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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.

Exhibit 99.1

601 – 90 Eglinton Ave East, Toronto, Ontario, Canada M4P 2Y3 +1 416 362 5135 | www.micon - international.com NI 43 - 101 Technical Report, Initial Mineral Resource Estimate for the Trixie Deposit, Tintic Project, Utah, United States of America Effective Date: January 10, 2023 Report Date: January 27, 2023 Prepared By: William J. Lewis, P.Geo. Ing. Alan J. San Martin, MAusIMM (CP) Richard Gowans, P.Eng. OSISKO DEVELOPMENT CORP. 1100, av des Canadiens - de - Montreal Suite 300, P.O. Box 211 Montreal, QC H3B 2S2 Tel: 1.514.940.0685

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Osisko Development Corp.

Osisko Development Corp. (Osisko Development) has retained Micon International Limited (Micon) to independently review and verify its initial mineral resource estimate (MRE) for the Trixie deposit located within the boundaries of its Tintic Project (the Project) in the State of Utah, USA. and to compile a Canadian National Instrument (NI) 43-101 Technical Report disclosing the results of the MRE.

The geologic modelling for the Trixie deposit was completed by Osisko Development’s senior production geologist Courtney Kurtz, P.G. using Leapfrog Geo software. The MRE was completed by Osisko Development’s chief resource geologist, Daniel Downton, P.Geo., using Datamine Studio RM Pro 1.12 software. The MRE was then reviewed and validated by William Lewis, P.Geo. and Alan San Martin, AusIMM(CP), of Micon.

For the purpose of disclosure in this Technical Report, William Lewis, P.Geo., who is independent of Osisko Development and is a Qualified Person within the meaning of NI 43-101, is responsible for the initial mineral resource estimate by virtue of his independent review and validation of the work conducted by Osisko Development.

A site visit was conducted from September 12 to September 16, 2022, by Mr. Lewis to independently verify the geology, mineralogy, drilling programs and the Quality Assurance/Quality Control (QA/QC) programs at the Tintic Project.

When conducting, reviewing and validating the initial mineral resource estimate, Osisko Development and the Qualified Persons (QPs) used the following guidelines, published by the Canadian Institute of Mining, Metallurgy and Petroleum (CIM):

This report discloses technical information, the presentation of which requires the QPs to derive sub-totals, totals and weighted averages that inherently involve a degree of rounding and, consequently, introduce a margin of error. Where these occur, the QPs do not consider them to be material.

The conclusions and recommendations of this report reflect the QPs best independent judgment in light of the information available to them at the time of writing. Micon and the QPs reserve the right, but will not be obliged, to revise this report and conclusions if additional information becomes known to them subsequent to the date of this report. Use of this report acknowledges acceptance of the foregoing conditions.

This report is intended to be used by Osisko Development subject to the terms and conditions of its agreement with Micon. That agreement permits Osisko Development to file this report as a Technical Report on SEDAR (www.sedar.com) pursuant to provincial securities legislation, or with the Securities and Exchange Commission (SEC) in the United States.

Osisko Development Corp.

Neither Micon nor the QPs have, nor have they previously had, any material interest in Osisko Development or related entities. The relationship with Osisko Development is solely a professional association between the client and the independent consultants. This report is prepared in return for fees based upon agreed commercial rates and the payment of these fees is in no way contingent on the results of this report.

Micon and the QPs are pleased to acknowledge the helpful cooperation of Osisko Development management, personnel and consulting field staff, all of whom made any and all data requested available and responded openly and helpfully to all questions, queries and requests for material.

This report supersedes and replaces all prior Technical Reports written for the Tintic Project.

The Tintic Project is located in western Utah County, approximately 64 km south of Provo, Utah and 95 kilometres south of Salt Lake City. The property on which the Trixie test mine or Trixie deposit is located encompasses most of the East Tintic District, surrounding and immediately east of the incorporated town of Eureka. The township of Eureka is located approximately 6.4 km northwest of the Trixie test mine.

The coordinates of the centre of the Project are 407,700mE and 4,423,400mN, referenced in NAD83, Northern UTM Zone 12. The Project area is located on Eureka Quadrangle, US Topographic Map 1:24,000 scale, 7.5 Minute Series.

The nearest rail siding, in use, is located at Tintic Junction, approximately 10 km west of the Project.

The area of the Tintic Project owned or controlled by Osisko Development comprises 1,105 claims totalling 5,746 ha (14,200 acres) of patented mining claims and a further 107 unpatented mining claims of approximately 1,214 ha (3,000 acres). Osisko Development owns a small and varying percentage, interest or royalty in a number of other claims outside the main claim package.

Osisko Development verified the status of the mineral title to certain patented mining claims by engaging Utah legal counsel to conduct a review of Osisko Development’s chain of title for the select patented mining claims within the land package, covering approximately 243 ha (600 acres) surrounding the Trixie and Burgin mines. Utah legal counsel conducted their title review by examining the United States Bureau of Land Management records, including the patents issued by the United States, mineral survey and master title plans, and the official records of the Utah County Recorder’s Office, including the abstract (tract), mining claims, and grantor/grantee indices, among miscellaneous other records. This consolidated land position has been acquired over a hundred years of prior consolidation in the District. Osisko Development also engaged Wolcott LLC, an independent consultant, to conduct field checks and generate a geospatial database.

On May 30, 2022, Osisko Development announced the acquisition of 100% of Tintic Consolidated Metals LLC (TCM) (the “Acquisition”) from IG Tintic LLC (IG Tintic) and Chief Consolidated Mining Co. (CCMC) (the “Vendors”) for total consideration at closing of approximately USD 177 million in cash and shares of Osisko and:

Osisko Development Corp.

The closest major airport to the Tintic Project is in Salt Lake City, Utah (UT), located to the north-northwest of the city of Provo, UT via Interstate 15. Access to the Tintic Project from Provo, is via Interstate 15, a distance of 36 kilometres (km) south to exit 248 to US 6, then west on US 6, 27 km to Silver Pass Road, and then south 3.2 km to the Burgin project office site. The Trixie test mine is located 2.6 km southwest of the Burgin office on the paved Silver Pass Access Road. Provo and other smaller towns, including Payson, Santaquin and Eureka are also adjacent to the Project.

The towns of Goshen, Santaquin, Payson and Provo are the main sources for supplies and services. Tintic Project personnel and contractors also live in these areas.

The Project has sufficient power and water to support a mining operation.

Topographic relief in the East Tintic District ranges from 1,494 m in the Goshen Valley east of the District to 1,996 m at nearby Mineral Hill. The elevation at Trixie is 1,852 m.

The Tintic Mountains host the scanty vegetation typical of an arid region. Different species of cactus, forbs and shrubs grow on exposed rocky points. The more common trees of the higher slopes are pinyon pine, juniper and mountain mahogany. At lower elevations, maple thickets occur in the dry ravines, especially on the eastern slopes, while aspens are found in sheltered spots, more commonly those of northern exposure. In the valleys, sagebrush, rabbitbrush, Brigham’s tea and cheat grass constitute almost the entire vegetation. Range improvement projects in the area have had some effect on improving grazing.

The climate of the East Tintic District is semi-arid. The U.S. Climate data website noted that the mean monthly low temperatures at the nearby town of Elberta range from -10° Celsius (C) (15° Fahrenheit (F)) in January to 15°C (58°F) in July. The mean monthly high temperatures range from 2°C (37°F) in January to 33°C (93°F) in July. The Project has year-round access and operating season.

The Project’s main office, laboratory, workshops and onsite processing facilities are located at the Burgin site, immediately off Highway 6 and northeast of the Trixie test mine. The Burgin mine is a past-producing underground operation that was last mined in 1976. All references to Burgin in this report are with respect to the main office and surface facilities located at this site, and not to the Trixie test mine or deposit, unless otherwise specified.

A mill facility previously operational in 2002 is located at the Burgin site. In October, 2021, a pilot vat leaching circuit was established within the old Burgin mill facility for the recovery of gold and silver from of the mineralized material from the Trixie test mine. Osisko Development’s recent operations also included trucking mineralized material to an offsite facility for vat and heap leaching. This activity occurred from late 2020 up to May, 2022.

Osisko Development Corp.

In 2022, a pilot tailings facility was constructed on site adjacent to the mill facility. The facility was double lined for potential future re-permitting and use as a heap leach facility.

The onsite laboratory at the Burgin site provides fire assay analysis for gold and silver for all underground grade control sampling from the Trixie test mine. Atomic Absorption Spectrometry (AAS) and bottle roll analysis to complement onsite VAT leaching and processing has also been established. Using an onsite laboratory to assay samples generated on site is common practice in the mining industry. Onsite laboratories usually participate in round robin exercises with government or independent laboratories as part of their Quality Assurance and Quality Control programs. In addition, onsite laboratories, such as the Burgin site usually send out check samples and engage laboratory auditing consultants to independently review their procedures.

The mineral property is sufficiently large that construction of further infrastructure at the Project will not be hindered by lack of space.

Economic mineralization in the Tintic District was first discovered in 1869 and, within a few years, most of the major outcropping ore bodies were being mined and many of the historic mining towns, including Diamond, Silver City, Mammoth, Eureka, Dividend and Knightsville had been established. By 1899, the Tintic District had become one of the richest mining districts in the USA. Active mining in the district continued through the 20th and the beginning of the 21st century.

Even though many claims in what is now identified as the East Tintic District had been staked before the turn of the 20th century, the only known occurrence of surface mineralization was in a small outcrop near the present Eureka Lilly shaft. All future discoveries of the blind ore bodies in the East Tintic District have been based on surface alteration and underground geological interpretation.

E.J. Raddatz became interested in the East Tintic District around 1906 and acquired a major holding in what is now the Tintic Standard area. Raddatz reasoned that, even though the surface rocks were inhospitable, there was a chance of discovery in the Ophir limestone at depth. It took a considerable amount of time, two shafts and thousands of feet (ft) of drift and winze workings but, in 1916, the Tintic Standard deposit was discovered and went on to become one of the major lead-silver mines in the world.

Mining geologists, attracted by the discovery of the Tintic Standard deposit, began to study the district. Based on these studies, a long drive on the 700 level of the Tintic Standard mine was commissioned. This exploration work intersected the mineral deposit that became the North Lily mine. Similar strategies led to the discovery of the Eureka Standard mine.

During World War II, the United States recognized that, in the event of a long war, new sources of raw material would be essential. As a result, the US Geological Survey undertook an exploration program seeking blind ore bodies in the East Tintic District. One of the blind targets identified by the USGS was the CCMC oxide area, a prominent outcrop of oxidized and pyritized volcanics which overlies the Burgin deposit. However, no major discovery was made from either the sinking of the 22.6 m (75 ft) deep CCMC shaft or the drift from the Apex Standard mine. It was later surface drilling that made the discovery of the Burgin ore body.

Osisko Development Corp.

District production slowly increased through discovery of new mines and peaked between 1921 and 1930. From that peak, production decreased to a low between 1961 and 1970. Production from the Burgin mine led to a second peak of between 1971 and 1976.

Following the discovery of the Tintic Standard deposit in 1917, the North Lily deposit in 1927 and the Eureka Standard deposit in 1928, interest was sparked over a poorly exposed structure overlying the current location of the Trixie test mine.

Intense hydrothermal alteration of volcanic rocks exposed at surface at the Trixie site attracted the attention of the U.S. Bureau of Mines, which, in 1946-1947 conducted a number of studies in the Trixie area.

Between 1954-1955 the USGS conducted sampling and mapping of the area immediately north of the current Trixie shaft location. This was followed up by the drilling that confirmed the presence of the Trixie fault and the validity of the surface anomalies when low-grade lead-zinc ore was intersected in the Trixie fault zone. After the conclusion of the USGS research program in 1956, Bear Creek Mining completed additional holes in the target area and several of these holes intersected strong lead-zinc replacement mineralization in the underlying limestone. Despite the apparent presence of ore-grade mineralization at depth, the disappointing core recoveries resulted in surface exploration work being terminated in 1957. Subsequently, the decision was made to conduct future exploration from underground.

The sinking of the Trixie shaft was initiated in 1968 and had reached the 750 ft level by 1969. Although the initial target of exploration at the Trixie historic mine was lead-zinc replacement mineralization in the hanging wall of the Trixie Fault, a gold-bearing structure was encountered during shaft sinking. This northerly-trending and steeply west-dipping structural zone became the primary source of ore, which was concentrated along three gold-silver mineralized shoots referred to as the 756 ore shoot, the 75-85 ore shoot, and the Survey zone.

The original carbonate replacement deposit (CRD) that was discovered at the Trixie historic mine in 1969 is located on the north end of the deposit within the downthrown carbonate sequence north of the Trixie fault. While limited in scale, the replacement mineralization consists of massive sulphide minerals and jasperoid between the 750 ft level and 900 ft level.

The 756 ore shoot represents the most productive of the three historically mined ore zones. This ore shoot plunges to the north, towards the Trixie and Eureka Standard faults and was mined continuously from approximately 75 ft above the 625 level to below the deepest 1350 level development. Based on limited historic drilling it remains open at depth.

Osisko Development Corp.

In 1976, as mining and exploration continued within the 756 ore shoot, the 75-85 ore shoot was discovered approximately 1,600 ft (488 m) south of the Trixie shaft. The 75-85 ore shoot was mined from approximately 50 ft (15 m) above the 625 level down to the 1200 level.

In early 1980, Bear Creek Mining discovered the Survey zone while exploring for the Sioux-Ajax fault by drifting south on the 1050 ft level of the Trixie historic mine. The Survey vein segment was explored and extensively developed by Kennecott on the 750, 900, 1050 and 1200 levels during the pre-1995 silica flux mining periods. The southern end of the Survey Vein is extended for a distance of 3,400 ft south of the main shaft along the 1050 level and it remains open to the south and at depth.

In 1980, Sunshine Mining Corporation leased the Burgin unit from CCMC and by 1983 had also begun work at Trixie where it re-started mining operations and undertook additional underground development and diamond drilling. Much of the underground development and drilling from this time appears to have been focused on the 900, 1050, 1200 and 1350 levels. Perhaps the most notable exploration efforts at Trixie during this time were the southerly extensions of the 900, 1050 and 1200 ft level drifts, following the discovery of the Survey zone and the northeastward extension from the 1350 ft level to connect with the 1100 ft level of the Eureka Standard mine. This connection provided the underground access needed to evaluate the Eureka Standard fault along-strike and down-dip from the original Eureka Standard mine workings. Sunshine operated the Trixie historic mine until terminating their lease with CCMC at the end of 1992.

Between 2000 and 2002, CCMC (through its affiliate Tintic Utah Metals LLC) undertook an aggressive surface and underground drilling program at Trixie resulting in the discovery of a small-tonnage gold-silver resource associated with the earlier mined 75-85 mineralized zone. The 625 ft level was developed within the mine in 2001, but mining was suspended due to the decrease in the price of gold below $300/oz and CCMC’s financial and reported management problems.

TCM acquired the historical Trixie mine at the beginning of 2019, and initially focused its assessment on the base-metal resource opportunity at the Burgin mine. However, high-grade gold opportunities that had potential for near-term production and revenue at Trixie quickly became the focus of the company. Since most of the historic mining was focussed on the steep west-dipping structural corridor with very little development or exploration into either the footwall or hanging wall, there was high potential to define additional mineralized structures in close proximity to the existing underground infrastructure.

In August, 2019, TCM made the decision to commence rehabilitation of the historic mine and shaft, with the intention of beginning underground drilling and exploration of documented targets on the historic 625 ft and 750 ft development levels.

Osisko Development Corp.

By December, 2019, TCM had compiled the historic Trixie datasets into a new 3D model of the deposit and identified a significant new target in the immediate footwall to the 610 stope. This new target, initially termed the North Survey Vein, was developed from reconsidering assays within historic surface RC holes which could not have originated from any of the historically mined areas. Further investigation of this target led to the discovery of the T2 and T4 structures.

The broad zones of mineralization encountered in the 2000-2001 surface RC drilling were originally interpreted to be caused by the smearing of mineralization within the holes. However, 2021 exploration work by TCM demonstrated that mineralization up to 60 ft in width is associated with the T4 stockwork. The broad zones of mineralization encountered in the 2000-2001 RC drilling were thus re-interpreted as intercepts of T2-T4 stockwork mineralization in the immediate footwall of the 75-85 structure.

Between February and June, 2020, refurbishment of the 625 level was completed and this allowed for the commencement of underground diamond drilling. A total of five diamond drill holes were completed between June and August, 2020.

Despite extremely difficult drilling conditions, visible mineralization within the footwall of the 610 stope was confirmed in three of the five holes. With the visual confirmation of the mineralization and structure, a decision was made by TCM management to commence development of an exploration drift eastward towards the target zone.

The decision to develop into the target zone proved extremely fortuitous as only 13 m (44 ft) east of the historic 625 ft level development, TCM drifted directly into the T2 structure.

Abundant visible gold associated with the striking green colour of the mineralized zone aided the visual identification and test mining of the T2 structure. Initial test mining continued north and south on-strike of the steeply east dipping structure to determine potential strike lengths of the mineralized zone. At the same time, the original 609 exploration cross-cut was extended further eastward to test ground immediately east of the T2 structure for further mineralization. Together with additional diamond drilling and exploration cross-cuts a broad zone of mineralized stockwork veining up to 25 m (80 ft) in width was identified, and this is referred to as the T4 stockwork zone of mineralization.

In November, 2020, the first shipment of mineralized material was shipped to an offsite processing facility and the first gold was poured by TCM. Continual underground development and drilling through 2021 helped define T2 mineralization over a 120 m (400 ft) strike length and led to the recognition of the scale of the T4 stockwork mineralization. Design work for a surface portal and internal decline ramp to access the Trixie underground development was commenced shortly thereafter. A geological model for T2-T4 mineralization identified the potential significance of the overlying Ophir Shale as a cap above the Tintic Quartzite host rock in influencing the T2-T4 mineralized zone. In the fall of 2021, the Burgin processing facility was equipped with an onsite vat leaching process. On May 30, 2022, Osisko Development announced the completion of its acquisition of TCM.

Osisko Development Corp.

The Tintic Project is located within the historic Tintic mining district, a cluster of base and precious metal deposits covering more than 200 square kilometres (km²) (or approximately 80 square miles) within the East Tintic Mountains of north-central Utah. The district is centred approximately 90 km (56 miles) south-southwest of Salt Lake City and 65 km (40 miles) south of the Bingham Canyon porphyry Cu-Au-Mo deposit. The East Tintic Mountains occupy a position within the Late Cretaceous Sevier fold and thrust belt approximately 30 km (20 miles) from the eastern limit of the Basin and Range extensional province, as defined by the surface expression of the Wasatch fault. District mineralization is associated with a post-Sevier compression and pre-Basin and Range extension period of magmatism spanning ca. 27-35 Ma (latest Eocene to Oligocene). Commonly divided into Main, East, North and Southwest subdistricts, the greater Tintic is collectively the second largest metal producing district in Utah state, with Bingham first and Park City a close third. The core Tintic Project area covers more than 90% of known deposits within the East Tintic subdistrict. Additional coverage extends north, west, and south into the North, Main and Southwest districts, respectively.

The geology of the Tintic district can be summarized as the record of four major phases of geologic evolution. These are 1) development of a Palaeozoic platformal sequence atop previously deformed Precambrian basement, 2) folding, faulting and uplift accommodating east-west shortening during Late Cretaceous Sevier Orogeny, 3) latest Eocene to Oligocene calc-alkaline magmatism associated with district mineralization, and 4) Miocene to recent Basin and Range extension.

Accommodation of east-west shortening during Late Cretaceous Sevier Orogeny resulted in the development of the district scale Tintic syncline-East Tintic anticline fold pair, and several associated district-scale generally west-vergent thrusts. The geometry of the sub-horizontal roughly north-south trending fold pair is responsible for the general basement architecture of the Tintic district, wherein the youngest (Mississippian) rocks of the Palaeozoic sequence are preserved along the trough of the Tintic syncline in the Main district and the Tintic Quartzite is present at its highest structural levels along the crest of the East Tintic anticline in the East district. High-angle structures developed in relation to the Sevier orogeny include a system of predominantly northeast trending faults, with strike-slip offset interpreted as accommodating differential displacement syn-compression, and a system of variably oriented normal faults developed in accommodation of late to post-orogenic gravitational collapse.

Extensive erosion following Sevier uplift resulted in the development of a rugged paleo-topography by the onset of district magmatism ca. 35 Ma. The latest Eocene to Oligocene magmatic record consists of a quartz latite flow and tuff dominant sequence of irregular thickness up to 1,500 m (5,000 ft) with cross cutting to coeval locally porphyritic monzonite to quartz monzonite intrusions of varying geometries. District mineralization, dated in the East Tintic at around 31 Ma, is contemporaneous and associated. In the East Tintic district, known fissure-vein and replacement deposits are nearly exclusively buried beneath the irregular volcanic cover. While the basal (pre-mineral) volcanic cover hosts no significant mineralization, it is commonly characterized by significant hydrothermal alteration. Several sub-km-scale lithocaps point to potential porphyry targets at depth, where more localized alteration along predominantly north to northeast-trending fissures with associated pebble dikes were used in successful targeting of many of the known historic deposits.

Osisko Development Corp.

The Palaeozoic sequence and its irregular volcanic cover are disrupted by Basin and Range extensional faulting. Miocene-age volcanics likely mark the onset of extension in the district ca. 16-18 Ma. While any pre-existing fault structures are likely primed for some degree of Basin and Range extensional reactivation, the most significant normal offsets occur along roughly north-south trending structures, e.g., the district-scale Eureka Lilly fault. The variably north-south striking and west-dipping Eureka Lilly fault forms a major aquitard through the East Tintic district, dividing a fresh, cool-water-table in its hanging-wall to the west from a hot and saline water table in its footwall to the east. Post-lava offset on the Eureka Lilly fault is apparently variable along strike and may account for only one-half to a third of the total offset across the structure, believed to have initiated during Late Sevier orogeny.

The four subdistricts of the Tintic are in part distinguishable in terms of their known mineral occurrences, hosted within the deformed Palaeozoic sequence and, to a more limited extent, Oligocene monzonitic intrusions. The Main district is the most historically productive district by far, with characteristic carbonate-hosted lead-zinc-silver replacement deposits that form predominantly north to northeast-trending sub-horizontal zones rooted into subvertical chimney-like mineralized bodies rich in copper, gold and silver. Carbonate-replacement deposits with economic zinc ± lead ± silver are likewise present in the East district and the historically least-productive North district. The East district is unique in terms of the relative structural complexity of its deposits, and by the added presence of gold and silver-rich high-sulphidation fissure vein systems hosted within the brittle and unreactive Tintic Quartzite, such as at Trixie. The Southwest district is characterised by a relative dominance of igneous rocks, containing fissure systems hosted within the Silver City stock and smaller associated monzonitic porphyry intrusions. The Southwest district is also host to the Southwest Tintic porphyry copper system, viewed as subeconomic but with minor historical production from peripheral high-sulphidation, copper-silver-lead veins. Several key observations suggest the presence of additional and potentially economic porphyry centres within the district. This includes indicator clay assemblages and elevated molybdenum and/or copper-lead ratios at the Big Hill, Silver Pass, and Government Canyon lithocaps, all contained within the Tintic Project claims area.

Mineralization at the Trixie test mine is structurally controlled within a north-south-trending fissure-vein and breccia system developed within the brittle Tintic Quartzite. Gold and silver-rich mineralization within the so-called Trixie vein system is best classified as high-sulfidation epithermal (see discussion in Section 8). Current development at Trixie is focused within the footwall to the historically productive steep-to-the-west-dipping 75-85 structure, targeting the subvertical-to-the-east-dipping T2 fissure vein, its hanging -wall T4 breccia zone, and a network of smaller-scale likewise north-south-trending mineralized fissures contained within it.

Sub-horizontal Palaeozoic strata exposed in underground at Trixie are believed to occupy a position within or proximal to the hinge zone of the East Tintic anticline, the nature of which may exert primary influence on the geometry, frequency, and distribution of grade controlling structures within the Trixie vein system. The stratigraphic contact between the Tintic Quartzite and overlying and impermeable lower shale member of the Ophir Formation appears to have a major controlling influence on the development and distribution grade and mineralization at Trixie. While controlling structures within the Trixie vein system do penetrate the younger overlying sequences, mineralization typically displays strong rheologic control and is restricted to the older and underlying brittlely fractured Tintic Quartzite host.

Osisko Development Corp.

The main shaft of the historic Trixie mine was collared at approximately 1,852 m (6,075 ft) elevation into an outcropping window of Middle Cambrian Teutonic Limestone. The shaft passes through the full thickness of the Ophir Formation to reach the Tintic Quartzite at a depth of approximately 125 m (410 ft). All current development stems off the historic 625-foot mine level, deeper historic workings include 750, 900, 1050, 1200 and 1350-foot levels. The full extent of both modern and historic development at Trixie resides within the hanging-wall to the district-scale Eureka Lilly fault. The fresh groundwater table of the Eureka Lilly hanging-wall at Trixie sits below the ca. 1,437 m (4,716 ft) elevation of the 1350-foot level, around 425 m below surface. The Late Eocene to Oligocene Packard Quartz Latite unconformably overlies the Palaeozoic Tintic-Ophir-Teutonic sequence in nearly every direction surrounding the Trixie main shaft. The Packard Quartz Latite is in local unconformable contact with both the Ophir Formation and Tintic Quartzite, reaching thicknesses up to 380 m (1,250 ft) directly south of the ventilation shaft.

The core of the Trixie vein system occupies a high-seated position within an east-west oriented horst, the bounding structures of which may have served as critical pathways for mineralizing fluids. North of the Trixie main shaft, the Tintic Quartzite is down-dropped an estimated 198 m (650 ft) across the east-west-trending sub-vertically north-dipping Trixie fault zone. At the very northern limits of development, the sequence is again offset relatively down to the north across the Eureka Standard fault zone, which appears to consist locally of at least two major east-northeast trending splays. Though not fully constrained, relative stratigraphic offset across the Eureka Standard fault zone is of similar or greater magnitude to that observed across the Trixie Fault zone. Approaching the southern end of development, the Tintic Quartzite and mineralized structures of the Trixie vein system appear to be offset across the presumably steep to the south-dipping Sioux-Ajax fault zone. The Sioux-Ajax fault zone has not been intersected by any modern-day development. Constraining its displacement and orientation is complicated by several intersecting west-dipping splays of the Eureka Lilly fault that appear to further offset the mineralization.

The Sioux-Ajax fault system is well-known within the Main District as a major ore controlling structure, with associated breccias hosting large replacement bodies in both the Mammoth and Iron Blossom mines. The Sioux-Ajax fault system of the Main district consists locally of two or more splays, generally striking east-southeast and dipping steeply to the north. The fault system is buried beneath volcanic cover projecting along strike into the East Tintic district, wherein its correlation and relationships with known structures have long been a topic of high interest and debate. Recent interpretations based on the integration of historical mapping with high-resolution magnetic data acquired in 2019 suggest that the Trixie, Eureka Standard, and south-dipping Sioux Ajax fault zones, as defined within the Trixie development area, are structurally linked with the Sioux Ajax zone of the Main district and may have collectively provided the deep-seated plumbing necessary for mineralization at Trixie.

The historic 756 ore shoot at the north end of Trixie development displays a steep northerly plunge in the footwall to the Trixie fault zone. At the southern end of Trixie development, higher grade ore shoots within the historically mined 75-85 zone exhibit a steep southerly plunge for which the presumed south-dipping Sioux Ajax fault zone is the interpreted structural control. These historical observations suggest that mineralization and grade within the T2 fissure vein and T4 zone currently in development in the immediate footwall to the 75-85 structure may be characterized by a similar geometry.

Osisko Development Corp.

Exploration work undertaken at the Tintic Project in 2022 consisted of coordinated underground mapping and sampling programs covering both new exploration drifts and development along and across the mineralization underground at Trixie. Post-advancement face, rib and back chip-sampling, and post-survey three-dimensional underground back and rib geologic mapping were conducted by the geological team.

No surface regional-scale mapping or sampling programs were conducted in 2022.

Surface reverse circulation (RC) drilling of the Trixie Deposit (T1, T2, T3, T4, and 75-85 mineralized zones) commenced in July, 2022 and a total of 6,937.25 m (22,760 ft) of RC drilling in 21 drill holes were completed by early December, 2022 when the program terminated.

At the time of writing, assay results from 8 RC drill holes from the 2022 RC surface drilling program have been received and incorporated into the MRE.

The 2022 underground diamond drilling program on the Trixie Deposit (T1, T2, T3, T4, and 75-85 mineralized zones) recommenced on April 1, 2022 and by December 19, 2022, 1,966.57 m (6,452 ft) of drilling was completed on the Trixie Deposit in 46 drill holes.

At the time of writing, assay results from 14 diamond drill holes were received and incorporated into the MRE.

Difficult drilling conditions addressed in previous reports have continued to be a hallmark of the RC and diamond drilling programs at Trixie. Although recovery in the diamond drilling program averages a reasonable 90.1%, the core suffers significant destruction during the drilling process resulting in difficult interpretations of significant mineralized structures, and increased uncertainty in the rock quality designation and recovery data. Broken ground, significant faulting, and hard abrasive lithologies have resulted in slow sample production and further compromised the structural interpretation. Average RC production of 27.4 m (90 ft) per day and diamond drill production of 9.4 m (31 ft) per day were typical of the 2022 program. In addition, the lack of structural data made true-width relationships difficult to determine from the drilling.

Osisko Development Corp.

Due to the issues with the drilling, the historical and current underground development have been the primary sources of information regarding the nature, orientation and extent of the mineralization at Trixie for the initial mineral resource estimate.

Slow turn-around times of 60 to 90 days at the assay laboratories have resulted in a significant lack of assay data and have prevented the inclusion of many diamond drill and RC holes in the initial mineral resource estimate.

Two bulk metallurgical composite samples were prepared by Osisko Development from mineralization obtained during the exploration test mining performed during 2021 and early 2022.

The first bulk composite (T2 Soil Sample) was prepared from laboratory high grade coarse reject samples, over an 8-month period from April to December, 2021. This 477.5 kg sample was selected to be representative of a T2/T4 high grade run of mine (ROM) material leached in the TCM pilot vat leach facility (VLF) during 2021 and 2022.

The second composite sample (T4 Soil Sample) was prepared using four sample increments at various mine accessible points of the T4 structure. This 171 kg sample was selected to be representative of the bulk T4 structure at the 625 level.

Metallurgical testing was undertaken by Kappes, Cassiday & Associates (KCA), Reno, Nevada and included the following primary testwork:

The head grades of the two samples were 64.1 g/t Au and 102 g/t Ag for T2, and 8.8 g/t Au and 14.5 g/t Ag T4.

Osisko Development Corp.

Both samples are characterized by high silica content (92% to 96%) and low sulphide sulphur content, typically less than 0.2% S^2-. Copper in the T2 sample measured about 750 g/t but only about half of this was readily cyanide soluble.

Diagnostic leach tests using samples of the two composites ground to 80% passing 74 microns indicated that approximately 99% of the gold in sample T2 and 88% in sample T4, is directly soluble. Mineralogical gold deportment studies showed that 99% of the gold in sample T2 was exposed and potentially cyanide soluble while T4 material showed that 81% of the gold was free gold with hessite and telluride associations of 7% and 10% respectively. The gold grains identified in sample T2 tended to be larger than those in T4.

Comminution tests showed that both samples were relatively hard and abrasive. Bond ball mill work indices of 18.2 kWh/t and 19.0 kWh/t were calculated for T2 and T4, respectively.

Deleterious elements often encountered in gold mineral resources are present in low concentrations in both these samples. Mercury is <3 ppm, selenium was analyzed at or below 5 ppm, and arsenic was 176 g/t on average for T2 and 29 g/t for the T4 sample. The T2 high grade structure sample did show relatively higher concentrations of these deleterious elements than the T4 material. The sulphide sulphur content was relatively low for both samples and therefore, it is unlikely that the mineralization will be acid generating.

Bottle roll cyanide leach tests gave results of up to 99% Au and 88% Ag extraction after 72 hours for sample T2. The corresponding best T4 tests achieved 98% Au and 84% Ag extraction.

Gravity separation tests using sample T2 suggested that approximately about 40% gold can be recovered by gravity separation.

The initial Mineral Resource Estimate for the Trixie test mine (the “initial MRE”), was conducted between December, 2022 and January, 2023.

The mineral resource area for the Trixie deposit covers a strike length of approximately 445 m down to a vertical depth of approximately 295 m below surface.

The wireframe models for the Trixie deposit were prepared using LeapFrog GEO v.2022.1 (LeapFrog). Wireframe modelling included the construction of five mineralized domains constrained to the extents of the regional-scale Tintic Quartzite lithologic unit and capped by shale belonging to the overlying lower member of the Ophir Formation. Geostatistical analyses were carried out using Datamine Snowden Supervisor v.8.15.0.1 (“Supervisor”). The estimation, block model and grade interpolation, were prepared using Datamine StudioTM RM Pro v.1.12.113.0 (Datamine). Resource-level potentially mineable underground shapes were created using the Deswik CAD v.2021.2.748 Shape Optimizer module (DSO).

Osisko Development Corp.

The close-out date for the Trixie deposit initial MRE database is December 12, 2022. It consists of 42 validated diamond drill holes, totalling 2,358.45 m of core and comprised of 1,802 sample intervals. The database also includes 8 validated RC drill holes, totalling 2,421.64 m of RC drilling and comprises 987 sample intervals, and 1,019 underground chip sample strings comprised of 4,467 sample intervals assayed for gold and silver.

The database includes validated location, survey, and assay results. It also includes lithological descriptions taken from drill core logs.

The database covers the strike length of each mineralized domain at variable drill hole and chip sample spacings, ranging between 1.5 and 50 m.

In addition to the tables of raw data, each database includes several tables of calculated drill hole composites and wireframe solid intersections, which are required for the statistical evaluation and mineral resource block modelling.

The geological model of the Trixie deposit was prepared in LeapFrog, using underground mapping, chip samples, RC drill holes, and validated diamond drill holes, all completed by December 12, 2022.

A total of five mineralized domains, were modelled with each domain restricted up dip by its contact with the lower shale member of the Ophir Formation, as this contact acts as an impermeable cap to mineralizing fluids.

The domains modelled were the T1, T2, T3, T4 and the 75-85. In addition, a north-south trending sub-vertically dipping fault structure has been mapped across multiple underground development headings near the 625 level and has been intercepted in multiple drill holes. Though the full extent of the structure is at present unknown, it is currently inferred to project through the entirety of the model. As underground mapping indicates a minor offset of the T2 structure across this fault, it is used as a hard boundary for geological modelling and grade interpolation. The model is thus split into east and west fault blocks, with each mineralized domain subdivided into respective east and west subdomains.

Most of the analytical samples were collected with lengths between 0.31 and 1.52 m. A modal composite length of approximately 0.61 m was applied to domains T2 and T3, generating composites as close to 0.61 m as possible, while creating residual intervals with a minimum length of 0.06 m. A modal composite length of 0.91 m was applied to all other domains. In all cases, composite files were derived from raw values within the modelled resource domains.

Osisko Development Corp.

Multiple capping (different capping at different ranges in each domain) was selected as the capping methodology for high grade outlier gold and silver assays at the Trixie deposit. After considering reconciliation results and geological continuity, the T2 domain uses a single capping level for gold. The top capping thresholds were selected based on the probability plots and vary from 20.0 g/t to 1,350.0 g/t Au and 200.0 g/t to 2,500.0 g/t Ag.

The maximum range for high-grade continuity was established using the indicator variograms, which suggests a loss of continuity after 4.5 m to 9.0 m, depending on the mineralized domain. A range of 7.6 m was selected and applied to all zones as a general average search range for the first pass grade top cut interpolation.

The density databases contain 512 measurements taken on samples across multiple geologic domains.

Average bulk density values in the mineralized domains were assigned to the T1 (2.616 t/m³), T2 (2.955 t/m³), T3 (2.638 t/m³), T4 (2.621 t/m³), and 75-85 (2.617 t/m³) domains.

A density of 0.00 t/m³ was assigned to the underground development from all past mining activities.

Bulk densities were used to calculate tonnages from the volume estimates in the block model.

The spatial distribution of gold and silver was evaluated through variogram analysis and spherical variograms were modelled for each of the mineralized domains.

All variogram analyses and modelling were performed in “Supervisor”. Primary directions and orientations of the variograms were observed in the data and visually in 3D space. These orientations were then examined statistically within the software package to ensure that they represented the best possible fit of the geology and grade continuity.

For the T2, T3 and 75-85 domains, the 3D directional-specific search ellipses were guided by the local structural orientation of the domain for an anisotropic search. For the T1 and T4 domains 3D directional-specific search ellipses were guided by the Au and Ag grade variograms. The search radii were influenced and determined by both the grade and indicator variograms.

Grade distributions and kriging neighbourhood analyses (KNA) were used to help guide the number of composites to use for the grade interpolations.

Search neighbourhoods used different capping levels, as determined through the threshold analyses.

Osisko Development Corp.

The criteria used in the selection of block size include drill hole spacing, composite length, the geometry of the modelled zone, and the anticipated mining methods. A block size of 1.22 m x 1.22 m x 1.83 m was used. Sub-cells were used, allowing a resolution of 0.30 m x 0.30 m x 0.30 m to better reflect the shape of the mineralization domains. Sub-cells were assigned the same values as their parent cell. No rotation was applied to the block model.

Four search passes were used for the grade interpolation and each one utilized a capped grade from the multiple capping levels determined through threshold analyses. A series of sensitivity runs were performed to examine the impact of various parameters on the estimation. Parameters were selected, and gold and silver were estimated using inverse distance squared (ID²). Each subsequent estimation pass used increasing search neighbourhood sizes, determined from grade and indicator variogram results. Samples from a minimum of two drill holes or chip strings were required to estimate all blocks.

Mineralized domain models were validated using a variety of methods including visual inspection of the model grades, grade distributions compared to the informing raw samples, statistical comparisons of informing composites to the model for local and global bias, and reconciliation comparing the model to observed grades from underground development.

All analyses indicate that the model follows the grade distribution of the informing composites and that the accuracy of the model has been demonstrated. The total global comparison for each resource classification is within a 20% tolerance for bias and reconciliation. The Micon QPs consider that the model is valid and is a reasonable representation of the Trixie mineralization, based on the current level of sampling and geological information.

Mineral Resource Classification was determined through geometric criteria deemed reasonable for the deposit.

Due to the lack of sample data that fully crosscut the T1 and 75-85 domains, no material has been classified as measured for these domains, and the characteristics used to classify indicated material have tighter constraints.

Due to the geological nature of the stockwork structures in the T4 domain, there is a degree of uncertainty in the ranges of the high-grade mineralization. Therefore, no material has been classified as measured in that domain.

Blocks estimated within the mineralized domains not meeting the criteria to classify them as either measured, indicated or inferred were not classified and are not part of the mineral resource estimate.

Osisko Development Corp.

A reasonable economic cut-off grade for resource evaluation at the Trixie deposit was determined using the parameters presented in Table 1.1. The QPs consider the selected cut-off grade of 4.85 g/t Au to be appropriate based on the current knowledge of the Project.

Table 1.1
Resource Cut-Off Grade Parameters

Table supplied by Osisko Development.

*ST represents short ton.

The Deswik Stope Optimizer (DSO) was used to demonstrate spatial continuity of the mineralized zones within “potentially mineable shapes”. The DSO parameters used a minimum mining shape of 6.1 m along the strike of the deposit, a height of 6.1 m and a minimum width of 1.5 m. The maximum shape measures 6.1 m x 6.1 m x 12.2 m in width. Only those blocks of the model constrained by the resulting conceptual mineable shapes are reported as resources.

In the opinion of the QPs, the use of the conceptual mining shapes as constraints to report Mineral Resource Estimates demonstrate that the reported resources meet the criteria defined in the CIM Definition Standards (2014), and the MRMR Best Practice Guidelines (2019) for reasonable prospects of eventual economic extraction.

The economics of the resources were evaluated solely on the gold content within the mineralized domains. By product silver resources reported are contained in those resource blocks that have potential economic viability based only on the contained gold.

All current underground development at the Trixie deposit has been conducted by TCM and the void solids for this development have been surveyed, modelled, and kept up to date by TCM. The historically mined development at Trixie has been modelled by TCM but to reduce the associated risk of uncertainty in void locations, a buffer solid of 6.1 m (20 ft) was developed around the historical shapes. The historical buffers and the current development voids are used to deplete the final mineral resource of the Trixie deposit. As underground diamond drilling continues to intersect historically mined voids, the void shapes will be refined, reducing the uncertainty, and the depletion buffers may be reduced.

Osisko Development Corp.

The QPs have classified the initial MRE as Measured, Indicated, and Inferred Mineral Resources based on data density, search ellipse criteria, and interpolation parameters. The initial MRE is considered a reasonable representation of the mineral resources of the Trixie deposit based on the current quality data and geological knowledge. The Mineral Resource Estimate follows the 2014 CIM Definition Standards on Mineral Resources and Reserves.

Table 1.2 displays the results of the initial MRE at the official 4.85 g/t Au cut-off grade for the Trixie deposit.

Table 1.3 shows the cut-off grade sensitivity analysis of gold and silver for the initial MRE. The reader should be cautioned that the figures provided in Table 1.3 should not be interpreted as a mineral resource statement. The reported quantities and grade estimates at different cut-off grades are presented for the sole purpose of demonstrating the sensitivity of the mineral resource model for gold to the selection of a reporting cut-off grade. Micon’s QP has reviewed the MRE cut-off grades used in the sensitivity analysis, and it is the opinion of the QP that they meet the test for reasonable prospects of eventual economic extraction at varying prices of gold or other underlying parameters used to calculate the cut-off grade.

Osisko Development Corp.

Table 1.2
Trixie Deposit Initial Mineral Resource Estimate (MRE) Statement

Notes:

Osisko Development Corp.

Table 1.3
Gold Grade Sensitivity Analysis at Different Cut-Off Grades

Table supplied by Osisko Development.

Osisko Development Corp.

With its purchase of TCM in May, 2022, Osisko Development has acquired a major portion of the historical East Tintic Mining District in Utah. The east Tintic district has been a prolific mining area throughout most of its history with several past producers located within the boundaries of Osisko Development’s Tintic Project.

The exploration, compilation and development work on the Trixie deposit conducted by Osisko Development since its acquisition have resulted in a better understanding of the geology and mineralization. Based upon the work, Osisko Development has been able to undertake an initial MRE for the Trixie deposit, which remains open at depth and along strike.

Micon QPs have reviewed and validated the programs conducted by Osisko Development which form the basis for the initial mineral resource estimate, as well as the mineral resource itself. It is Micon’s QPs’ opinion that the underlying exploration programs have been conducted according to industry best practices as outlined by CIM. Therefore, Micon’s QPs believe that the initial mineral resource estimate can be used as the basis for further exploration and development work to expand the mineral resources and to begin to conduct work leading to the undertaking of a Preliminary Economic Assessment (PEA) for the Trixie deposit.

The budgets presented in Table 1.4 and Table 1.5 summarize the estimated costs for completing the recommended drilling and exploration program described below. The budget is a cost estimate and guideline to complete the work. The budget is divided into a two-phase approach, with the second phase contingent on the successful completion of the first.

It is the opinion of the Micon QPs that all of the recommended work is warranted and that only the amount of exploration drilling on new targets needs to be finalized. Micon and its QPs appreciate that the nature of the programs and expenditures may change as the further studies are undertaken, and that the final expenditures and results may not be the same as originally proposed.

The Micon QPs are of the opinion that Osisko Development’s recommended work program and proposed expenditures are appropriate, warranted and well thought out. The Micon QPs believe that the proposed budget reasonably reflects the type and amount of the activities required to advance the Trixie deposit.

Osisko Development Corp.

Table 1.4
Tintic Project, Recommended Budget for Further Work, Phase 1 (USD)

Table provided by Osisko Development.

Table 1.5
Tintic Project, Recommended Budget for Further Work Phase, 2 (USD)

Table provided by Osisko Development.

Based on the results of the initial MRE, Micon’s QPs recommend further exploration and development of Trixie deposit. It is recommended that Osisko Development continues with underground exploration drilling at Trixie 625 L, together with continued face sampling and mapping along strike and down dip of the mineral resource and to infill areas currently defined as containing inferred resources. It is also recommended that, since the continued underground face sampling has been beneficial to the development of the Project, exploration development continue in order to improve underground access from surface to the deeper levels of the mine. In addition to exploration at Trixie, it is recommended that Osisko Development continue its exploration program on the other mineral targets on the Tintic Property with continued surface mapping and sampling, data compilation and surface drilling of regional high sulphidation, CRD and porphyry targets.

Osisko Development Corp.

It is recommended that Osisko Development move to a Preliminary Economic Assessment (PEA) at Trixie, by conducting additional metallurgical work, along with further engineering studies on mining and reconciliation, continuing with environmental, permitting and community engagement and conducting a detailed economic analysis.

In summary, the following work program is recommended.

It is recommended that the following program of metallurgical testing be undertaken during the next stage of project development:

Osisko Development Corp.

Osisko Development Corp.

2.0   Introduction

Osisko Development Corp. (Osisko Development) has retained Micon International Limited (Micon) to independently review and verify its initial mineral resource estimate (MRE) for the Trixie deposit located within the boundaries of its Tintic Project (the Project) in the State of Utah, USA., and to compile a Canadian National Instrument (NI) 43-101 Technical Report disclosing the results of the MRE.

The geologic modelling for the Trixie deposit was completed by Osisko Development’s senior production geologist Courtney Kurtz, P.G., using Leapfrog Geo software. The MRE was completed by Osisko Development’s chief resource geologist, Daniel Downton, P.Geo., using Datamine Studio RM Pro 1.12 software. The MRE was then reviewed and validated by William Lewis, P.Geo. and Alan San Martin, AusIMM(CP), of Micon.

For the purposes of disclosure in this Technical Report. William Lewis, P.Geo., who is independent of Osisko Development and is a Qualified Person (QP) within the meaning of NI 43-101, is responsible for the initial mineral resource estimate, by virtue of his independent review and validation of the work conducted by Osisko Development.

When conducting, reviewing and validating the initial mineral resource estimate, Osisko Development, Micon’s QPs used the following guidelines, as issued by the Canadian Institute of Mining, Metallurgy and Peroleum (CIM):

This report discloses technical information, the presentation of which requires the QPs to derive sub-totals, totals and weighted averages that inherently involve a degree of rounding and, consequently, introduce a margin of error. Where these occur, the QPs do not consider them to be material.

The conclusions and recommendations of this report reflect the QPs best independent judgment in light of the information available to them at the time of writing. Micon and the QPs reserve the right, but will not be obliged, to revise this report and conclusions if additional information becomes known to them subsequent to the date of this report. Use of this report acknowledges acceptance of the foregoing conditions.

This report is intended to be used by Osisko Development subject to the terms and conditions of its agreement with Micon. That agreement permits Osisko Development to file this report as a Technical Report on SEDAR (www.sedar.com) pursuant to provincial securities legislation, or with the Securities Exchange Commission (SEC) in the United States.

Neither Micon nor the QPs have, nor have they previously had, any material interest in Osisko Development or related entities. The relationship with Osisko Development is solely a professional association between the client and the independent consultants. This report is prepared in return for fees based upon agreed commercial rates and the payment of these fees is in no way contingent on the results of this report.

Osisko Development Corp.

Micon and the QPs are pleased to acknowledge the helpful cooperation of Osisko Development management, personnel and consulting field staff, all of whom made any and all data requested available and responded openly and helpfully to all questions, queries and requests for material.

This report supersedes and replaces all prior Technical Reports written for the Tintic Project.

In order to undertake the review and validation of the initial mineral resource estimate for the Trixie deposit, the QPs of this Technical Report held a number of discussions and meetings with Osisko Development’s personnel and contractors to discuss details relevant to the exploration programs, Quality Assurance/Quality Control (QA/QC) programs, parameters used for the mineral resource estimate and the mineral resource estimate itself. The discussions were held via email chains and phone calls, as well as Microsoft Teams and Zoom meetings. The discussions were open, frank and at no time was information withheld or not available to the QPs.

A site visit was conducted from September 12 to September 16, 2022. The site visit was undertaken by Mr. Lewis to independently verify the geology, mineralogy, drilling programs and the QA/QC programs. A number of samples were collected during the 2022 site visit and the verification program on those samples is discussed in Section 12 of this report.

Prior to the site visit, the objectives of that visit were discussed between Osisko Development’s Vice President of Exploration, Maggie Layman, P.Geo. and William Lewis. Mr. Lewis visited the different areas of the property, with an emphasis on verifying the exploration/evaluation works completed to date, as well as obtaining a general overview of the current work at the Trixie test mine. An inspection was made of the underground workings at the Trixie deposit, along with a visit to the surface drilling site. During the visit, Mr. Lewis was accompanied by Ms. Layman and had the opportunity to meet the personnel responsible for the various areas of technical services (mining, metallurgy and process), exploration and underground geology as well as a number of contractors. A number of open and frank discussions were held regarding the exploration programs, sampling QA/QC procedures, mineral resource modelling and the parameters and procedures used for the mineral resource estimate.

Open and frank discussions continued throughout the mineral resource process on all aspects of the process, culminating in completion of the initial mineral resource estimate in January, 2023.

The QPs responsible for the preparation of this report and their areas of responsibility and sites visits are summarized in Table 2.1.

Osisko Development Corp.

Table 2.1
Qualified Persons, Areas of Responsibility and Site Visits

Micon’s review of the Tintic Project, and the Trixie deposit in particular, was based on published material researched by the QPs, as well as data, professional opinions and unpublished material submitted by the professional staff of Osisko Development or its consultants. Much of these data came from reports prepared and provided by Osisko Development. The information and reference sources for this report are identified in Section 28.0.

The descriptions of geology, mineralization and exploration used in this report are taken from reports prepared by various organizations and companies or their contracted consultants, as well as from various government and academic publications. The conclusions of this report use, in part, data available in published and unpublished reports supplied by the companies which have conducted exploration on the property, and information supplied by Osisko Development. The information provided to Osisko Development was supplied by reputable companies and the QPs have no reason to doubt its validity. Micon has used the information where it has been verified through its own review and discussions.

Some of the figures and tables for this report were reproduced or derived from reports on the property written by various individuals and/or supplied to the QPs by Osisko Development. A number of the photographs were taken by Mr. Lewis during his September, 2022 site visit. In cases where photographs, figures or tables were supplied by other individuals or Osisko Development, the source is referenced below that item. Figures or tables generated by Micon are unreferenced.

All currency amounts are stated in United States of America dollars (USD), unless otherwise stated. Quantities are generally stated in metric units, the standard Canadian and international practice, including metric tonnes (t) and kilograms (kg) for mass, kilometres (km) or metres (m) for distance, hectares (ha) for area, grams (g) and grams per metric tonne (g/t) for gold and silver grades (g/t Au, g/t Ag). Wherever applicable, US units of measure have been converted to Système International d’Unités (SI) units for reporting consistency, but the US units may be stated in brackets after the metric units. Precious and base metal grades may be expressed in parts per million (ppm) or parts per billion (ppb) and their quantities may also be reported in troy ounces (ounces, oz) for precious metals and in pounds (lbs) for base metals, a common practice in the mining industry.

Osisko Development Corp.

The original work on the initial resource estimate for the Trixie deposit was performed by Osisko Development personnel in the United States and used US units of measurement. For reporting in a Technical Report under Canadian NI 43-101 requirements, the US units have been converted to metric units.

Table 2.2 summarizes the conversion factors from US measurement units to international metric units. Table 2.3 provides a list of abbreviations that are used in this report. Appendix 1 contains a glossary of mining and other related terms that are used in this report.

Table 2.2
Conversion Factors for this Report

*Formula to Convert Fahrenheit to Celsius is (°F − 32) × 5/9 = °C

Table 2.3
List of Abbreviations

Osisko Development Corp.

Osisko Development Corp.

One previous Technical Report has been published on the Tintic Project:

Osisko Development Corp.

3.0   Reliance on other experts

In this Technical Report, discussions in Sections 1.0 and 4.0 regarding royalties, permitting, taxation and environmental matters are based on material provided by Osisko Development. The QPs and Micon are not qualified to comment on such matters and have relied on the representations and documentation provided by Osisko Development for such discussions.

All data used in this report were originally provided by Osisko Development. The QPs have reviewed and analyzed these data and have drawn their own conclusions therefrom.

The QPs and Micon offer no legal opinion as to the validity of the title to the mineral concessions claimed by Osisko Development and have relied on information provided by Osisko Development.

Osisko Development has confirmed to Micon that it verified the status of the mineral title to certain patented mining claims by engaging Utah legal counsel, Holland and Hart LLP, to conduct a review of Osisko Development’s chain of title for the select patented mining claims within the land package covering approximately 243 ha (600 acres) surrounding the Trixie and Burgin mines. Holland and Hart LLP conducted its title review by examining the United States Bureau of Land Management records, including the patents issued by the United States, mineral survey and master title plans, and the official records of the Utah County Recorder’s Office, including the abstract (tract), mining claims, and grantor/grantee indices, among miscellaneous other records. This consolidated land position has been acquired over a hundred years of prior consolidation in the district. Osisko Development also engaged with Wolcott LLC, an independent consultant to conduct field checks and generate a geospatial database for the mineral claims.

Information related to royalties, permitting, taxation and environmental matters have been updated by Osisko Development through personal communication with the QPs. Previous NI 43-101 Technical Reports, as well as other references, which were used in the compilation of this report are listed in Section 28.0.

Osisko Development Corp.

4.0   Property Description and Location

The Tintic Project is located in western Utah County, approximately 64 kilometres (km) south of Provo, Utah and 95 km south of Salt Lake City. The property in which the Trixie test mine or Trixie deposit is located encompasses most of the East Tintic District, surrounding and immediately east of the incorporated town of Eureka. The town of Eureka is located approximately 6.4 km northwest of the Trixie test mine. Figure 4.1 shows the Project location within the state of Utah.

The coordinates of the centre of the Project are 407,700mE and 4,423,400mN, referenced in NAD83, Northern UTM Zone 12. The Project area is located on Eureka Quadrangle, US Topographic Map 1:24,000 scale, 7.5 Minute Series.

The nearest rail siding, in use, is located at Tintic Junction, approximately 10 km west of the Project.

Figure 4.1
Location Map for the Tintic Project

Figure provided by Osisko Development.

Osisko Development Corp.

The area of the Tintic Project owned or controlled by Osisko Development comprises 1,105 claims totalling 5,746 ha (14,200 acres) of patented mining claims (Figure 4.2), and a further 107 unpatented mining claims of approximately 1,214 ha (3,000 acres) (Figure 4.3). Figure 4.2 displays the Tintic Consolidated Metals LLC (TCM) property outline within the East Tintic District. Osisko Development owns a small and varying percentage interest or royalty in a number of other claims outside the main claim package and these are shown as leased on the map in Figure 4.3. Figure 4.4 displays the individual patented surface (and mineral rights) owned by Osisko Development.

On May 30, 2022, Osisko Development announced the acquisition of 100% of Tintic Consolidated Metals LLC (TCM) (the “Acquisition”) from IG Tintic LLC (IG Tintic) and Chief Consolidated Mining Co. (CCMC) (the “Vendors”) for total consideration at closing of approximately USD 177 million in cash and shares of Osisko and:

Osisko Development entered a binding metals stream (“Stream”) term sheet with Osisko Gold Royalties Ltd. (Osisko Gold Royalties) for total cash consideration of USD 20 million. Under the Stream, Osisko Development will deliver to Osisko Bermuda Ltd., a wholly owned subsidiary of Osisko Gold Royalties, 2.5% of all metals produced from Tintic at a purchase price of 25% of the relevant spot metal price. Once 27,150 ounces of refined gold have been delivered, the Stream rate will decrease to 2.0% of all metals produced. The proceeds from the Stream will be used to advance the development of the Tintic Project.

Osisko Development Corp.

Figure 4.2
TCM Property Outline within the East Tintic District

Figure provided by Osisko Development.

Osisko Development Corp.

Figure 4.3
Tintic Project Individual Claims Map

Figure provided by Osisko Development.

Osisko Development Corp.

Figure 4.4
Tintic Project Surface Ownership

Figure provided by Osisko Development.

Osisko Development Corp.

Effective upon the closing of the acquisition, Osisko Development acquired 5,746.53 ha (14,200 acres) of patented mineral claims in the East Tintic District (Appendix 2) as well as rights to acquire an additional 1,214.06 ha (3,000 acres) of patented mineral claims within the East and Main Tintic Districts. Osisko Development also acquired surface rights over approximately 243 ha (600 acres) surrounding the Trixie and Burgin mines (Table 4.1 and Table 4.2), with an option to acquire additional surface rights as needed for construction of additional mining infrastructure. Osisko Development has agreed all necessary easements with the surface rights owner for water, transportation and infrastructure access to the mine site.

As part of the Acquisition, two 1% net smelter return royalties (NSRs) were granted, each with a 50% buyback right in favour of Osisko Development, each for USD 7.5 million within 5 years. The NSRs were granted to IG Tintic and Emerald Hollow LLC.

The state of Utah is entitled to a 0.78% mining severance tax.

There are no further underlying royalty or other property payments owed to any third party on the TCM property, other than those described above.

Table 4.1
Trixie Mineral Claims

*Owns all right, title, and interest (100%) interest in the surface and mineral estates.

Table provided by Osisko Development.

Osisko Development Corp.

Table 4.2
Burgin Mineral Claims

*Owns all right, title, and interest (100%) interest in the surface and mineral estates.

Table provided by Osisko Development.

Permitting of the Trixie test mine is well advanced, with many project components already permitted and bonded by the Utah Division of Oil, Gas and Mining (DOGM). These include the Trixie shaft and surface facilities. Full development of the Trixie test mine will require a number of additional Agency approvals, none of which is anticipated to be problematic to obtain. Pursuant to the Stream Agreement, Osisko Bermuda has a first ranking security interest over all of the present and future assets of TCM. TCM is a division of Osisko Development.

Effective upon the closing of the Acquisition, Osisko Development’s rights to use and access all surface and water rights conveyed to Emerald Hollow LLC (Emerald Hollow) are governed by a Framework Agreement executed at closing and dated effective May 27, 2022 (the “Framework Agreement”). Under the Framework Agreement, Osisko Development has the right to conduct exploration activities and has agreed easements to use the surface rights owned by Emerald Hollow. Osisko Development also has the right to purchase surface rights from Emerald Hollow at market rates if it has reasonably determined that actual use and occupation of such lands for facilities for more than eighteen (18) months are necessary for economic exploitation of proven or probable reserves or measured, indicated, or inferred resources.

Osisko Development has also retained a right of first offer in the event that Emerald Hollow desires to sell, assign, or otherwise transfer to a third party all or a portion of its interest in the surface rights it owns, as well as a first priority right to purchase from Emerald Hollow, at a price based on prevailing market rates, a maximum annual water flow rate of 2.45 cubic feet per second (cfs) and a maximum annual volume of 1,776.64 acre-feet of water from Emerald Hollow for its mining activities.

Osisko Development Corp.

There are no other known significant factors and risks that may affect access, title, or the right or ability to perform work on the property.

TCM maintains adequate financial surety of USD 1,473,167 with the Utah DOGM. This financial surety was last updated in August, 2021 with the addition of a pilot process operation. TCM is currently in the process of updating its large mine permit with Utah DOGM and expects the surety to be updated as part of this process.

TCM maintains all necessary environmental permits to operate within the Tintic operations area, including the current large mine permit update. As part of this update, environmental resources within the Tintic Test Mine were reviewed. As of the date of this report, all water rights and other water sources have been secured and agreed upon. Furthermore, the US Fish and Wildlife Service has deemed that this area does not contain areas of critical wildlife concern.

There are no other known significant factors and risks that may affect access, title, or the right or ability to perform work on the property.

TCM is working under the Notice of Intent (NOI) Large Mine Operations (LMO) plan permit approved by the Utah DOGM in 2017. An updated LMO was submitted in February, 2022 and is currently going through the review/approval process. TCM has exploration permits in place (i.e., surety bonding) to support surface diamond drilling and the excavation of the Trixie Portal (Brandy Lee Decline). Once approved, the exploration for the decline will fall within the updated LMO. Under agreement with the Utah DOGM and the Utah Department of Water Quality (DWQ), TCM is permitted to operate a pilot processing facility and a tails holding pad. TCM does not discharge any water or effluents from current operations.

Micon and the QPs are not aware of any significant factors or risks, other than those discussed in this Technical Report, that may affect access, title, or the right or ability to perform work on the property by Osisko Development. It is Micon’s and the QP’s understanding that further permitting and environmental studies will be required, if further exploration, test mining and economic studies demonstrate that the mineralization is sufficient to host a mining operation.

The area of the Tintic Project is large enough to be able to locate and accommodate the infrastructure necessary to host any future mining operations, if Osisko Development advances the Trixie test mine towards a production decision.

Osisko Development Corp.

5.0   Accessibility, climate, local resources, infrastructure and physiography

The closest major airport to the Tintic Project is in Salt Lake City, Utah, located to the north-northwest of the city of Provo, via Interstate 15. Access to the Tintic Project from Provo, is via Interstate 15, a distance of 36 km south to exit 248 to US 6, then west on US 6 for 27 km to Silver Pass Road, and then south 3.2 km to the Burgin administration office site. The Trixie test mine is located 2.6 km southwest of the Burgin office on the paved Silver Pass Access Road (Figure 5.1). Provo is the fourth largest city in Utah, and other smaller towns, including Payson, Santaquin and Eureka are also adjacent to the Project.

Figure 5.1
Overview of the Trixie Test Mine looking towards the Northeast

Figure provided by Osisko Development.

The towns of Goshen, Santaquin, Payson and Provo are the main sources for supplies and services. Tintic Project personnel and contractors also live in these areas.

The Project has sufficient power and water to support a mining operation.

The nearest perennial surface water body is Utah Lake, which is located approximately 14 km northeast of the Project area.

Osisko Development Corp.

Three small perennial springs discharge from perched ground water in the upper portion of the volcanic cap rocks at an elevation of 1,950 m on the western slope of the upper Silver Spring Pass Canyon drainage. Perennial flow is limited to short reaches below these springs. The company anticipates that additional water will be available for the Project from various surface and underground water sources pursuant to written agreements with the owners of water rights in the vicinity.

A 46 kVA high tension power line owned by Rocky Mountain Power crosses the property near the Burgin administrative complex. The installation of new transformers and electrical infrastructure to service both the Trixie test mine and the Burgin administrative complex was completed by TCM in December, 2021, with peak load usage up to 4.5 MW. Estimated peak load power requirement for Trixie is 3 MW.

Topographic relief in the East Tintic District ranges from 1,494 m in the Goshen Valley east of the District to 1,996 m at nearby Mineral Hill. The elevation at Trixie is 1,852 m.

The Tintic Mountains host the scanty vegetation typical of an arid region. Different species of cactus, forbs and shrubs grow on exposed rocky points. The more common trees of the higher slopes are pinyon pine, juniper and mountain mahogany. At lower elevations, maple thickets occur in the dry ravines, especially on the eastern slopes, while aspens are found in sheltered spots, more commonly those of northern exposure. In the valleys, sagebrush, rabbitbrush, Brigham’s tea and cheat grass constitute almost the entire vegetation. Range improvement projects in the area have had some effect on improving grazing.

The climate of the East Tintic District is semi-arid. The U.S. Climate data website (https://www.usclimatedata.com/climate/elberta/utah/united-states/usut0068) noted that the mean monthly low temperatures at the nearby town of Elberta range from -10 degrees (°) Celsius (C) or 15° Fahrenheit (F) in January to 15° C (58° F) in July. The mean monthly high temperatures range from 2° C (37° F) in January to 33° C (93° F) in July. The Project has year-round access and operating season.

The Project’s main office, laboratory, workshops and onsite processing facilities are located at the Burgin site, immediately off Highway 6 and northeast of the Trixie test mine (Figure 5.2). The Burgin mine is a past-producing underground operation containing lead-zinc-silver ores that was last mined by Kennecott in 1976. All references to Burgin in this report are with respect to the main office and surface facilities located at this site, and not to the Trixie test mine or deposit, unless otherwise specified.

A mill facility previously operational in 2002 is located at the Burgin site. In October, 2021, a pilot vat leaching circuit was established within the old Burgin mill facility for cyanide vat leaching of the mineralized material from the Trixie test mine. Osisko Development’s recent operations also included trucking mineralized material to an offsite facility for vat and heap leaching from late 2020 to May, 2022.

In 2022, a pilot tailings facility was constructed on site adjacent to the mill facility. The facility was double lined for future re-permitting and operation as a heap leach facility.

Osisko Development Corp.

Figure 5.2
Burgin Site Infrastructure

Figure provided by Osisko Development. 

There is a current effort to design and construct a test milling facility in the Burgin mill building to further demonstrate the leach recovery results from the pilot vat leach facility in operation through late 2022. There is a tailings facility north of the processing facilities which will be redesigned and reconstructed to support tailings storage for the currently in-development Burgin Test Mill. Additional to the milling facilities, a permanent crusher installation is in development to prepare feed for the test mill or as part of future milling/processing facilities.

The onsite laboratory at the Burgin site provides fire assay analysis for gold and silver for all underground grade control sampling from the Trixie test mine. Atomic Absorption Spectrometry (AAS) and bottle roll analysis to complement onsite VAT leaching and processing have also been established. Using an onsite laboratory to assay samples generated on site is common practice in the mining industry. Onsite laboratories usually participate in round robin exercises with government or independent laboratories as part of their QA/QC programs. In addition, onsite laboratories, such as the Burgin site, usually send out check samples and engage laboratory auditing consultants to independently review their procedures.

The mineral property is sufficiently large that construction of further infrastructure at the Project will not be hindered by lack of space.

Osisko Development Corp.

6.0   History

Much of the material in this section is taken from the Chief Consolidated Mining Retrospect and Prospect 2005 Report. The mines, resources and reserves quoted in this section are historical in nature and should not be relied upon. It is unlikely that any of the resources or reserve estimates would comply with current NI 43-101 criteria or CIM Standards and Definitions. Historical resource and reserve estimates included in this section are for illustrative purposes only and should not be disclosed out of context. The QP did not review the database, key assumptions, parameters, or methods used for the historic mining on the East Tintic District as they are no longer available or were never recorded.

Economic mineralization in the Tintic District was first discovered in 1869 and within a few years, most of the major outcropping ore bodies were being mined and many of the historic mining towns, including Diamond, Silver City, Mammoth, Eureka, Dividend and Knightsville had been established (Krahulec and Briggs, 2006). By 1899, the Tintic District had become one of the richest mining districts in the USA. Active mining in the district continued through the 20th and beginning of the 21st century. Major replacement type ore bodies were discovered along three main structures known as the Gemini, Mammoth-Chief and Godiva ore runs. In 1905, a fourth ore run which was not outcropping, the Iron Blossom, was discovered by Jesse Knight. This “blind” discovery by Knight, some distance east of the outcropping ore runs, opened the possibility of further deposits to the east (Figure 6.1).

Even though many claims in what is now identified as the East Tintic District had been staked before the turn of the 20th century, the only known occurrence of surface mineralization was in a small outcrop near the present Eureka Lilly shaft. All future discoveries of the blind ore bodies in the East Tintic District would be based on surface alteration and underground geological interpretation.

E.J. Raddatz became interested in the East Tintic District around 1906 and acquired a major holding in what is now the Tintic Standard area. Raddatz reasoned that, even though the surface rocks were inhospitable, there was a chance of discovery in the Ophir limestone at depth. It took two shafts and thousands of feet of drift and winze workings but in 1916 the Tintic Standard deposit was discovered and went on to become one of the major lead-silver mines in the world.

Mining geologists, attracted by the discovery of the Tintic Standard deposit, began to study the district. Among these was Paul Billingsley, who observed that the volcanic cover in the east was pre-mineral and was altered by various stages of mineralizing fluids contemporaneous with ore deposition. Mr. Billingsley also recognized that the dikes and fissures cutting the volcanics continued at depth into the underlying sediments. Based on these ideas, a long drive on the 700 level of the Tintic Standard mine was commissioned. The target was projected from a surface exposure of a strong alteration zone, along with persistent dikes mapped within the volcanics. This exploration work intersected the mineral deposit that became the North Lily mine. Similar strategies led to the discovery of the Eureka Standard mine.

Osisko Development Corp.

Figure 6.1
Overview of the Major Historic Mineral Deposits of the Tintic District

Figure provided by Osisko Development.

During World War II, the United States recognized that, in the event of a long war, new sources of raw material would be essential. As a result, the US Geological Survey undertook an exploration program seeking blind ore bodies in the East Tintic District. One of the blind targets identified by the USGS was the CCMC oxide area, a prominent outcrop of oxidized and pyritized volcanics which overlies the Burgin deposit. However, no major discovery was made from either the sinking of the 22.6 m (75 ft) deep CCMC shaft or the drift from the Apex Standard mine. It was later surface drilling that made the discovery of the Burgin ore body.

Osisko Development Corp.

District production slowly increased through discovery of new mines and peaked between 1921 and 1930, when according to data from the U.S. Bureau of Mines, production for that decade from the combination of the Main Tintic and East Tintic mining districts reached 4,250,000 tons. From that peak, production decreased to a low of 662,000 tons between 1961 and 1970. Production from the Burgin mine led to a second peak of 1,200,000 tons between 1971 and 1976. Total recovered metal from the greater Tintic District is summarized in Table 6.1.

Following the discovery of the Tintic Standard deposit in 1917, the North Lily deposit in 1927 and the Eureka Standard deposit in 1928, interest was sparked over a poorly exposed structure overlying the current location of the Trixie test mine. Two shallow prospecting shafts known as the Trump shaft (94 ft or 28.5 m deep) and South Standard shaft (102 ft or 31 m deep) were sunk, but due to their shallow depth, failed to intersect mineralization.

Intense hydrothermal alteration of volcanic rocks exposed at surface at the Trixie site attracted the attention of the U.S. Bureau of Mines, which, in 1946-1947, conducted gravimetric and spectrographic surveys as well as geological studies of the Trixie area.

Between 1954-1955 the USGS conducted geochemical sampling and geological mapping of the area immediately north of the current Trixie shaft location. This was followed up by the drilling of nine holes that confirmed the presence of the Trixie fault and the validity of the surface geochemical anomalies when low-grade lead-zinc ore was intersected in the Trixie fault zone. After the conclusion of the USGS research program in 1956, Bear Creek Mining (an exploration subsidiary of Kennecott Copper Corp. (Kennecott)) completed eight additional core holes in the target area and several of these holes intersected strong lead-zinc replacement mineralization in the underlying limestone. Despite the apparent presence of ore-grade mineralization at depth, the disappointing core recoveries resulted in surface exploration work being terminated in 1957. Subsequently, the decision was made to conduct future exploration from underground.

The sinking of the Trixie shaft was initiated in 1968 and had reached the 750 ft level by 1969. Although the initial target of exploration at the Trixie historic mine was lead-zinc replacement mineralization in the hanging wall of the Trixie Fault, a gold-bearing structure was encountered during shaft sinking at a depth of 584 ft. This northerly-trending and steeply west-dipping structural zone became the primary source of ore, which was concentrated along three gold-silver mineralized segments. From north to south these ore shoots were referred to as the 756 ore shoot, the 75-85 ore shoot, and the Survey zone (Figure 6.2).

Osisko Development Corp.

Table 6.1
Total Recovered Metal and Production Values from the Tintic District

Table from Krahulec and Briggs, 2006.

Osisko Development Corp.

Figure 6.2
Oblique 3D Model View of all Historic and Modern (T2) Development at Trixie

Figure provided by Osisko Development.

Osisko Development Corp.

The original carbonate replacement deposit (CRD) that was discovered at the Trixie historic mine in 1969 is located on the north end of the deposit within the downthrown carbonate sequence north of the Trixie fault. While limited in scale, the replacement mineralization consists of massive sulphide minerals and jasperoid that locally enclose irregular blocks of argillized shale and limestone between the 750 ft level and 900 ft level. Metal zonation within the deposit was documented at the time of mining with the upper levels displaying higher grade zinc and gold values, which diminish down-plunge, while copper and silver values increase at depth and lead concentrations remain consistent throughout (Morris et al., 1979).

The 756 ore shoot represents the most productive of the three historically mined ore zones. This ore shoot was developed up to nine feet in width and over 900 ft in strike length and was mined for over 1,000 vertical feet. The shoot plunges to the north towards the Trixie and Eureka Standard faults and was mined continuously from approximately 75 ft above the 625 level to below the deepest 1350 level development. Based on limited historic drilling, the 756 ore shoot continues for at least 300 ft below the 1350 level and remains open at depth.

In 1976, as mining and exploration continued within the 756 mineralized shoot, the 75-85 ore shoot was discovered approximately 1,600 ft (488 m) south of the Trixie shaft. The 75-85 ore shoot was mined from approximately 50 ft (15 m) above the 625 level down to the 1200 level.

In early 1980 Bear Creek Mining discovered the Survey zone while exploring for the Sioux-Ajax fault by drifting south on the 1050 ft level of the Trixie historic mine. The Survey vein segment was explored and extensively developed by Kennecott on the 750, 900, 1050 and 1200 levels during the pre-1995 silica flux mining periods. The southern end of the Survey Vein is extended for a distance of 3,400 ft south of the main shaft, along the 1050 level and remains open to the south and at depth.

In 1980, Sunshine Mining Corporation (Sunshine Mining) leased the Burgin unit from CCMC and by 1983 had also begun work at Trixie where it re-started mining operations and undertook additional underground development and diamond drilling. Much of the underground development and drilling from this time appears to have been focused on the 900, 1050, 1200 and 1350 levels. Perhaps the most notable exploration efforts at Trixie during this time were the southerly extensions of the 900, 1050 and 1200 ft level drifts following the discovery of the Survey zone and the northeastward extension from the 1350 ft level to connect with the 1100 ft level of the Eureka Standard mine. This connection provided the underground access needed to evaluate the Eureka Standard fault along-strike and down-dip from the original Eureka Standard mine workings. Sunshine Mining operated the Trixie historic mine until terminating its lease with CCMC at the end of 1992.

Between 1969 and 1995, the historic Trixie mine was operated as a source of silica flux ore for direct shipment to Kennecott’s Bingham Canyon smelter. Payments were received for gold, silver and variably for copper. Production from 1969 through to 1992 totaled 808,240 tons, containing 159,289 oz of gold and 4.75 million oz of silver. Ore mined during this period was heavily diluted (as much as 3:1) with footwall and hanging wall Tintic Quartzite. Open stope mining methods and poor ground control practices appeared to be only partially responsible for the dilution of ore. Production of 100 tons per day was required from the historic Trixie mine to provide a precious metal-rich silica flux ore to Kennecott’s Bingham Canyon smelter. Since the Tintic Quartzite was as good a source of silica flux as the mineralized quartz veins themselves, dilution of the Trixie ore with Tintic Quartzite was a deliberate practice to obtain the daily tonnage requirements. A diluted mining grade of 0.15 to 0.3 oz/t Au during this time was an optimal grade to obtain the required tonnage for the Bingham Canyon smelter, covering the cost of extraction and shipping of the silica flux.

Osisko Development Corp.

As a result of a settlement of litigation between the then-operator Sunshine Mining and CCMC, underground mining at the Trixie operation ceased in 1992. CCMC mined and shipped some low-grade surface stockpile material for smelter flux between 1993 and 1995, but with changes to Kennecott’s smelting process in 1995, its Garfield smelter no longer required Trixie flux ore. There were other western smelters with requirements for high-silica metals-bearing flux, but the costs of transportation to these smelters, coupled with low ore prices reduced the overall profit potential of mining the Trixie and other known silica-hosted precious metal deposits in the East Tintic District.

Between 2000 and 2002, CCMC (through its affiliate Tintic Utah Metals LLC (Tintic Utah Metals)) undertook an aggressive surface and underground drilling program at Trixie, resulting in the discovery of a small-tonnage gold-silver resource associated with the earlier mined 75-85 mineralized zone. In the case of the gold-silver resource, a new level (the 625 ft level) was developed within the mine in 2001, and approximately 11,120 tons of gold-silver ore, averaging 0.66 oz/t Au, were produced before mining was suspended due to the decrease in the price of gold below $300/oz and CCMC’s financial and reported management problems.

Table 6.2 summarizes the production from the Trixie mine from before 1883 to 2002.

TCM acquired the historic Trixie mine at the beginning of 2019, and initially focused its assessment on the base-metal resource opportunity at the Burgin mine. However, high-grade gold opportunities that had potential for near-term production and revenue Trixie mine quickly became the focus of the company. A preliminary economic report dated 2010 indicated the presence of known and documented resource opportunities at the Trixie mine, though these required in-depth evaluation and additional work to quantify. Since most of the historic mining was focussed on the steep west-dipping structural corridor with very little development or exploration into either the footwall or hanging wall, there was high potential to define additional mineralized structures in close proximity to the existing underground infrastructure.

Osisko Development Corp.

Table 6.2
Trixie Mine Historic Production Summary

Table supplied by Osisko Development but originally prepared by Tom Gast for CCMC, October 2010.

*ST = US Short Tons

Osisko Development Corp.

The historic Trixie mine together with the entire East Tintic property had been in a state of care and maintenance followed by near abandonment, since 2014, and this resulted in wide-spread vandalism and damage to the property and physical assets. This included destruction of the primary hoist, hoist foundation and building at Trixie that was used to operate the conveyance and provide access to the underground development. In August, 2019, TCM made the decision to commence rehabilitation of the historic mine and shaft (Figure 6.3), with the intention of beginning underground drilling and exploration of documented targets on the historic 625 ft and 750 ft development levels.

By December, 2019, TCM had compiled the historic Trixie datasets into a new 3D model of the deposit and identified a significant new target in the immediate footwall to the 610 stope. This new target, initially termed the North Survey Vein, was developed from reconsidering assays within historic surface RC holes which could not have originated from any of the historically mined areas (Figure 6.4). Further investigation of this target lead to the discovery of the T2 and T4 structures.

Figure 6.3
Trixie Headframe

Micon site visit photograph.

Osisko Development Corp.

Figure 6.4
Cross Section, Looking North, of the Surface RC Hole Intersections that Led to
Discovery of the T2 Structure

Figure provided by Osisko Development.

The broad zones of mineralization encountered in the 2000-2001 surface RC drilling were originally interpreted to be caused by the smearing of mineralization within the holes, given that the known mineralized structures were typically no more than six to eight feet in width. However, exploration work by TCM in 2021 demonstrated that mineralization up to 60 ft in width is associated with the T4 stockwork. The broad zones of mineralization encountered in the 2000-2001 RC drilling were thus re-interpreted as intercepts of T2-T4 stockwork mineralization in the immediate footwall of the 75-85 structure.

Between February and June, 2020, refurbishment of the 625 level was completed by TCM with new services installed to commence underground diamond drilling. A total of five diamond drill holes were completed between June and August, 2020, all collared from the only suitable drilling position, just north of the ventilation shaft (Figure 6.5).

Osisko Development Corp.

Figure 6.5
Plan Map of the 625 and 750 Levels and the T2 and T4 Mineralized Zones

Figure provided by Osisko Development.

Despite extremely difficult drilling conditions, visible mineralization within the footwall of the 610 stope was confirmed in three of the five holes. With the visual confirmation of the mineralization and structure a decision was made by TCM management to commence development of an exploration drift eastward towards the target zone. This exploration drift would open-up the target structure for sampling and visual examination, as well as opening up more favourable positions from which to drill on the east side of the 610 stope.

Osisko Development Corp.

The decision to develop into the target zone by TCM management proved extremely fortuitous. Only 13 m (44 ft) east of the historic 625 ft level development, TCM drifted directly into the T2 structure. The first three grab samples taken returned 1,234 g/t Au (36 oz/t Au), 1,947 g/t Au (56.8 oz/t Au) and 5,417 g/t Au (158 oz/t Au). Figure 6.6 shows one of the earliest underground mining faces on the T2 structure, with composite chip sampling across the face returning 2.4 m of 3,497 g/t Au and 6,583 g/t Ag (8 ft of 102.0 oz/t Au and 192 oz/t Ag).

Figure 6.6
An Early Mining Face on the T2 Structure Looking North

Figure provided by Osisko Development.

Abundant visible gold associated with the striking green colour of the mineralized zone aided the visual identification and mining of the T2 structure. Initial mining continued north and south on-strike of the steeply east-dipping structure to determine potential strike lengths of the mineralized zone. At the same time the original 609 exploration cross-cut was extended further eastward to test ground immediately east of the T2 structure for further mineralization. Together with additional diamond drilling and exploration cross-cuts, a broad zone of mineralized stockwork veining up to 25 metres (80 ft) in width has now been identified, and is referred to as the T4 stockwork zone of mineralization.

Figure 6.7 displays an overview of the historic mine development and new mining completed by TCM between 2020-2021, with the T2 and T4 development located only 13 m (44 ft) east of the historic mine infrastructure on the 625 level.

Osisko Development Corp.

Figure 6.7
Overview Map of the Southern End of 625 ft Level

Figure provided by Osisko Development.

In November, 2020 the first shipment of mineralized material was made to an offsite processing facility and the first gold was poured by TCM. Continual underground development and drilling through 2021 helped define T2 mineralization over a 400 ft strike length and led to the recognition of the scale of the T4 stockwork mineralization. Design work for a surface portal and internal decline ramp to access the Trixie underground development was commenced shortly thereafter. A geological model for T2-T4 mineralization identified the potential significance of the overlying Ophir Shale, as a cap above the Tintic Quartzite host rock, in influencing the T2-T4 mineralized zone. In the fall of 2021, the Burgin Processing Facility was equipped with an onsite vat leaching process. On May 30, 2022, Osisko Development announced the completion of its acquisition of TCM.

Osisko Development Corp.

7.0   geological setting and mineralization

The Tintic Project is located within the historic Tintic mining district, a cluster of base and precious metal deposits covering more than 200 square kilometres (or approximately 80 square miles) within the East Tintic Mountains of north-central Utah (Figure 7.1). The district is centred approximately 90 km (56 miles) south-southwest of Salt Lake City and 65 km (40 miles) south of the Bingham Canyon porphyry Cu-Au-Mo deposit. The East Tintic Mountains occupy a position within the Late Cretaceous Sevier fold and thrust belt (e.g., Allmendinger & Jordan, 1982; Yonkee & Weil, 2015) approximately 30 km (20 miles) from the eastern limit of the Basin and Range extensional province as defined by the surface expression of the Wasatch fault. District mineralization is associated with a post-Sevier compression and pre-Basin and Range extension period of magmatism, spanning ca. 27-35 Ma (latest Eocene to Oligocene) (e.g., Moore et al., 2007). Commonly divided into Main, East, North and Southwest subdistricts, the greater Tintic is collectively the second largest metal producing district in Utah state, with Bingham first and Park City a close third (Krahulec and Briggs, 2006). The core Tintic project area covers more than 90% of known deposits within the East Tintic subdistrict. Additional coverage extends north, west and south into the North, Main, and Southwest districts, respectively.

The geology of the Tintic district can be summarized as the record of four major phases of geologic evolution. These are 1) development of a Palaeozoic platformal sequence atop previously deformed Precambrian basement, 2) folding, faulting, and uplift accommodating east-west shortening during the Late Cretaceous Sevier Orogeny, 3) latest Eocene to Oligocene calc-alkaline magmatism associated with district mineralization, and 4) Miocene to recent Basin and Range extension.

Precambrian basement in the Tintic district consists of phyllitic shales and coarse-grained quartzite of the Big Cottonwood Formation, exposed on the western limits of the East Tintic mountains but encountered only as xenoliths within the Eureka quadrangle at the district core. Deposited unconformably above the Big Cottonwood Formation, the Palaeozoic platformal sequence consists of a 701 to 975 m (2,300 to 3,000 ft) basal quartzite (the Lower Cambrian Tintic Quartzite) that grades through a relatively thin sequence of calcareous shales and lesser limestone facies (the Middle Cambrian Ophir Formation) into an extensive carbonate sequence that spans into the Late Mississippian. Total stratigraphic thickness of the Palaeozoic sequence exceeds 2,743 m (9,000 ft) (e.g., Morris, 1964: Geology of the Eureka Quadrangle; Morris, 1964: Geology of the Tintic Junction Quadrangle; Morris et al., 1979) (Figure 7.2).

Osisko Development Corp.

Figure 7.1
Map of the Tintic District Displaying Mineral Occurrences and Regional Tectonic Framework

Figure provided by Osisko Development.

Osisko Development Corp.

Figure 7.2
Palaeozoic Stratigraphy of the Tintic District

Figure provided by Osisko Development.

Osisko Development Corp.

Accommodation of east-west shortening during the Late Cretaceous Sevier Orogeny resulted in the development of the district scale Tintic syncline-East Tintic anticline fold pair, and several associated district-scale, generally west-vergent thrusts (Morris, 1964: Geology of the Eureka Quadrangle; Morris et al., 1979). The geometry of the sub-horizontal roughly north-south trending fold pair is responsible for the general basement architecture of the Tintic district, wherein the youngest (Mississippian) rocks of the Palaeozoic sequence are preserved along the trough of the Tintic syncline in the Main district and the Tintic Quartzite is present at its highest structural levels along the crest of the East Tintic anticline in the East district (Figure 7.3). High-angle structures developed in relation to the Sevier orogeny include a system of predominantly northeast trending faults with strike-slip offset interpreted as accommodating differential displacement syn-compression, and a system of variably oriented normal faults developed in accommodation of late to post-orogenic gravitational collapse. (e.g., Morris, 1964: Geology of the Eureka Quadrangle; Morris et al., 1979).

Extensive erosion following Sevier uplift resulted in the development of a rugged paleotopography by the onset of district magmatism ca. 35 Ma (Figure 7.4). The latest Eocene to Oligocene magmatic record consists of a quartz latite flow and tuff dominant sequence of irregular thickness up to 1,500 m (5,000 ft) with cross-cutting to coeval locally porphyritic monzonite to quartz monzonite intrusions of varying geometries (e.g., Morris, 1964: Geology of the Eureka Quadrangle; Morris, 1964: Geology of the Tintic Junction Quadrangle; Morris et al., 1979; Keith and Kim, 1990) (Figure 7.4). District mineralization, dated in the East Tintic at around 31 Ma (Laughlin et al., 1969) is contemporaneous and associated. In the East Tintic district, known fissure-vein and replacement deposits are nearly exclusively buried beneath the irregular volcanic cover (Figure 7.5). While the basal (pre-mineral) volcanic cover hosts no significant mineralization, it is commonly characterized by significant hydrothermal alteration. Several sub-km-scale lithocaps point to potential porphyry targets at depth, where more localized alteration along predominantly N to NE-trending fissures with associated pebble dikes were used in successful targeting of many of the known historic deposits (e.g., Morris et al., 1979).

The Palaeozoic sequence and its irregular volcanic cover are disrupted by Basin and range extensional faulting. Miocene-age volcanics likely mark the onset of extension in the district ca. 16-18 Ma (Figure 7.4). While any pre-existing fault structures are likely primed for some degree of Basin and Range extensional reactivation, the most significant normal offsets occur along roughly north-south trending structures, e.g., the district-scale Eureka Lilly fault. The variably north-south striking and west-dipping Eureka Lilly fault forms a major aquitard through the East Tintic district, dividing a fresh, cool-water-table in its hanging-wall to the west from a hot and saline water table in its footwall to the east. Post-lava offset on the Eureka Lilly fault is apparently variable along strike and may account for only one-half to a third of the total offset across the structure, believed to have initiated during Late Sevier orogeny (Morris et al., 1979).

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Figure 7.3
Partial N-Facing 7.5’ Eureka Quadrangle Section A-A’

Figure provided by Osisko Development but originally digitized from Morris (1964) Geology of the Eureka Quadrangle.

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Figure 7.4
Oligocene Volcano-Magmatic Stratigraphy of the Tintic District with
Select Reported Geochronologic Data

Figure provided by Osisko Development.

Osisko Development Corp.

Figure 7.5
Simplified USGS Geologic Map of the East Tintic District

Figure provided by Osisko Development.

Osisko Development Corp.

The four subdistricts of the Tintic are in part distinguishable in terms of their known mineral occurrences, hosted within the deformed Palaeozoic sequence and, to a more limited extent, Oligocene monzonitic intrusions. The Main district is the most historically productive district by far (Section 6.0), with characteristic carbonate-hosted lead-zinc-silver replacement deposits that form predominantly north to northeast-trending sub-horizontal zones rooted into subvertical chimney-like mineralized bodies rich in copper, gold and silver (e.g., Krahulec and Briggs, 2006 [after Morris, 1969]) (Figure 7.1). Carbonate-replacement deposits with economic zinc ± lead ± silver are likewise present in the East district and the historically least-productive North district. The East district is unique in terms of the relative structural complexity of the deposits, and by the added presence of gold and silver-rich high-sulphidation fissure vein systems hosted within the brittle and unreactive Tintic Quartzite, such as at Trixie. The Southwest district is characterised by a relative dominance of igneous rocks, containing fissure systems hosted within the Silver City stock and smaller associated monzonitic porphyry intrusions (e.g., Krahulec and Briggs, 2996). The Southwest district is also host to the Southwest Tintic porphyry copper system, viewed as subeconomic but with minor historical production from peripheral high-sulphidation, copper-silver-lead veins (Krahulec and Briggs, 2006). Several key observations suggest the presence of additional and potentially economic porphyry centres within the district. This includes indicator clay assemblages and elevated molybdenum and/or copper-lead ratios at the Big Hill, Silver Pass, and Government Canyon lithocaps, all contained within the Tintic Project claims area (e.g., Sillitoe, 2006; 2022; Leveille, 2021) (Figure 7.1) (Discussion in Section 8).

In addition to an association with both the low- and high-angle faults developed regionally through the Late Cretaceous Sevier Orogeny, mineralization within the East Tintic is often linked with a more localized network of high-angle structures, apparently developed pre to syn-mineral in association with latest Eocene to Oligocene magmatism (e.g., Morris et al., 1979). These structures formed conduits for the emplacement of pebble dikes, monzonitic intrusions, and their associated hydrothermal fluids. They range in orientation from north-south to more prevalent north-easterly trends and are particularly well-developed as faults and fissures within the brittle Tintic Quartzite. The Tintic Quartzite is brought to its highest structural levels within the East district, along the crest of the East Tintic anticline in the hanging-wall to the East Tintic thrust, which is itself complexly folded through progressive deformation. The geometry and nature of the East Tintic anticline are largely interpreted from underground mapping and the exact location of its axial trace at the base of the younger volcanic cover is unknown. Sub-horizontal Palaeozoic strata of the Trixie area are believed to occupy a position within or proximal to the hinge zone of the anticline (Morris et al., 1979). North of Trixie, the fold axis is interpreted to have been offset significantly eastward and fold geometry is described as asymmetric, with a shallow to the west dipping western limb, and steep to locally overturned eastern limb, intensely deformed along the East Tintic thrust.

A little more than half of the historical production within the East Tintic district has been sourced from massive lead-zinc-silver replacement deposits formed at a variety of locations where faults that juxtapose younger carbonates directly against the Tintic Quartzite are cross-cut by, or intersect with, high-angle northeast-trending structures (Krahulec and Briggs, 2006). Replacement ore bodies of the Burgin deposit are largely localized within a fault-bound wedge of deformed Ophir Formation and Teutonic carbonate facies rocks overthrust by the Tintic Quartzite, in the hanging-wall of the main East Tintic thrust (Morris et al., 1979). Several interpreted syn-Sevier strike-slip structures, including the Eureka Standard and Apex faults are the presumed conduits for mineralizing fluids, despite observations that they root into and do not crosscut the East Tintic Thrust (Morris et al., 1979). Replacement bodies at the historic North Lilly mine are found at its higher structural levels where northeast-trending fissures locally exploited by monzonitic porphyry dikes, intersect carbonates of the Middle Ophir Formation down-dropped into direct contact with the Tintic Quartzite, along the dip-slip normal reactivated Tintic Standard Thrust.

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High-sulphidation gold – silver ± copper deposits hosted within fissure vein systems in the Tintic Quartzite account for the remaining historic production and all mineralized zones currently under development within the East Tintic district (Krahulec and Briggs, 2006). Structural trend at the Trixie, as dictated by the subvertical-to-the-east-dipping T2 structure and smaller scale fissures within its hanging wall T4 breccia zone, is north south. At the historic Eureka Standard mine, about 1.6 km (1 mi) to the north-northeast, deposit-scale geometry is largely controlled by the northeast-southwest striking and moderately northwest dipping Eureka Standard fault zone, however, individually mapped mineralized fissures within the zone, range from fault-parallel to subvertical and predominantly northeast trending. At the historic North Lily mine, approximately 2 km (1.2 mi) farther north, high-sulphidation mineralization is intimately associated with a series of sub-vertical northeast-trending fissures and parallel monzonitic dikes.

Mineralization at the Trixie test mine is structurally controlled within a north-south-trending fissure-vein and breccia system, developed within the brittle Tintic Quartzite. Gold and silver-rich mineralization within the so-called Trixie vein system is best classified as high-sulphidation epithermal (see discussion in Section 8). Current development at Trixie is focused within the footwall to the historically productive steep-to-the-west-dipping 75-85 structure, targeting the subvertical-to-the-east-dipping T2 fissure vein, its hanging -wall T4 breccia zone, and a network of smaller-scale likewise north-south-trending mineralized fissures contained within it.

Sub-horizontal Palaeozoic strata exposed in underground workings at Trixie are believed to occupy a position within or proximal to the hinge zone of the East Tintic anticline (Morris et al., 1979), the nature of which may exert primary influence on the geometry, frequency, and distribution of grade controlling structures within the Trixie vein system. The stratigraphic contact between the Tintic Quartzite and overlying and impermeable lower shale member of the Ophir Formation appears to have a major controlling influence on the development and grade distribution of mineralization at Trixie. While controlling structures within the Trixie vein system do penetrate the younger overlying sequences, mineralization typically displays strong rheologic control and is restricted to the older and underlying brittlely fractured Tintic Quartzite host.

The main shaft of the historic Trixie mine was collared at approximately the 1,852 m (6,075 ft) elevation into an outcropping window of Middle Cambrian Teutonic Limestone. The shaft passes through the full thickness of the Ophir Formation to reach the Tintic Quartzite at a depth of approximately 125 m (410 ft). All current development stems off the historic 625-foot mine level, while deeper historic workings include 750, 900, 1050, 1200, and 1350-foot levels. The full extent of both modern and historical development at Trixie resides within the hanging-wall to the district-scale Eureka Lilly fault. The fresh groundwater table of the Eureka Lilly hanging-wall at Trixie sits below the ca. 1,437 m (4,716 ft) elevation of the 1350-foot level, around 425 m below surface. The Late Eocene to Oligocene Packard Quartz Latite unconformably overlies the Palaeozoic Tintic-Ophir-Teutonic sequence in nearly every direction surrounding the Trixie main shaft. The Packard Quartz Latite is in local unconformable contact with both the Ophir Formation and Tintic Quartzite, reaching thicknesses up to 380 m (1,250 ft) directly south of the vent shaft (Figure 7.6).

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The core of the Trixie vein system occupies a high-seated position within an east-west oriented horst, the bounding structures of which may have served as critical pathways for mineralizing fluids (Figure 7.6). North of the Trixie main shaft, the Tintic Quartzite is down-dropped an estimated 198 m (650 ft) across the east-west-trending sub-vertically north-dipping Trixie fault zone (Morris et al., 1979). At the very northern limits of development, the sequence is again offset relative down to the north across the Eureka Standard fault zone, which appears to consist locally of at least two major east-northeast trending splays. Though not fully constrained, relative stratigraphic offset across the Eureka Standard fault zone is of similar or greater magnitude to that observed across the Trixie Fault zone. Approaching the southern end of development, the Tintic Quartzite and mineralized structures of the Trixie vein system appear to be offset across the presumably steep to the south-dipping Sioux-Ajax fault zone. The Sioux-Ajax fault zone has not been intersected by any modern-day development. Constraining its displacement and orientation is complicated by several intersecting west-dipping splays of the Eureka Lilly fault that appear to further offset mineralization.

The Sioux-Ajax fault system is well-known within the Main District as a major ore controlling structure, with associated breccias hosting large replacement bodies in both the Mammoth and Iron Blossom mines (Morris et al., 1979). The Sioux-Ajax fault system of the Main district consists locally of two or more splays generally striking east-southeast and dipping steeply to the north. The fault system is buried beneath volcanic cover projecting along strike into the East Tintic district, wherein its correlation and relationships with known structures have long been a topic of high interest and debate (e.g., Morris et al., 1979). Recent interpretations based on the integration of historical mapping with high-resolution magnetic data acquired in 2019 suggest that the Trixie, Eureka Standard, and south-dipping Sioux Ajax fault zones as defined within the Trixie development area, are structurally linked with the Sioux Ajax zone of the Main district and may have collectively provided the deep-seated plumbing necessary for mineralization at Trixie.

The historic 756 ore shoot at the north end of Trixie development displays a steep northerly plunge in the footwall to the Trixie fault zone. At the southern end of Trixie development, higher grade ore shoots within the historically mined 75-85 zone exhibit a steep southerly plunge, for which the presumed south-dipping Sioux Ajax fault zone is the interpreted structural control. These historical observations suggest that mineralization and grade within the T2 fissure vein and T4 zone currently in development in the immediate footwall to the 75-85 structure may be characterized by a similar geometry.

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Figure 7.6
East-Facing Geological Long Section Displaying Underground Development at Trixie

Figure provided by Osisko Development.

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8.0   deposit types

There are three interrelated deposit types of particular interest within the East Tintic district:

The distribution of both CRDs and high-sulphidation epithermal vein systems in the East Tintic district is strongly lithologically controlled, with known high-sulphidation epithermal veins restricted to the Tintic Quartzite, and CRD type base-metal deposits hosted in the overlying carbonate sequence. This is in part reflecting a rheological control, due to the brittle nature of the quartzite which makes it more prone to the development of breccia hosted epithermal veins, and in part a geochemical control, due to the more reactive nature of the carbonates to acidic fluids. The same strongly acidic hydrothermal fluid, sourced from a potential deep-seated porphyry centre, may be responsible for both the precipitation of high-sulphidation mineral assemblages within the quartzite and, once buffered during interaction with overlying carbonate facies rocks, the precipitation of CRD deposits. A generalized model for each of the deposit types and their idealized location relative to depth of emplacement and stratigraphic control is presented in Figure 8.1.

Figure 8.1
Generalized Model of Deposit Styles in the East Tintic District

Source: Modified from TCM 2021.

Osisko Development Corp.

CRDs account for more than 90 percent of all ore produced in the East Tintic district (Morris & Lovering, 1979). Silver rich lead-zinc CRDs of the historic Burgin, Tintic Standard and North Lily mines, are characterized by the replacement of limestone by massive sulphide adjacent to intersections between steeply dipping northeast-trending faults and shallow to moderately west or southwest dipping faults. The complex geometry of the more shallowly dipping fault zones demonstrates an imbricate nature, with repeated fault bound slivers of mineralized stratigraphy, as well as localized folding of thrust sheets forming pockets or “pot-hole” structures that provided favourable focal points for mineralization. The mineralogy of the replacement deposits typically consists of massive galena ± sphalerite, with lesser silver sulphides and sulphosalts (Figure 8.2). In general, there is a zonation observed within the replacement bodies with a core which is richer in lead and silver and an increase in zinc and manganese toward the peripheries (Morris & Lovering 1979).

Steeply dipping northeast trending fissures transect the CRD deposits and localize silver and gold-silver rich mineralization along structurally controlled planes, such as the Silver Fissure at the historic Burgin mine.

Figure 8.2
CRD-Style Base-Metal Mineralization, Massive Galena Typical of the Historic Burgin,
Tintic Standard and North Lily Mines

Figure provided by Osisko Development.

Osisko Development Corp.

High-sulphidation epithermal vein systems containing enargite-gold-silver ores (Figure 8.3) are structurally controlled and limited in known occurrence to the basal Tintic Quartzite unit. The brittle and relatively geochemically inert nature of the Tintic Quartzite make it particularly well-suited to focus ascending mineralizing fluids along permeable faults and breccia zones developed within the otherwise relatively impermeable rock, allowing for the deposition of precious metal-rich gold-silver mineralization, as seen at Trixie, the historic Eureka Standard mine and in the deeper levels of the historic North Lily mine, associated hydrothermal fluids which tend to be strongly acidic, with elevated sulphur fugacity (John et al., 2018). The conditions of the hydrothermal fluids can be deduced from the stability of the assemblage of ore and gangue minerals that precipitate from them, as well as from fluid inclusions within individual minerals. The assemblage enargite ± pyrophyllite ± alunite which is common in the known vein systems hosted in the Tintic Quartzite is indicative of high-sulphidation conditions (John et al., 2018). Precipitation of minerals from a hydrothermal fluid may be related to changes in temperature, pressure, pH, sulphur fugacity or a number of other controlling factors. Rapid releases in fluid pressure are of particular importance as they can trigger flash boiling, a process which simultaneously cools the fluid while partitioning volatile phases such as H₂S and CO₂ into the exsolved vapour leading to changes in pH and sulphur fugacity, all of which can contribute to the formation of high concentrations of gold (Hedenquist, 1985).

Figure 8.3
Typical Sulphide Au-Ag-Rich Vein Mineralization found at Trixie and in the Historic Eureka Standard Mine, Hand Sample taken from the Eureka Standard Dump Pile

Figure provided by Osisko Development.

Osisko Development Corp.

Apparent controlling structures within the East Tintic high-sulphidation epithermal vein systems are typically narrow (approximately 0.1-3 m or approximately 0.3-10 ft wide) polymetallic quartz-barite fissure veins, such as are observed at the core of the gold and silver-rich telluride-bearing T2 structure at Trixie. High-sulphidation epithermal mineralization also occurs within silica ledges and silica-sulphide-sulphosalt flooded breccia zones adjacent to primary controlling structures, such as in the T4 breccia zone at the Trixie mine. High-sulphidation ores are oxidized above the water table, locally characterized by the in-situ replacement of copper bearing tellurides and sulphides by bright green and blue supergene copper tellurates and copper carbonates. Oxidation and leaching of sulphides above the water table have the added benefit of releasing any refractory gold that may have otherwise been bound in the crystal structure of the sulphides. The water table at Trixie is 425 m (1,394 ft) below surface, at an elevation of 1,425 m (4,765 ft) and is reported at a similar elevation in the other historic mines west of the Eureka Lilly fault (Morris and Lovering, 1979). East of the Eureka Lilly fault the water table is hot and saline and is approximately 50 m lower in elevation than on the west side.

Five unique interrelated and/or cross cutting structurally controlled domains of mineralization with varying gold grades are recognized at Trixie: 75-85, T1, T2, T3, and T4 (Figure 8.4). Though controlling structures may penetrate younger stratigraphic horizons, mineralization is limited to the Tintic Quartzite, as overlying shales belonging to the lower member of the Ophir Formation formed an impermeable cap to mineralizing fluids.

The 75-85 domain consists of a discrete north-south striking moderate to steeply west-dipping polymetallic silica-sulphide cemented breccia zone. The domain connects two historically developed tabular mineralized bodies, the 756 at the north end of Trixie development, and the 75-85 mineralized shoot to the south (Morris et al., 1979) (Figure 8.5). Historically documented primary economic minerals include a wide range of silver, copper, lead and/or zinc bearing sulphides and sulphosalts (e.g., argentite, proustite, polybasite, silver-bearing tennantite-tetrahedrite, enargite, chalcopyrite, bornite, galena, sphalerite and pyrite) as well as native gold (Morris et al., 1979). Gangue minerals are chiefly crystalline quartz and barite.

Combined modern modelling and historic documentation define the structure along a strike length of approximately 700 m (2,300 ft), from northern termination in a series of horsetail fractures about 30 m (100 ft) south of the Trixie fault (Morris et al., 1979) to its southerly abutment against the Sioux Ajax Fault, across which it is unconstrained but likely offset. Historic development on the 756 ore shoot extends approximately 23 m (75 ft) below the 1350-foot development level (approximately 1,416 m; 4,645 ft elevation). The mineral potential for this zone is open at depth.

Current modelled dips for the structure are slightly less than the historically documented average of 75°, ranging from approximately 60° down to approximately 40° where the structure appears to shallow locally through the 750 ft development level. The strike of the structure is historically documented to range locally from 005° through 340° (Morris et al., 1979). Similar-scale deflections from an average strike of approximately 350° are apparent at the scale of the current model as well. The breccia zone ranges in width from less than 1 m (3 ft) to upwards of 12 m (40 ft).

Current data suggest that the 75-85 structure truncates both the T2 structure and T4 stockwork zone, implying that it is the youngest of the mineralization and grade controlling structures at Trixie.

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Figure 8.4
North Facing Geological Cross-Section displaying Mineralized Domains
and Controlling Structures at Trixie

Figure provided by Osisko Development but modified from TCM June, 2022.

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Figure 8.5
East facing Geological Long-Section showing Mineralization and Development at Trixie

Figure provided by Osisko Development modified from TCM June, 2022.

Osisko Development Corp.

The T1 domain consists of Tintic Quartzite-hosted disseminated mineralization constrained within a footwall wedge between the intersecting discrete T2 and 75-85 structural domains. The mineralization appears to extend no further than around 15 m (approximately 50 ft) into the footwall of either bounding structure and, therefore, is interpreted to have developed as a lower-grade halo to them.

The structurally controlled T2 domain is a discrete subvertical to the east-dipping fissure vein and breccia zone characterized by polymetallic gold and silver-rich telluride-bearing mineralization, with quartz-barite gangue. While some evidence for historic exploitation of the structure around the 675-foot sublevel is indicated by the presence of minor stoping dating from the 1970s, the continuity and full potential of the structure was not recognized until its ‘discovery’ by TCM in 2021.

The T3 domain consists of a discrete and narrow (approximately 1 m; 2-3 ft-wide) fissure fault zone, characterized by base and precious metal mineralization with quartz-barite gangue in breccia fill and lenses. The structure strikes north-south and dips steeply (approximately 77°) to the east. As currently constrained, the structure is of limited measurable length along strike and down-dip, maximum 150 m (490 ft) and 35 m (115 ft), respectively, but is open for potential in either dimension. The structure as currently constrained is completely contained within the 75-85 hangingwall, thus its potential interactions with the other mineral and grade-controlling structures are unknown.

The gold and silver-rich T2 structure at the Trixie is located in the immediate footwall of the historically mined west-dipping 75-85 structure. The T2 structure is a discrete 0.2 to 0.8 m wide central fissure vein developed within the Tintic Quartzite, characterized by a prominent striking green-blue mosaic framework breccia consisting of angular Tintic Quartzite clasts within a highly mineralized fracture fill cement matrix (Figure 8.6). The matrix consists of mosaic to drusy quartz intergrown with coarse-crystalline bladed barite, sulphosalts, native gold and gold-silver bearing tellurides, which have been variably oxidized to form copper-tellurates (Figure 8.7). Gold values in the thousands of ppm are associated with significant visible free gold and Ag ± Au-tellurides.

Mineralization on the T2 structure is capped by the contact with the lower shale member of the Ophir Formation, approximately 25 to 40 m (80 to 130 ft) above the 625 level of mining. The relatively impermeable shale is thought to play a critical role in confining the gold mineralization to structures within the Tintic Quartzite. At depth, the T2 breccia resolves itself into a discrete 1-3-metre-wide structure where it has been encountered in drilling. The anomalous gold grades and exotic telluride and copper-tellurate mineralogy associated with the T2 structure are markedly different to the historically mined polymetallic mineralization found in the 75-85 and associated structures. However, evidence of earlier polymetallic mineralization within the T2 structure is provided by the presence of spotty base-metal and sulphide-rich mineralization within historic drill hole intercepts both at depth and along strike to the north.

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Figure 8.6
Left: Hand Sample from the T2 Structure; Right: Hand Sample from the T4 Stockwork Zone

Figure provided by Osisko Development.

Figure 8.7
Thin Sections from the T2 Structure

Figure provided by Osisko Development modified from APSAR 2020.

A broad zone of quartz-stockwork veining and gold mineralization identified as the T4 stockwork zone is located east, and in the immediate hanging wall of the T2 structure. The stockwork mineralization has been traced from above the 625 level down to at least the 750 level. Although lower in grade than the T2 structure, the stockwork mineralization averages approximately 9 ppm Au and can be up to 25 m in width.

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The T4 stockwork zone is characterized by a broad zone of quartz-barite stockwork veining, with prominent drusy quartz filling open spaces. Stockwork veining is often accompanied by dark sulphosalt inclusions that are less than 0.5% of vein mass, but typically relate to elevated gold grades between 7 and 100 ppm Au.

Intensity of stockwork veining is typically greatest within an 2.5-3.5 m envelope of the T2 structure, where the stockwork is also accompanied by intense silica-alunite alteration of the Tintic Quartzite host. Within the broader 25 m wide stockwork envelope, discrete structurally controlled zones do display locally greater percentages of veining and alunite alteration, where the stockwork may take on a more planar sheeted vein character, typically with a flatter 40 to 65-degree dip towards the east, sympathetic to the steeper easterly dip of the T2 fissure vein.

A geological cross-section of the T2 structure and T4 stockwork zone was presented previously in Figure 8.4.

The steeply east dipping T2 structure is part of a larger extensional fault system that pre-dates mineralization. Localized polymetallic mineralization within the T2 structure indicates that it was genetically linked to the 75-85 mineralizing event but that it remained or became permeable to a later, more evolved, gold-telluride rich hydrothermal fluid phase, with accompanying Au-tellurium deposition.

Two key geological elements are interpreted to be critical in facilitating the emplacement and localization of gold mineralization along the T2 structure, as identified above the 625 level. First, the overlying lower shale member of the Ophir Formation acts as an impermeable cap to mineralizing fluids along the T2 structure. Second is the intersection of the east-west trending Sioux Ajax structural corridor with the Trixie vein system, at a location immediately south of the ventilation shaft, as displayed on the geological long section, Figure 8.5. The intersection of these two structures aligns with the south-plunging mineralized shoots historically mined in the 75-85 mining panels.

The intersection of the Sioux Ajax fault zone with the T2 structure is interpreted to have provided the deep-seated plumbing that facilitated the upward migration of later and overprinting Au-telluride hydrothermal fluids along it. In this scenario, gold rich fluids that ascended through the Sioux Ajax-T2 intersection zone encountered the impermeable overlying lower shale member of the Ophir Formation and flowed along a gently northerly raking up-dip shale-quartzite contact northwards, facilitated by localized dilation along the centre of the T2 structure. At a point in time, the hydrothermal fluids are interpreted to have over-pressurized the T2 structure, with hydrostatic fluid pressure exceeding the confining lithostatic pressure resulting in sudden release of pressure and flash boiling of the hydrothermal fluids. Flash boiling can cause the rapid deposition of free gold (Hedenquist and Henley, 1985) and is evidenced by abundant gas-rich fluid inclusions found in thin sections from areas surrounding gold-bearing mineralization within T2 (Figure 8.7). The deposition of significant native free gold, electrum and Au-Ag-tellurides within a quartz-barite rich matrix which cements angular silica-alunite altered quartzite breccia clasts within the T2 structure also supports a brecciation-boiling model (Figure 8.8). However, some degree of brecciation likely predates mineralization, associated with the initial formation of the T2 structure itself.

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Hydrothermal fluids have also migrated into the adjacent brecciated hanging wall of the T2 structure, with mineralizing fluids again pooling beneath the shale sediment cap, leading to development of the broad T4 stockwork zone of mineralization.

Figure 8.8
Schematic Section of Mineralization and Alteration Associated with the T2 Structure

Figure provided by Osisko Development.

Geological and mineralogical observations, together with overall grade-distributions on the T2 and T4 mineralized zones, led to the development of the genetic model proposed above, where gold-bearing mineralization developed as a sub-horizontal blanket underlying the Tintic Quartzite-Ophir Formation contact. The potential for a steeply dipping, south-plunging mineralized shoot on the southern end of the T2 structure associated with the intersection of the Sioux Ajax fault, still needs to be properly drill tested.

The Tintic district has long been recognized for its porphyry mineralization potential, located 65 km south of the Bingham Canyon mine and in a mineral district displaying many similar characteristics. The Bingham Canyon porphyry copper-gold-molybdenum deposit is associated with a halo of carbonate replacement zinc-lead-silver deposits, like those of the Tintic district. Known low-grade porphyries are located immediately to the south of TCM’s land holding at the Southwest Tintic Porphyry deposit and the Treasure Hill area. Several potential porphyry centres are interpreted beneath the East Tintic district itself, likely responsible for driving the hydrothermal fluid flows that are reflected in the carbonate replacement and high-sulphidation deposits throughout the district (Figure 8.9).

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Several alteration lithological caps have been identified on surface, indicative of the upward (or lateral) flow of hot acidic hydrothermal fluid from depth, and have been the focus of limited exploration drilling by Anglo American and Rio Tinto between 2008 and 2014. Of particular interest is the area surrounding Big Hill, where a coincident gold and molybdenum in soil anomaly coincides with an area where B-type quartz veinlets have been mapped on surface. The potential for the discovery of a large copper porphyry centre or centres beneath the East Tintic district will depend on well designed greenfields exploration and drilling programs.

Figure 8.9
Mapped Lithological Caps Relative to Known Deposits

Figure provided by Osisko Development modified from Morris, 1964.

Osisko Development Corp.

9.0   Exploration

Exploration work undertaken at the Tintic Project in 2022 consisted of coordinated underground mapping and sampling programs covering both new exploration drifts and development along the mineralization underground at Trixie. Post-advancement face, rib, and back chip-sampling, and post-survey three-dimensional underground back and rib geologic mapping were conducted by the geological team. The effective cut-off date for work description and assays reported herein is December 12, 2022. No regional-scale mapping or sampling programs were conducted in 2022.

Geologists conduct underground mapping for all new development headings. Mapping consists of analog data collection on letter page size base maps prepared in the Maptek™ 3D modelling program Vulcan™. Once a newly developed area has been line-surveyed and updated in Vulcan, the geologist can begin map preparation. The geologist will load two survey files, one containing the rib outline, the other the back and sill lines. The rib survey is extruded outward by the average difference between the sill and back elevations to match the height of the heading. Following these steps, the geologist can generate base maps containing spatially accurate 2D areas for the ribs, face, and back, which are then printed off at a 1:20 scale (Figure 9.1).

Prior to data collection underground, the geologist will wash down the area to be mapped to obtain a clearer exposure of the geological units. Map data collected include lithology, structure, alteration and mineralization. Direct measurements of structures including bedding, fractures and veins, are collected using a Brunton® Standard Transit compass (Brunton® compass) and directly plotted onto maps.

Completed maps are transferred to mylar compilation level maps. When the levels are complete, they are scanned and saved onto the network. Geologists register the maps in the Maptek™ 3D modelling program Vulcan™ and digitize the back mapping. Finally, the mapping data and structural data are used in conjunction with sample data to aid 3D computer modelling.

Trixie underground chip samples are classified as one of three types: face, rib, or back. Face chip samples are collected along structure-parallel cuts at all development faces, following each round of advancement (Figure 9.2). Rib chip samples are collected parallel to development along headings designed to cross perpendicular to structures of interest, e.g., exploration drifts. Back chip samples are collected to decrease data spacing in areas of overbreak or, in instances where face sampling was not completed prior to further advancement, they may run either perpendicular or parallel to development. Face chip widths are limited by the width of development, averaging approximately 1.75 m (5.75 ft) in 2022. Rib chips, by nature of being parallel to development, are typically much longer, ranging from a minimum of 1.2 m (4 ft) to greater than 24 m (80 ft) during 2022. While face chips are the most commonly collected chip type, accounting for more than 75% of individual chips reported herein, they account for only 51% of the total length of development sampled in 2022. Back chips account for less than 5% of the total length of sampling in 2022.

Osisko Development Corp.

Figure 9.1
Example of an Underground Map Sheet

Figure provided by Osisko Development.

Figure 9.2
Schematic illustrating the Three Classifications of Chip Sample Sequences Underground at Trixie

Figure provided by Osisko Development.

Osisko Development Corp.

Prior to chip sampling, a geologist will inspect the development face to be sampled and fill out a digital data form referred to as a face sheet (Figure 9.3). Basic data captured on each face sheet include a parent face identification (ID), indicating the development name, chip/site ID, the distance and bearing from the nearest survey point, the face azimuth and sampling width, the name of the sampling geologist and the date.

Figure 9.3
Example of a Chip Sampling Sketch and Data Sheet, CH1317

Figure provided by Osisko Development.

Chip/site IDs are a three to four-digit number assigned in sequence, e.g., 738 and 1355 for the first and last chips reported herein. A prefix of CH is added in the database to distinguish from underground diamond and surface RC drill holes, e.g., CH1208. Distance from the nearest surveyed reference point is measured to the face along either the left or right rib, depending on the survey point location. Face azimuth is calculated by adding 90° to a bearing shot perpendicular to the face, using a Brunton® compass. All distance measurements are recorded in feet.

Osisko Development Corp.

While advancing along mineralized structures, each face chip consists ideally of a minimum of three samples to ensure separate coverage of the footwall, hanging wall and the target structure, i.e., vein. The first sample in sequence will typically begin at the left-rib-face intersection and extend to the margin of the vein. The second sample will typically cover the full width of the vein, and the third sample will extend from the right vein margin to the right-rib-face intersection. The geologist may collect fewer than three samples if the overall width of the face or location of the vein within it does not allow for separate footwall, hanging wall, and vein samples greater than or equal to a minimum sampling width of 0.5 ft. For rib chips and any face chips that cut multiple veins or otherwise complex geology, the geologist will collect as many samples as are necessary for adequate representation and coverage from the minimum 0.5 to a maximum sample width of 5 ft.

For every chip, a full colour schematic sketch is made at a 1:60 (1 in. = 5 ft.) scale within a pre-labeled grid contained within the face sheet; 3x3 in. for face sketches and 2x3 in. for back sketches. Sketches are carried across multiple face sheet forms for chip sample sequences longer than 15 ft. Typical quartzite host rock is sketched in yellow, shale in brown and veins in red. Any zones of brecciation are indicated with an ‘X’ pattern hatching. For all chips crossing veining, the sampling geologist will take a minimum of one direct vein measurement using the Brunton® compass, label the measurement at its point of collection on the sketch, and record its orientation in strike and dip (000°/00°), using the North American right-hand rule convention. Multiple structural measurements will be taken and recorded in instances of multiple veins and/or notable differences between hanging wall and footwall orientation.

Samples are recorded and collected from left to right, with intervals indicated on the face sketch and the corresponding sample IDs recorded in a table at the bottom of the face sheet. Sample IDs are derived from the chip/site ID. A prefix of F, B, or R is assigned to distinguish face, back and rib chips, respectively. A two-digit numerical suffix counting in sequence from 01, is then added to distinguish individual chip samples within a sequence, e.g., the resulting ID F131701 indicates the first sample in sequence along face chip site 1317. The sample table at the bottom of the face sheet includes additional observational fields to be filled out row-by-row for each individual sample, including width, lithology and lithologic unit (i.e., USGS map unit code), as well as abundances of visible gold, identifiable tellurium-bearing minerals, tetrahedrite, barite, copper oxides, and sulphides.

Individual samples are collected into 10” by 17” CGS protexo cloth bags labelled with the sample ID as recorded on the corresponding face sheet. Beginning with the leftmost sample 01, each labelled bag is placed in a container and held at a height of approximately 1.5 m (5 ft) from the sill floor while material is chipped into it, moving across the face from left to right. At the end of one sample interval, the geologist will tie the bag, remove it from the container and continue with the next sample.

Once all samples are collected, the geologist will mark the vein/sample margins on the face with spray paint and take a photograph (Figure 9.4). All samples are brought to the Burgin mine laboratory for assaying at the end of a shift. Back at the office, the geologist will hand-enter the day’s data into the Datamine software DH Logger, where the sample IDs can be connected with assay values once the assays certificates are complete. The geologist will then scan all face sheets for registration/georeferencing in Vulcan™.

Osisko Development Corp.

Figure 9.4
Post-Sampling Face Photo of Site CH1317

Figure provided by Osisko Development.

Chip sample sequences are effectively captured in the database as drill holes, moving “downhole” left to right, from a zero-depth collar referenced from the start of sampling back to the nearest surveyed reference point. As all face chips are collected horizontally, each is assigned dip of 0, input with the calculated face azimuth representing trend into a single data row within the DH Logger downhole survey table. Rib chips may be assigned a positive or negative dip value to appropriately represent sampling along ramps and declines.

Point survey updates are conducted by an in-house surveyor two to three times per week. Following an update, geologists will load the surveys in Vulcan™ and measure the recorded distance from the nearest surveyed reference point along the trend of the heading, to acquire XYZ collar coordinates for all recent chips. These coordinates are recorded on the chip’s face sheet and entered into DH Logger.

Chips are loaded in Vulcan™ weekly to ensure that the strings are located properly. Face chips strings should run perpendicular to the development heading and be centred on the rib survey, to account for equal overbreak on either rib during advancement. Rib chips should parallel either the left or right rib survey, referenceable within the parent Face ID.

Osisko Development Corp.

From January through December 12, 2022, (which is the cut-off for data presented herein), a total of 2,115 samples from 547 individual sample sequences were collected across a number of different test mining and exploration development areas underground at Trixie (Table 9.1, Figure 9.5). All samples were assayed for gold and silver at the on-site Tintic laboratory. Assays are presented herein within a series of maps and sections by development area (Figure 9.6 to Figure 9.18), and as composites with selected individual sample highlights within Table 9.2, which uses metric lengths and grades.

Table 9.1
2022 Trixie Underground Chip Sampling Summary by Development Area