Sterling Metals Discovers Cu-Mo Porphyry Stock 1.5km from MEPS Discovery Zone Confirming Scale of Porphyry Copper System

Executive Summary

• First drill hole of the 2026 program intersected a >400 m thick felsic porphyry stock hosting widespread copper‑molybdenum sulphide mineralization and potassic alteration.
• The discovery lies ~1.5 km from the previously announced MEPS Discovery, reinforcing Sterling’s view that the Soo Copper Project hosts a giant porphyry copper system.
• Planned follow‑up drilling will test the western edge of the same ZTEM resistivity anomaly and additional targets beneath the MEPS Discovery area.

Key Details

• Hole SC-26-01: Initiated at ~530 m vertical depth, transitioned from altered mafic volcanics into a coarse‑grained felsic porphyry stock; drilling continued for >400 m and is still ongoing toward ~1,000 m depth.
• Mineralogy: Stock contains fine disseminations of chalcopyrite and bornite, coarser grains in veins, and common molybdenite within quartz veins (both with/without chalcopyrite). Potassic feldspar alteration is pervasive; minor epidote zones also noted.
• Geologic Interpretation: Core logging indicates a granite‑to‑quartz monzonite porphyry intrusive, typical of large porphyry copper systems worldwide, with abundant phenocrysts (plagioclase, orthoclase, quartz) and hydrous mafic minerals (hornblende, biotite).
• Alteration & Veining: Strong potassic alteration; early biotite veins and later quartz‑sulphide A‑veins observed. Vein density higher in an early‑stage felsic porphyry dike reminiscent of the GFP dykes at MEPS.
• Strategic Significance: The stock’s location 1.5 km from the MEPS Discovery supports a >7 km × 3 km copper corridor and suggests a much larger, higher‑grade peripheral zone yet to be intersected.
• Next Steps: Upcoming drill hole will target the western shoulder of the ZTEM anomaly for potentially higher‑grade porphyry copper; additional winter program holes will test a similar resistivity low beneath the MEPS Discovery.
• Quotes: Neil O'Brien, Chief Geologist – “The discovery… validates both our contention of there being a giant porphyry copper complex … and that our exploration targeting approach is right.”
• PDAC Attendance: Sterling will be at PDAC 2026 (Mar 1‑2) – Core Shack Session A, Booth 3113A.

Notable Quotes

“The discovery of a source porphyry stock… is an incredible early result. It validates both our contention of there being a giant porph​yry copper complex … and that our exploration targeting approach is right and will lead us to where there is the greatest potential for large concentrations of copper.” – Neil O'Brien, Chief Geologist

All technical data reviewed and approved by Jeremy Niemi, P.Geo., SVP Exploration & Evaluation.