Great Southern Copper PLC (LSE:GSCU, FRA:E9E) told investors it has extended high-grade copper-silver mineralisation at depth at its Cerro Negro prospect in Chile, after new Phase III assays supported a stacked, multiple-lens interpretation around the Mostaza discovery.
Chief executive Sam Garrett highlighted that it marks an important step forward in the firm's understanding of the high grade Mostaza system.
Giving more detail, the company said results from holes DD033 and DD036 point to a mineralised system that may be broadening with depth, with higher-grade copper-silver lenses occurring within wider, lower-grade envelopes. DD036 returned 19.2 metres at 1.02% copper and 58.4 g/t silver from 191 metres, including 3.0 metres at 2.11% copper and 119.9 g/t silver, while a broader composite interval totalled 39.6 metres at 0.57% copper and 34.7 g/t silver from 170.6 metres.
Great Southern also highlighted anomalous lead-zinc mineralisation in breccia above the deeper Cu-Ag zone, which it said could indicate a zoned system and potentially widen the mineralised package to more than 80 metres. At Lens 5, scout hole DD034 intersected sulphide Cu-Ag mineralisation beneath surface leached material, returning 5.0 metres at 0.48% copper and 45.22 g/t silver from 62 metres, a result the company said supports the case for a broader bulk-tonnage target that complements the higher-grade lens-style mineralisation at Mostaza.
Phase III drilling has been completed, with further assays pending for holes CNG25-037 to -046 alongside metallurgical testwork, while planning is advancing for a Phase IV programme that is expected to include resource drilling at Mostaza and follow-up work around the Monolith target.
"Cerro Negro is increasingly demonstrating the characteristics of a scalable copper-silver system with both discrete high-grade lenses within wider lower-grade envelopes, and we continue to refine the geological model to guide the next phase of drilling and prioritise high-impact targets along trend and at depth," Garrett said.
He added: "Planning is now at an advanced stage for Phase IV drilling at Cerro Negro which we hope will build on this momentum and further define the broader-scale potential of the system."