Mr. Jorge Ganoza reports

FORTUNA ESTABLISHES PRESENCE IN THE GUYANA SHIELD THROUGH QUARTZSTONE EARN-IN AGREEMENT

Fortuna Mining Corp. has entered into an earn-in agreement with Qstone Inc., a private Guyanese company, pursuant to which Fortuna may earn up to a 70-per-cent interest in the Quartzstone project, a large land package comprising 29,600 hectares located in the greenstone belt of north-central Guyana.

Jorge A. Ganoza, president and chief executive officer of Fortuna, commented, "We are excited to establish a presence in the Guyana Shield, a highly prospective region with a strong history of gold discoveries." Mr. Ganoza continued, "The Quartzstone project, where historical drilling has identified multiple high-grade zones of near-surface gold mineralization, is located in a prolific exploration camp, and this transaction provides Fortuna with a staged path to unlock its potential through systematic exploration and drilling."

Previous drill highlights

A total of 183 diamond core drill holes, comprising 23,190 metres, were completed between 2010 and 2017. Drilling along a five-kilometre corridor identified multiple zones of high-grade near-surface gold mineralization. Drill highlights included in the attached table.

The Quartzstone project is located approximately 120 kilometres west of Georgetown and 35 kilometres northwest of G Mining's Oko West project. The project hosts an orogenic gold system along the contact between a granitoid complex and Lower proterozoic greenstone rocks within the Guyana Shield, a geological setting known for significant gold deposits.

Local geology comprises granitoids, metavolcanic and metasedimentary rocks, cut by a west-dipping, north-south-striking thrust and shear zone that extends over 26 kilometres. Gold mineralization is hosted in quartz-tourmaline-carbonate veins and breccias within a high-strain corridor up to 100 metres wide along the principal north-south shear and associated northeast-trending structures. Drilling to date has tested only approximately five kilometres of the 26-kilometre shear zone within the concession area. Several geochemical anomalies along northeast-southwest-trending cross structures also remain untested and will be prioritized by the exploration program.

Planned exploration

Fortuna's initial exploration program, budgeted at approximately $5.5-million (U.S.), will focus on advancing priority targets already defined at Quartzstone, while generating additional targets along the highly prospective 26-kilometre main shear zone. Planned work includes airborne magnetic surveys to develop a detailed structural framework, supported by high-resolution satellite imagery and digital elevation modelling. Field programs will include infill geochemical sampling, auger drilling, and detailed geological and regolith mapping over prospective geophysical targets and known anomalous areas. An initial 5,000-metre diamond drilling program is planned to test historical targets and workings, as well as priority structural corridors along the main contact and northeast-trending intersections.

Earn-in agreement terms

Fortuna may earn an initial 51-per-cent interest in the Quartzstone project by completing a minimum of 60,000 metres of drilling within four years, while paying all licence fees and funding all related expenditures. Upon exercise of the first option, Fortuna will form a joint venture with Qstone.

Fortuna may earn an additional 19-per-cent interest in the Quartzstone project, for an aggregate 70-per-cent interest, by solely funding a feasibility study within three years of exercising the first option and continuing to pay all license fees. Upon signing the earn-in agreement, the company paid Qstone a non-refundable cash option premium of $5-million (U.S.).

In addition to royalties payable to the State on gold production, the Quartzstone project is subject to a 4.5-per-cent net smelter returns royalty in favour of a prior owner, which may be repurchased at a price to be determined by the parties at any time.

Quality assurance and quality control for previous exploration drill program

All diamond drilling (DD) drill holes started with PQ sized diametre (85-millimetre core), before reducing to HQ diametre (63.5 mm core) diamond drill bits on intersecting fresh rock. The core was logged, marked up for sampling using standard lengths of one metre 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 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 prepared by WBDG at the in-house sample preparation facility at the Quartzstone camp where samples were dried and crushed to 95 per cent passing a 10-mesh screen. Following crushing, samples were riffled to 500 gram and pulverized to 80 per cent passing a 150-mesh screen to produce a final 50-gram pulp sample.

Prior to 2013, pulps were securely transported to either Loring Laboratories Ltd., in Georgetown, Guyana, or Acme laboratory located in Santiago, Chile, for assay analysis. Samples were analyzed by fire assay using 50-gram sample charge with atomic absorption spectroscopy finish. If the result was greater than 1.0 g/t Au the sample was reassayed by fire assay with gravimetric finish.

The 2013 exploration program used the Acme Laboratory in Abidjan, Ivory Coast and ALS Laboratory in Lima, Peru. Acme assayed samples using the bulk leach extractable gold method with solvent residue assayed using a standard fire assay with atomic absorption spectroscopy finish using 50-gram sample charges. ALS used gold by bulk extended leach cyanide using one-kilogram sample charges.

Since 2015 Activation Laboratories Canada (Actlabs), with a laboratory in Georgetown, Guyana, used for analysis by fire assay with gravimetric finish and leachwell 500 gram sample charges. In 2016 Actlabs were used for reanalysis of rejects by leachwell 500-gram sample charges. The 2017 drilling was analyzed at Actlabs in Georgetown, Guyana, by metallic screens and fire assay with gravimetric finish.

Quality control procedures included the systematic insertion of blanks, duplicates and sample standards into the sample stream. In addition, the laboratories inserted their own quality control samples.

Qualified person

Paul Weedon, senior vice-president, exploration, for Fortuna Mining, is a qualified person as defined by National Instrument 43-101 being a member of the Australian Institute of Geoscientists (membership No. 6001). Mr. Weedon has reviewed and approved the scientific and technical information contained in this news release. Mr. Weedon conducted a site visit to the Quartzstone project in June, 2025, where mineralized intervals of drill core were examined; surface exposures of mineralization were visited, and discussions held with geology staff regarding historical sampling and analytical techniques underlying the drilling data. To further verify the data, original assay certificates were compared to the database and independent sampling of core was performed that confirmed the presence of gold in randomly selected mineralized intervals. There were no limitations to the verification process.

About Fortuna Mining Corp.

Fortuna Mining is a Canadian precious metals mining company with three operating mines and a portfolio of exploration projects in Argentina, Ivory Coast, Mexico and Peru, as well as the Diamba Sud gold project in Senegal. Sustainability is at the core of the company's operations and stakeholder relationships. The company produces gold and silver while creating long-term shared value through efficient production, environmental stewardship and social responsibility.

We seek Safe Harbor.