Great Southern Copper expands Mostaza discovery in Chile with grades of up to 6.55% copper and 320 g/t silver

Great Southern Copper has reported new drilling results from Mostaza at its Cerro Negro project in Chile, extending mineralization to more than 400 metres with high copper and silver grades.

Great Southern Copper plc has reported new drilling results from the Cerro Negro prospect, part of its Especularita Project in Chile, confirming that the Mostaza copper-silver discovery continues to expand to the south and at depth.

The company said hole CNG25-DD042 extended the mineralized system to more than 400 metres of strike length, with mineralization still open to the south and at depth. The results come from the company’s ongoing Phase III drilling programme and further support the growth potential of the Mostaza system.

Step-out drilling confirms strong copper-silver mineralization

Hole DD042 was designed to test the interpreted southern extension of Lens 2, approximately 300 metres along trend from the historic Mostaza mine. According to the company, the hole intersected multiple zones of base and precious metals mineralization, reinforcing the scale potential of the discovery.

Among the most significant intercepts reported were 21.8 metres grading 1.04% copper and 52.26 g/t silver from 73.0 metres, including 6.0 metres at 2.56% copper and 128.16 g/t silver from 79.0 metres, and a higher-grade section of 1.6 metres at 6.55% copper and 319.75 g/t silver from 82.0 metres.

These results point to a robust mineralized structure and continue to demonstrate the presence of high-grade copper-silver zones within the broader Mostaza fault system.

Lead-zinc-silver interval suggests a more complex system

Great Southern Copper also identified an upper silica breccia zone rich in lead, zinc and silver, with grades of up to 22.4 g/t silver, 1.9% lead and 0.34% zinc. The company said this mineralization is similar to that previously identified in the hanging wall to Lens 2.

According to the company, these lead- and zinc-rich intervals add further evidence that Mostaza may form part of a complex, multiphase stacked mineralized system, which could become increasingly important as exploration advances.

Mostaza continues to emerge as a growing discovery

With the latest hole, Great Southern Copper said the Mostaza system now extends over 400 metres of strike, representing a meaningful increase in the known footprint of mineralization.

Chief Executive Officer Sam Garrett said the latest step-out results continue to highlight the discovery’s strong growth potential, noting that intersecting mineralization at this distance from the historic workings provides further evidence that the Mostaza Fault Zone hosts a much broader mineralized system than previously understood.

That suggests the project may still be in the early stages of defining its full scale, particularly as mineralization remains open in multiple directions.

Phase IV drilling plans already under way

The company said assay results are still pending for the final diamond drill holes and for all reverse circulation holes completed as part of the current programme. At the same time, planning is already in progress for a fully funded Phase IV campaign, which is expected to include both resource drilling and additional exploration drilling.

Great Southern Copper also noted that it holds an option to acquire 100% of the Cerro Negro project, including the Mostaza mine, and highlighted the project’s favorable location at low elevation with access to mining-related infrastructure.

Positive signal for copper-silver exploration in Chile

The latest results further position Especularita as one of the more closely watched junior copper-silver exploration stories in Chile. In a market increasingly focused on new copper discoveries, the continuity, grades and scale potential reported at Mostaza could help raise the project’s profile as Great Southern Copper moves toward the next stage of drilling.