Antares Metals’ 9km Copper Zone Discovery Raises Exploration Stakes in Mount Isa

• Discovery of a 9km long copper mineralised shear zone at Cromwell
• Rock chip samples show copper grades up to 22.5% Cu
• Mineralised structures up to 30m wide and remain open along strike
• 36% of samples exceed 1% copper content
• Planned follow-up includes geophysical surveys and further mapping

A Breakthrough in Mount Isa North

Antares Metals Limited (ASX, AM5) has announced a significant copper discovery at its Cromwell prospect within the Mount Isa North Project. The company’s recent fieldwork uncovered a previously unrecognised district-scale copper mineralisation zone stretching over nine kilometres. Rock chip sampling has returned impressive copper grades, peaking at 22.5% Cu, a standout figure that signals strong potential for future resource development.

The discovery centres on a series of north-south trending shear zones branching from the major Paroo fault, with the largest, dubbed the Cromwell “A” zone, mapped and sampled over 9km of strike length. These mineralised structures vary in width up to 30 metres and remain open-ended, suggesting the mineralisation footprint could extend further beyond current boundaries.

Sampling Highlights and Geological Insights

Antares collected 81 rock chip samples across the prospect, with approximately 36% returning copper values above 1% and 17% exceeding 2%. Such high-grade surface results are rare and promising, especially given the mineralisation is hosted within shear zones in metamorphosed basalts; rock types previously underexplored in this region. The copper occurs mainly as malachite, chalcocite, chrysocolla, and cuprite, with quartz veins showing textures indicative of significant sulphide presence.

Interestingly, the copper mineralisation is often not visible on rock exteriors, which likely explains why previous explorers overlooked this zone. Antares’ field geologists’ detailed observations and “out of the box” approach were key to identifying this extensive mineralised corridor.

Next Steps in Exploration

Looking ahead, Antares plans to intensify exploration efforts with additional mapping, sampling, and geophysical surveys, including soil geochemistry and airborne gravity/magnetics. These techniques aim to refine target areas within the shear zones and identify potential “hot spots” of higher-grade mineralisation. The company’s CEO, Johan Lambrechts, emphasised the scale and potential of the Cromwell prospect, underscoring its district-scale opportunity and the need for systematic follow-up work.

While no drilling results or resource estimates have been reported yet, the discovery marks a pivotal moment for Antares Metals. The company’s Mount Isa North Project now commands renewed attention as a promising copper exploration frontier.

Context Within the Mount Isa Region

The Mount Isa region is globally renowned for its large sediment-hosted copper deposits, and Antares’ discovery adds a new dimension by highlighting mineralisation within basalt-hosted shear zones. This expands the geological understanding of copper distribution in the area and could have implications for exploration strategies targeting similar rock types.

With a market cap of just $4.6 million and cash reserves of $1.3 million as of June 2025, Antares Metals is well-positioned to advance its exploration program. Investors will be watching closely as the company progresses from surface sampling to more detailed geophysical and drilling campaigns.

Bottom Line?

Antares Metals’ Cromwell discovery could reshape copper exploration in Mount Isa, but the path to resource definition remains ahead.

Questions in the middle?

• How will upcoming geophysical surveys refine the understanding of mineralisation extent?
• When will Antares initiate drilling to test the depth and continuity of the copper zones?
• What are the potential economic implications if the mineralisation extends beyond current open boundaries?