Capstone Copper Reports Results of Phase 1 Drill Program at Mantoverde

Executive Summary

• Capstone Copper released initial assay results for ~24,700 m of its 30,000 m Phase 1 drill program at the Mantoverd​e copper‑gold project in Chile.
• Multiple intercepts returned copper grades above the current block model, notably in the Brecha Flores sector (e.g., DDH25DS16 – 176 m @ 0.77% Cu, including 24 m @ 1.50% Cu).
• Results support potential resource growth and reserve conversion, and underpin plans for a ~20,000 m Phase 2 program slated to start Q4 2025.

Key Details

• Drill Program Scope – Phase 1: 30,000 m total; assay data received for ~24,700 m.
• High‑grade Intercepts (Brecha Flores)
• DDH25DS16: 176 m @ 0.77% Cu from 654 m (incl. 24 m @ 1.50% Cu)
• DDH25DS28: 162 m @ 0.73% Cu from 660 m (incl. 18 m @ 1.07% Cu)
• DDH25DS01: 144 m @ 0.65% Cu from 528 m (incl. 18 m @ 1.88% Cu)
• Consistent Results (Mantoverde Sur & Norte)
• DDH25DS24: 146 m @ 0.52% Cu (incl. 34 m @ 1.07% Cu)
• DDH25DS26: 274 m @ 0.39% Cu (incl. 20 m @ 1.30% Cu)
• Santa Clara Corridor – Step‑out Drilling
• DDH25DS08: 376 m @ 0.43% Cu (incl. 64 m @ 0.98% Cu)
• DDH25DS32: 100 m @ 0.43% Cu (incl. 42 m @ 0.62% Cu)
• DDH25DS27: 82 m @ 0.77% Cu (incl. 30 m @ 1.04% Cu)
• Animas Extension – mineralization continues northward:
• DDH25DS21: 102 m @ 0.41% Cu, 26 m @ 0.46% Cu, 46 m @ 0.49% Cu
• DDH25DS25: 112 m @ 0.45% Cu (incl. 28 m @ 0.67% Cu)
• District‑scale Exploration – 10‑km Induced Polarization (IP) survey completed Q1 2025, guiding Phase 2 target selection.
• Phase 2 Plan – ~31,500 m total drilling to begin Q4 2025:
• ~20,000 m follow‑up on northern pit targets (grade improvement & mineralization addition).
• ~11,500 m testing of high‑priority IP‑defined targets along the northern corridor.
• Operational Context – Phase 1 part of a two‑year $25 M exploration program (total 61,500 m planned); up to seven rigs currently on site.
• Qualified Person – Peter Amelunxen, P.Eng., SVP Technical Services, reviewed and approved the technical content.

Notable Quotes

“We are excited by the initial results from the Phase 1 drill program at Mantoverde… The early success supports our commitment to building a world‑class, long‑life copper district in the Tier 1 jurisdiction of Atacama, Chile.” – Cashel Meagher, President & CEO

Materiality: Material – Positive (significant drilling results that could materially affect resource estimates and future production outlook).