibility studies. As presented in Figure 15-9, the Grey Fox water balance accounts for precipitation, runoff, evaporation, and infiltration flows at each identified mine site component. The water balance represents the mine site components at full development during operation.
To reduce the mine water inventory, non-contact runoff is proposed to be diverted using perimeter berming and ditching to allow runoff to naturally flow offsite. Contact water collected on site will be pumped via pipelines to the Black Fox site.
The site-wide water balance was developed using an average climate scenario based on Climate Normals precipitation data for the 1981-2010 period (Class A climate data) from the Environment and Climate Change Canada (ECCC) Victor M. Power Airport climate station (Station ID 6078285). A portion of precipitation during colder months, from October to March, was assumed to be stored as snow with partial
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melt occurring in October, November, and March, and a larger snowmelt event occurring in April during the spring freshet.
The percentage of precipitation that results in runoff from the stockpile areas was accounted for in the water balance model by balancing precipitation less evaporation and net infiltration losses for each catchment. Net infiltration represents the sum of groundwater infiltration and toe seepage, less any soil moisture losses. This proportion of net infiltration reports to perimeter seepage collection ditches and is diverted to the water management ponds.
Figure 15-9 presents the water balance transfer rates, identified in cubic metres per day (m3/d), to the Black Fox site under average climate conditions. Actual instantaneous flow rates are expected to vary seasonally and annually depending on climate conditions. The water balance model was used to analyze the volume of excess water that will be transferred via pipeline to the Black Fox site.

Figure 15-9: Conceptual Water Balance Schematic
15.9.3Mine Dewatering
The underground mine dewatering system is described in Section 13.10 of this report. The peak underground net flow at full mine development is expected to be approximately 3,270 m3/d from each underground area, for a combined total of approximately 6,540 m3/d.
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15.9.4Sewage Handling
Domestic wastewater from the administration office and mine dry, and process washroom facilities will be discharged to an on-site septic bed located to the northwest of the facilities.
15.9.5Domestic Water
A fully enclosed and climate-controlled domestic water treatment plant will be installed to treat water from an on-site well for non-potable uses (showers, toilets, and sinks in the mine dry, and office complexes). Potable water for consumption will be provided as bottled water.
15.10 Tailings Storage Facilities
15.10.1 Stock Mill Complex Tailings Management Area
The McEwen Stock Mill complex is located approximately 34 km west of the Black Fox mine and proposed Grey Fox mine, along Highway 101 (Figure 15-10). Ore from Grey Fox will be transported to the existing Stock Mill for processing, and the produced tailings will be stored within the existing tailings facility and a planned western expansion of the Stock Mill Tailings Management Area (TMA), currently referred to as the Western Expansion Area (WEA). Haul distance from Grey Fox to the Stock Mill is approximately 39 km.

Figure 15-10: Grey Fox to Stock Mill Haul Route
As of April 2026, the Stock Mill has a currently permitted design capacity of 3,200 t/d, with current mill production ranging from approximately 900 t/d to 1,500 t/d. At the start of Grey Fox mining, mill production is planned to comprise approximately 50% from Grey Fox and 50% from the Stock West underground (located at the Stock Mill site) and other sources (e.g., custom milling). As mining progresses, the Grey Fox feed will gradually ramp up to approximately 100% of the Stock Mill feed.
15.10.2 Stock Mill Complex TMA Western Expansion
McEwen-leased lands to the west and north of the existing Stock Mill TMA and northern water management pond provide room for expansion of the facility. A planned western expansion of the Stock Mill complex
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TMA (i.e., the WEA) is projected to provide approximately 3 Mm3 (4.2 Mt) of additional tailings storage capacity. This estimate assumes an in-place tailings density of approximately 1.38 t/m3 based on historical operational data for slurry tailings placement, at approximately 39-40% solids by weight, and a full buildout dam crest elevation similar to the Stock Mill TMA of 285.0 m. Similar to the existing Stock Mill TMA, decant water and stormwater from the expansion will be routed through the water management pond for recirculation and treatment, as needed.
At a planned tailings placement rate of 3,000 t/d, the WEA is expected to provide approximately 3.8 years of operational storage capacity, necessitating additional future expansions to accommodate the full projected tailings volumes from Grey Fox Mine and other tailings sources. The footprint of the WEA is limited to less than 50% of the existing TMA footprint in accordance with SOR/2019-285, Schedule (Section 2), part 19(c) of the Government of Canada Physical Activities Regulations.
The projected operational life and capacity of the TMA expansion is currently less than the total projected mine life and tailings storage needs for Grey Fox. However, additional McEwen-leased lands located to the northwest and north of the currently planned expansion area can accommodate additional expansion stages. Alternate tailings storage methods are also actively being explored, including dry stacking, to largely eliminate the need for a dam and allow for additional storage capacity within a similar footprint, and tailings storage within the open pit at the Black Fox Mine site, located immediately north of Grey Fox. These alternatives are being further evaluated as the Project progresses toward Feasibility.
The current expansion concept (Figure 15-11) includes approximately 2,600 linear meters of dam construction comprising a 2H:1V upstream slope, 3H:1V downstream slope, and 4-m top width (similar to the current TMA). With an average dam height of approximately 9.8 m (reaching a maximum height of approximately 14 m), the total embankment volume is estimated at approximately 730,000 m3. The dam would be raised in stages to allow for consolidation of the underlying soft clays in between raises, with a currently estimated one-third of the required borrow material to be sourced from the upper firm silty clay layer within the expansion footprint. This borrow volume is therefore added to the available tailings storage capacity estimate.
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Figure 15-11: Stock Mill TMA and Conceptual Western Expansion Area
Tailings generated at the existing milling facility will be pumped to the TMA expansion via extension of the tailings pipeline servicing the existing Stock Mill TMA. Based on historical operational data, the tailings slurry is characterized by an average solids content of 39.5% by weight, with a solids specific gravity of 2.89 t/m3. At a maximum permitted production rate for the Stock Mill of 3,200 t/d, the system will be designed to manage a nominal slurry flow rate of approximately 250 m3/h and is projected to comprise approximately 4,500 m (total length) of 8-inch (219-mm) diameter SDR 11 HDPE fusion-welded pipeline.
A distribution system will be designed to promote uniform beach development and geotechnical stability through controlled deposition. At this conceptual stage, the main line is planned to run the perimeter of the TMA expansion, with tee-offs spaced at 20-m intervals extending into the impoundment area. Similar to the current Stock Mill operation, for summer operations, each tee is planned to be equipped with a removable manifold consisting of three 3-inch (90-mm) diameter cyclone spigot lines to facilitate thin-layer beaching. In winter months, the spigot lines would be disconnected to allow for direct end-of-pipe discharge, mitigating the risk of freezing. A series of isolation and bypass valves will be installed at each tee location to allow operators to effectively cycle discharge points and manage the tailings pond elevation and beach development.
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15.10.3 Water Management and Recirculation
The Stock Mill utilizes a recirculating water management system designed to prioritize the reuse of process water. Tailings decant water is directed to the existing on-site water management pond for recirculation to the mill. To maintain a sustainable site water balance, treated volumes in excess of mill requirements are directed to a dedicated polishing pond for final clarification. This treated water is subsequently discharged to the environment in compliance with the site’s Environmental Compliance Approval (ECA).
A new engineered spillway will be constructed along the adjoining edge of the new expansion dam and the existing water management pond to convey decant water from the TMA expansion into the water management pond. From there, water will be recirculated for treatment and mill use or discharged to the environment using the Stock Mill’s existing recirculation system.
15.10.4 Subsurface Conditions and Foundation Design
Geotechnical investigations within the TMA expansion footprint (Golder, 2015) indicate a typical Northern Ontario glaciolacustrine profile.
The stratigraphy consists of:
| ● | 0 to 0.15 m BGS: Topsoil/Peat (to be removed prior to dam construction; thicker in low-lying areas) |
| ● | 0.15 m to 3.0 m BGS: Firm silty clay |
| ● | 3.0 m to 18.0 m BGS: Very soft varved clays and silts |
| ● | 18.0 m+ BGS: Very dense glacial till (silty sand to sandy silt) |
Due to the thickness of the underlying soft clay unit, the dam design is projected to include an additional 15% overbuild volume to address settlement during its operational life. Borrow material for dam construction will be sourced on-site, primarily utilizing the upper firm silty clay layer and waste rock generated from the on-site underground mining operation.
15.10.5 Seepage Control and Stabilization
As a component of the WEA dam construction, a seepage cutoff wall will be constructed along the dam alignment, approximately 2 m into the underlying varved clay (i.e., layered lenses of clay and silty sand that represent seasonal deposition in the historical lake that once covered the area), to cut off near-surface varves (i.e., the silty sand lenses) from lateral seepage out of the impoundment.
Additionally, because the expansion will share an adjoining dam with the existing TMA, a waste rock toe berm will be included to mitigate phreatic surface mounding in the existing dam’s outer toe during new tailings placement. The design of the new dam will also incorporate internal chimney and blanket drains, as needed, to mitigate the risk of piping. Additionally, due to the soft varved clays underlying the WEA, wick drains will be installed under the dam footprint to accelerate pore-pressure dissipation and foundation consolidation.
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15.10.6 Future Tailings Storage Facility Expansion
The Stock Mill Complex has existing access to leased lands immediately adjacent to the existing tailings facility that are estimated to provide at least 193 ha of additional tailings containment, conceivably accommodating up to approximately 24 Mt of additional storage capacity. Following the initial western expansion of the Stock Mill TMA by 41 ha and 4 Mt (comprising Stock Mill and Grey Fox tailings), Grey Fox is anticipated to provide an additional 7.4 Mt of tailings to the Stock Mill site.
Additionally, the existing open pit at Black Fox mine (located immediately north of Grey Fox) provides a potential opportunity for future storage of Grey Fox tailings, with an anticipated lower environmental-risk profile and lower cost than Stock Mill. This alternative is currently under evaluation, in addition to alternative methods of tailings management at Stock Mill, as the project approaches feasibility.
15.10.7 Geotechnical and Operational Risks
The primary risk to the conceptual layout of the TMA expansion and its maximum tailings storage capacity is the interplay between the underlying soft clay stratigraphy and the fixed regulatory footprint.
Capacity Reduction Risk: Because the footprint is limited by the 50% regulatory objective, any side-slope flattening required to address geotechnical concerns would need to be accommodated within the approved footprint, reducing the estimated storage capacity. Mitigation measures include using prefabricated vertical drains (PVDs) or wick drains to improve foundation pore-pressure dissipation and strength gain.
Settlement and Staged Construction: The underlying soft clay is expected to cause notable settlement and elevated pore pressures during construction and operation, depending on the rate and magnitude of dam raises and corresponding tailings placement. Accordingly, a staged construction approach will be used to allow pore-pressure dissipation and strength gain in between raises, which will impact the timing of available storage. Methods and rates of pore-pressure dissipation and construction staging will be further evaluated as the Project approaches feasibility.
Foundation Seepage Management: To accelerate the timeline for subgrade consolidation and dam construction, the design includes installation of PVDs and a granular drainage blanket to increase the rate of pore-pressure dissipation and strength gain in the foundation soils. Additionally, to reduce the potential for infiltration of tailings pore waters into near-surface silt lenses (varves) in the underlying varved clay, which could provide a horizontal seepage pathway out of the impoundment, a slurry or in-situ stabilization cutoff wall is envisioned to disrupt the near-surface varves. The design of the PVDs, drainage blanket, and the seepage-cutoff wall will be explored in greater detail as the Project approaches Feasibility, in addition to exploring alternative tailings placement methods (e.g., dry-stack tailings) that could potentially reduce cost and risk.
Regulated TMA Footprint: The current ECA for the Stock Mill (ECA #4371-B2KHZT) lists a footprint area of 56 ha. However, aerial imagery of the site and past design documents show an outer footprint of approximately 82 ha. The actual regulated footprint of the existing TMA will need to be verified with the Ministry of Environment and Mines (MEM) and the Ministry of the Environment, Conservation and Parks (MECP) prior to detailed design of the western expansion, as the 56 ha listed in the current ECA appears to either be in error or representative of a condition other than the outermost TMA footprint. Additionally, it has
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been confirmed verbally with the MEM that future expansions of the TMA would be held to a similar rule based on the active footprint of the facility at that time, allowing additional future expansions to proceed similarly, without the need for a full federal environmental assessment, assuming adherence to the 50% rule. Changes to this interpretation could alter the timeline and feasibility of future facility expansions.
15.10.8 Supporting Information
The following tables summarize the geometric parameters and characteristics associated with the conceptual layout of the WEA storage facility. The grading design for the conceptual layout was developed in Autodesk Civil 3D, with dam and tailings volumes calculated as volumetric comparisons between the conceptual-grading design surfaces and an existing-grade surface represented by 2025 aerial drone LiDAR data gathered by Arcadis combined with the 2016 COOP 2-m DEM for areas outside of the modified portions of the Stock Mill tailings storage facility.
Table 15-1 presents the design parameters for the conceptual WEA layout used in preliminary tailings storage cost estimation. Table 15-2 and Table 15-3 provide WEA storage capacity and operational life, and tailings slurry design parameters, respectively.
Table 15-1: WEA Geometric Design Criteria
Dam Component | Value | Unit | Source/Notes |
Total Dam Length | 2,632 | m | Concept Layout |
Upstream Slope | 2H:1V | Horizontal:Vertical | Existing Dams |
Downstream Slope | 3H:1V | Horizontal:Vertical | Planning Assumption |
Crest Width | 4.0 | m | Existing Dams |
Average Dam Height | 9.2 | m | Local Topography |
Maximum Dam Height | 14.0 | m | Local Topography |
Dam Embankment Footprint | 131,269 | m2 | Concept Layout |
Foundation Key-in Depth | 2.0 to 3.0 | m | Historical Borings |
Spillway Type | Sheet pile weir with | - | Existing Dams |
Maximum Footprint | 41 | ha | 50% of Existing TMA (82 |
Key-in Depth (slurry or in-situ | 4 to 5 | m | Subsurface Stratigraphy |
Additional Stabilization of | 37,772 | m3 | Concept Grading Design |
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Table 15-2: WEA Storage Capacity and Operational Life
Dam Component | Value | Unit | Source/Notes |
Total Available Storage Volume | 3.0 | Million m3 | Concept Grading |
Average Deposited Dry Density | 1.38 | tonnes/m3 | Historical Data |
Total Storage Tonnage | 4.2 | Million tonnes | Combined Grey Fox |
Daily Tailings Production | 3,000 | t/d | Mine plan |
Annual Tailings Production | 1.10 | Million tonnes | Calculation |
Projected Life for the Western | 3.8+ | years | Calculation; additional |
Supplemental Capacity | Additional Expansion | - | Viable options based |
Table 15-3: Tailings Slurry Design Parameters
Parameter | Value | Unit | Source/Notes |
Maximum Throughput | 3,200 | t/d | Peak permitted capacity of the Stock |
Solids Content by Weight | 39.5 | % | Historical Data |
Density (Solids) | 2.89 | t/m3 | Historical Data |
Slurry Flow Rate (Nominal) | 250.4 | m3/h | Calculated |
Pipeline Material | HDPE SDR 11 | - | Fusion-welded |
Pipeline Diameter (OD) | 8 (219) | in (mm) | Recommended |
Pipeline Length | 4,500 | m | Site Layout |
Static Elevation Head | +13 | m | Survey Data |
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15.11 Sitewide Water and Mass Balance Model
Arcadis constructed a water and solute mass balance model to evaluate flow rates and water quality for mine water potentially requiring water treatment as part of development of the Grey Fox mine. Since water generated at the Grey Fox mine is to be sent to Black Fox for handling and treatment prior to discharge, the water balance model includes the Grey Fox underground mining features, the Black Fox Pit, and surrounding water-management facilities.
The water/mass balance model was constructed using the GoldSim model platform. The GoldSim model represents an expansion and refinement of the previous water balance developed for Black Fox Mine by Wood (2021) to include the simulation of Black Fox pit filling and Grey Fox underground mining. Model development assumptions and results are provided below.
15.11.1 Model Development and Assumptions
The GoldSim model was constructed to couple water flows and water quality and allow for evaluation of water management scenarios. A schematic of the overall water balance is provided in Figure 15-12.

Figure 15-12: Water Balance Schematic
A brief overview of key model components and assumptions is provided below.
| ● | The site-wide water and mass balance model uses historical daily precipitation for past periods and long-term monthly average precipitation from the Timmins Climate Station for future periods to represent seasonal conditions at the site. With the use of monthly-average precipitation, it was effectively run for a climate normal year, and since the model usage was for a relatively short period of 15 years during mine operation, potential climate change effects were not considered. Only the climate normal model results (without wet or dry years) is provided here, but buffering of |
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wet year flows is discussed further below. Open-water evaporation losses are included using monthly evaporation rates from the Timmins Victor Power A Weather Station and exposed water surface areas for each modeled subunit
· | Surface runoff is estimated using monthly precipitation, catchment areas, and representative runoff coefficients for key mine features and disturbed areas at both Black Fox and Grey Fox. The model also accounts for snow accumulation, sublimation, and snowmelt, with rainfall contributing immediate runoff while snow is carried forward and released according to monthly melt assumptions. |
· | The Black Fox portion of the model includes major mine water features such as the open pit, southwest pond, southeast pond, holding pond, and treatment pond. Black Fox pit filling is controlled by direct precipitation, runoff, and groundwater inflow, with the largest groundwater contribution coming from overburden and an additional smaller contribution from bedrock. Model simulations indicate that following Black Fox mine operations, the pit will fill with water and has water storage capacity until at least 2043. As such, water flows from the Black Fox Pit do not enter the Grey Fox water balance during the project period from 2027 through 2041. As a conservative assumption, the model simulation does not include any other potential mine reclamation and closure activities that could occur at Black Fox before 2043. |
· | The Grey Fox portion of the model includes the underground mine, process area, process area pond, waste rock stockpile, and waste rock pond, as described further in Section 15.9. During Grey Fox operations, runoff and underground dewatering water are collected in the Grey Fox Process Area Pond and then pumped to the Black Fox holding pond, where Grey Fox and Black Fox waters are blended for treatment and discharge. |
Solute mass balance was added to the water balance model for the following analytes of interest:
· | Major cations: Calcium, magnesium, potassium, and sodium. |
· | Major and minor anions: Alkalinity, sulphate, chloride, nitrate. |
· | Metals, oxyanions, and other water quality constituents: Arsenic, antimony, cobalt, copper, iron, lead, nickel, zinc, selenium, molybdenum, vanadium, cadmium, and ammonia. |
Cyanide was not included as a model parameter, since the Grey Fox and Black Fox units do not include mill tailings contact water. Water management associated with the Stock Mill Complex is summarized in Section 15.10.3.
Although pH is not directly modeled in GoldSim, pH was calculated based on the mass balance of acidity and alkalinity. For calculation of pH, carbon dioxide and calcite are both assumed to sustain a slight supersaturation, with an assumed log (pCO2) of -3.0 and a calcite saturation index of 0.3.
Development of the solute mass balance required determination of water quality for each flow input to the model. Table 15-4 summarizes the water quality data used in developing the geochemical water quality source terms for each flow term in the model. Additional details on the available test data for Grey Fox used in the development of geochemical source terms are provided in Section 17.2.
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Table 15-4: Summary of Water Quality Geochemical Source Terms and Data Sources
Water Flow | Description/Source | |
Direct precipitation | Major ion contents for typical rainwater in North America; concentrations assumed zero for metals. | |
| ||
Natural runoff | Water quality from the Pike River monitoring station, median of data collected from 01/2020 through 10/2020. | |
| ||
West Waste Rock Stockpile drainage | Average of 2024 monthly water quality results from West Waste Rock Stockpile monitoring location. | |
| ||
East Waste Rock Stockpile drainage | Average of 2024 monthly water quality results from East Waste Rock Stockpile monitoring location. | |
| ||
Black Fox Pit groundwater inflow | Average of 2024 quarterly water quality results from Interceptor Well 147125. | |
Black Fox Pit wall runoff | Calculated as flow-weighted difference between Black Fox Pit/underground mine sump water quality and groundwater inflow. | |
| ||
Grey Fox waste rock stockpile | Developed from Grey Fox Week 0 humidity cell test results (see Section 17.2), scaled based on comparison with Black Fox Waste Rock Stockpile drainage. | |
Grey Fox Underground Mine dewatering | Assumed the same chemistry as the Grey Fox waste rock stockpile source term, based on similar geologic rock types intersected during mining. | |
15.11.2Model Scenario and Results
The water and solute mass balance model was used to simulate future water management associated with Grey Fox underground mining with water management at Black Fox.
The model was set to run from January 1, 2027 through December 31, 2041. The Grey Fox underground dewatering rate was assumed to increase to 1,500 m3/day within the first year, up to an operational rate of 1,938 m3/day by the second year. For simplicity, the full operational footprint of the Grey Fox site features, including the process area and waste rock stockpile, were assumed to be present at the start of the modeling period. Model outputs include flow rates and estimated water quality over the modeled timeframe. This evaluation informs the water treatment requirements as described in Section 15.12.
The model simulation results indicate that with pumping of Grey Fox contact water to Black Fox, the average flow to the holding pond varies seasonally between 2,200 and 4,700 m3/day with an annual average of approximately 3,300 m3/day which was the rate used in sizing of a potential water treatment system in Section 15. Importantly, this value is an annual average, and the actual flow at any given time will likely exceed this average. Although the various holding ponds at Black Fox and Grey Fox were designed to buffer short-term storm and runoff events, the ponds are not large enough to retain water during the spring snowmelt period (average flow rates of 4,700 m3/day) for a water treatment plant designed to handle the annual average flow rate (3,300 m3/day). However, for the purposes of this evaluation, it is assumed that treatment of annual-average flow rates based on average annual precipitation is reasonable. In practice, it is likely that the Black Fox open pit itself can be used for seasonal water storage to buffer flows to the holding pond.
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The holding pond/treatment pond water quality was compared to water quality standards to understand potential treatment requirements. For this evaluation, simulated water quality is compared to the existing ECA values issued in 2019, understanding that these values may no longer be applicable when the ECA is revised following incorporation of Grey Fox. Specifically, the values included in the 2019 ECA were based on criteria in Ontario Regulation (O. Reg.) 560/94, which McEwen understands was revoked in June 2021 with O. Reg. 462/21. Updated effluent criteria will need to be developed based on MECP Procedure B-1-5 1. This development will likely include consideration of the more recent Canadian Metal and Diamond Mining Effluent Regulations (MDMER) 2, Canadian Council of Ministers of the Environment Canadian Environmental Quality Guidelines for the Protection of Aquatic Life 3, Federal Environmental Quality Guidelines for freshwater 4, and British Columbia Ministry of Environment and Parks Water Quality Guidelines 5. However, Procedure B-1-5 specifically refers to the use of Ontario PWQO 6 values for surface water. For preliminary identification of parameters of potential concern and evaluation of potential water treatment requirements, the water quality predictions are compared with PWQOs. A comparison to MDMER monthly mean concentrations is also provided purely for comparison purposes.
Results for key water quality constituents, including those exceeding potentially relevant water quality standards, are summarized in Table 15-5. Parameters of potential concern include arsenic, cobalt, copper, iron, nickel, molybdenum, vanadium, and zinc. Antimony, cadmium, and lead were evaluated based on their elevated levels in specific geochemical sources, but simulation results do not predict an exceedance of PWQOs in the holding pond. Observations from the analysis relevant to water treatment demands include the following:
| ● | The alkalinity of the water reporting to the holding pond is simulated to be between 130 and 150 mg/L as calcium carbonate (CaCO3). The pH of the water in the holding pond is predicted to be between 7.9 and 8.1, with a tendency to precipitate calcite with carbon dioxide off-gassing. |
| ● | Arsenic, cobalt, copper, iron, nickel, molybdenum, and zinc are predicted to exceed PWQO values throughout the year. |
| ● | There is a chance that vanadium may slightly exceed the PWQO seasonally. |
1https://www.ontario.ca/page/b-1-5-deriving-receiving-water-based-point-source-effluent-requirements-ontario-waters; last accessed on 7/2/2026.
2https://www.canada.ca/en/environment-climate-change/services/managing-pollution/sources-industry/mining-effluent/metal-diamond-mining-effluent/metal-diamond-mining-effluent-regulation.html; last accessed on 4/9/2026.
3 | https://ccme.ca/en/resources/water-aquatic-life; last accessed on 7/2/2026. |
4https://www.canada.ca/en/health-canada/services/chemical-substances/fact-sheets/federal-environmental-quality-guidelines.html; last accessed on 7/2/2026.
5https://www2.gov.bc.ca/gov/content/environment/air-land-water/water/water-quality/water-quality-guidelines/approved-water-quality-guidelines; last accessed on 7/2/2026.
6https://www.ontario.ca/page/water-management-policies-guidelines-provincial-water-quality-objectives; last accessed on 4/9/2026.
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Table 15-5: Holding Pond Water Quality during the Project Period
Analyte | Result | | | 2019 ECA | | MDMER |
| | | | (Monthly | PWQO | (Monthly Mean |
| Min | Max | Average | Concentration | (mg/L) | Concentration; |
| | | | Limit; mg/L) | | mg/L) |
Arsenic | 0.026 | 0.173 | 0.108 | 0.5 | 0.005 | 0.10 |
Antimony | 0.0053 | 0.0091 | 0.0072 | - | 0.02 | - |
Cadmium | 0.00018 | 0.00028 | 0.00023 | - | 0.0001-0.0005 a | - |
Cobalt | 0.106 | 0.206 | 0.156 | - | 0.0009 | - |
Copper | 0.0094 | 0.0167 | 0.0131 | 0.3 | 0.005 a | 0.10 |
Lead | 0.00052 | 0.00083 | 0.00068 | 0.2 | 0.003-0.005 a | 0.08 |
Iron | 0.56 | 0.70 | 0.63 | 1.0 | 0.3 | - |
Nickel | 0.072 | 0.122 | 0.097 | 0.5 | 0.025 | 0.25 |
Molybdenum | 0.108 | 0.134 | 0.121 | - | 0.04 | - |
Vanadium | 0.0050 | 0.0073 | 0.0062 | - | 0.006 | - |
Zinc | 0.046 | 0.087 | 0.066 | 0.5 | 0.02 | 0.40 |
Notes:
BOLD – exceeds the MDMER Monthly Mean Concentration
Underline – exceeds the PWQO
a PWQOs for cadmium, copper, and lead are hardness based. Water quality simulations predict an average hardness of 146 mg/L as CaCO3 (seasonal range of 45 to 194 mg/L). For copper, the PWQO of 0.005 mg/L (applicable above 20 mg/L hardness) is assumed to apply throughout the year. For cadmium and lead, the ranges in values applicable within the simulated hardness range are shown.
15.12Water Treatment Plant Infrastructure
The Grey Fox water treatment requirements are informed by the water and mass balance evaluation as described in Section 15.11. The annual average discharge flow rate and water quality were used as the basis for the conceptual water treatment process design, capital cost estimate, and annual operating cost estimate.
15.12.1Flow Rate
The Black Fox holding pond outflow is predicted to vary between 2,200 and 4,700 m3/day with an annual average of approximately 3,300 m3/day. The nominal hydraulic capacity of the water treatment plant would be based on this annual average flow rate. Over the course of a year, variability in water inputs to the site is largely dependent on precipitation, evaporation, and snowmelt levels. Although the available water storage capacity within the holding and treatment ponds is designed for wet weather events and not anticipated to be sufficient to accommodate storage during extended high-water input periods (e.g., during snowmelt), the excess during spring snowmelt can be accommodated in the Black Fox pit. As such, the average discharge rate of 3,300 m3/day can be maintained throughout the year.
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15.12.2Target Constituents
Target constituents for treatment were identified in the water and mass balance evaluation as described in Section 15.12. Water quality predictions were compared with potentially relevant water quality standards to determine potential exceedances. The following constituents were identified as potentially requiring treatment based on comparison of average and maximum annual values against the site’s 2019 ECA and PWQOs.
| ● | Arsenic |
| ● | Cobalt |
| ● | Copper |
| ● | Iron |
| ● | Nickel |
| ● | Molybdenum |
| ● | Vanadium |
| ● | Zinc |
The average and maximum concentrations in the holding pond water are summarized in Table 15-5 above.
All of the listed constituents exceed at least one of the applicable standards listed above. In addition to the constituents listed above, discharge water quality is expected to be subject to limits for total suspended solids and pH. The conceptual water treatment system design will consider these additional limits in configuring the treatment process.
Any changes to the regulatory framework that impact the target constituent list or discharge requirements would be reflected in the water treatment process design as it advances through design and permitting.
15.12.3Conceptual Design
The conceptual water treatment process consists of two primary stages to address the target constituents listed above. The proposed treatment technology is based on precipitation, primarily to remove iron and associated constituents through a two-step process as described below.
Step 1 will consist of iron oxidation and greensand filtration. This step would oxidize any ferrous iron to ferric iron to induce precipitation at the circumneutral pH. Minor amounts of arsenic and molybdenum may co-precipitate with iron during this step. The precipitated solids would be removed using a greensand filter, producing a low total suspended solids (e.g., < 10 mg/L). This would require continuous injection of an oxidizer, typically sodium hypochlorite or oxygen, into the feed stream to oxidize the reduced iron and other metals. The filters would require periodic backwash to remove accumulated solids and maintain permeability. Backwash solids would require thickening and dewatering prior to final disposal.
Step 2 will consist of ion exchange to remove the residual low-level metals and meet discharge requirements. Given the range of potential constituents, the ion exchange step would include a strong base anion (SBA) resin to remove the oxyanion species (arsenic, molybdenum, and vanadium) and a strong acid cation (SAC) resin to remove trace metals (copper, cobalt, iron, nickel, and zinc). Both resin types may be regenerated using a sodium chloride brine, which represents the primary input to this stage of the treatment
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process. Brine may be made up directly from solid sodium chloride (NaCl) salt at the site. Spent regenerant solution would require treatment or offsite disposal as a waste brine. As an alternative, non-regenerable specialty resins could be used, in which case the primary residual would be exhausted resin rather than spent regenerant. At this stage of the conceptual process development, it is assumed that spent brine will be disposed of offsite. If onsite treatment is required due to cost or limited availability of offsite brine treatment, it may be evaluated at a later time.
These two steps are not anticipated to substantially affect discharge pH or total suspended solids. If additional conditioning is required to meet applicable discharge requirements, additional steps such as pH adjustment and alkalization may be included.
Waste residuals collected from steps 1 and 2 would require temporary storage prior to onsite treatment or offsite disposal. Solids are expected to be thickened and dewatered prior to disposal. Sludge will first be thickened using a high-rate plate clarifier, followed by dewatering using a filter press. Dewatered sludge can then be disposed at a designated land repository at the site subject to assessment, design considerations, and approval, as may be required.
And overall conceptual design is provided in Figure 15-13.

Figure 15-13:Water Treatment Plant Conceptual Design
15.12.4Implementation and Operations
The water treatment plant will operate under a series of treatment trains.
The water treatment plant will consist of two parallel treatment trains for greensand filtration followed by ion exchange. Each train will have a capacity of approximately 1,650 m3/day to accommodate the design flow
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rate of 3,300 m3/day. Constructing the system in two 1,650 m3/day trains would allow for more flexible operation during low flow periods.
Filtration will consist of pressurized filter vessels with the appropriate chemical storage and injection pumps, as well as water pumps for backwashing. Backwash solids will be separated from the backwash water in a dedicated tank using a dewatering polymer to aid solids separation. Supernatant liquid may be returned to the head of the filtration units, and solids will be dewatered using either a screw press or filter press. Dewatered solids are expected to consist primarily of iron solids and may be disposed of in a suitable on-site or offsite repository.
The ion exchange step would be completed through a series of pressurized SBA and SAC resin beds. The ion exchange system would include a brine solution makeup tank and supply pump to regenerate the resin beds. Spent regenerant brine would be stored in a separate tank for offsite disposal. A single storage tank would be used to store brine from both treatment trains.
Each train will consist of a dedicated containerized treatment system for each step in the treatment process (i.e., one container for greensand filtration and a second for ion exchange). Each container will house the primary filters as well as the chemical injection, backwash, and resin regeneration equipment. Treatment residuals will be managed, processed, and temporarily stored either in separate containers or in an external insulated and heat-traced tank.
Containerized treatment systems offer the advantage of off-site fabrication and delivery of complete systems, requiring minimal on-site mechanical and electrical assembly beyond service connections for water and power. Each individual container can be climate-controlled to account for temperature extremes at the site, if required; though, a climate-controlled building enclosure has been assumed for conceptual design purposes. Additional heat tracing and insulation of connection lines and external infrastructure (e.g., brine storage tank) would be completed on-site, as needed.
Ongoing operations would require the following inputs:
| ● | Sodium hypochlorite – continuous injection to concentration of approximately 10 mg/L based on the influent iron concentration. |
| ● | Sodium chloride – used as a regenerant for the SBA and SAC resins. |
| ● | Dewatering polymer – used to thicken solids removed from the greensand filters during backwashing. |
| ● | Power (480 V - 3-phase service) – Process and backwash water pumps, chemical feed pumps and mixers, dewatering equipment, building HVAC and lighting, heat trace, instrumentation and controls. |
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16 Market Studies and Contracts
16Market Studies and Contracts
16.1Market Studies
Gold is traded freely at widely known prices, consequently, the prospects for the sale of any production of the metal are virtually assured. A market study for the saleability of gold products or for the expected price of gold was not undertaken.
Based on monthly closing data from April 2024 to April 2026, the approximate two-year trailing average gold price is US$3,000 per ounce. This period reflects a rapid rise in gold prices, starting from approximately $2,285 in April 2024 and exceeding $4,700 by April 2026. A two-year time frame (April 2024 to April 2026) is standard for this type of disclosure because it balances long-term stability with recent market momentum. Since gold experienced a price surge during this period. A shorter window (e.g., 6 months) would artificially inflate the baseline price projection, while a longer window (e.g., 5 years) would heavily weigh outdated, lower-priced data.
Note: The calculation is based on monthly spot closing prices available as of April 2026.
16.2Contracts
The terms contained within any future sales contracts are expected to be typical and consistent with standard industry practice and contracts for the supply of doré. Currently there are no contracts in place for the Grey Fox Project.
The selling costs related to the refining of the doré to produce saleable gold and to the doré shipping cost estimates used in this analysis were benchmarked based on existing McEwen contracts in the same region as Grey Fox. Refer to Table 16-1.
Table 16-1: Selling Costs for Gold Doré
Description | Unit | Value |
Refining Cost (Au) | US$/oz | $0.41 |
Gold Payable | % | 99.95 |
Doré Shipping Charge | US$/oz | $2 |
16.3QP Opinion on Markets and Contracts
The QPs note the following:
| ● | McEwen can market the doré products produced from the Grey Fox Project; and |
| ● | The terms contained within the sales contracts are based on existing McEwen contracts. |
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17 | Environmental Studies, Permitting, and Plans, Negotiations, or Agreements with Local Individuals or Groups |
17.1Existing Environment
17.1.1Location and Land Use
The Eastern Properties of the Fox Complex is located in Hislop Township, approximately 10 km east of Matheson, Ontario, within the District of Timiskaming. The site falls within the geological setting of the Porcupine-Destor fault zone, a region recognized for its gold deposits with considerable current and historical mineral exploration and mining activity.
Land use is governed by the Township of Black River-Matheson Official Plan (MMM Group 2017), which zones the broader area as “rural” with the Black Fox Mine site designated as an active mining area. The Froome and Grey Fox deposits fall within a mineral aggregate resource area centered on Highway 101. Prior to the 1990s, predominant land uses were hay production, pasturing, and forestry. The site lies within the Abitibi River Forest (Management Unit No. 110) and Wildlife Management Unit 28.
17.1.2Climate
The site climate is typical of the northern boreal forest. Extended sub-zero temperatures occur from November through March; July is the warmest month and January the coldest. Maximum rainfall occurs in July and maximum snowfall in December. Prevailing winds are from the south and northwest in winter, and from the south and west in summer. Mean annual precipitation is approximately 840 mm/yr based on long-term records (1956-2019) from the Timmins Climate Station (Wood 2022a), with roughly equal contributions from rain and snow.
17.1.3Soils and Surficial Geology
The region is characterized by flat glaciolacustrine clay plains interspersed with rock knobs, ancient raised beaches, eskers, and other outwash deposits. Overburden in the Fox Complex area ranges from 10 to 60 m in thickness (averaging approximately 20 m) and consists of silty clay at surface, underlain by variable silty sand and till, with a basal till resting on weathered bedrock. Flat topography, low permeability, and cool climate have contributed to the formation of an overlying peat layer over much of the clay plain east of the site. A series of north-south trending esker complexes, composed of sorted sands, gravels, cobbles, and boulders, are present throughout the region; an esker formation intersected during open pit mining at Black Fox is a significant contributor to groundwater inflow to the pit.
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17.1.4Surface Water
The Fox Complex sits at the northern end of the Black River watershed (total drainage area 1,372 km²). Two sub-catchments are directly associated with the Fox Complex: the Pike River (westward flow through lacustrine plains and an esker ridge) and Salve Creek (southern portion of the Fox Mine property). Surface water quality is monitored at multiple stations in accordance with site ECAs and MDMER; treated effluent currently meets all applicable discharge requirements. Long-term background data is available for the Pike River, Froome Lake, Lawlar Lake, Leach Lake, and several tributary stations.
17.1.5Groundwater
The hydrogeological setting of the Fox Complex is dominated by the overburden sequence described in Section 17.1.3 (clay, silt, sand/till, basal till) and underlying weathered and competent bedrock. Hydraulic conductivities are lowest in the silty clay unit and highest in the esker/alluvial formation. Regional groundwater flow is controlled by topography, with flow generally towards local surface water features. Active dewatering of the Black Fox open pit and underground workings has modified local groundwater gradients; monitoring indicates that nearby Froome Lake is hydraulically separated from the mine workings by low-permeability basal sediments.
A comprehensive groundwater monitoring program (monitoring wells at Black Fox, Froome, and Grey Fox) confirms all groundwater quality consistently below permitted limits with no adverse temporal trends identified. Local groundwater users within approximately 1 km of mine workings have been identified; none rely on groundwater from within the modelled zone of mining influence.
17.1.6Ecological Setting
Vegetation and wildlife communities at the Fox Complex are typical of the mixed-boreal forest region of northeastern Ontario. Upland communities include deciduous, mixed-wood, and coniferous forest in various stages of succession, with trembling aspen and balsam poplar as dominant species. Wetland communities include swamp, fen, and marsh-type habitats. The majority of flora and fauna species are rated common to very common (provincial and global rarity rank 4 or 5, per NatureServe) within their respective habitats.
Baseline surveys documented 88 breeding bird species typical of the southern boreal forest. Thirteen avian Species at Risk are known to occur within the broader Kirkland Lake District; no species listed under the federal Species at Risk Act were detected during field surveys at the time. Candidate significant wildlife habitats present at the project include bat hibernacula, bat maternity colony roost habitat, amphibian breeding habitats (wetlands), mast-producing areas, and amphibian movement corridors. The surrounding landscape supports moose, black bear, white-tailed deer, beaver, and common furbearers. Appropriate surveys and registration / mitigation measures will be completed prior to development.
17.1.7Aquatic Setting
The Fox Complex discharges surface effluent to the Pike River through a 2.4 km pipeline, with the river serving as the receiving aquatic environment. The Pike River is a naturally mineral-rich, turbid, moderately hard, circumneutral northern watercourse with elevated background aluminium, ammonia, and iron, and
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sediments naturally above the LEL for chromium, iron, manganese, and nickel across both upstream and downstream areas. Effluent disperses rapidly—an estimated 2.4% of end-of-pipe concentration within 250 m downstream—and six phases of MDMER Environmental Effects Monitoring have found no ecologically significant mine-related effects on water quality, sediment, the benthic community, or fish, with arsenic the only constituent showing a modest, localized exposure-area signal that remains below applicable guidelines.
17.2Site Water Quality and Geochemistry
Static and kinetic tests were conducted to evaluate the chemistry of Grey Fox mine materials and the potential for release of metals and acidity from development rock. Shake flask tests were conducted as part of a geochemical characterization static testing program conducted on Grey Fox drill cuttings (Wood 2022b, references therein). Although the method used was not specified, this test typically involves reacting solids in deionized water in a 3-parts water to 1-part solid ratio for 24 hours, per Mine Environment Neutral Drainage (MEND) guidance (Price, 2009). Tests were conducted on 84 samples covering the seven major geologic rock types encountered at Grey Fox. The sample results were averaged within geologic unit, and then a geologic-unit-weighted average was calculated to represent mixed/ROM rock at Grey Fox.
In addition to the shake flask tests, humidity cell tests were conducted on Grey Fox drill cuttings collected from exploration boreholes (Wood, 2022b; WSP, 2024). A total of 11 humidity cell tests were conducted representing the four most abundant geologic rock types, including Massive Mafic Volcanic, Pillowed Mafic Volcanic (PMV), Variolitic Mafic Volcanic, and Sedimentary (SED).
One of the key objectives of the humidity cell tests was to evaluate potential for mine materials to become acid generating. Of the geologic rock types at the site, acid-base accounting results indicated that the presence of potentially acid-generating (PAG) material was particularly associated with SED and PMV geologic units, although all units primarily contained non-PAG (NPAG) material (Wood 2022b). For this reason, the humidity cell tests for SED and PMV material included both PAG and NPAG material to evaluate the potential for PAG materials to go acidic over time. The humidity cell tests were run for between 84 and 131 weeks. Over this time, two humidity cells (SED cell HC-02 and PMV cell HC-03) went acidic; however, based on a comparison of acidity generated in these two cells relative to the alkalinity generated in other cells, coupled with a material mass balance based on acid-base accounting results and anticipated waste rock tonnages for different geologic units, it was determined that the mixed ROM material would maintain net-alkaline. Further, the humidity cell test results indicated that all materials regardless of their potential to go acidic exhibited similar constituent leaching behavior (particularly for oxyanions including arsenic and molybdenum).
Per MEND guidance (Price 2009), humidity cell tests are typically run until constituent concentrations are stable for at least five weeks, noting that at least 40 weeks may be required. The humidity cell tests conducted for Grey Fox (between 84 and 131 weeks) were run until constituent concentrations stabilized. This long timeframe is often required to evaluate depletion of acid neutralization potential, noting that many sulfidic rock types start out acid neutralizing but become acid generating after acid neutralization potential is depleted. Because of this, concentrations of several constituents (including acid soluble metals) can increase as humidity cells progress, and the long-term stabilized concentrations are used to develop geochemical source terms. However, for the rock types at Grey Fox, several constituents were higher in the
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first few weeks of the humidity cell tests due to the washout of soluble constituents from freshly exposed rock surfaces. This “first flush” of constituents is anticipated to be an important influence on Grey Fox contact water quality during operations, and therefore both the Week 0 and average of post-Week 30 humidity cell test concentrations were considered in developing geochemical source terms. Additional details are provided in Section 15.11.1.
17.3Environmental Setting
Environmental baseline (pre-development) investigations were completed for a number of the Fox Complex properties prior to mine development and provide a basis for future closure comparison. These studies establish background conditions for surface water, groundwater, aquatic ecology, and terrestrial ecology. Key baseline investigations completed include the following:
| ● | Pre-development environmental baseline investigations were completed for all Fox Complex properties covering surface water, groundwater, aquatic ecology, and terrestrial ecology (AMEC, 2008, 2012, 2014; Golder, 2015; BZ Environmental, 2006; supplementary data ongoing at Fox West properties). These studies establish background conditions for future closure comparison. All relevant baseline references are listed in Section 24. |
As required by existing permits and approvals, McEwen operates a comprehensive environmental monitoring program at the Fox Complex. Information collected supports current compliance and future permitting application requirements. Currently, all McEwen Fox Complex properties are in compliance with all applicable regulatory requirements, including Ontario Regulation 35/24 – Mine Development and Closure and the Mine Rehabilitation Code of Ontario. Financial assurance, as set out in Part VII of the Mining Act and Ontario Regulation 35/24, has been provided for required closure activities. Refer to Section 17.5 for further details on closure cost estimates and financial assurance.
17.4Regulatory Framework
17.4.1Impact and Environmental Assessment
Mining projects in Canada can be reviewed under one or more Environmental Assessment (EA) or Impact Assessment processes, whereby design choices, environmental impacts, and proposed mitigation measures are reviewed to determine how best to proceed through the approvals and permitting process. Entities involved in the review process normally include government agencies, Indigenous communities, interested parties, and the general public.
Based on proposed activities at the Grey Fox, Stock, and Western Properties, a Federal Impact Assessment process under the Impact Assessment Act is not required as per Sections 18 and 19 (Mine and Metal Mills) of the Physical Activities Regulations (SOR/2019-285). The Ontario Environmental Assessment Act regulates the environmental assessment process for mining projects in Ontario and requires that potential environmental impacts be assessed before a project begins. Mining projects and infrastructure developments on Crown land or using Crown resources may be required to complete a Class EA assessment with the Ontario Ministry of Mines.
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17.4.2Environmental Approvals
Federal environmental approvals associated with mine site developments generally correlate to the Fisheries Act and the Canadian Navigable Waters Act. Based on current information, federal environmental approvals under these Acts are not expected to be required. Environment and Climate Change Canada regulates the mine effluent under the federal MDMER under the Fisheries Act.
A large number of active environmental approvals are currently held for individual Western Properties. A comprehensive listing of existing active approvals is provided in Table 17-1. Amendments to existing approvals, or new approvals, will be required depending on final project designs for Grey Fox and associated infrastructure. Table 17-2 provides a preliminary listing of applicable approvals and amendments that may be required as the Grey Fox, Stock, and Western Properties progress.
Table 17-1: Existing Environmental Approvals
Site | Regulatory | Reference No. | Type | Issue Date | Expiration | Status / Notes |
| Agency | | | | | |
Black Fox | MECP | 0328-8XVPXT | ECA-ISW | January 23, 2019 | N/A | Active – |
| | | | | | Amendment |
| | | | | | required for |
| | | | | | effluent transfer to |
| | | | | | Black Fox holding |
| | | | | | pond for Grey Fox |
| | | | | | mine water |
Black Fox | MECP | 2126-DRUJZW | ECA-Air | April 27, 2026 | N/A | Active – |
| | | | | | Amendment |
| | | | | | completed for |
| | | | | | Grey Fox |
| | | | | | Operations |
Black Fox | MECP | 6824-9VCNXB | PTTW | October 26, 2020 | October 26, | Active – No |
| | | | | 2030 | change |
| | | | | | anticipated |
Black Fox | MEM | N/A | Closure | June 2018 | N/A | Active – |
| | | Plan | | | Amendment |
| | | | | | required for Grey |
| | | | | | Fox closure costs |
| | | | | | (Black Fox |
| | | | | | Closure Plan |
| | | | | | Amendment 2026 |
| | | | | | filed) |
Grey Fox | MECP | Pending | PTTW | Pending | TBD | Pending – New |
| | | | | | permit required for |
| | | | | | underground mine |
| | | | | | dewatering |
Stock Mill | MECP | 4371B2KHZT | ECA-ISW | August 2, 2018 | N/A | Active |
Stock Mill | MECP | 1357-A4KKFS | ECA-Air | December 11, | N/A | Active |
| | | | 2015 | | |
Stock Mill | MECP | 6377-88UJE5 | PTTW | September 18, | September | Active |
| | | | 2018 | 18, 2028 | |
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Site | Regulatory | Reference No. | Type | Issue Date | Expiration | Status / Notes |
Stock Mill | NDMNRF | N/A | Closure | June 2018 | N/A | Active |
Notes: ECA-ISW: Environmental Compliance Approval – Industrial Sewage Works; ECA-Air: Environmental Compliance Approval – Air and Noise; MECP: Ministry of Environment, Conservation and Parks; MEM: Ministry of Energy and Mines; PTTW: Permit to Take Water; N/A: not applicable (no expiry date); NP: not provided.
Table 17-2: Anticipated Provincial Approval/Amendment Requirements
Approval | Responsible | Description |
| Ministry | |
Closure Plan Amendment | MEM | Mine construction / production and closure for |
| | Grey Fox / Stock, including updated financial |
| | assurance. Offline dams above the high-water |
| | mark of local watercourses (e.g., TMA). |
Environmental Compliance Approval(s) – | MECP | Release of air emissions and noise from haul |
Air and Noise | | trucks, process plant, refuelling / oil / lubrication |
| | areas, administration complex, and onsite |
| | laboratory. |
Environmental Compliance Approval – | MECP | Operation of a waste transfer site; transportation |
Waste Disposal Site / Waste Management | | of waste materials offsite and onto Provincial |
| | highways. |
Environmental Compliance Approval – | MECP | Domestic sewage treatment plant. Not expected |
Domestic Sewage | | to be required if pre-approved mobile sewage |
| | treatment systems are used. |
Environmental Compliance Approval(s) – | MECP | Construction of mine / mill water treatment |
Industrial Sewage Works | | system(s) discharging to the environment; |
| | includes TMA, ponds, mine water, stormwater, |
| | stockpile runoff, and fuelling areas. |
Permit(s) to Take Water – Ontario Water | MECP | Taking of groundwater or surface water (>50,000 |
Resources Act | | L/day) for process water balance and mine |
| | dewatering. May also be required for construction |
| | dewatering. |
Forest Resource License(s) – Crown | MNRF | Cutting of Crown merchantable timber for site |
Forest Sustainability Act | | development or transmission line construction. |
Work Permit(s) – Lakes and Rivers | MNRF | Work / construction on Crown land. Dam |
Improvement Act / Public Lands Act | | construction on any lake or river requires written |
| | approval for location and plans and specifications. |
Township of Black-River Matheson | Municipality | Construction-related building permits as required. |
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17 Environmental Studies, Permitting, and Plans, Negotiations, or Agreements with Local Individuals or Groups
17.4.3Permitting Critical Path and Schedule
The critical path for commencement of Grey Fox underground development is anticipated to be the Closure Plan Amendment, the Grey Fox PTTW for dewatering of underground workings and ISW-ECA amendment to the Black Fox mine effluent discharge (0328-8XVPXT). The Grey Fox PTTW will be a Category 3 application under Ontario Regulation 387/04, requiring a full hydrogeological study prepared by a QP given the scale of anticipated dewatering (estimated at up to 1,938 m³/d, equivalent to approximately 1.94 million L/d) and determination of influence to nearby Pike River and Salve Creek. Category 3 PTTW applications are technically complex and typically require a minimum of 6 to 9 months from application submission to permit issuance, exclusive of the time required for data collection, hydrogeological modeling, and supporting report preparation. The Closure Plan Amendment, to incorporate Grey Fox mine production and associated updated closure costs, requires filing with MEM and confirmation of updated financial assurance—typically a 3-to-6-month review period following submission of a complete application.
ECA-ISW amendments at Black Fox (for effluent transfer, treatment and discharge to handle Grey Fox mine water) will be required prior to commencement of mine operations; this application should be submitted in parallel with the PTTW process. The key requirement for the ISW-ECA related to Grey Fox transfer, treatment and discharge will be the establishment of new effluent criteria for the Black Fox water treatment plant in accordance with MECP Procedure B-1-5 and the development of an acceptable surface and groundwater monitoring plan(s) to MECP. Both these pre-application components must be developed and accepted by MECP before the ISW-ECA application is submitted. MECPs service standard for complete and acceptable ISW-ECA applications is 12 months after submission. McEwen’s intent is to progress all key permit applications concurrently and as soon as necessary project design information is available. McEwen has an established regulatory record at the Fox Complex that supports efficient permit processing.
17.5Environmental Aspects and Sensitivities
17.5.1Water Discharge
Contact water from the Grey Fox site will be collected and stored on-site and then transferred to the Black Fox mine for treatment and discharge into the Pike River following treatment at the currently permitted discharge point in accordance with an MECP amended industrial sewage works Environmental Compliance Approval. Treatment within the holding pond prior to discharge involves sulphuric acid addition to lower pH, and ferric sulphate dosing to precipitate arsenic. A coagulant (e.g., poly-aluminum chloride) may also be used to enhance the settling of suspended solids in the Holding Pond, if required. Additional treatment options are being considered to meet anticipated approval limits, including arsenic, zinc, nickel, molybdenum and copper. Loading values are dependant on seasonal fluctuations and assimilative capacity of the Pike River. Modeling and discussions with stakeholders is on-going.
To reduce the mine water inventory, non-contact runoff at the Grey Fox site will be diverted using perimeter berms to allow runoff to naturally flow off site. Contact water collection ditches to collect runoff and toe seepage will be constructed around the perimeters of project components, including the waste rock stockpile, ore stockpile, and laydown area. Areas where fuel storage or handling may occur will be isolated to avoid potential cross-contamination of petroleum hydrocarbons. Contact water collection ditches will
| Project: 169525666 | 17-7 |
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17 Environmental Studies, Permitting, and Plans, Negotiations, or Agreements with Local Individuals or Groups
drain by gravity to the extent practicable to reduce pumping requirements. Excavated sumps and pumps will be used where site topography is not conducive to draining by gravity. The contact water collection ditches will discharge the collected water to water management ponds.
The water management ponds and collection ditches will be designed to contain water from a 1 in 100-year AEP of a 24-h duration storm event, considering snowmelt. The spillways of the ponds will be designed for the climate change adjusted 1 in 100-year annual exceedance probability of a 24-h duration storm event. Two ponds are anticipated to be required for water management, a stockpile pond and a holding pond. The holding pond will have a permanent pool to promote settling and provide extended detention and storage of settled materials. The holding pond will be designed to receive pumped inflows from the underground dewatering in addition to site contact water and will serve as a source of water for service underground water requirements and site surface water needs (e.g., dust suppression).
Ore will be processed, and tailings disposed of at existing processing and tailings storage facilities at the Stock Mill site.
17.5.2Site Plan Layout
The Grey Fox mine works including waste rock piles and water management infrastructure will be designed to avoid watercourses and waterbodies to address concerns with a Fisheries Act MDMER Schedule 2 prohibition regarding the deposition of mine waste in waterbodies frequented by fish.
17.6Social and Community
The McEwen Fox Complex is located within territories traditionally used by Indigenous peoples. Consultation and engagement activities with Indigenous Nations regarding the Fox Complex have been ongoing since 2006. Nations consulted include:
| ● | Apitipi Anicinapek Nation (formerly Wahgoshig First Nation) – Reserve located approximately 23 km east of the Fox Complex and the closest Indigenous community to the Site; |
| ● | Matachewan First Nation – Reserve located approximately 60 km southwest; |
| ● | Métis Nation of Ontario – Timmins Community Council; |
| ● | Métis Nation of Ontario – Northern Lights Council; and |
| ● | Temiskaming Métis Council. |
An Impact Benefit Agreement (IBA) is currently in place with the Apitipi Anicinapek Nation, the Indigenous community in closest proximity to the Black Fox Complex. The IBA includes a pathway for discussing approval amendments, considerations and related potential impacts prior to submission. Concerns or questions raised are addressed within this process. In accordance with the IBA, the filed Closure Plan Amendment for the Black Fox Complex was provided to Apitipi Anicinapek Nation for review prior to submission.
McEwen continues to discuss all projects that require government permits or approvals with First Nations in advance of submission. Details of the agreements and discussions with local Indigenous communities are provided in Section 3.3.2 of this TRS.
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17 Environmental Studies, Permitting, and Plans, Negotiations, or Agreements with Local Individuals or Groups
Consultation and engagement will also be required with other stakeholders, including regulatory agencies, local communities, and residential and industrial neighbors where development is proposed in proximity to existing properties or operations. Community members will be engaged as appropriate.
17.7Mine Closure
McEwen has prepared and filed a Closure Plan Amendment for the Fox Complex, which was filed with the Ministry of Energy and Mines (Formerly Ministry of Northern Development, Mines, Natural Resources and Forestry) in 2026. The Closure Plan Amendment supersedes all previously submitted closure plan amendments and is to be considered in its entirety. The overall objectives of site rehabilitation and closure measures are to stabilize the site and to reduce, mitigate, and/or eliminate risks of hazards and the release of mine-related constituents into the surrounding environment.
Site reclamation work will be fulfilled progressively during active operations as practicable, consistent with industry best practice and the filed Closure Plan Amendment. The closure plan addresses three phases: Temporary Suspension, State of Inactivity, and Close Out. The post-closure land use for the site is forest and wildlife habitat, with potential for forestry operations, mineral exploration, agriculture, and recreational uses.
17.7.1Conceptual Closure
Table 17-3 summarizes preliminary closure concepts for major infrastructure and site features at the Fox Complex per the filed Closure Plan Amendment.
Table 17-3: Closure Approaches
Feature | Concept Summary |
Open Pit (Black Fox) | Remove all infrastructure and equipment from within the open pit. |
| Reshape if needed and revegetate overburden slopes to a stable |
| condition. Allow pit to fill naturally with water via seepage and runoff. |
| Ramps will be barricaded and a safety berm established around the |
| perimeter. Construct overflow channel from the open pit to a tributary |
| of Salve Creek to the north. Batch treatment of pit water as |
| appropriate. |
Underground Mine (Black Fox, Froome, | Remove all infrastructure and equipment presenting environmental |
Grey Fox, Stock) | hazard or with salvage value. Allow workings to flood naturally via |
| groundwater seepage. Seal all entrances to underground workings. |
Buildings, Machinery, Equipment and | Salvageable machinery and equipment dismantled and removed from |
Infrastructure (All Sites) | site. Remaining items managed in accordance with regulatory |
| requirements at an approved onsite landfill or licensed offsite facility. |
| Above-grade concrete structures broken to near-grade; rebar cut flush |
| with surface; concrete structures infilled with clean mine rock if |
| required. |
Chemicals, Petroleum Products and | All petroleum products, chemicals, and explosives removed from site |
Explosives (All Sites) | and transported to a licensed disposal facility. Contaminated soil |
| handled in accordance with regulatory requirements. |
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17 Environmental Studies, Permitting, and Plans, Negotiations, or Agreements with Local Individuals or Groups
Feature | Concept Summary |
Onsite Infrastructure – Roads and Power | Roads not needed in the long term scarified and seeded. Onsite power |
(All Sites) | distribution lines and associated materials dismantled and deposited in |
| an approved landfill if unable to be sold or re-used. |
Tailings Management Area (Stock) | Tailings surface progressively covered with soil and revegetated. |
| Tailings pond drained; water treated prior to discharge. |
Waste Rock (Black Fox) | Progressive reclamation during operations. Regrading of slopes to 3:1 |
| (overall) where required. Placement of overburden cover followed by |
| revegetation. Pumping of stockpile runoff / seepage to open pit during |
| State of Inactivity. |
Waste Rock (Grey Fox, Stock) | Regrading of stockpiles to acceptable slopes. Waste rock stockpile |
| surfaces will be covered and revegetated with material that meets the |
| long term cover requirements for reactive material as per the Ontario |
| Mine Rehabilitation Code. |
Rehabilitation measures will include:
| ● | The waste rock pile will be built with overall embankment slopes that are adequate for long-term physical stability so that no re-contouring is required at closure. Available stockpiled soil will be used to vegetate waste rock piles as practical to conform to the local landscape. Mine rock types that pose a chemical stability risk will be managed in accordance with the management plan that will be developed as part of the closure plan. |
| ● | Final removal of the water management infrastructure will be conducted once no longer required. |
| Project: 169525666 | 17-10 |
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18 Capital and Operating Costs
18Capital and Operating Costs
18.1Methodology
The capital and operating cost estimate meets the criteria to be classified as a Class-3 estimate, as defined by AACE International with an approximate accuracy of +20%/-15%. All costs included in the estimate are reported in Q1 2026 US dollars (US$).
The cost estimates reflect a detailed bottom-up approach based on key engineering deliverables that define the project scope. This scope is described and quantified within material takeoffs in a series of line items. The costs have been compared against project benchmarking, along with McEwen existing operations in the area.
18.2Total Capital Cost Estimates
The total combined capital cost estimates was prepared by Stantec, DRA, and Arcadis, with contributions from McEwen. The total pre-production capital expenditure (CAPEX) is estimated at $180.8 million, followed by $173.8 million in sustaining capital costs (SUSEX), and $7.4 million for closure. The capital cost estimate is divided into three broad scope areas:
| ● | Mining |
| ● | Processing |
| ● | Other |
A summary of the estimated LOM CAPEX is presented in Table 18-1, with detailed cost breakdowns summarized in the sub-sections that follow.
The project period CAPEX is defined as all costs incurred from 2026 to the end of 2029, while SUSEX is incurred from 2030 through to the end of mine life. Pre-production CAPEX has been divided into the following:
| ● | Engineering and procurement services. |
| ● | Non-development mining cost (e.g., equipment, construction, underground infrastructure). |
| ● | Mining development cost (including vertical development). |
| ● | Surface infrastructure. |
| ● | Pre-production operating costs (operating costs that occur during the project period). |
| ● | Contingency. |
SUSEX are related to the following:
| ● | The initial equipment fleet is planned to be leased by McEwen and included in the operating cost (refer to Section 18.3.1.5). The new equipment required for Grey Fox South, plus the planned rebuild and replacement equipment, is included in the sustaining capital cost. |
| ● | Mining development cost (including vertical development). |
| ● | Underground infrastructure construction. |
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18 Capital and Operating Costs
| ● | Surface construction. |
| ● | Mine closure. |
The cost presented in this technical report outlines an initial pre-production capital cost estimate of $180.8 million, which includes a contingency of $27.11 million and pre-production operating costs of $4.2 million. Estimated LOM capital costs are presented in Table 18-1.
Table 18-1: Capital Cost Estimate ($ millions)
Description | Project Period | Sustaining Capital | Total Capital Cost | |
| ||||
Mining | | | | |
Engineering | $5.8 | $0.0 | $5.8 | |
Procurement | $4.4 | $48.0 | $52.4 | |
Construction / Excavations | $98.5 | $125.6 | $224.1 | |
Indirects | $31.8 | $0.2 | $32.0 | |
Contingency | $25.9 | $0.0 | $25.9 | |
Total Mining | $166.4 | $173.7 | $340.1 | |
Surface Crusher Facility | | | | |
Engineering | $0.3 | $0.0 | $0.3 | |
Mechanical Equipment Supply + Install | $1.7 | $0.0 | $1.7 | |
Commodities | $1.0 | $0.0 | $1.0 | |
Indirects | $1.0 | $0.0 | $1.0 | |
Contingency | $0.5 | $0.0 | $0.5 | |
Total Surface Crusher Facility | $4.4 | $0.0 | $4.4 | |
Water Treatment Plant | | | | |
Engineering | $0.7 | $0.0 | $0.7 | |
Procurement | $3.6 | $0.0 | $3.6 | |
Construction | $0.2 | $0.0 | $0.2 | |
Indirects | $0.4 | $0.0 | $0.4 | |
Contingency | $0.7 | $0.0 | $0.7 | |
Total Water Treatment Plant | $5.7 | $0.0 | $5.7 | |
Total | $176.5 | $173.7 | $350.3 | |
Pre-Production Costs | $4.2 | $0.0 | $4.2 | |
Closure | $0.0 | $7.4 | $7.4 | |
Net Capital Costs | $180.8 | $181.1 | $361.9 | |
Notes:
| ● | All figures are rounded to reflect the relative accuracy of the estimate. |
| ● | Totals may not sum due to rounding as required by reporting guidelines. |
| ● | Pre-production costs include operating costs incurred prior to any profits. |
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18 Capital and Operating Costs
18.2.1Mining Capital Costs
The total project period mining capital of $166.4 million primarily includes surface construction, lateral and vertical mine development, underground infrastructure construction, as well as the purchase and installation of stationary mine equipment. The cost excludes the pre-production OPEX, estimated at $4.2 million.
The total mining sustaining capital of $173.7 million primarily includes lateral and vertical mine development, underground infrastructure construction, and mobile fleet rebuilds and replacement.
The estimated LOM CAPEX and SUSEX for mining-related activities are presented in Table 18-2.
Table 18-2: Mining Preproduction Capital and Sustaining Costs ($ millions)
| Preproduction Capital | Sustaining Capital | |
Item | ($ millions) | ($ millions) | |
Detailed Engineering | $5.8 | $0.0 | |
Procurement | | | |
Contractor Mob/Demob | $1.4 | $0.1 | |
Mobile Equipment Rental | $0.6 | $0.0 | |
Mobile Equipment Rebuilds/Replacement | $0.0 | $47.9 | |
Packaged Equipment and Bulks | $2.5 | $0.0 | |
Total Procurement | $4.4 | $48.0 | |
Mine Construction / Excavations | | | |
Underground Mine | $45.6 | $117.3 | |
Surface | $42.3 | $6.7 | |
Pre-Commissioning | $0.8 | $1.1 | |
Contractor Indirects | $9.8 | $0.5 | |
Total Underground Mine Construction | $98.5 | $125.6 | |
Construction Indirects | | | |
Logistics and Freight | $3.0 | $0.0 | |
Capital/Commissioning/Operating Spares | $2.0 | $0.0 | |
Vendor Support | $2.0 | $0.0 | |
Total Construction Indirects | $7.1 | $0.0 | |
Project Indirects | | | |
EPCM | $24.7 | $0.2 | |
Total Project Indirects | $24.7 | $0.2 | |
Contingency | $25.9 | $0.0 | |
Mining Totals | $166.4 | $173.7 | |
| Project: 169525666 | 18-3 |
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18 Capital and Operating Costs
18.2.1.1 Underground Mine Construction / Excavations
Detailed Engineering
Summarizes the cost estimate to complete the detailed engineering for the following:
| ● | Mine design and scheduling |
| ● | Underground facilities |
| ● | Backfill |
| ● | Ventilation |
| ● | Surface facilities |
| ● | Geomechanical modelling |
Procurement
The procurement includes the costs associated with the contractor indirects, short term equipment rental for early mine development, and package equipment, which equipment that isn’t specific to a single construction activity, for example underground subs that would be moved, jumbo cable etc.
The initial mobile equipment fleet is included in the operating cost estimate as a lease. The procurement of fixed plant equipment, such as fans, pumps, compressors, are included in the facility cost under underground or surface construction.
Underground Construction / Excavations
The underground mine construction consists of all project period lateral and vertical excavations, and any underground facilities constructed. The underground lateral development and installations contractor will be responsible for the initial underground ramp, lateral and vertical (raising) development (in waste rock only) starting from the construction of the north access portal to the initial ore access at Whiskey Jack, and construction/installation of stationary mine infrastructure. Once the deposit is accessed at Whiskey Jack, McEwen’s labor workforce will assume all underground development and construction activities.
The project period cost for the underground construction and excavations are presented in Table 18-3. See Table 13-43 for list of underground facilities included in the cost estimate.
Table 18-3: Underground Construction and Excavation during Project Period
Item | Cost ($ millions) |
Definition Drilling | $9.9 |
Mine Development - Ramp/Lateral | $17.9 |
Mine Development - Vertical | $2.7 |
Underground Construction | $15.1 |
Total | $45.6 |
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Surface Construction
Surface infrastructure construction capital is estimated to be $42.3 million, and is exclusive of indirect and contingency costs. The surface construction costs during the project period include a portal, administration building, dry and security facility, surface maintenance shop, ventilation/heating plants, electrical substation, water collection ponds, access roads, and all earth works related to excavating and levelling the site. The project period cost for the surface construction activities are presented in Table 18-4.
Table 18-4: Surface Construction During the Project Period
Item | Cost ($ millions) |
Site Clearing, Roads, Bridges, Ponds, etc. | $12.7 |
Surface Facilities | $15.8 |
Surface Utilities | $3.7 |
Portals with Fans | $1.3 |
Ventilation Collars | $1.4 |
Main Ventilation Fans | $3.8 |
Pipeline from Grey Fox to Black Fox | $3.7 |
Total | $42.3 |
18.2.1.2 Construction Indirects
Indirect construction costs include freight and logistics for the delivery of equipment and materials to site, spare parts for fixed plant equipment, and vendor commissioning support for fixed plant equipment. Costs are estimated as a percentage of the total fixed plant equipment capital estimate, with the percentages applied as follows:
| ● | Freight – 3% |
| ● | Spare parts – 2% |
| ● | Vendor support – 2% |
18.2.1.3 Project Indirects
Indirect project costs account for all labor and expenses, and required indirect fleet and vehicle operating costs, associated with the execution of the project. The project team organization chart, labor forecasts, and fleet requirements are developed based on the project execution plan, and the costs are then developed from first principles.
18.2.1.4 Mining Sustaining Capital Costs
Sustaining Capital is associated with of the remaining lateral and vertical excavations, underground and surface infrastructure, equipment rebuilds and replacement, along with all indirects costs associated with the work completed during the project period. The annual sustaining capital costs are presented in Table 18-5.
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18 Capital and Operating Costs
Table 18-5: Annual Sustaining Capital Costs ($ million)
Item | Cost | 2030 | 2031 | 2032 | 2033 | 2034 | 2035 | 2036 | 2037 | 2038 | 2039 | 2040 | 2041 | |
Procurement | | |||||||||||||
Contractor Mob/Demob | $0.1 | $0.1 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | |
Mobile Equipment | $47.9 | $0.0 | $2.4 | $2.6 | $6.1 | $4.9 | $4.4 | $3.3 | $7.3 | $9.9 | $6.9 | $0.0 | $0.0 | |
Underground Construction and Excavations | | |||||||||||||
Definition Drilling | $29.7 | $1.0 | $3.1 | $1.2 | $5.1 | $4.4 | $1.0 | $5.2 | $2.8 | $3.9 | $1.9 | $0.1 | $0.0 | |
Mine Development - Ramp/Lateral | $44.9 | $1.4 | $4.7 | $1.8 | $7.7 | $6.6 | $1.6 | $7.8 | $4.2 | $6.0 | $2.9 | $0.1 | $0.0 | |
Mine Development - Vertical | $3.5 | $0.1 | $0.4 | $0.1 | $0.6 | $0.5 | $0.1 | $0.6 | $0.3 | $0.5 | $0.2 | $0.0 | $0.0 | |
Underground Construction | $39.2 | $1.3 | $4.1 | $1.6 | $6.7 | $5.8 | $1.4 | $6.8 | $3.7 | $5.2 | $2.5 | $0.1 | $0.0 | |
Surface Construction | | |||||||||||||
Ventilation Collars | $1.4 | $1.4 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | |
Main Ventilation Fans | $5.3 | $5.3 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | |
Pre-Commissioning | $1.1 | $0.0 | $0.2 | $0.0 | $0.2 | $0.2 | $0.0 | $0.2 | $0.1 | $0.1 | $0.1 | $0.0 | $0.0 | |
Contractor Indirects | $0.5 | $0.1 | $0.1 | $0.1 | $0.1 | $0.1 | $0.1 | $0.1 | $0.1 | $0.1 | $0.1 | $0.0 | $0.0 | |
Project Indirects | $0.2 | $0.2 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | $0.0 | |
Total | $173.7 | $10.8 | $15.0 | $7.5 | $26.5 | $22.5 | $8.5 | $23.9 | $18.5 | $25.6 | $14.5 | $0.4 | $0.0 | |
| Project: 169525666 | 18-6 |
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18 Capital and Operating Costs
18.2.2Surface Crushing Facility
A primary crusher with a stacking conveyor will be located on the ore pad at the Grey Fox site. ROM ore will be trucked from either the North or South Portal and deposited near the primary crusher. A loader will be used to feed the crusher. Crushed ore will be placed in temporary stockpiles with the stacking conveyor, and then loaded into surface haulage trucks and hauled to the Stock Mill for processing.
Bulk earthworks costs are included with the surface construction costs presented in Table 18-2.
The estimate presented in Table 18-6 includes the cost of crusher, conveyor, and related equipment, engineering, indirect costs, and contingency.
Table 18-6: Surface Crusher Costs ($ millions)
Item | LOM Total |
Mechanical Equipment Supply and Install | $1.7 |
Commodities | $1.0 |
Contractor Indirects | $0.4 |
Freight and Land Transport Cost | $0.3 |
Spares and Inventory | $0.1 |
EPCM | $0.3 |
Commissioning and Vendor Representative | $0.3 |
Contingency | $0.5 |
Total Capital Costs | $4.5 |
18.2.3Water Treatment Plant Capital Costs
The capital cost estimate for the Grey Fox water treatment plant has been developed based on several key assumptions. The treatment system is assumed to be housed within a new 24 m x 46 m industrial metal featuring insulated metal panels, an HVAC system, and a concrete foundation designed to withstand anticipated site temperature extremes. The process configuration, as described in Section 15, is based on projected holding pond water chemistry and is designed to meet Ontario PWQO discharge limits. Allowances for design and engineering have been estimated at 20% of capital equipment costs, while project management and QA/QC have been estimated at 10% of the combined capital equipment and construction costs. Table 18-7 summarizes the water treatment plan costs.
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Table 18-7: Water Treatment Plant Costs
Description | Cost ($ millions) | Notes |
Direct Costs | | |
Building | $2.8 | 80’ x 150’ Industrial metal building and foundation |
Filtration System | $0.4 | Includes initial filtration media |
Containerized IX System | $0.4 | Includes initial resin load |
Containerized Dewatering System | $0.1 | |
Field Installation | $0.2 | Site civil, electrical connection, and piping |
| | interconnect |
Indirect Costs | | |
Design and Engineering | $0.7 | See assumptions |
Project Management, Procurement, | $0.4 | See assumptions |
and QA/QC | | |
Contingency | $0.7 | See assumptions |
Total | $5.7 | |
18.2.4Contingencies
A contingency factor was applied against all project capital, excluding engineering and indirect labor costs, resulting in a total estimated contingency of $27.1 million.
18.2.5Pre-Production Operating Costs
The pre-production costs include operating costs incurred within the project period associated with operating waste development and ore development/production, mine operating indirect costs, fixed plant maintenance, processing, and utilities. The pre-production cost total is $4.2 million.
18.2.6Closure
Closure costs have been estimated in the 2026 Closure Plan Amendment. The total estimated cost of closure activities, as described in the Closure Plan Amendment and reflected in the LOM financial model, is $7.40 million. This estimate includes active care, passive care (long-term monitoring), and provision for periodic in-situ batch treatment of open pit water, post-closure.
It is noted that current closure cost estimates reflect the Black Fox Mine Closure as currently configured, including the Grey Fox deposit at its current advanced exploration footprint (the Grey Fox Advanced Exploration Closure Plan costs are included). This estimate does not yet incorporate the full mine production infrastructure associated with the Grey Fox mine as described in this technical report. A further Closure Plan Amendment will be required once Grey Fox mine design is finalized at future design study
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18 Capital and Operating Costs
stages, and this amendment will include updated closure cost estimates and a corresponding update to financial assurance.
18.3 Total Operating Cost Estimates
Stantec, DRA, and Arcadis, with contributions from McEwen, developed operating cost estimates to determine the annual production costs. Unit costs are expressed in total LOM and $/tonne processed. All costs included in the estimate are reported in Q1 2026 US dollars.
Total LOM OPEX is estimated at $1,398 million, exclusive of pre-production operating costs, refining and shipping and royalties. Expenditures that are non‑ capital costs that occur during the project period are classified as Pre-production operating costs. Pre-production operating costs incurred in 2028 only have been capitalized in the economic models (refer to Section 18.2.5).
The operating cost estimate is divided into the following broad areas:
| ● | Mining |
| ● | Processing |
| ● | Tailings |
| ● | Wastewater Treatment |
The operating costs detailed herein are based on mine and process plant design criteria and engineering and unit cost information derived from various sources.
A summary of the estimated LOM operating costs is presented in Table 18-8 and details of the cost breakdowns are summarized in the sub-sections that follow:
Table 18-8: Total Operating Cost Estimate
Operating Cost Item | LOM Total ($ millions) | Cost $/tonne Processed |
Mining | $1,013.3 | $107.7 |
Processing | $267.0 | $28.4 |
Tailings | $114.6 | $12.2 |
Water Treatment | $2.8 | $0.3 |
Total | $1,397.7 | $148.6 |
Note:
| ● | All figures are rounded to reflect the relative accuracy of the estimate. |
| ● | Totals may not sum due to rounding as required by reporting guidelines. |
| Project: 169525666 | 18-9 |
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18 Capital and Operating Costs
18.3.1Mining – Operating Costs
Mine operating costs have been built up from first principles, using detailed mine development and production schedules together with a variety of unit costs (quoted by suppliers, or using benchmark data and operational experience). The costs have been scheduled by period and built up by type for each basic mining activity (i.e. lateral development, stoping, fixed plant maintenance, utilities and general mine/indirect activities). Mine operating costs in the years prior to the processing of ore have been capitalized. A summary of overall mine OPEX is presented in Table 18-9.
Table 18-9: Summary of Mining OPEX
Operating Cost Item | LOM Total (US$ | Cost $/tonne Processed | |
| |||
Underground Production | $651 | $69.17 | |
Mine Operations Indirect | $145 | $15.40 | |
Utilities (Power/Gas) | $122 | $12.94 | |
Fixed Plant Operating | $22 | $2.34 | |
Leasing - Equipment & Infrastructure | $62 | $6.62 | |
Project Period Mining Direct | $12 | $1.26 | |
Total | $1,013 | $107.73 | |
Notes:
| ● | All figures are rounded to reflect the relative accuracy of the estimate. |
| ● | Totals may not sum due to rounding as required by reporting guidelines. |
18.3.1.1 Underground Production
The underground production costs have been developed from first principles for all ore development and production and ore haulage related activities. Unit costs for development and production activities, were calculated from first principles and include labor, materials/consumables and mobile equipment operating. The unit cost calculations are provided for direct costs only. Varying unit costs are calculated for both the project and operating periods.
The labor component is based upon the crew size and the calculated performance per day to determine the total hours per unit of measure, which are then applied to the crew labor rates. Materials costs are based on the quantity take offs per unit, derived from the mine design criteria. Equipment operating is based on the calculated performance per day to determine the total hours per unit of measure, which are then applied to the equipment operating costs per hour.
See Table 18-10 and Table 18-11 for operating development and stoping unit costs during the project period and operating period, respectively.
| Project: 169525666 | 18-10 |
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18 Capital and Operating Costs
Table 18-10: Operating Development Unit Costs
Description | Unit Cost | |
| ||
Contractor | | |
Stope Access - Single Heading (PP) - 4.0 x 4.3 m (WxH) | $3,265.68 | |
Stope Access - Multiple Heading (PP) - 4.0 x 4.3 m (WxH) | $3,201.48 | |
Sill Cut - Single Heading (PP) - 4.0 x 4.0 m (WxH) | $3,119.31 | |
Sill Cut - Multiple Heading (PP) - 4.0 x 4.0 m (WxH) | $3,053.77 | |
Sill Cut - Single Heading (PP) - 3.5 x 4.0 m (WxH) | $2,865.44 | |
Sill Cut - Multiple Heading (PP) - 3.5 x 4.0 m (WxH) | $2,501.15 | |
McEwen | | |
Stope Access - Single Heading (OP) - 4.0 x 4.3 m (WxH) | $3,275.49 | |
Stope Access - Multiple Heading (OP) - 4.0 x 4.3 m (WxH) | $2,770.69 | |
Sill Cut - Single Heading (OP) - 4.0 x 4.0 m (WxH) | $3,081.93 | |
Sill Cut - Multiple Heading (OP) - 4.0 x 4.0 m (WxH) | $2,661.16 | |
Sill Cut - Single Heading (OP) - 3.5 x 4.0 m (WxH) | $2,902.96 | |
Sill Cut - Multiple Heading (OP) - 3.5 x 4.0 m (WxH) | $2,481.89 | |
Note: PP = project period; OP = operating period
Table 18-11: Stoping Unit Cost by Deposit
Description | Unit Cost | |
| ||
Underground Mine Stoping - Whiskey Jack | $52.47 | |
Underground Mine Stoping – Gibson / Grey Fox South | $64.14 | |
18.3.1.2 Mine Operations Indirect
Owner’s Team
The Owner’s team operating cost listed in Table 18-9 includes personnel comprised of Management, Technical Services, Operating (non-direct), and Maintenance personnel. The non-direct operating includes underground general foreman, shift bosses, and grader operators, etc.
| Project: 169525666 | 18-11 |
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18 Capital and Operating Costs
Indirect Mobile Equipment
The operating cost for the indirect equipment is based on Stantec’s internal benchmarking and project experience, along with mining industry published standards aligned with the proposed equipment fleet.
18.3.1.3 Utilities
Power
The total power demand for the underground operations was calculated by considering the connected load and adjusting for utilization (operating hours), demand factor (percentage of nameplate draw), drive efficiency, and system losses. Power for the operating period will be provided by a 27.6 kV power line installed by Ontario Hydro, with an estimated cost of $0.085/kWh for steady-state power. Details of the power distribution are described in Section 15.6.
The estimated total power consumption for the operating period is 1,379 M kWh, with a total estimated cost of $86.7 million.
Compressed Natural Gas
The compressed natural gas operating costs are based on the following assumptions:
Heating of mine air takes place over an average period of 8 months per year.
Compressed natural gas supply costs will include the rental of all required infrastructure and delivery charges, and the all-in supply rate is assumed to be $0.79/standard cubic metre. This rate is based on current database costs for similar projects in Northern Ontario.
18.3.1.4 Fixed Plant Operating
Fixed plant maintenance costs have been estimated based on Stantec’s internal benchmarking and project experience, along with mining industry published standards aligned with the scope of work.
18.3.1.5 Leasing
McEwen will finance the initial purchase of all fleet, this leasing cost was carried as an operating cost. The estimate assumes that an interest payment of 6.99% will be applied to the repayment of each fleet unit, and that the repayment schedule will be three years per unit.
18.3.1.6 Project Period Mining Direct
The project period mining costs include all operating development, production and ore haulage related activities that occur during the project period.
| Project: 169525666 | 18-12 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
18 Capital and Operating Costs
18.3.2Processing – Operating Costs
18.3.2.1 Basis of Estimate
The operating cost estimate for processing Grey Fox material through the Stock Mill has been developed based on defined operating parameters, metallurgical testwork, and industry benchmarks. The estimate assumes an annual plant throughput of 536,550 tonnes at a head grade of 3.4 g/t Au. Reagent consumption rates are based on metallurgical testwork results described in Section 10, supplemented where necessary with standard industry benchmarks in the absence of specific test data (e.g., cyanide detoxification). Comminution circuit power requirements were derived through process modeling using ore hardness parameters established during test programs. The overall process design reflects a combination of testwork outcomes and conventional industry best practices. Unit pricing for reagents and consumables was provided by McEwen based on current delivered costs to the Stock Mill, while costs for wear components such as polyurethane panels, cyclone parts, and screen cloths were estimated using DRA’s internal database of comparable projects.
18.3.2.2 Operating Cost Summary
Table 18-12 below summarizes the processing plant OPEX by cost element.
Table 18-12: Process Plant OPEX Summary ($ millions)
Element | $ per year | $ per tonne | Contribution% |
Personnel | $7.1 | 13.28 | 46.5% |
Electrical power | $1.4 | 2.65 | 9.3% |
Reagent consumption | $2.8 | 5.31 | 18.6% |
Consumables consumption | $2.2 | 4.04 | 14.1% |
Laboratory costs | $0.4 | 0.75 | 2.6% |
Contract maintenance | $0.1 | 0.23 | 0.8% |
Spare parts and miscellaneous | $1.2 | 2.33 | 8.2% |
Total Operating Cost | $15.3 | 28.58 | 100.0% |
| ● | Personnel costs include all salaried employees associated with the operating plant including the laboratory staff, water treatment plant operators and maintenance crews. |
| ● | Electrical power includes all electrical energy consumed by the site excluding the mining operation. |
| ● | Reagent consumption includes all reagents added to the slurry streams in the process plant including smelting fluxes, antiscalant, and water treatment chemicals. Sodium cyanide contributes $2.30 per tonne of ore treated which is close to half of the total reagent costs. |
| ● | Consumables include grinding media, crusher/mill liners, diesel, propane (for heating), compressed natural gas (smelting furnace), lubricants, cyclone wear parts, polyurethane screen panels, crucibles and stainless steel wool. |
| ● | Laboratory costs include consumables such as crucibles for fire assays, glass beakers, laboratory chemicals, etc. |
| Project: 169525666 | 18-13 |
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18 Capital and Operating Costs
| ● | Contract maintenance covers all contract services including annual mill relining, environmental monitoring services, safety audits and inspections, mobile equipment maintenance, etc. |
| ● | Spare parts and miscellaneous costs is an allowance for the replacement of equipment, as required, that may fail during operations. It also includes pipe fittings and platework replacement as required. |
| ● | A more detailed breakdown of each element is provided in the sections below. |
18.3.2.3 Personnel Costs Estimate
Table 18-13 below summarizes the estimated plant personnel costs.
Table 18-13: Personnel Costs Summary
Position | Schedule | Number | Total Costs ($/year) | Unit Costs |
| | | | ($/tonne) |
Mill Manager | Day | 1 | 191,932 | 0.36 |
Mill Superintendent | Day | 1 | 130,240 | 0.24 |
Administrative Clerk/Trainer | Day | 1 | 99,136 | 0.18 |
Maintenance Superintendent | Day | 1 | 130,240 | 0.24 |
Gold Room Supervisor | Day | 1 | 121,166 | 0.23 |
Chief Metallurgist | Day | 1 | 150,000 | 0.28 |
Junior Metallurgist (EIT) | Day | 1 | 99,136 | 0.18 |
Laboratory Supervisor | Day | 1 | 130,240 | 0.24 |
Laboratory Technician | Day | 6 | 594,813 | 1.11 |
Shift Operations Supervisor | Shift | 4 | 520,960 | 0.97 |
Control Room Operator | Shift | 4 | 520,959 | 0.97 |
Plant Operator | Shift | 24 | 2,379,253 | 4.43 |
Maintenance Planner | Day | 1 | 121,166 | 0.23 |
Instrumentation Technician | Shift | 4 | 484,663 | 0.90 |
Millwright | Shift | 6 | 726,994 | 1.35 |
Electrician | Shift | 4 | 484,663 | 0.90 |
Lube Technician | Day | 2 | 242,331 | 0.45 |
Totals | | | 7,127,892 | 13.26 |
There are six Plant Operators per shift crew covering all areas of the Plant. One or two of these also assist in the gold room with smelting duties (twice weekly) as there are no dedicated refiners in the personnel complement. Provision has not been made for a dedicated Relief Operator position to cover leave and training; the assumption is that the crew size is sufficient to cover these eventualities.
| Project: 169525666 | 18-14 |
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18 Capital and Operating Costs
A day shift is based on 2,080 hours per year (52 weeks of 40 hours per week). There are four shift crews which allows for a two-weeks-in and two-weeks-out rotation. Their total hours are 2,190 hours per year (12-hour days for 14 consecutive days each month). The costs include all benefits and bonuses.
18.3.2.4 Electrical Energy Costs Estimate
Table 18-14 summarizes the expected energy consumption costs. The total unit energy consumption is estimated at 44.5 kWh/t.
Table 18-14: Estimated Energy Consumption Costs
Area | Installed | Combined | Consumed | Total Costs | Unit Costs |
| Power (kW) | Factors | (kWh/yr) | ($/year) | ($/tonne) |
Air and water services | 349 | 90 | 1,993,845 | $118,634 | 0.22 |
Primary crushing | 55 | 70 | 235,550 | $14,015 | 0.03 |
Crushed ore handling | 48 | 92 | 303,895 | $18,082 | 0.03 |
Crushed ore reclaim | 34 | 88 | 224,445 | $13,355 | $0.02 |
Secondary and tertiary crushing | 130 | 71 | 787,141 | $46,835 | $0.09 |
Primary grinding circuit | 1,250 | 91 | 9,616,446 | $572,179 | $1.07 |
Secondary grinding circuit | 784 | 91 | 6,042,543 | $359,531 | $0.67 |
Leaching and adsorption | 405 | 86 | 2,337,392 | $139,075 | $0.26 |
Cyanide destruction and tailings disposal | 137 | 90 | 927,867 | $55,208 | $0.10 |
Acid washing, elution and regeneration | 255 | 24 | 459,422 | $27,336 | $0.05 |
Refinery | 120 | 37 | 365,081 | $21,722 | $0.04 |
Reagents | 44 | 39 | 87,674 | $5,217 | $0.01 |
Lime mixing | 16 | 22 | 24,660 | $1,467 | $0.00 |
Allowance for Site Overheads (water pumps, lighting, plugs, etc.) | 118 | 53 | 469,714 | $27,948 | $0.05 |
Total | 3,744 | | 23,875,675 | $1,420,603 | $2.65 |
Notes:
| ● | Installed power includes all standby motors |
| ● | “Combined factors” are the product of the load factor (i.e., how much of the installed power is used when the motor is running), the utilization factor (i.e., the total running hours as a fraction of the total hours in a calendar year), and the inverse of the efficiency factor (i.e., how efficiently is energy drawn from the grid). |
| ● | The utilization factor was applied to non-standby motors only so the product of the installed power and the combined factors number will not equate to the energy consumption presented in Table 21-3. The numbers shown in Table 21-3 are summaries of more detailed motor-by-motor calculations in the mechanical equipment list. |
| ● | The Allowance for Site Overheads cover all electricity users not pertinently listed in the Major Equipment List (e.g., site stormwater management pumps, sewage system, lighting, plugs). |
| Project: 169525666 | 18-15 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
18 Capital and Operating Costs
18.3.2.5 Reagents Costs Estimate
Table 18-15 summarizes the reagent consumption and cost estimates.
Table 18-15: Reagent Consumption and Costs
Description | Consumed | Delivered Price | Total Costs | Unit Costs |
Sodium Cyanide Solution (30%w/v) | 0.56 | $4.13 | $1,240,933 | $2.31 |
Activated Carbon | 0.017 | $4.57 | $41,694 | $0.08 |
Hydrated Lime | 3.14 | $0.51 | $857,968 | $1.60 |
Nitric Acid Solution (68%) | 0.013 | $0.78 | $5,469 | $0.01 |
Caustic Soda | 0.02 | $2.01 | $18,325 | $0.03 |
SMBS Solution (38% w/w) | 1.02 | $0.73 | $398,382 | $0.74 |
Copper Sulphate | 0.040 | $3.83 | $82,208 | $0.15 |
Antiscalant | 0.02 | $5.08 | $54,460 | $0.10 |
Allowance for Water Treatment Plant Chemicals | | | $110,895 | $0.21 |
Flocculant | 0.015 | $4.60 | $37,014 | $0.07 |
Smelting Fluxes (combined) | | | $352 | $0.00 |
Total | | | $2,847,698 | $5.31 |
Notes:
| ● | The allowance for water treatment plant chemicals was calculated from an industry benchmark of $0.40/m3 treated and a preliminary water balance estimate of 277,200 m3 to be treated annually. |
| ● | All consumption numbers in the table are per tonne of ROM feed. |
18.3.2.6 Consumables Costs Estimate
Table 18-16 summarizes the consumption of consumable items not included in the mechanical equipment or reagents lists.
Table 18-16: Miscellaneous Consumables Costs
Description | Consumed | Delivered Price | Total Costs | Unit Costs |
Jaw crusher liners | 0.080 | $3.000 | $128,772 | $0.24 |
Cone crushers liners | 0.140 | $3.000 | $225,351 | $0.42 |
Ball Mills Media | 1.560 | $0.805 | $674,134 | $1.26 |
Ball Mills Liners | 0.156 | $6.730 | $563,313 | $1.05 |
Diesel | | | $40,425 | $0.07 |
Propane (Heating) | | | $257,600 | $0.48 |
| Project: 169525666 | 18-16 |
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18 Capital and Operating Costs
Description | Consumed | Delivered Price | Total Costs | Unit Costs |
Compressed Natural Gas | | | $504 | $0.00 |
| Sets/annum | USD/set | | |
Crucibles and SS Wool | | | $15,000 | $0.03 |
Lubricants | | | $30,000 | $0.06 |
Cyclone Body Parts | 8 | $17,000 | $136,000 | $0.25 |
ADR Circuit Screens Poly Panels | 1 | $12,000 | $12,000 | $0.02 |
Scalping Screens Poly Panels | 4 | $20,529 | $82,114 | $0.15 |
Total | | | $2,165,214 | $4.04 |
Notes:
| ● | Media and liner consumption rates for the tumbling mills are based on an assumed abrasion index and in-house empirical correlation calculating steel consumption based on the energy consumed by the mill and the abrasion index of the ore. The total steel consumption is estimated at 1.9 kg/t which aligns well with industry standards. |
| ● | Diesel consumption was estimated at 35,000 L/yr covering forklifts, bobcats and light vehicles used in the Plant and a diesel price of CAD 1.65/litre (USD 1.16/L). |
| ● | Propane consumption (heating) was benchmarked at USD 0.48/t against similar sites in Ontario. Note that this benchmark also includes the electrical energy consumed for heat tracing. |
| ● | An allowance of $15,000 was added for goldroom crucibles and stainless steel wool. |
| ● | An allowance of $30,000 was added for lubricants. |
| ● | For cyclones it was assumed that each operating cyclone (8 of) will be replaced once annually, i.e., 8 sets in total per year. |
| ● | Vibrating screen panels was assumed to have a life of 6 months. |
18.3.3Tailings - Operating Costs
Table 18-17 summarizes the costs associated with the Stock Mill WEA tailings storage.
| Project: 169525666 | 18-17 |
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18 Capital and Operating Costs
Table 18-17: Tailings Storage Costs for Stock Mill WEA
Cost Item | Quantity | Unit of | Unit Cost | Cost | Basis of Estimate |
Dam Construction | 724,350 | m³ | $28.80 | $20.9 | Concept Grading Design (2,632 m; 14 m max height; 9.2 m avg height; 4 m top width; 3H:1V ds slope; 2H:1V us slope; firm silty clay sourced from on-site; average 1 km round trip) |
Overbuild for Settlement | 108,653 | m³ | $28.80 | $3.1 | 15% Overbuild |
Adjoining Dam Stabilization | 37,772 | m³ | $9.72 | $0.4 | Waste Rock against adjoining West Dam (464 m; 10H:1V; 1 m avg thickness; waste rock available on-site (5 km round trip) |
HDPE-lined Emergency Spillway | 1 | LS | $720,000 | $0.7 | Sheet Pile Weir (5 m deep, 25 m wide, 1 m projecting above grade) and Engineered Riprap-Lined Channel (trapezoidal, 2H:1V sides, 20m base width, 0.5 m deep, D50=10” rock at 0.6 m thick; 50 m length) |
Tailings Pipeline (8” SDR11 HDPE & fittings, 3” SDR11 HDPE & fittings) | 1 | LS | N/A | $1.2 | 8” SDR11 HDPE (5 km). 8” fittings (22 tees, 44 shutoff valves) (assumes 10% of piping cost) 3” SDR11 HDPE (1.7 km) 3” fittings (44 tees, 44 elbows) (assumes 30% of piping cost) |
Slurry Pump Upgrades | 1 | LS | $720,000 | $0.7 | High-head slurry pump for 4.5 km 8” pipeline at 250 m3/h (1,100 gpm), +13m static head |
Slurry Wall Seepage Cutoff | 10,528 | m² | $187 | $2.0 | In-situ stabilization slurry cutoff wall (2,632 m x 4 m deep; assumes 2 m average depth of firm brown clay + 2 m penetration into soft gray varved clay) |
PVD Installation & Equipment Mobilization | 2,147,238 | m | $1.44 | $3.1 | PVDs (denser spacing under dam with transition zone beyond toe; 131,269 m2 at 1.2 m spacing + 109,350 m2 at 3.0 m spacing; 18 m depth) Mobilization of standard wick-drain installation rig |
| Project: 169525666 | 18-18 |
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18 Capital and Operating Costs
Cost Item | Quantity | Unit of | Unit Cost | Cost | Basis of Estimate |
PVD Granular Drainage Blanket | 120,310 | m³ | $28.80 | $3.5 | Assumes 0.5 m thick granular drainage blanket over full footprint of PVD placement |
Geotechnical Instrumentation | 1 | LS | $360,000 | $0.4 | VWPs/Inclinometers (assumed cost) |
Subtotal: Direct Costs | | | | $35.9 | |
Engineering and Permitting | 18% | | | $6.5 | ~18% of Direct Costs |
Indirects and Contingency | | | | $8.5 | Calculated against project capital |
Total TMA Expansion Cost | | | | $50.8 | |
Initial Tailings Storage Cost (Grey Fox representing ~50% of total tailings storage through 2034) | 2,087,619 | tonnes | | $12.18 | $/tonne mined |
Future Tailings Storage Cost (starting in 2035, Grey Fox represents 100% of total tailings storage) | 4,175,238 | tonnes | | $12.18 | $/tonne mined |
Notes:
| ● | LS = Lump Sum, PVD = Pre-Fabricated Vertical Drain |
| ● | Dam Construction and Adjoining Dam Stabilization quantities are based on conceptual earthwork grading designs in Autodesk Civil 3D compared to existing grade elevations that are based on a combination of drone-based aerial LiDAR survey conducted by Arcadis in 2025 and the 2016 COOP 2-m DEM obtained from the COOP GeoHub portal. |
| ● | Unit costs for Dam Construction (and overbuild), Adjoining Dam Stabilization, Tailings Pipeline & Distribution, PVD Equipment Mobilization, and PVD Granular Drainage Blanket have been estimated using the Reclaim 7.0 model developed by the Government of the Northwest Territories. These costs have been converted from March 2014 dollars to January 2026 dollars using a conversion rate of 1.32. |
| ● | Tailings storage costs assume that the full expansion cost would be recurring for every 4.2 million tonnes of tailings (total) stored at Stock Mill, which, at approximately 3,000 t/d, represents a recurrence interval of approximately every 3.8 years (~46 months). |
| ● | In calculating initial and future tailings storage costs, a percentage of the total expansion capital cost proportional to the percentage of Grey Fox tailings stored at the facility is divided by the respective quantity of Grey Fox tailings, resulting in a normalized unit rate of $12.18 US$/tonne over the LOM. |
| ● | TSF costs are conceptual and may vary as design advances, with potential cost impacts mitigated by contingency and procurement strategies. |
| ● | More economical tailings storage options may be available that are either currently under evaluation or have not yet been evaluated (e.g., thickened tailings with central deposition; dry-stack tailings; construction of a new mill at Black Fox to facilitate on-site ore processing and tailings storage in the Black Fox Open Pit). |
| Project: 169525666 | 18-19 |
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18 Capital and Operating Costs
18.3.4Water Treatment Plant OPEX
The annual operating cost estimate for the Grey Fox water treatment plant is based on the following assumptions listed below as well as the operating summary described in Section 15.12.4:
| ● | Sodium hypochlorite dosed at 5 mg/L to the influent stream flow. |
| ● | 1% of flow through the greensand filter is used for backwash. |
| ● | Greensand backwash contains 1% solids. |
| ● | The backwash sludge volume was estimated by modeling the iron content as ferric chloride (FeCl3) assuming all iron in the influent stream, iron added as part of the greensand filtration process, and dewatering polymer, dosed at 5 mg/L, are captured as waste sludge. |
| ● | Greensand media replacement is completed every 4 years. |
| ● | IX resin replacement is completed every 10 years. |
| ● | Spent IX regenerant brine is disposed of at an offsite brine treatment facility. |
| ● | Ion exchange resins are regenerated once per week at a sodium chloride dose of 160 g/L. |
| ● | Weekly performance sampling for metals, total suspended solids, and pH at a third-party laboratory. |
The total annual estimated operating cost for the water treatment plant is $202,700.
| Project: 169525666 | 18-20 |
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19 Economic Analysis
19Economic Analysis
An economic model was prepared for the Grey Fox Project to estimate annual cash flows and assess the sensitivity of the Project to certain economic parameters.
The Project indicates an after‑tax cash flow of $493.2 million, after‑tax NPV (5%) of $282.1 million, and after-tax IRR of 24.8%. The Project is most sensitive to the head grade and gold price.
The base case discount rate for the Project is 5%. The discounted present values of the cash flows are summed to determine the project’s NPV. In addition to the NPV, the IRR and the payback period are also calculated. The IRR is defined as the discount rate that results in an NPV equal to zero. The payback period is calculated as the time required to achieve positive cumulative cash flow for the Project from the start of mineral processing.
Tax assumptions were modelled using input from McEwen and its tax advisors.
19.1Financial Results
A summary of the economic parameters for the Project are illustrated in Table 19-1, Table 19-2, and Figure 19-1.
Table 19-1: Summary of Economic Metrics for the Project
Description | Units | Value |
Pre-Tax | | |
NPV at 5% | $ million | $428.6 |
Internal rate of return | % | 30.7% |
Payback period | Years | 3.9 |
After-Tax | | |
NPV at 5% | $ million | $282.1 |
Internal rate of return | % | 24.8% |
Payback period | Years | 4.6 |
Note: Payback period calculated from start of processing.
Table 19-2: Calculation of After-tax Cash Flow
Description | Units | Value |
Gross revenue | $ million | $2,573.0 |
NSR Royalties | $ million | -$73.3 |
Net Revenue | $ million | $2,499.7 |
OPEX & SUSEX | $ million | -$1,578.8 |
| Project: 169525666 | 19-1 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
19 Economic Analysis
Description | Units | Value |
Net Operating Income | $ million | $920.9 |
NPI Royalty | $ million | -$16.3 |
EBITDA (Net Revenue) | $ million | $902.4 |
Non Cash Costs | $ million | -$144.1 |
EBIT | $ million | $758.2 |
Taxes | $ million | -$228.4 |
After-Tax Income | $ million | $529.9 |
Non Cash Costs - Added Back in | $ million | $144.1 |
Operating Cash Flow | $ million | $674.0 |
Capital Costs | $ million | -$180.8 |
Total Free Cash Flow (After-Tax) | $ million | $493.2 |

Figure 19-1: Undiscounted After-Tax Cash Flow
19.2 Cautionary Statement
The economic analysis results are based on forward‑looking information that is subject to a number of known and unknown risks, uncertainties, and other factors that may cause actual results to differ materially from those presented herein. Forward-looking statements in this section include, but are not limited to, statements with respect to:
· | Future gold prices. |
· | Currency exchange rate fluctuations, primarily the CAD:USD rate. |
· | Estimation of Mineral Reserves. |
· | Realization of Mineral Reserve estimates. |
· | Estimated costs and timing of CAPEX and OPEX, including labor, fuel, materials, consumables, supplies, and services. |
| Project: 169525666 | 19-2 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
19 Economic Analysis
19.3Assumptions
The economic model includes revenue, costs, taxes, and other factors applicable to the Project from the beginning of final design and construction through to the end of mine life. Corporate obligations, financing costs, and corporate-level taxes are excluded.
The model was prepared using mining schedules developed on an annual basis. The financial model is based on the following assumptions:
· | All costs are reported in US dollars (US$) and referenced as “$” unless otherwise stated. |
· | 100% equity ownership. |
· | Escalation and inflation have not been applied. |
· | Additional project development costs, including feasibility studies and permitting activities, are excluded. |
· | Annual gross revenue is determined by applying estimated metal prices to the annual payable metal estimated for each operating year. |
· | Constant commodity prices. |
· | A constant exchange rate of US$1.00 = C$1.35 (or C$1.00 = US$0.74) is applied. |
19.4Economic Model Parameters
19.4.1Mineral Resource, Mineral Reserve, and Mine Life
The mine plan presented in Section 13 of this report was used as the basis for revenue and cost estimates in the discounted cash flow, and also represents the current Mineral Reserve estimate. The mine plan excludes all material from the Inferred Resource category.
The stated Probable Mineral Reserve is 9.4 Mt at 3.24 g/t Au.
The mine plan considers a 15‑year LOM. The mill processing profile is presented in Figure 19-2.
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19 Economic Analysis

Figure 19-2: Life of Mine Processing Profile (tonnes)
The production profile for payable Au is presented in Figure 19-3.

Figure 19-3: Life of Mine Production Profile (Payable Au)
19.4.2Metallurgical Recoveries
The average metal recoveries for the different ore zones that have been used for the economic analysis are summarized in Table 19-3. Various grade versus recovery formulas were used to calculate recovery metrics on an annual basis within the financial model. A detailed review of metallurgical recoveries is provided in Section 10 of this report.
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Table 19-3: Life of Mine Average Metallurgical Recoveries
Zones | Gold |
Whiskey Jack | 91.8% |
Gibson | 85.7% |
Contact | 83.8% |
147NE + 147 + South | 88.8% |
Overall | 87.5% |
19.4.3Metal Prices
The metal price for Au used for the economic analysis was based on monthly closing data from April 2024 to April 2026; the approximate two-year trailing average gold price is US$3,000 per ounce. This period reflects a rapid rise in gold prices, starting from approximately $2,285 in April 2024 and exceeding $4,700 by April 2026. The metal price used is summarized in Table 19-4. A two-year time frame (April 2024 to April 2026) is standard for this type of disclosure because it balances long-term stability with recent market momentum. Since gold experienced a price surge during this period. A shorter window (e.g., 6 months) would artificially inflate the baseline price projection, while a longer window (e.g., 5 years) would heavily weigh outdated, lower-priced data.
Table 19-4: Metal Price Assumption
Metal | Units | Price |
Gold | US$ / oz | 3,000 |
Note: The calculation is based on monthly spot closing prices available as of April 2026.
A detailed review of metal prices is provided in Section 16 of this report.
19.4.4Capital Costs
A summary of pre‑production and sustaining capital costs is provided in Table 19-5. A detailed description of the capital costs is provided in Section 18.1 of this report.
Table 19-5: Capital Cost Summary (US$ millions)
Description | Total |
Detailed Engineering | $6.6 |
Physical Procurement | $10.8 |
Construction | $98.7 |
Project Indirects | $33.3 |
Capitalized OPEX | $4.3 |
Total capital before contingency | $153.7 |
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Contingency | $27.1 |
Sustaining | $173.7 |
Closure | $7.4 |
Total Capital Costs | $362.0 |
19.4.5Operating Costs
A summary of LOM operating costs is presented in Table 19-6 and Table 19-7. A detailed description of operating costs is provided in Section 18.3 of this report.
Table 19-6: Life of Mine Operating Cost Summary
Operating Cost Item | Cost | Cost |
Mining | $108.02 | $1,184.1 |
Processing | $28.4 | $311.2 |
Tailings | $12.2 | $133.5 |
Total | $148.6 | $1,628.8 |
Note: Mining costs include water treatment plant.
Table 19-7: Life of Mine Cash Costs C1 & All-In Sustaining Costs
Cash Cost | LOM Total | Unit/Tore | Unit/Oz |
Royalties | $90 | $9.53 | $104.43 |
Mining | $1,016 | $108.02 | $1,184.09 |
Processing / Tailings | $382 | $40.57 | $444.71 |
Selling | $22 | $2.33 | $25.50 |
Production Tax (Gov’t Royalty) | $64 | $6.80 | $74.56 |
Total C1 Costs | $1,573 | $167.25 | $1,833.29 |
DD&A | $144 | $15.32 | $167.98 |
Sustaining Capital | $181 | $19.26 | $211.11 |
All-in Sustaining Cost | $1,898 | $201.83 | $2,212.37 |
19.4.6Royalties
Three royalties have been included in the economic analysis, each calculated as a percentage of the NSR for portions of the ore zones, as summarized in Table 19-8.
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19 Economic Analysis
Table 19-8: Royalties as % of NSR & Percent of total Oz per Royalty
Name of Royalty | % of NSR | % of Total Oz |
Gray | 0.15% | 20% |
Newmont | 2.50% | 16% |
Schumacher | 3.00% | 64% |
A fourth royalty, calculated as a percentage of the NPI for portions of the ore zones, is presented in Table 19-9.
Table 19-9: Royalties as % of NPI & Percent of total Oz
Name of Royalty | % of NPI | % of Total Oz |
Parsons-Ginn | 5.0% | 36% |
19.4.7Working Capital
Allowances for working capital beyond metals in inventory at the mine and mill have been excluded for the purposes of this economic analysis.
19.4.8Taxes
A taxation model has been developed within the economic model with input from McEwen’s internal tax experts. Tax calculations for the Project are based on current federal and provincial tax rates and include the existing Mineral Property Tax Pools associated with the Project. McEwen internal tax experts reviewed the final tax calculations.
The tax inputs used in the economic model reflect current conditions; however, the actual taxes payable will depend on several factors, including, but not limited to, the timing of capital expenditures, changes in federal or provincial tax policy, and any investment incentives that may be available to McEwen.
19.4.9Closure Costs
Closure costs are estimated at $7.4 million and represent the cost of closure for the Grey Fox Project as well as the contiguous Black Fox site, which is under a single closure plan.
A bonding strategy has not been developed at this stage, and closure costs are assumed to be incurred during the last year of production.
19.4.10Financing
Project-level financing has not been considered in this economic analysis. 100% equity ownership is applied.
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19 Economic Analysis
The economic analysis does take into account financing terms offered by the vendor for‑ a ‑portion of the mining equipment fleet and certain surface facilities. These terms are based on a lease to own structure with a 15% down payment and an effective financing rate of 0.79% over a 36-month period.
19.5Sensitivity Analysis
A discounted cash flow calculation was prepared for the Project based on the various cost and revenue inputs. Sensitivity analysis was completed by applying ±30% variations to gold price, head grade, recovery, exchange rate, CAPEX, SUSEX, OPEX, fuel costs, and labor costs. The results are illustrated in
Figure 19-4.

Figure 19-4: Sensitivity Analysis
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19 Economic Analysis
For the press release Titled “Pre-Feasibility Study for Grey Fox at Fox Complex – High Returns, Manageable Capital, Mine Life Extended to 2041” and dated June 8, 2026 a gold price of $4500 per ounce (enhanced case) was used to understand the sensitivity of the project to gold price beyond the +30% presented in Figure 19-4. The results of the enhanced case are the following:
· | Cash costs and all-in sustaining costs per ounce over the LOM of $2,042 and $2,421, respectively, at a gold price of $4,500 per ounce. |
· | Pre-tax NPV (5%) increases to $1.25 billion, with an IRR of 70%, and payback of 2 years |
· | Post-tax NPV (5%) increases to $841 million, with IRR of 55% and payback of 2.3 years. |
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20 Adjacent Properties
20Adjacent Properties
The Grey Fox deposit is located proximal to the PDDZ in the Abitibi Greenstone Belt, a region with significant historical and current gold production. The Fox Complex, which includes Grey Fox, is located within an active exploration and mining district, surrounded by claims and leases held by exploration companies and operators including Onyx Gold Inc., STLLR Gold Inc., Mayfair Gold Corp., and Agnico Eagle Mines Ltd.
20.1Hislop
Located immediately south of Grey Fox is the formerly producing gold mine on the Hislop property, owned by Agnico Eagle Mines Ltd. (Figure 20-1). The Hislop property is also located immediately east and southwest of the Stroud deposit (100% McEwen ownership). McEwen has no ownership interest in the Hislop property, and information concerning this adjacent property has not been independently verified.
Current geological interpretations suggest that mineralization at Grey Fox may extend toward the northern portion of the Hislop property, however this has not been fully verified.
Gold mineralization at the Hislop property occurs in two principal settings associated with a syenite dyke complex:
· | To the south, in carbonate and carbonate breccia rocks separating the syenite dykes from the less altered ultramafic volcanic rocks; and |
· | To the north, in quartz veinlets, stockworks, and fractures within hematite-altered and syenitized mafic metavolcanic rocks (RPA, 2009). |
Mineralization north of the syenite dyke may be analogous to mineralization observed at the southern extent of the Grey Fox Project.
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20 Adjacent Properties

Figure 20-1: Plan View of Grey Fox and Stroud Projects in relation to Hislop Property
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21 Other Relevant Data and Information
21Other Relevant Data and Information
There is no other relevant data or information.
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22 Interpretation and Conclusions
22Interpretation and Conclusions
The QPs note the following interpretations and conclusions in their respective areas of expertise, based on the reviews and interpretations of data available for this TRS.
22.1Ownership
In the opinion of the Qualified Person, the ownership of the Grey Fox Project is well established, with McEwen holding a 100% interest in the mineral tenure covering the deposit area. The mineralized zones are situated on a contiguous group of patented and leased mining claims that collectively provide full control over the resource area. This ownership structure is sufficient to support the development and operation of the Project as contemplated in this Pre-Feasibility Study, and no material ownership constraints have been identified.
22.2Mineral Tenure, Surface Rights, Water Rights, Royalties and Agreements
In the opinion of the Qualified Person, the mineral tenure, surface rights, and associated agreements for the Grey Fox Project are well defined and provide a solid foundation for Project development. The deposit is located on a combination of patented claims and mining leases, with surface rights largely held or accessible for planned activities. The Project is subject to royalty agreements that are typical for the region and have been incorporated into the economic analysis. Existing agreements and ongoing engagement with Indigenous communities and other stakeholders are in place and support Project advancement. Overall, the tenure position, rights, and encumbrances are considered appropriate for the stage of study and do not present any material limitations to the Project as evaluated.
22.3Geology and Mineralization
The Grey Fox deposit is interpreted, based on the geological, structural, alteration, and mineralization relationships described above, to represent a structurally controlled gold system with characteristics consistent with an epizonal orogenic gold environment. Mineralization is hosted within a geologically complex package of mafic metavolcanic rocks, metasedimentary units, and the Gibson Syenite. The interpretation presented herein is considered appropriate for the current level of study and is intended to support geological modeling, Mineral Resource estimation, and PFS-level mine planning under S-K 1300 reporting frameworks.
The principal controls on gold mineralization are interpreted to be the interaction of favourable host lithologies, rheological contrasts, and multiple generations of veining and deformation. The dominant mineralized system comprises steeply dipping, northeast-southwest striking C1-vein arrays that are best developed in the 147, 147NE, Grey Fox South, and Gibson zones. Additional mineralization is localized along the Contact Fault and within the Whiskey Jack shear system. These domains are genetically and spatially related within the broader Grey Fox system, but they display sufficient geological, structural, and
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22 Interpretation and Conclusions
grade-continuity differences to warrant separate consideration during geological interpretation, domain modeling, estimation, and mine-design work.
The strongest and most laterally persistent mineralization is interpreted to occur where the C-vein system intersects chemically favourable iron-rich variolitic mafic metavolcanic flows and, in the Gibson area, where veins crosscut metasedimentary rocks proximal to the Gibson Syenite. These relationships indicate that both structure and host-rock composition exert first-order controls on gold deposition. In the volcanic-hosted zones, quartz-carbonate-albite veining, iron-rich host rocks, hematite-bearing alteration, and later sulphide-bearing alteration are interpreted to reflect fluid-rock reaction and changes in redox conditions that may have contributed to gold precipitation. In the Gibson zone, some mineralization is preferentially associated with quartz-sericite-sulphide alteration in metasedimentary rocks, localized brecciation, and stronger alteration near and below the syenite intrusion.
The structural architecture of the deposit is a material consideration for resource interpretation and mine planning. The Contact Fault, A-1 thrust fault, Gibson-Kelore Shear Zone, and Whiskey Jack shear define important geological boundaries and mineralized corridors. Variations in C-vein orientation across the Contact Fault are interpreted to reflect changes in host-rock competency between mafic metavolcanic rocks, metasedimentary rocks, and syenite. These variations should be reflected in geological modeling, domain definition, estimation strategy, and geotechnical assessment. The Whiskey Jack Zone is distinguished from the C-vein dominated zones by more continuous shear-hosted mineralization, higher average grades, and a deeper brittle-ductile style of deformation.
Overall, the geological setting and mineralization characteristics support the interpretation that Grey Fox comprises multiple related mineralized domains within a broader structurally controlled gold system. The primary opportunities for resource growth and refinement are expected along down-plunge and along-strike extensions of mineralized C-vein intersections with favourable metavolcanic and metasedimentary units, within structurally prepared zones adjacent to major faults and shears, and at depth in the Gibson area where drilling has indicated potential for higher-grade breccia-hosted mineralization below approximately 500 m. Further work should focus on refining structural controls, validating interpreted plunge continuity, assessing the extent and continuity of deeper Gibson mineralization, and integrating deportment results into metallurgical, sampling, reconciliation, and resource-modeling assumptions. These recommendations are intended to reduce geological uncertainty and support future updates to the Mineral Resource estimate and mine plan in accordance with applicable S-K 1300 disclosure requirements.
22.4Exploration
The Grey Fox deposit appears to be a combination of an epizonal and orogenic gold deposit made up of a network of sheeted vein sets present in multiple orientations. The drilling densities at the various zones that make up the Grey Fox deposit are good and in the QP’s opinion, the current geological and mineralization models are satisfactory.
Additional stripping for potential outcrops containing structures and mineralization is recommended to test against the validity of the current geological and mineralization models. It will be important to tighten the drill spacing for select areas at Grey Fox to improve the classification of mineral resources. Finally, the
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22 Interpretation and Conclusions
Exploration team should continue to update the lithological-structural models for local accuracy, control of density and resource domaining.
22.5Metallurgical Testwork
The principal conclusions arising from the metallurgical testwork completed on Grey Fox mineralized material are summarized below:
· | Comminution Characteristics |
Comminution testwork conducted on representative samples of Grey Fox mineralized material indicates that the material is relatively hard and competent compared with ores typically processed in conventional gold treatment facilities. The tested samples returned an average Bond Ball Mill Work Index (BWi) of 23.4 kWh/t, with the hardest sample, representing Domain 31, exhibiting a BWi of 27.1 kWh/t. These results indicate that the Grey Fox material will require relatively high grinding energy for comminution, and that installed grinding power is expected to be a key design consideration for process plant throughput and overall circuit performance.
· | Gravity Recoverable Gold Potential |
Gravity concentration testwork returned gold recoveries to gravity concentrate ranging from 4% to 32%, with average gravity recovery below 20%. These results indicate that the gravity recoverable gold component is generally modest, although certain samples exhibited recoveries that may justify consideration of gravity concentration within the process flowsheet. On the basis of the testwork completed to date, inclusion of a gravity recovery stage may provide incremental recovery benefit but is not considered fundamental to the overall metallurgical recovery strategy.
· | Whole-Ore Cyanidation Performance |
Whole-ore cyanidation testwork returned gold recoveries ranging from approximately 71% to 94%. The broad range of recoveries demonstrates significant metallurgical variability within the Grey Fox mineralized material. This variability is expected to have implications for recovery forecasting, geometallurgical domaining, and potential process optimization strategies, and should be considered in future metallurgical evaluation and mine planning.
22.6Mineral Resource Estimates
The Mineral Resources estimates are considered reliable and thorough, and based on quality data that has been evaluated and verified. In cases where historical data was unable to be fully validated, resources were restricted to the inferred classification. Geological interpretations and parameters used in the MREs were assessed and considered reasonable.
· | The Grey Fox deposit is estimated to contain (inclusive of mineral reserves) 18.8 Mt at 3.28 g/t for 2.0 Moz of gold at the indicated classification and 5.0 Mt at 2.69 g/t for 438 koz of gold at the inferred classification. |
· | The Grey Fox deposit is estimated to contain (exclusive of mineral reserves) 9.7 Mt at 2.25 g/t for 701 koz of gold at the indicated classification and 4.7 Mt at 2.57 g/t for 388 koz of gold at the inferred classification. |
· | The Stroud deposit is estimated to contain, in inferred classification, 1.9 Mt at 2.80g/t for 168 koz of gold. |
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· | The Black Fox deposit is estimated to contain, in the combined measured and indicated classification, 385 kt at 3.57 g/t for 44 koz of gold. At the inferred classification it is estimated to contain 385 kt at 2.90g/t for 36 koz of gold. |
· | The Froome deposit is estimated to contain, in the combined measured and indicated classification, 651 kt at 2.78 g/t for 58 koz of gold. At the inferred classification it is estimated to contain 302 kt at 2.93 g/t for 28 koz of gold. |
· | The Stock West and Main deposits are estimated to contain 3.2 Mt at 2.63 g/t for 268 koz of gold at the indicated classification and 2.5 Mt at 2.31g/t for 184 koz of gold at the inferred classification. |
· | The Stock East deposit is estimated to contain 1.8 Mt at 2.12 g/t for 122 koz of gold at the indicated classification and 1.4 Mt at 2.02g/t for 87 koz of gold at the inferred classification. |
· | The Davidson-Tisdale deposit is estimated to contain, in the combined measured and indicated classification, 294 kt at 6.23 g/t for 59 koz of gold. At the inferred classification it is estimated to contain 200 kt at 3.44 g/t for 22 koz of gold. |
22.7Mineral Reserve Estimate
The Mineral Reserves estimate for the Grey Fox Project has been completed in accordance with accepted practice and meets Item 1300 of Regulation S-K and the CIM Definition Standards for Mineral Resources and Reserves (2014).
Many factors may affect the mineral reserves estimate such as dilution, metal prices, metallurgical recoveries, geotechnical characteristics of the deposit and host rock, and the capital and operating cost assumptions. These factors have been taken into account subject to the information and means available to QPs at the time of this study, as described in this report.
The metal price used to estimate Mineral Reserves was $2,200 per ounce of gold. The QP considers this price to be reasonable based on historical three-year trailing averages. A three-year time frame for the reserve estimate is standard for this type of disclosure because it balances long-term stability with recent market momentum. A shorter window (e.g., 6 months) would artificially inflate the baseline price projection, while a longer window (e.g., 5 years) would heavily weigh outdated, lower-priced data.
The reserves were estimated by designing mineable stope shapes in Deswik using DSO. The dimensions of the shapes were determined using geotechnical modeling and modifying factors such as dilution and mining recovery were applied. The shapes were then interrogated against the resource block model and included in the mine plan where the Gold value exceeded the cut-off value. The result was the reserve estimate on which the mine plan was based.
The mineral reserve estimate is shown in Table 22-1.
Table 22-1: Mineral Reserve Estimate, March 27, 2026
Classification | Ore Tonnes (t) | Au (g/t) | Gold Ounces (Oz) |
Total Reserve | 9,405,829 | 3.24 | 980,303 |
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22.8Mining
McEwen has other existing mining properties (operating and shutdown) in the same area as the Grey Fox Project, and thus has significant experience in mining operations in the region. The planned production rates, modifying factors, and costs are benchmarked against other operations to ensure they are suitable. The project is planning to employ an underground mining method consisting primarily of longitudinal longhole open stoping, which is deemed suitable considering the geometry and quality of the orebody. A small portion of the tonnes will be recovered via cut-and-fill. Longhole open stoping provides operational flexibility and scalability. Given the steeply dipping orebody geometry and the competent hanging wall and footwall conditions, the project is proposed to use predominantly longhole stoping on 20 m to 30 m sublevels in ground conditions expected to range from fair to good. The stopes will be backfilled with a combination of unconsolidated rock fill plus cemented rock fill to prevent backfill dilution in subsequent stopes while also minimizing the use of cement.
All mining activities will be conducted using rubber-tired equipment. Ore will be hauled to surface via the ramp using underground haul trucks. An existing portal near the Whiskey Jack and Gibson deposits will provide initial access to the underground operations. The operation is targeting a steady-state production rate of approximately 1,500 t/d until 2035 then ramping up to 2,700 t/d until 2040, ramping down in 2041. The equipment fleet has been sized to deliver the scheduled mining volumes with fleet expansion and the rebuild and replacement of gear included in the capital spending schedule. Push-pull ventilation system using intake fans at raises/portals and exhaust fans at return raises, with heaters to prevent freezing delivering up to 250 m³/s of fresh air.
22.9Infrastructure
The Grey Fox Project will consist of a compact, centralized mining infrastructure supporting underground operations via North and South portals. Core site infrastructure includes ore and waste stockpiles, a primary crushing facility, water management systems, ventilation plants, and key support buildings such as administration offices, mine dry, maintenance shop, warehouses, and security gatehouse. Site access is provided via Tamarack Road connecting to Highway 101, with ore hauled ~34 km to the Stock Mill. Electrical power will be supplied through a 27.6 kV grid connection along Tamarack Road.
22.10Tailings Storage
Primary conclusions related to tailings storage are outlined below:
· | The planned western expansion of the Stock Mill TMA is anticipated to provide approximately |
4.2 Mt of storage capacity within an outer footprint of approximately 41 ha. Existing leased lands at the Stock Mill are anticipated to provide at least an additional 193 ha of future expansion potential, for an estimated total expansion capacity of approximately 24 Mt.
· | Due to the geotechnical challenges associated with the underlying, soft, varved clays at the Stock Mill site, foundation-dewatering and seepage-control measures, in the form of prefabricated vertical drains (PVDs; wick drains) and appurtenant dewatering measures, have been included in the costs for the Stock Mill western expansion. |
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· | Other tailings management and storage methods, including using the Black Fox open pit, are currently being evaluated that may provide more economical and safer alternatives to slurry placement. |
22.11Water/Solute Mass Balance and Water Treatment
A water and solute mass balance model was developed in GoldSim to quantify mine contact water flows and water quality that may require treatment prior to discharge. Details on methods and results of this water/solute mass balance model are provided in Section 15. These results were used as the basis for the concept-level design of a water treatment plant, as well as treatment plant capital and annual operation cost estimates (provided in Section 18). The water balance was constructed based on the proposed mine water management plan involving pumping of contact water from Grey Fox (including underground workings dewatering water and runoff from mine facilities) to the Black Fox Mine holding pond.
Key conclusions of the water/solute mass balance evaluation are summarized below.
· | Average flows to the Holding Pond are anticipated to vary seasonally between 2,200 and 4,700 m3/day, with an annual average of approximately 3,300 m3/day. This includes water pumped from Grey Fox, as well as contact runoff at Black Fox from the Waste Rock Stockpile. |
· | Although several analytes may be elevated in concentration in mine contact water, arsenic is the only analyte predicted to exceed Canadian MDMER water quality standards, and the exceedance is predicted to be minimal and potentially seasonal. |
· | Arsenic and other constituents (cobalt, copper, iron, nickel, molybdenum, and zinc) are predicted to exceed Provincial PWQO values. There is also a smaller chance that vanadium may exceed PWQO values. |
· | Importantly, model results are highly sensitive to uncertainties in development rock geochemical source terms. |
Based on these simulation results, the anticipated water treatment system will consist of iron oxidation (potentially using a chemical oxidant such as oxygen or sodium hypochlorite) and greensand filtration, followed by ion exchange for low level metals removal, including a SBA resin for oxyanion removal (arsenic, molybdenum, and vanadium) and a SAC resin for removal of divalent cation metals (copper, cobalt, nickel, and zinc).
22.12Market Studies and Contracts
Gold is traded freely at widely known prices, consequently, the prospects for the sale of any production of the metal are virtually assured. A market study for the saleability of gold products or for the expected price of gold was not undertaken.
22.13Capital and Operating Cost Estimates
The estimate meets the classification standard for a Class 3 estimate as defined by AACE International and has an intended accuracy of +20%/-15%. The estimate is reported in Q1 2026 US dollars.
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22 Interpretation and Conclusions
An all in project capital cost is estimated at $181 million. SUSEX are estimated at $174 million, and a closure cost of $7.4 million.
The total operating cost is estimated at $1,398 million or $149 per tonne of ore milled.
22.14Economic Analysis
The ‑Project indicates an after‑tax cash flow of $493.2 million, after‑tax NPV (5%) of $282.1 million, and after tax IRR of 24.8%. The Project is most sensitive to the head grade and gold price.
22.15Risks
The QPs have not identified any significant risks or uncertainties that would reasonably be expected to impact the reliability or confidence of the exploration data, mineral resource estimates, or projected results. They are also not aware of any metallurgical, environmental, permitting, legal, title, taxation, socio-economic, marketing, political, or other factors that could materially influence the Mineral Resource estimates. However, it should be noted that substantial fluctuations in metal prices could potentially affect the project’s economic viability.
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23 Recommendations
23Recommendations
The work completed as part of this Technical Report Summary indicates that the Grey Fox Project is economically feasible based on the stated inputs and assumptions. The authors recommend that McEwen advance development of the Grey Fox Project.
The following work programs are recommended by the QPs to further support project advancement and enhance project value. Estimated costs for the recommended work are provided in Table 23-1.
23.1Recommended Work Programs
23.1.1Early Works
An early works program is recommended to confirm assumptions related to surface geotechnical conditions, including surface overburden characteristics, the condition of the existing portal, and surface conditions at the planned locations of the ventilation raise collars and the south portal.
23.1.2Further Exploration
Future exploration drilling at Grey Fox should focus on:
· | The northwestern extent of the Gibson Zone, where there is evidence of repeating vein sets associated with the contact between the Gibson syenite and adjacent metasediments to the east. |
· | Areas below the 300 m elevation at the Whiskey Jack Zone, where mineralization remains open. |
· | Deeper drilling (>300 m elevation) at Grey Fox South and 147, where drill density is lower relative to other areas of the property. |
In addition to continued diamond drilling, recommended exploration activities include geochemical modeling, downhole televiewer surveys to refine vein orientation, and additional LIBS scanning to better characterize lithological and mineralized domains.
23.1.3Mining
23.1.3.1Geomechanical
The following geochemical work is recommended to support advancement beyond PFS-level studies:
· | Conduct cemented rock fill mix trials to identify designs that meet required strength criteria, including for conditions involving mining beneath cemented rock fill sills. |
· | Complete additional geotechnical core logging and sampling to support IFC design, including: |
oLaboratory testing (e.g., UCS testing by lithology).
oEnhanced characterization of joint conditions (e.g., roughness and alteration).
Further evaluation of crown pillar stability over the LOM is recommended, including:
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23 Recommendations
· | Drilling a minimum of two boreholes within the planned crown pillar to obtain oriented geotechnical core logging data, with packer testing in zones of low RQD. |
· | Collection of laboratory samples (e.g., UCS and Brazilian strength tests) from representative lithologies. |
· | Numerical modeling of crown pillar and upper stope stability, as required based on changes to design assumptions or geological conditions. |
23.1.3.2Mining Optimization
Opportunities have been identified to further improve project economics, including:
· | Optimization of mine plan and stope sequencing, evaluation of alternative mining methods, and assessment of overall mine development sequence (e.g., earlier development of the South Portal). |
· | Continued optimization of cut-off grades to improve resource conversion, extend mine life, and balance economic and sustainability objectives. |
· | Ongoing evaluation of methodologies for excavation and support of ventilation raise collars particularly in areas characterized by poor-quality overburden. |
· | Review stope excavation dimensions versus geomechanical recommendations. Confirm smaller stopes with less high cost per tonne vs. large tonnes, lower cost per tonne but dilution and recovery factors. |
· | Evaluation mining equipment for multiple purpose, i.e. slot raise machines can be use for escape raises, etc. |
· | Evaluation of emerging technologies to improve operational efficiency and safety, including increased use of automation and semi-autonomous production equipment. |
23.1.4Mineral Processing and Metallurgical Testwork
The following metallurgical testwork is recommended to further characterize processing response of mineralized material from the Grey Fox deposit and to evaluate opportunities for process optimization. As of the publication date of this Technical Report Summary, a metallurgical program is underway that is expected to address items outlined below:
· | Additional Flotation Testwork to evaluate recovery potential and assess concentrate upgrading through cleaner flotation stages. |
· | Preg-Robbing Assessment using cyanidation testwork with and without activated carbon to confirm potential impact on gold recovery. |
· | Sedimentation and Settling Testwork to establish settling rates, underflow density potential, and flocculant requirements, and to provide design criteria for thickening and tailings management infrastructure. |
· | Oxidation and Fine Grinding Evaluation to assess potential improvement in liberation of gold encapsulated within the pyrite matrix and downstream gold recovery. Future metallurgical programs should evaluate this treatment option to determine its technical effectiveness and economic viability relative to the base case processing flowsheet. |
| Project: 169525666 | 23-2 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
23 Recommendations
23.1.5Tailings Storage
Additional evaluation of tailings management alternatives is recommended to align with GISTM Best Available Practices and Best Available Technologies and to reduce risk. In particular, consideration should be given to avoiding tailings deposition at the Stock Mill by evaluating the use of the Black Fox open pit as a tailings management facility.
23.1.6Surface Infrastructure
Based on the current level of engineering, the following work is recommended:
| ● | Access and Transportation |
oInspection of the Tamarack Road Bridge prior to construction.
o | Completion of hydrotechnical and geotechnical investigations to confirm bridge substructure capacity. |
· | Infrastructure and Site Development |
o | Detailed site investigations to refine topsoil volume estimates and support reclamation planning. |
o | Investigate bringing increased line power to site for future expansion and electrification options. |
o | Confirmation of availability and integration of Black Fox infrastructure to support early works. |
23.1.7 | Hydrogeology |
The current hydrogeological model was developed based on an open pit mining scenario at Grey Fox. It is recommended that the model be updated to reflect the current underground-only mining approach in order to confirm the assumptions regarding groundwater inflows to the underground workings. Based on available data, additional drilling is not considered necessary to complete the model update.
23.2Estimated Costs
Estimated costs for the recommended work programs are summarized in Table 23-1.
Table 23-1: Estimated Costs for Recommended Work for the Grey Fox Project
Description | Amount ($ millions) |
Early Works | $6.0 |
Further Exploration | $5.0 |
Geotechnical and mining studies | $0.9 |
Mineral Processing and Metallurgical Testwork | $0.2 |
Tailings Storage | $0.1 |
Surface Infrastructure | $0.7 |
Hydrogeology | $0.6 |
Total | $13.5 |
| Project: 169525666 | 23-3 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
24 References
24References
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Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
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Dyck, D. (2007). Apollo Gold Corporation Black Fox Project: Project description for small pit and mill operation update. AMEC Earth & Environmental.
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Ferguson, S. (1968). Geology and ore deposits of Tisdale Township. Ontario Department of Mines.
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Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
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Garber, J.A. (1997). Pike River summary: Hislop Township, Larder Lake Mining Division, Ontario (NTS 42A/9) [Unpublished report]. Battle Mountain Gold.
Gebre-Mariam, M., Hagemann, S.G., & Groves, D.I. (1995). A classification scheme for epigenetic Archean lode-gold deposits. Mineralium Deposita, 30, 408–410. https://doi.org/10.1007/BF00202283
Golder Associates. (2015). Summary of rock slope design recommendations for the 147 and Contact open pits, Black Fox Extension-Grey Fox Deposit Project: Technical memorandum (Draft Version, GAL-016-TM-RevA).
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Groves, D. I., Goldfarb, R. J., Gebre-Mariam, M., Hagemann, S. G., & Robert, F. (1998). Orogenic gold deposits: A proposed classification in the context of their crustal distribution and relationship to other gold deposit types. Ore Geology Reviews, 13, 7–27.
Groves, D. I., Santosh, M., & Zhang, L. (2020). A scale-integrated exploration model for orogenic gold deposits based on a mineral system approach. Geoscience Frontiers, 11(3), 719–738. https://doi.org/10.1016/j.gsf.2019.12.007
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Hodgson, C.J. (1989). The structure of shear-related, vein-type gold deposits: A review. Ore Geology Reviews, 4, 635–678.
Hodgson, C.J. (1993). Mesothermal lode-gold deposits. In R. V. Kirkham, W. D. Sinclair, R. I. Thorpe, & J. M. Duke (Eds.), Mineral deposit modeling (Special Paper 40, pp. 635–678). Geological Association of Canada.
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24 References
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Liu, Y., & Sloan, B. (2020). Metallurgical and environmental test work for the Grey Fox deposit, Timmins, Ontario (KM6034). Prepared for McEwen Mining. Internal report
Markham, B. and Gautrey, S. Grey Fox Groundwater Seepage Inflow Estimates to Open Pit and Underground Mine Workings – Draft. WSP prepared for McEwen.
Marchand, J. (2026). Grey Fox Project GTP validation/characterization/optimization study, Phase 1. Prepared for McEwen Inc.
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Ontario Ministry of Mines – Mining Lands Administration System (MLAS: Mining Lands Administration System | ontario.ca).
Parkhurst, D.L. and C.A.J. Appelo. (2013). Description of input and examples for PHREEQC version 3 – a computer program for speciation, batch-reaction, one-dimensional transport, and inverse geochemical calculations. U.S. Geological Survey Technical Methods, Book 6, 497.
Pelletier, C., Richard, P., & Turcotte, B. (2013). Technical report and mineral resource estimate for the Grey Fox Project (Effective date June 21, 2013). InnovExplo. Prepared for Brigus Gold Corporation.
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24 References
Price, W.A. 2009. Prediction Manual for Drainage Chemistry from Sulphidic Geologic Materials. Canadian Mine Environment Neutral Drainage (MEND) Report 1.20.1. Chapter 11. Prepared by CANMET Mining and Mineral Sciences Laboratories, Smithers, British Columbia. Prepared for MEND Program. December.
Rhys, D., & Ross, K. (2020). Review of mineralized intervals and petrography of selected drill core samples from the Stock West and Stock East areas [Internal report].
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Robert, F. (2000). World-class greenstone gold deposits and their exploration. 31st International Geological Congress, Rio de Janeiro, Brazil.
Robert, F. (2004). Geologic footprints of gold systems. In J. Muhling et al. (Eds.), SEG 2004: Predictive mineral discovery under cover (Publication 33, pp. 97–101). Centre for Global Metallogeny, University of Western Australia.
Robert, F., & Poulsen, K.H. (2001). Vein formation and deformation in greenstone gold deposits. In J. P. Richards & R. M. Tosdal (Eds.), Structural controls on ore genesis (Reviews in Economic Geology, Vol. 14, pp. 111–155). Society of Economic Geologists.
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Roscoe, W.E., Evans, L., Rennie, D.W., & Brady, B.S. (2003). Report on the Clavos, Stock Mine, Taylor, Central Timmins, and Golden Reward properties in the Timmins area of northeastern Ontario.
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| Project: 169525666 | 24-5 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
24 References
Taylor, B. E. (2007). Epithermal gold deposits. In W. D. Goodfellow (Ed.), Mineral deposits of Canada: A synthesis of major deposit types, district metallogeny, the evolution of geological provinces, and exploration methods. Geological Association of Canada. Special Publication No. 5, pp. 113–139.
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Tim McBride, B.Sc., P.Geo. Hydrogeologist AMEC Environment & Infrastructure (AMEC). 2012. Hydrogeological Assessment Grey Fox Project Hislop Township, Timiskaming - Cochrane District, Ontario. Prepared for Brigus Gold Corp. Report Number TC111515. 8 March 2012.
Tuba, G. (2019). Fluid inclusion characteristics and implications for gold formation at the Grey Fox Deposit [Internal report]. McEwen Mining Ltd.
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| Project: 169525666 | 24-6 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
25 Reliance on Information Provided by the Registrant
25Reliance on Information Provided by the Registrant
25.1Mineral Tenure, Surface Rights, and Encumbrances
In this Technical Report Summary, information regarding mineral tenure, surface rights, royalties, permitting, taxation, and environmental matters is based on material provided by McEwen. The QPs are not qualified to provide legal opinions on such matters and have relied on information and documentation provided by McEwen.
Certain data used in this Report were provided by McEwen. The QPs have reviewed and analyzed these data and have drawn independent conclusions based on their professional judgment.
The QPs offer no legal opinion as to the validity of title to the mineral claims and mining leases and have relied on information provided by McEwen in that regard.
25.2Taxation
The QPs have relied upon, and disclaim responsibility for, taxation information provided by McEwen. Invoices were compiled, examined and cross-referenced for payment confirmation or account statements were requested by the governing body to ensure payment compliance.
The QPs believe it is reasonable to rely on this information because the corporate tax structures and local jurisdictional regulations applicable to this project fall outside the standard technical expertise of the QPs, requiring specialized legal and accounting counsel. The retained experts providing the data are reputable, licensed professionals in good standing within the relevant jurisdiction.
This information supports the economic analysis presented in Section 19 and Mineral Reserve estimate presented in Section 12.
25.3Royalties
The QPs have relied upon, and disclaim responsibility for, information provided by McEwen regarding royalties applicable to the Project, including:
· | Parsons Ginn Royalty (5% net profits interest (NPI)) |
· | Triple Flag Royalty (formerly Newmont Royalty) (2.5% NSR) |
· | Frederick W. Schumacher Royalty (3% NSR) |
· | Gray Royalty (0.15% NSR) |
The QPs believe it is entirely reasonable to rely on this information for the following reasons:
· | · Legal Ownership: Legal agreements, underlying deeds, and land titles are corporate or legal matters that fall outside the technical expertise of a QP. |
| Project: 169525666 | 25-1 |
Grey Fox Project Prefeasibility Study S-K 1300 Technical Report Summary
25 Reliance on Information Provided by the Registrant
· | · Client Verification: The client has provided formal confirmation that these specific royalty parameters represent the current legal encumbrances on the property. |
This information supports the economic analysis in Section 19 and the Mineral Reserve estimate presented in Section 12.
| Project: 169525666 | 25-2 |
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