Fortuna Mining Confirms Sunbird's Rich Gold Zones with 18.9m of Premium-Grade Mineralization at 492m Depth

Recent exploration drilling at the Sunbird deposit within the Séguéla Mine in Côte d’Ivoire has delivered compelling results that validate the project’s significant resource expansion potential. Fortuna Mining Corp. (NYSE: FSM | TSX: FVI) announced the completion of an intensive drilling campaign that successfully extended high-grade gold mineralization far deeper than previously mapped, with standout intercepts demonstrating the deposit’s continued wealth at depth.

The most impressive result emerged from drill hole SGDD148, which returned 6.1 g/t Au over an estimated true width of 18.9 meters starting from the 492-meter depth mark. This extended intercept, combined with multiple premium-grade zones within the same hole—including 25.4 g/t Au, 27.4 g/t Au, and 16.8 g/t Au over narrower intervals—establishes the 492-meter depth horizon as a particularly rich mineralized zone. The breadth of this intercept is particularly significant, as it demonstrates that high-grade mineralization maintains substantial width at considerable depth, a key indicator for underground mining economics.

Extended High-Grade Intercepts Reveal Resource Expansion Pathway

Beyond the flagship 492-meter result, the drilling program delivered a series of rich intercepts across multiple holes. Drill hole SGRD2473 encountered 15.4 g/t Au over 4.2 meters from 478 meters depth, with a higher-grade shoot of 26.2 g/t Au concentrated over 2.1 meters. Similarly, SGRD2477 returned consecutive zones of 10.9 g/t Au (2.1m true width) and 13.9 g/t Au (4.9m true width), each containing ultra-high-grade layers exceeding 23 g/t Au.

The drilling has successfully delineated mineralization approximately 400 meters beyond the existing Mineral Resource and Mineral Reserves envelopes, a substantial lateral and vertical expansion. Drill hole SGDD149, one of the deepest intersections, returned 13.0 g/t Au over 4.2 meters from 686 meters depth, including 31.1 g/t Au over 1.4 meters, confirming that the lower mineralized shoot extends well beyond previous estimates.

Paul Weedon, Senior Vice President of Exploration, noted that the five drill rigs currently focused on Sunbird operations have consistently validated the premise that “high grade mineralization remains wide open at depth.” These results build systematically on previously disclosed high-grade intercepts and substantiate the potential for meaningful resource growth at the Sunbird deposit.

Infill Drilling Bridges Upper and Lower Shoots

In addition to extension drilling targeting depth, the company’s infill program has focused on delineating the connection between the upper and lower mineralized shoots. Results from drill hole SGRD2487 illustrate this strategy, returning 4.1 g/t Au over an estimated true width of 11.9 meters from 499 meters depth, with a 10.2 g/t Au zone over 0.7 meters. This drilling has effectively reduced geological uncertainty between the two previously separate mineralized bodies, potentially unlocking a more continuous, larger resource block.

A total of 22 additional drill holes totaling 9,816 meters was completed as part of the resource confidence and extension program. All results derive from drilling executed after the June 30, 2025 data cutoff date used for the most recent Séguéla Mineral Resources and Mineral Reserves estimate released in January 2026, meaning these intercepts represent entirely new information for potential resource modeling updates.

Rigorous Quality Assurance Underpins Data Reliability

The reliability of these drilling results rests on comprehensive quality assurance and quality control (QA-QC) protocols supervised throughout by Fortuna Mining personnel. Reverse circulation (RC) drilling employed standard 5.25-inch face sampling pneumatic hammers, with samples collected into 60-liter plastic bags and maintained dry through controlled air pressure. When water ingress occurred, drilling seamlessly transitioned to diamond core methodology to preserve sample integrity.

All RC samples underwent systematic splitting through three-tier rifflers, yielding a representative 12.5 percent subsample for analytical submission while the 87.5 percent coarse reject fraction was retained at the drill site for validation purposes. Diamond drilling commenced with HQ-diameter core and reduced to NQ diameter upon intersecting fresh rock, with one-meter or geological-boundary-defined samples carefully halved using precision diamond saws.

Sample transportation to either ALS Global’s preparation facility in Yamoussoukro or Bureau Veritas’ laboratory in Abidjan followed strict chain-of-custody protocols. Gold analysis was performed using a standard 50-gram charge with fire assay and atomic absorption finish at ALS’s Ouagadougou facility or Bureau Veritas’ Abidjan laboratory. Samples assaying above 10 ppm Au underwent confirmatory reanalysis using gravimetric finish techniques. Both laboratories independently inserted blanks, duplicates, and certified standards into the analytical stream to verify procedural accuracy throughout the campaign.

Independent Expert Verification and Forward Outlook

Paul Weedon, designated as a Qualified Person under National Instrument 43-101 and holding membership with the Australian Institute of Geoscientists, has personally reviewed and verified the scientific and technical information disclosed. His verification included examination of geochemical and geological databases and direct review of diamond drill core, with no limitations to the verification process.

Mineralization at the Sunbird deposit continues to demonstrate open geometry both at depth and along strike, with Fortuna Mining planning to sustain drilling operations throughout 2026. The breadth of mineralization documented at the 492-meter depth, combined with the deposit’s demonstrated extension potential and consistent high-grade intercepts, positions Sunbird as a compelling near-term resource growth asset within Fortuna Mining’s portfolio spanning Argentina, Côte d’Ivoire, Mexico, Peru, and the Diamba Sud project in Senegal.

The combination of geological evidence, rigorous analytical verification, and independent expert confirmation establishes a solid technical foundation for advancing Sunbird toward the next phase of development and resource estimation refinement.