Fortuna Mining Corp 6-K, filed Dec 8, 2025

Fortuna Mining Corp. (FSM)

6-K 2025-12-08 For: 2025-12-08

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Added on April 11, 2026

About this 6-K

Fortuna Mining Corp filed this 6-K on December 8, 2025.

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	Fortuna Mining Corp.
	(Registrant)

Date: December 8, 2025	By:	/s/ "Jorge Ganoza Durant"
		Jorge Ganoza Durant
		President and CEO

	·	ongoing infill drilling to support increased resource confidence, and
	·	continued step-out drilling to the southwest, east, and south, where mineralization remains open

DSDD555:	6.8 g/t Au	over an estimated true width of 35.5 meters from 48.6 meters, including
	24.0 g/t Au	over an estimated true width of 0.8 meters from 65 meters, and
	13.1 g/t Au	over an estimated true width of 0.8 meters from 68.5 meters, and
	18.5 g/t Au	over an estimated true width of 0.8 meters from 74 meters, and
	18.7 g/t Au	over an estimated true width of 5.6 meters from 80 meters

DSDD558:	1.8 g/t Au	over an estimated true width of 12.8 meters from 25 meters
	8.8 g/t Au	over an estimated true width of 14.4 meters from 96 meters, including
	22.1 g/t Au	over an estimated true width of 0.8 meters from 101 meters, and
	18.0 g/t Au	over an estimated true width of 0.8 meters from 103 meters, and
	11.5 g/t Au	over an estimated true width of 0.8 meters from 110 meters

DSDD562:	4.5 g/t Au	over an estimated true width of 5.6 meters from 146 meters
	8.0 g/t Au	over an estimated true width of 11.2 meters from 174 meters, including
	46.3 g/t Au	over an estimated true width of 1.6 meters from 183 meters

DSDD563:	5.8 g/t Au	over an estimated true width of 20.8 meters from 50 meters, including
	23.3 g/t Au	over an estimated true width of 1.6 meters from 53 meters, and
	21.8 g/t Au	over an estimated true width of 1.6 meters from 71 meters
	12.2 g/t Au	over an estimated true width of 5.8 meters from 86 meters, including
	14.7 g/t Au	over an estimated true width of 0.8 meters from 87 meters, and
	22.1 g/t Au	over an estimated true width of 2.2 meters from 90 meters
	2.7 g/t Au	over an estimated true width of 6.4 meters from 106 meters
	7.0 g/t Au	over an estimated true width of 4.8 meters from 118 meters, including
	15.3 g/t Au	over an estimated true width of 1.6 meters from 120 meters

DSDD567:	4.6 g/t Au	over an estimated true width of 26.6 meters from 96.8 meters, including
	15.6 g/t Au	over an estimated true width of 0.8 meters from 103 meters, and
	13.6 g/t Au	over an estimated true width of 1.6 meters from 105 meters, and
	18.3 g/t Au	over an estimated true width of 1.6 meters from 114 meters

DSDD574:	1.7 g/t Au	over an estimated true width of 29.6 meters from 93 meters
	2.0 g/t Au	over an estimated true width of 20.0 meters from 135 meters, including
	18.4 g/t Au	over an estimated true width of 0.8 meters from 158 meters

DSDD577:	4.2 g/t Au	over an estimated true width of 21.6 meters from 116.2 meters, including
	30.0 g/t Au	over an estimated true width of 1.6 meters from 125 meters, and
	18.9 g/t Au	over an estimated true width of 1.1 meters from 134.3 meters

DSDD578:	4.9 g/t Au	over an estimated true width of 16.8 meters from 15 meters, including
	29.5 g/t Au	over an estimated true width of 1.6 meters from 15 meters

DSDD584:	5.5 g/t Au	over an estimated true width of 17.0 meters from 32.7 meters, including
	20.3 g/t Au	over an estimated true width of 0.8 meters from 38 meters, and
	14.3 g/t Au	over an estimated true width of 0.8 meters from 50 meters, and
	17.8 g/t Au	over an estimated true width of 0.8 meters from 53 meters
	7.8 g/t Au	over an estimated true width of 1.4 meters from 95.7 meters

DSDD589:	3.5 g/t Au	over an estimated true width of 26.8 meters from 16 meters, including
	15.8 g/t Au	over and estimated true width of 0.8 meters from 34 meters

HoleID	Easting (WGS84_29N)	Northing (WGS84_29N)	Elev. (m)	EOH^1,2 Depth (m)	UTM Azimuth	Dip	Depth^2,3 From (m)	Depth² To (m)	Drilled² Width (m)	ETW⁴ (m)	Au (ppm)	Hole Type⁵	Area
DSDD486	232278	1426476	148	249	150	-50	NSI					DD	Southern Arc
DSDD493	232347	1426501	148	207	150	-50	165.0	174.0	9.0	7.2	2.4	DD	Southern Arc
						including	168.0	169.0	1.0	0.8	13.2	DD	Southern Arc
DSDD494	232532	1426112	142	131	150	-50	38.0	49.0	11.0	8.8	1.4	DD	Southern Arc
DSDD495	232310	1426500	149	186	150	-50	NSI					DD	Southern Arc
DSDD496	232674	1426074	143	176	150	-50	38.3	50.0	11.7	9.4	2.2	DD	Southern Arc
						including	44.0	45.0	1.0	0.8	15.5	DD	Southern Arc
							96.0	102.3	6.3	5.0	2.3	DD	Southern Arc
							107.0	119.5	12.5	10.0	6.8	DD	Southern Arc
						including	115.0	116.0	1.0	0.8	19.2	DD	Southern Arc
						and	117.0	118.0	1.0	0.8	19.8	DD	Southern Arc
							135.0	167.0	32.0	25.6	0.8	DD	Southern Arc
DSDD497	232884	1426027	143	129	150	-50	108.8	121.7	12.9	10.3	3.6	DD	Southern Arc
						including	117.0	118.0	1.0	0.8	17.0	DD	Southern Arc
DSDD498	232714	1426155	145	132	150	-50	84.3	89.7	5.4	4.3	1.9	DD	Southern Arc
DSDD555	232868	1426115	144	120	150	-50	48.6	93.0	44.4	35.5	6.8	DD	Southern Arc
						including	53.2	53.7	0.4	0.4	Core Loss	DD	Southern Arc
						and	65.0	66.0	1.0	0.8	24.0	DD	Southern Arc
						and	67.2	67.8	0.6	0.5	Core Loss	DD	Southern Arc
						and	68.5	69.5	1.0	0.8	13.1	DD	Southern Arc
						and	70.6	71.2	0.6	0.5	Core Loss	DD	Southern Arc
						and	74.0	75.0	1.0	0.8	18.5	DD	Southern Arc
						and	80.0	87.0	7.0	5.6	18.7	DD	Southern Arc
DSDD556	232738	1426053	144	201	150	-50	105.0	134.0	29.0	23.2	1.5	DD	Southern Arc
							138.0	153.0	15.0	12.0	2.8	DD	Southern Arc
DSDD557	232838	1426172	143	165	150	-50	39.0	57.0	18.0	14.4	1.9	DD	Southern Arc
							67.0	73.0	6.0	4.8	1.2	DD	Southern Arc
							104.7	127.0	22.3	17.8	3.8	DD	Southern Arc
						including	108.0	109.0	1.0	0.8	11.8	DD	Southern Arc
						and	114.0	115.0	1.0	0.8	30.4	DD	Southern Arc
							139.0	141.0	2.0	1.6	3.7	DD	Southern Arc
							145.0	161.2	16.2	13.0	3.4	DD	Southern Arc
DSDD558	232809	1426139	144	146	150	-50	25.0	41.0	16.0	12.8	1.8	DD	Southern Arc
							96.0	114.0	18.0	14.4	8.8	DD	Southern Arc

Metrics	Units	Results
Gold price	$/oz	2,750
Life of mine	years	8.1
Processing Duration	years	7.9
Total mineralized material mined¹	kt	17.8
Contained gold in mineralized material mined¹	koz	932
Strip ratio	Waste: mineralized material	5.5:1
Throughput initial 3 years (primarily oxide)	Mtpa	2.5
Throughput after 3 years (primarily fresh)	Mtpa	2.0
LOM grade	g/t	1.63
Recoveries	%	90
Gold production
Total Production over LOM	koz	840
Average annual production over LOM	koz	106
Average annual production over first 3 years	koz	146
Per unit costs LOM
Mining	$/t, mined	4.82
Processing	$/t, processed	13.9
G&A	$/t, processed	6.7
Cash costs¹
Average operating cash costs²over LOM	$/oz	1,081
Average operating cash costs² over first 3 years	$/oz	759
AISC¹
Average AISC²over LOM	$/oz	1,238
Average AISC²over first 3 years	$/oz	904
Capital costs
Initial capital expenditure	$ M	283
Sustaining capital expenditure + Infrastructure (includes closure costs)	$ M	48
Returns
NPV5%, pre-tax (100% Project basis)	$M	772
Pre-tax IRR	%	86
NPV5%, after-tax (100% Project basis)	$M	563
After-tax IRR	%	72
After Tax Payback Period	years	0.8
Annual EBITDA ²
Average EBITDA² over LOM	$ M	167
Average EBITDA² over first 3 years	$ M	277

1.	The pit optimization shells used for the mine plan were generated using a gold price of $2,300 per ounce.
2.	This is a non-IFRS financial measure. The definition and purpose of this non-IFRS financial measure is included in the Company’s management’s discussion and analysis for the three and nine months ended September 30, 2025, under the heading “Non-IFRS Measures”. Non-IFRS financial measures have no standardized meaning under IFRS and therefore, may not be comparable to similar measures presented by other issuers.
3.	Average operating cash costs and average AISC represent costs for projected production for the LOM at the time of gold sales.
4.	The PEA is presented on a 100 percent project basis. However, upon the granting of the exploitation permit, the Senegalese Government is entitled to a 10 percent free-carried interest in Boya , with the right for the State to acquire an additional contributory interest of up to 25 percent.
5.	The economic analysis was carried out using a discounted cash flow approach on a pre-tax and after-tax basis, based on the gold price of $2,750/oz.
6.	The IRR on total investment that is presented in the economic analysis was calculated assuming a 100% ownership in Diamba Sud.
7.	The NPV was calculated from the after-tax cash flow generated by the Project, based on a discounted rate of 5% and an effective date of October 10, 2025.
8.	The PEA assumes that the percentage of certain royalties and taxes payable to the State, the percentage of the investment tax credit available to the company and the percentage payable to the social development fund will be in accordance with the provisions of the Mining Convention between Boya S.A. and the State of Senegal dated April 8, 2015. It should be noted, however, that the State retains the sovereign prerogative to review or revisit certain fiscal terms during the exploitation permit approval process, and as such, the current framework may be subject to amendment.
9.	The PEA is preliminary in nature, and it includes inferred mineral resources that are considered too speculative geologically to have the economic considerations applied to them that would enable them to be categorized as mineral reserves, and, as such, there is no certainty that the PEA results will be realized. Mineral resources that are not mineral reserves do not have demonstrated economic viability.
10.	Further information regarding the PEA, including details on key assumptions, parameters, opportunities, risks and other factors are contained in the Technical Report prepared for the Company entitled “Diamba Sud Gold Project, Kedougou Region, Senegal” with an effective date of October 15, 2025, which has been filed on SEDAR+ and on EDGAR under the Company’s profile.