Great Southern Copper PLC (LSE:GSCU, FRA:E9E) told investors that surface sampling at its Monolith target in Chile has widened the known footprint of copper-silver mineralisation at Cerro Negro, with results now defining a system across roughly 700 metres by 400 metres and leaving it open to the south and west.
The company said all 15 exploration channel samples returned copper-silver mineralisation.
Best channel results included 6 metres at 0.29% copper and 34.8 grams per tonne silver from CH025, 4 metres at 0.53% copper and 47.5 g/t silver from CH030, and 4 metres at 0.38% copper and 53.2 g/t silver from CH033.
Rock chip assays from 13 grab samples returned grades of up to 1.5% copper and 95.8 g/t silver.
Great Southern said the oxide character of the surface mineralisation points to weathering and leaching near-surface, which it believes may mean higher-grade sulphide mineralisation is preserved at depth.
The company also said vein, breccia and stockwork-style mineralisation at Monolith appears similar to that seen at Mostaza, around 400 metres away, where earlier drilling identified high-grade copper-silver mineralisation.
Chief executive Sam Garrett said the results showed the Mostaza mineralised system extending across a broader target area at Cerro Negro.
"The combination of strong channel sample grades, high-grade rock chips, and widespread alteration demonstrates the scale potential of the system.
Importantly, the surface mineralisation is strongly weathered and leached, reinforcing our belief that higher-grade sulphide mineralisation may be preserved at depth," Garrett said.
"The copper-silver mineralised system identified at Monolith remains open to the south and west, highlighting the significant growth potential of the target."
The next steps are continued mapping and sampling to the south and west, an extension to the earlier IP geophysics survey, and planning and permitting for scout RC drilling within the Phase IV drilling programme.