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Fortuna Files Environmental and Social Impact Assessment for the Diamba Sud Gold Project in Senegal and provides update on Preliminary Economic Assessment status

Permits & Approvals

NEWS RELEASE

Fortuna Files Environmental and Social Impact Assessment for the

Diamba Sud Gold Project in Senegal and provides update on

Preliminary Economic Assessment status

Vancouver, October 7, 2025: Fortuna Mining Corp. (NYSE: FSM | TSX: FVI) reports that

it has filed an Environmental and Social Impact Assessment (ESIA) for the Diamba Sud Gold

Project with the Direction de la Réglementation Environnementale et du Contrôle (DiREC) ,

which is part of the Ministry of the Environment and Sustainable Development of Senegal.

The filing of the ESIA marks an important milestone in the permitting process and reinforces

the Company´s commitment to advancing Diamba Sud to a construction decision in the first

half of 2026 . Fortuna also provides an update on the status of the project’s Preliminary

Economic Assessment (PEA) and ongoing drilling activities.

Jorge A. Ganoza, President and CEO, commented, “The filing of the ESIA represents a key

step forward in advancing Diamba Sud towards development. The document contains

Fortuna’s commitment to high environmental and social standards and to working in

partnership with government, host communities, and various stakeholders in Senegal. ”

Mr. Ganoza continued, “We plan to complete the project’s preliminary economic assessment

during the fourth quarter and move to a definitive feasibility study and construction decision

during the first half of 2026.”

Highlights

• Submission of ESIA to the Senegalese authorities in accordance with national

legislation and alignment with international standards

• ESIA covers the project description and benefits for the country, the institutional and

regulatory framework, environmental and social baseline studies, the public

consultation, impact assessment and proposed mitigation and monitoring plans and

programs

• PEA study advancing on schedule, with completion planned during the fourth quarter

of 2025

• 52,110 meters drilled year-to-date in 2025 leading to a mineral resource expansion

for the project of 53 percent in Measured and Indicated and 93 percent in Inferred

categories for the project (refer Fortuna news release dated August 5, 2025)

• Drilling is planned to restart during October after the end of the rainy season and will

continue until year-end with the aim of testing extensions of open mineralization

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Environmental and Social Impact Assessment

The submission of the ESIA is a prerequisite for obtaining an environmental permit, which

forms part of the overall permitting process required for project development. The ESIA

addresses key environmental and social considerations associated with the potential

development of Diamba Sud including:

• Compliance with all applicable national regulations and alignment with the Equator

Principles and IFC Performance Standards

• Regular engagement with local communities and national stakeholders to integrate

feedback into project design and planning

• Environmental and social management plans designed to mitigate impacts and

enhance local benefits , such as environmental and social management plan,

stakeholder engagement plan, capacity building plan, livelihood restoration program,

mine rehabilitation and closure plan and a voluntary environmental and social

investment program

Preliminary Economic Assessment status

Fortuna is advancing work on the PEA for Diamba Sud, which will provide a first look at the

project´s potential economics and development alternatives. Engineering, metallurgical

testwork, and trade-off studies are currently underway, with completion scheduled for early

in the fourth quarter of 2025. A Definitive Feasibility Study (DFS) will follow the PEA in the

first half of 2026, incorporating results from the ESIA process, and drilling to be completed

by year-end.

Drilling program update

Fortuna has advanced its 2025 drilling program with a total of 52,110 meters completed to

date. Exploration continues to focus on resource expansion, infill drilling, and testing of new

targets defined by recent geochemical and geophysical surveys.

Recent highlights include the delineation of a maiden Inferred Mineral Resource at Southern

Arc of 3.85 Mt at an average gold grade of 1. 57 g/t containing 194,000 ounces of gold

(refer Fortuna news release dated August 5, 2025 ), where mineralization remains open at

depth and along strike to the east and south. Drilling to test the Southern Arc extensions is

scheduled to resume in early October with four drill rigs after the conclusion of the annual

rainy season.

Drilling will also continue to advance project generation and target testing across Diamba

Sud and the contiguous Bondala exploration property, where several geochemical, structural

and geophysical anomalies have been identified.

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Qualified Person

Eric Chapman, Senior Vice President, Technical Services, is a Professional Geoscientist of

the Association of Professional Engineers and Geoscientists of the Province of British

Columbia (Registration Number 36328) and a Qualified Person as defined by Nati onal

Instrument 43-101- Standards of Disclosure for Mineral Projects. Mr. Chapman has reviewed

and approved the scientific and technical information contained in this news release and has

verified the underlying data.

About Fortuna Mining Corp.

Fortuna Mining Corp. is a Canadian precious metals mining company with three operating

mines and a portfolio of exploration projects in Argentina, Côte d’Ivoire, Mexico, and Peru,

as well as the Diamba Sud Gold Project in Senegal. Sustainability is at the core of our

operations and stakeholder relationships. We produce gold and silver while creating long -

term shared value through efficient production, environmental stewardship, and social

responsibility. For more information, please visit our website at www.fortunamining.com

ON BEHALF OF THE BOARD

Jorge A. Ganoza

President, CEO, and Director

Fortuna Mining Corp.

Investor Relations:

Carlos Baca | [email protected] | fortunamining.com | X | LinkedIn | YouTube

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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 may include, without limitation, the Mineral Resource estimates at Diamba Sud;

the Company’s proposed exploration plans at Diamba Sud including that drilling with four rigs will restart in

October after the end of the rainy season with the aim of testing extensions of open mineralization; that drilling is

also intended to advance project generation and target testing across the Diamba Su d property and the

contiguous Bondala property; statements that a preliminary economic analysis is expected to be completed in the

fourth quarter of 2025 and that a definitive feasibility study and a construction decision are expected to follow the

PEA in the first half of 2026 ; statements about the Company’s business strategies, plans and outlook; the

Company’s plans for its mines and mineral properties; changes in general economic conditions and financial

markets; the impact of inflationary pressures on the Company’s business and operations; the future results of

exploration activities; expectations with respect to metal grade estimates and the impact of any variations relative

to metals grades experienced; assumed and future metal prices; the merit of the Company’s mines and mineral

properties; and the future financial or operating performance of the Company. Often, but not always, these

Forward-looking Statements can be identified by the use of words such as “estimated”, “potential”, “open”, “future”,

“assumed”, “projected”, “proposed”, “used”, “detailed”, “has been”, “gain”, “planned”, “reflecting”, “will”,

“anticipated”, “estimated” “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 o r implied by the Forward-looking Statements. Such uncertainties and

factors include, among others, operational risks associated with mining and mineral processing; uncertainty

relating to Mineral Resource and Mineral Reserve estimates; uncertainty relating to capital and operating costs,

production schedules and economic returns; risks relating to the Company’s ability to replace its Mineral

Reserves; risks related to the conversion of Mineral Resources to Mineral Reserves; risks associated with mineral

exploration and project development; uncertainty relating to the repatriation of funds as a result of currency

controls; environmental matters including obtaining or renewing environmental permits and potential liability

claims; uncertainty relating to nature and climate conditions; laws and regulations regarding the protection of the

environment (including greenhouse gas emission reduction and other decarbonization requirements and the

uncertainty surrounding the interpretation of omnibus Bill C -59 and the related amendments to the C ompetition

Act (Canada); risks associated with political instability and changes to the regulations governing the Company’s

business operations; changes in national and local government legislation, taxation, controls, regulations and

political or economic developments in countries in which the Company does or may carry on business; risks

associated with war, hostilities or other conflicts, such as the Ukrainian – Russian, and Israeli – Hamas conflicts,

and the impacts they may have on global economic activity; risks relating to the termination of the Company’s

mining concessions in certain circumstances; developing and maintaining relationships with local communities

and stakeholders; risks associated with losing control of public perception as a result of social media and other

web-based applications; potential opposition to the Company’s exploration, development and operational

activities; risks related to the Company’s ability to obtain adequate financing for planned exploration and

development activities; property title matters; risks related to the ability to retain or extend title to the Company’s

mineral properties; risks relating to the integration of businesses and assets acquired by the Company;

impairments; risks associated with climate change legislation; reliance on key personnel; adequacy of insurance

coverage; operational safety and security risks; legal proceedings and potential legal proceedings; uncertainties

relating to general economic conditions; risks relating to a global pandemic, which could impact the Company’s

business, operations, financial condition and share price; competition; fluctuations in metal prices; risks

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associated with entering into commodity forward and option contracts for base metals production; fluctuations in

currency exchange rates and interest rates; tax audits and reassessments; risks related to hedging; uncertainty

relating to concentrate treatment charges and transportation costs; sufficiency of monies allotted by the Company

for land reclamation; risks associated with dependence upon information technology systems, which are subject

to disruption, damage, failure and risks with implementation an d integration; labor relations issues; as well as

those factors discussed under “Risk Factors” in the Company's Annual Information Form for the fiscal 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, the accuracy of the Company’s current Mineral Resource and Mineral

Reserve estimates; that the Company’s activities will be conducted in accordance with the Company’s public

statements and stated goals; that there will be no material adverse change affecting the Company, its properties

or its production estimates (which as sume accuracy of projected ore gr ade, mining rates, recovery timing, and

recovery rate estimates and may be impacted by unscheduled maintenance, labor and contractor availability and

other operating or technical difficulties); the duration and effect of global and local inflation; the dur ation and

impacts of geo-political uncertainties on the Company’s production, workforce, business, operations and financial

condition; the expected trends in mineral prices, inflation and currency exchange rates; that all required approvals

and permits will be obtained for the Company’s business and operations on acceptable terms; that there will be

no significant disruptions affecting the Company's 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 these 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

All 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 miner al projects. 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.