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Vancouver, May 27, 2025: Fortuna Mining Corp. (NYSE: FSM | TSX: FVI) - https://www.commodity-tv.com/play/fortuna-mining-ceo-on-excellent-q1-results-and-future-growth/ - is pleased to provide an update on its exploration programs at the Diamba Sud Gold Project in Senegal.

Diamba Sud Gold Project exploration highlights

Paul Weedon, Senior Vice President of Exploration, commented, “Our exploration work at Diamba Sud continues to yield strong results, particularly from areas with limited historical drilling. Notably, recent drilling at the Southern Arc prospect has delivered some of our most compelling intercepts to date - highlighted by 8.6 g/t gold over an estimated true width of 13.6 meters in hole DSR906, and 9.3 g/t gold over 11.8 meters in hole DSDD404. These results further reinforce the project’s potential for near-term resource growth.”  

Mr. Weedon concluded, “Infill drilling at Area A, Area D, and Karakara has also returned highly encouraging results, including a standout intercept of 113.7 g/t gold over 6.4 meters estimated true width in hole DSDD385 at Area D. Meanwhile, regional target generation is progressing steadily, with systematic auger drilling identifying several promising gold-in-soil anomalies across the broader property.”

Southern Arc Prospect Drilling highlights include: 

Exploration drilling at the Southern Arc prospect (Figure 1) successfully intersected multiple zones of mineralization. The program, comprising 38 reverse circulation (RC) and diamond core drill holes for a total of 4,210 meters, was designed to test and refine the geological model - focusing on lithological and structural interactions and their controls on mineralization.

Mineralization at Southern Arc is hosted within an extensive hematite-altered tectonic breccia and occurs as stockworks or discrete veins - consistent with other prospects across the Diamba Sud Project. Figure 2 illustrates the relationship between the tectonic breccia, mineralization, and the overlying limestone units. Importantly, mineralization remains open at depth and along strike, with further drilling ongoing. Results from this program will be incorporated into the next Diamba Sud resource update.

In addition, several nearby coincident geochemistry and geophysical anomalies further underscore the exploration potential of Southern Arc, including possible linkages to the adjacent Kassasoko deposit, located approximately one kilometre to the west.

Figure 1: Diamba Sud Project location plan. Current deposits are highlighted in blue.

Figure 2: Cross Section through Southern Arc prospect showing recent results. Oblique section line, view is looking north-east.

Area A, Area D, and Karakara deposit infill drilling highlights include: 

1.                 DSDD385 includes intervals of lost core due to poor drilling conditions.  These intervals have been assigned nil assay value for interval calculation.

An additional 33 drill holes for a total of 4,550 meters were completed at Area A, Area D, and Karakara (Figure 1), concluding a final round of infill drilling. This program was designed to achieve several key objectives: increasing resource confidence in targeted zones and confirming the geological controls on high-grade mineralization at depth.

Notably, several drill holes intersected mineralization adjacent to - but outside - the currently proposed open pit boundaries, indicating potential for further resource growth. For example, hole DSDD399 at Area A returned 3.0 g/t gold over an estimated true width of 28.8 meters from a depth of 153 meters (Figure 3), while hole DSDD385 at Area D intersected 2.6 g/t gold over 40 meters estimated true width

(Figure 4).

These encouraging results will be incorporated into the forthcoming resource update for the Diamba Sud Project and underscore the potential for future resource expansion, particularly in Area A.

Figure 3: Cross section through Area A deposit with results from DSDD399 - view looking east.

Figure 4: Cross section through Area D deposit with results from DSDD385 - view looking east

Moungoundi and Moungoundi North prospects

Exploration drilling at the pre-resource stage Moungoundi prospect and its northern extension, Moungoundi North - located approximately 300 meters to the northeast - was successfully completed, with a total of 85 RC and diamond core drill holes drilled for 9,472 meters.

The program significantly improved the understanding of this geologically and structurally complex area, characterized by intercalated tectonic breccias, carbonate metasediments, and granitic and dioritic intrusive units. Mineralization is typically associated with various vein arrays, preferentially hosted within the tectonic breccias.

Results from this program will be incorporated into the next resource update for the Diamba Sud Project, contributing valuable insight into the broader mineral system.

Western Splay deposit

A total of 24 RC and diamond core drill holes, totalling 2,531 meters, were completed at the Western Splay deposit. The drill program was designed to test strike and dip extensions, perform select infill following the previous drilling campaign (refer to Fortuna news release dated: September 12, 2024), and the completion of the maiden resource estimate (refer to Fortuna news release dated: March 12, 2025).

Geologically, Western Splay shares similarities with the adjacent Moungoundi prospect and comprises a series of tectonic breccias (previously classified as conglomerates), granitic and dioritic intrusive units, and metasediments. Mineralization is primarily associated with vein arrays preferentially hosted within the tectonic breccia units.

This recent drilling campaign has strengthened confidence in the local geological interpretation and contributes to refining the broader geological and structural model at the project scale.

Refer to Appendix 1 for full details of the drill holes and assay results for this drill program.

Quality Assurance & Quality Control (QA - QC)

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 reverse circulation (RC) drilling used a 5.25-inch face sampling pneumatic hammer with samples collected into 60-liter plastic bags. Samples were kept dry by maintaining enough air pressure to exclude groundwater inflow. If water ingress exceeded the air pressure, RC drilling was stopped, and drilling converted to diamond core tails. Once collected, RC samples were riffle split through a three-tier splitter to yield a 12.5 percent representative sample for submission to the analytical laboratory. The residual 87.5 percent samples were stored at the drill site until assay results were received and validated. Coarse reject samples for all mineralized samples corresponding to significant intervals are retained and stored on-site at the Company-controlled core yard.

All diamond drilling (DD) drill 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 one meter 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 RC and DD samples were transported to ALS’s preparation laboratory in Kedougou, Senegal, before also being transported via commercial courier to ALS’s facility in Ouagadougou, Burkina Faso. Routine gold analysis using a 50-gram charge and fire assay with an atomic absorption finish was completed for all samples. Quality control procedures included the systematic insertion of blanks, duplicates and sample standards into the sample stream. In addition, the ALS laboratory inserted its own quality control samples.

Qualified Person

Paul Weedon, Senior Vice President, Exploration for Fortuna Mining Corp., is a Qualified Person as defined by National Instrument 43-101 being a member of the Australian Institute of Geoscientists (Membership #6001). Mr. Weedon has reviewed and approved the scientific and technical information contained in this news release. Mr. Weedon 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 and exploration activities in Argentina, Côte d’Ivoire, Mexico and Peru, as well as the Diamba Sud Gold Project located in Senegal. Sustainability is integral to all our operations and relationships. We produce gold and silver and generate shared value over the long-term for our stakeholders through efficient production, environmental protection, and social responsibility. For more information, please visit www.fortunamining.com.

ON BEHALF OF THE BOARD

Jorge A. Ganoza

President, CEO, and Director

Fortuna Mining Corp.

Investor Relations:

Carlos Baca | info@fmcmail.com | fortunamining.com | X | LinkedIn | YouTube

In Europe

Swiss Resource Capital AG

Jochen Staiger & Marc Ollinger

info@resource-capital.ch

www.resource-capital.ch

Forward-looking Statements

This news release contains forward-looking statements which constitute “forward-looking information” within the meaning of applicable Canadian securities legislation and “forward-looking statements” within the meaning of the “safe harbor” provisions of the Private Securities Litigation Reform Act of 1995 (collectively, “Forward-looking Statements”). All statements included herein, other than statements of historical fact, are Forward-looking Statements and are subject to a variety of known and unknown risks and uncertainties which could cause actual events or results to differ materially from those reflected in the Forward-looking Statements. The Forward-looking Statements in this news release include, without limitation, statements about the potential of the Diamba Sud Gold Project based on the exploration results at the Southern Arc, Moungoundi and Moungoundi North prospects, and from the Area A, Area D, Karakara and Western Splay deposits; statements relating to the potential to progress prospects at the Diamba Sud Gold Project; expectations that results from the drill programs will be able to be expand the current mineral resource at the Diamba Sud Gold Project and will be incorporated into a mineral resource update; statements regarding the exploration potential at the Southern Arc prospect including possible linkages to the Kassasoko deposit;mineral reserve and mineral resource estimates; expectations regarding additional drilling and exploration programs planned; the Company’s business strategy, plans and outlook; the merit of the Company’s mines and mineral properties; mineral resource and reserve estimates; timelines; the future financial or operating performance of the Company; expenditures; approvals and other matters. Often, but not always, these Forward-looking Statements can be identified by the use of words such as “estimated”, “potential”, “open”, “future”, “assumed”, “projected”, “used”, “detailed”, “has been”, “gain”, “planned”, “reflecting”, “will”, “containing”, “remaining”, “to be”, or statements that events, “could” or “should” occur or be achieved and similar expressions, including negative variations. Forward-looking Statements involve known and unknown risks, uncertainties and other factors which may cause the actual results, performance or achievements of the Company to be materially different from any results, performance or achievements expressed or implied by the Forward-looking Statements. Such uncertainties and factors include, among others, changes in general economic conditions and financial markets; changes in prices for gold, silver, and other metals; the timing and success of the Company’s proposed exploration programs; technological and operational hazards in Fortuna’s mining and mine development activities; risks inherent in mineral exploration; fluctuations in prices for energy, labor, materials, supplies and services; fluctuations in currencies; uncertainties inherent in the estimation of mineral reserves, mineral resources, and metal recoveries;  the Company’s ability to obtain all necessary permits, licenses and regulatory approvals in a timely manner; governmental and other approvals; political unrest or instability in countries where Fortuna is active; labor relations issues; as well as those factors discussed under “Risk Factors” in the Company's Annual Information Form for the financial year ended December 31, 2024. Although the Company has attempted to identify important factors that could cause actual actions, events or results to differ materially from those described in Forward-looking Statements, there may be other factors that cause actions, events or results to differ from those anticipated, estimated or intended. Forward-looking Statements contained herein are based on the assumptions, beliefs, expectations and opinions of management, including but not limited to expectations regarding the results from the exploration programs conducted at the Company’s mineral properties including the  Séguéla Mine; expected trends in mineral prices and currency exchange rates; the accuracy of the Company’s information derived from its exploration programs at the Company’s mineral properties; current mineral resource and reserve estimates; the presence and continuity of mineralization at the Company’s properties; that the Company’s activities will be in accordance with the Company’s public statements and stated goals; that there will be no material adverse change affecting the Company or its properties;   that all required approvals will be obtained; that there will be no significant disruptions affecting operations and such other assumptions as set out herein. Forward-looking Statements are made as of the date hereof and the Company disclaims any obligation to update any Forward-looking Statements, whether as a result of new information, future events or results or otherwise, except as required by law. There can be no assurance that Forward-looking Statements will prove to be accurate, as actual results and future events could differ materially from those anticipated in such statements. Accordingly, investors should not place undue reliance on Forward-looking Statements.

Cautionary Note to United States Investors Concerning Estimates of Reserves and Resources

Reserve and resource estimates included in this news release have been prepared in accordance with National Instrument 43-101 Standards of Disclosure for Mineral Projects ("NI 43-101") and the Canadian Institute of Mining, Metallurgy, and Petroleum Definition Standards on Mineral Resources and Mineral Reserves. NI 43-101 is a rule developed by the Canadian Securities Administrators that establishes standards for public disclosure by a Canadian company of scientific and technical information concerning mineral projects. Unless otherwise indicated, all mineral reserve and mineral resource estimates contained in the technical disclosure have been prepared in accordance with NI 43-101 and the Canadian Institute of Mining, Metallurgy and Petroleum Definition Standards on Mineral Resources and Reserves. Canadian standards, including NI 43-101, differ significantly from the requirements of the Securities and Exchange Commission, and mineral reserve and resource information included in this news release may not be comparable to similar information disclosed by U.S. companies.

Appendix 1