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

Executive Summary

• Fortuna Mining filed its Environmental and Social Impact Assessment (ESIA) for the Diamba Sud Gold Project with Senegal’s regulatory authority, a key step toward obtaining an environmental permit.
• The company confirmed that the Preliminary Economic Assessment (PEA) is on schedule for completion in Q4 2025, with a Definitive Feasibility Study and construction decision targeted for H1 2026.
• Drilling to date totals 52,110 m in 2025, expanding inferred resources by 93% and measured/indicated resources by 53%; drilling will resume in October after the rainy season.

Key Details

• ESIA filing: Submitted to the Direction de la Réglementation Environnementale et du Contrôle (DiREC), meeting Senegalese legislation and international standards (Equator Principles, IFC Performance Standards).
• Permitting impact: ESIA is a prerequisite for an environmental permit; its approval moves the project toward a construction decision in the first half of 2026.
• PEA status: Engineering, metallurgical testwork, and trade‑off studies underway; PEA expected Q4 2025. A Definitive Feasibility Study will follow in H1 2026, incorporating ESIA outcomes.
• Drilling program (2025): 52,110 m completed YTD. Results have expanded the resource:
• Measured & Indicated ↑ 53%
• Inferred ↑ 93% (including a maiden inferred resource at Southern Arc: 3.85 Mt @ 1.57 g/t Au ≈ 194,000 oz Au).
• Future drilling: Restart in early October with four rigs after the rainy season; focus on extending open mineralization at Southern Arc and testing new targets across Diamba Sud and adjacent Bondala property.
• Qualified Person: Eric Chapman, SVP Technical Services, reviewed and approved all technical information per NI 43‑101.

Notable Quotes

“The filing of the ESIA represents a key step forward in advancing Diamba Sud towards development… 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.” – Jorge A. Ganoza, President & CEO

Materiality Assessment: Material – Positive (milestone permitting step, significant resource expansion, and clear path toward feasibility and construction).