Fortuna's Sunbird Gold Deposit: Drilling Reveals Exceptional High-Grade Mineralization at Séguéla Mine, with Critical 611-Meter Results

Fortuna Mining Corp., the NYSE and TSX-listed precious metals producer, has unveiled compelling new drilling results from its Sunbird deposit located at the Séguéla Mine in Côte d’Ivoire. The latest exploration campaign has successfully demonstrated the continuity of high-grade gold mineralization at depth while identifying and expanding a secondary mineralized zone, positioning Sunbird as a key growth driver for the company’s resource base.

Key Drilling Achievements: Confirming Depth Continuity

The most significant result comes from drill hole SGDD148, which intercepted 6.1 g/t Au over an estimated true width of 18.9 meters—a result that underscores the broad, consistent nature of Sunbird’s mineralization envelope. This particular intercept includes multiple high-grade sub-zones, with assays of 25.4 g/t Au, 27.4 g/t Au, and 16.8 g/t Au, each over narrow true widths from 569 to 589 meters depth. Complementing this achievement, drill hole SGDD149 returned 13.0 g/t Au over 4.2 meters from 686 meters depth, including 31.1 g/t Au over 1.4 meters, demonstrating that mineralization extends well beyond the existing Mineral Resource envelope.

The drilling program has also produced numerous high-grade intercepts across the 611-meter surveyed depth range, with SGRD2477 yielding 10.9 g/t Au over 2.1 meters and 13.9 g/t Au over 4.9 meters at depths between 483 and 492 meters. Similarly, SGRD2491 delivered 5.2 g/t Au and 8.2 g/t Au intervals over substantial widths of 8.4 meters each, further validating the lateral extent of the mineralized system.

Resource Extension and Structural Insights

With five drill rigs currently focused on Sunbird, Fortuna has completed a total of 22 additional drill holes totaling 9,816 meters as part of its underground resource confidence program. These results build upon previously announced intercepts and confirm that high-grade mineralization remains wide open at depth—a statement corroborated by Paul Weedon, Senior Vice President of Exploration, who notes that the continuous drilling success underscores the deposit’s significant potential for resource growth.

The drilling has successfully extended mineralization approximately 400 meters beyond the existing Mineral Resource and Mineral Reserves boundaries, with particular success in delineating the lower ore shoot. Infill drilling targeting the upper and lower shoot linkage has also yielded encouraging results, such as the 4.1 g/t Au intercept over 11.9 meters from drill hole SGRD2487, suggesting a structural continuity that could unlock additional ounces as the resource model is refined.

Technical Rigor and Quality Assurance Standards

All drilling operations have been conducted under strict quality assurance and quality control (QA-QC) protocols, supervised by Fortuna’s in-house exploration personnel. Reverse circulation (RC) drilling employed 5.25-inch face sampling pneumatic hammers with samples collected into 60-liter plastic bags, with water management controlled through air pressure maintenance. Diamond drilling (DD) commenced with HQ-diameter core, then transitioned to NQ-diameter bits upon reaching fresh rock, with samples processed using standard one-meter intervals or geological boundaries.

Sample preparation and analysis were carried out by two internationally recognized laboratories: ALS Global in Yamoussoukro and Bureau Veritas in Abidjan, with gold analysis standardized at a 50-gram charge using fire assay methods. Samples exceeding 10 ppm Au were re-analyzed using gravimetric finishes to ensure accuracy. The systematic insertion of blanks, duplicates, and standards into the sample stream, combined with laboratory-level QA-QC measures from both ALS and Bureau Veritas, provides robust assurance of data integrity.

Strategic Implications and Exploration Continuity

The Sunbird deposit’s continued performance validates Fortuna’s confidence in the Séguéla Mine as a cornerstone asset within its multi-national portfolio, which also encompasses operations and exploration projects in Argentina, Mexico, Peru, and the Diamba Sud project in Senegal. The persistent identification of high-grade mineralization at depth positions Sunbird for potential resource expansion in the coming years, particularly as the company continues exploration drilling throughout 2026.

With mineralization remaining open at depth and along strike, and the company’s commitment to maintaining five dedicated drill rigs on the property, Sunbird exemplifies Fortuna’s operational discipline and its capacity to unlock value through systematic, technically rigorous exploration. The 611-meter surveyed depth range has yielded world-class grade intercepts, signaling that the geological model underpinning the deposit remains robust and capable of supporting substantial resource growth as infill and extension drilling progresses.

Paul Weedon’s verification of all data—including sampling, analytical results, and core review—provides professional assurance that aligns with National Instrument 43-101 standards, reinforcing the credibility of Fortuna’s exploration narrative and positioning the company favorably within the competitive landscape of global gold exploration and development.