Fortuna Expands Southern Arc Mineralization with Drill Intercept of 1.7 g/t Au over 29.6 meters and a further 2.0 g/t Au over 20.0 meters from DSDD574 at the Diamba Sud Gold Project, Senegal
Fortuna Drills Point to Larger Senegal Mine as Cash Pile Exceeds Development Costs
On December 8, 2025, Fortuna Mining announced additional strong exploration results from its Diamba Sud Gold Project in Senegal. The headline highlighted intercepts from hole DSDD574, which returned 1.7 g/t gold over an estimated true width of 29.6 meters and a further 2.0 g/t gold over 20.0 meters.
Other significant intercepts reported in the release from the Southern Arc deposit include: - DSDD555: 6.8 g/t Au over a true width of 35.5 meters - DSDD558: 8.8 g/t Au over a true width of 14.4 meters - DSDD563: 5.8 g/t Au over a true width of 20.8 meters, and 12.2 g/t Au over a true width of 5.8 meters - DSDD567: 4.6 g/t Au over a true width of 26.6 meters
The drilling program, comprising both infill and extensional holes, successfully expanded mineralization to the southwest of the current optimized pit shell defined in the October 2025 Preliminary Economic Assessment (PEA). The results from this ongoing 63-hole, 9,619-meter program will be included in an updated Mineral Resource Estimate (MRE) scheduled for Q1 2026, which will form the basis of a Definitive Feasibility Study (DFS).
The drill results announced on December 8 are materially positive. While presented as a routine exploration update, they provide critical confirmation and expansion of mineralization at the company's most important growth project, Diamba Sud. The results, particularly the high-grade, wide intercepts not featured in the headline, reinforce the quality of the deposit and increase confidence that the upcoming MRE and subsequent DFS will improve upon the already robust economics outlined in the October 2025 PEA (after-tax IRR of 72% and NPV5% of US$563 million).
This news is the latest in a consistent stream of positive developments over the past year that demonstrate flawless execution of a well-defined strategy: 1. Portfolio Optimization: Fortuna successfully divested its non-core, higher-cost, and shorter-life assets, the San Jose mine in Mexico (April 2025) and the Yaramoko mine in Burkina Faso (May 2025). This streamlined the portfolio and de-risked the company by exiting a challenging jurisdiction. 2. Balance Sheet Fortification: These divestitures, combined with record free cash flow from operations, have created a fortress balance sheet. As of Q3 2025, Fortuna reported a net cash position of $266 million and liquidity of $588 million. This is more than sufficient to internally fund the entire initial capex for Diamba Sud, estimated at $283 million in the PEA, eliminating financing risk. 3. Growth at Séguéla: The flagship Séguéla mine has been a star performer, consistently exceeding production expectations. Aggressive and successful exploration throughout 2025, particularly at the Sunbird and Kingfisher deposits, led to a significant MRE update on November 18, extending the mine life to 7.5 years. This immediately prompted the initiation of a plant expansion study (announced December 3) to increase annual production toward 200,000 ounces. 4. De-risking Diamba Sud: The company has systematically advanced Diamba Sud, meeting every timeline. The project delivered a major resource update in August, a stellar PEA in October, and achieved a key permitting milestone with the ESIA filing in October. The continued positive drill results, including today's, provide strong evidence that the project's scale will likely grow.
The December 8 news confirms that the exploration momentum at Diamba Sud is strong, setting up the Q1 2026 MRE as the next major positive catalyst. The company is successfully advancing a powerful, fully-funded, two-pronged organic growth strategy that promises to significantly increase production and shareholder value in the coming years.
Fortuna Mining Corp. is a precious metals producer with a diversified portfolio of assets in West Africa and Latin America. The company currently operates three mines: the Séguéla and Lindero gold mines in Côte d'Ivoire and Argentina, respectively, and the Caylloma polymetallic (silver, lead, zinc) mine in Peru.
The company's primary focus is on organic growth through two key avenues: 1. Séguéla Mine Expansion: Séguéla is the company's flagship producing asset. Following significant exploration success, Fortuna is studying an expansion to increase throughput and boost annual production towards 200,000+ ounces of gold. 2. Diamba Sud Gold Project: This is the company's flagship development project in Senegal. A recent PEA highlighted robust economics with low initial capex. The company is fast-tracking the project towards a construction decision in H1 2026, with a target of becoming Fortuna's next producing mine.
Fortuna's overarching strategy is to grow its annual production to approximately 500,000 gold equivalent ounces through these fully-funded organic growth projects.