Fortuna Mining Corp. (NYSE: FSM | TSX: FVI) is pleased to report results from infill drilling designed to test open mineralization at depth and upgrade Inferred Mineral Resources below the current life-of-mine pit design of the gold porphyry deposit at the Lindero Mine in Argentina. The results confirm that gold mineralization extends significantly below the current reserve pit design.

Eric Chapman, Senior Vice President of Technical Services, commented, “The 2026 infill drilling program returned multiple intersections with gold grades consistent with or higher than the corresponding grades estimated in the block model.” Mr. Chapman added, “We are incorporating the drill results into an updated block model and pit design, targeted for completion by year-end. This work will support a revised LOM plan and an updated Mineral Reserve estimate for Lindero, incorporating both the upgraded gold mineralization and existing Indicated Mineral Resources currently located below the pit.” Mr. Chapman concluded, “This zone remains open at depth.”

Lindero Mine Drilling highlights

Note: Gold mineralization at Lindero is circular in nature and associated with a porphyry intrusive; therefore, a specific azimuth or dip cannot be defined for reporting estimated true widths.

The 2026 drill program consisted of 31 diamond drilling (“DD”) holes, totalling 8,534 meters, having been extended from the initially planned 6,000-meter program due to the success from the initial holes. The program was designed with two objectives, firstly to upgrade Inferred Mineral Resources below the current LOM pit design in the south portion of the Lindero Deposit, where higher gold grade mineralization was identified at depth. Secondly, to obtain metallurgical samples to affirm projected recoveries in areas planned for mining in the next two years. The upgrade drilling successfully encountered higher than expected gold mineralization in several holes, such as, LDH-259 that intersected 0.85 g/t Au over 236 meters from surface, including 94 meters averaging 0.66 g/t Au below the current pit design (refer to Figure 1) and LDH-272 that intersected 0.96 g/t Au over 350 meters from surface, including 98 meters averaging 0.91 g/t Au below the pit design (refer to Figure 2). An updated Mineral Resource and Mineral Reserve estimate will be prepared for inclusion in the year-end consolidated report, planned for release in the first quarter of 2027.

Gold mineralization at the Lindero Deposit forms a circular body approximately 600 meters in diameter and extends vertically more than 300 meters below the current topographic surface. The distribution of gold mineralization shows a strong relationship to lithology, stockwork veinlets, and alteration assemblages. Higher gold grades of more than 1 g/t Au, characterized by native, free-milling gold, are commonly associated with sigmoidal quartz, quartz-magnetite-sulfide, biotite-magnetite-chalcopyrite, magnetite-chalcopyrite, and quartz-limonite–hematite stockworks that are strongly associated with K-feldspar alteration. This association is most common in the southern and eastern portions of the deposit, where the highest gold grades occur. Where one or more stockwork types are absent or fracturing is less intense, mineralization tends to be weaker and gold grades lower at approximately 0.4 g/t Au.

Figure 1: Lindero Mine cross section 2623075E showing drill hole LDH-259

Figure 2: Lindero Mine cross section 7226125N showing drill hole LDH-272

Quality Assurance & Quality Control  

All drilling data completed by the Company utilized the following procedures and methodologies. All drilling was carried out under the supervision of the Company’s personnel.

All DD holes started with HQ sized diameter, before reducing to NQ diameter diamond drill bits on intersecting fresh rock. The core was logged, marked up for sampling using standard lengths of two meters or to a geological boundary. Samples were then cut into equal halves using a diamond saw. One half of the core was left in the original core box and stored in a secure location at the Company core yard at the project site. The other half was sampled, catalogued, and placed into sealed bags and securely stored at the site until shipment.

All DD samples were transported by commercial transport to ALS Patagonia S.A. preparation laboratory in Mendoza, Argentina. Sample pulps prepared by ALS Patagonia were then transported via commercial courier to ALS’s facility in Lima, Peru. Routine gold analysis using a 30-gram charge and fire assay with an atomic absorption finish was completed for all samples at ALS’s Lima laboratory plus ME-ICP61, analysis of 34 elements four acid ICP-AES. Samples returning assays >10 ppm Au were reanalysed using a 30-gram charge and fire assay with a gravimetric finish. Quality control procedures included the systematic insertion of blanks, duplicates and sample standards into the sample stream. In addition, ALS inserted their own quality control samples.

Qualified Person

Eric Chapman, Senior Vice President, Technical Services for Fortuna Mining Corp., is a Professional Geoscientist registered with Engineers and Geoscientists British Columbia (Registration No. 36328). Mr. Chapman has reviewed and approved the scientific and technical information contained in this news release. Mr. Chapman has verified the data disclosed, including the sampling, analytical and test data underlying the information or opinions contained herein by reviewing geochemical and geological databases and reviewing diamond drill core. There were no limitations to the verification process.

About Fortuna Mining Corp.

Fortuna Mining Corp. is a Canadian precious metals mining company with three operating mines in Argentina, Côte d’Ivoire, and Peru, and the feasibility-stage Diamba Sud Gold Project in Senegal. Our exploration portfolio spans our operating jurisdictions as well as Guinea and Guyana. Sustainability is at the core of our operations and stakeholder relationships. We produce gold and silver while creating long-term shared value through efficient production, environmental stewardship, and social responsibility.