Great Southern Copper plc (LON: GSCU) has reported encouraging preliminary metallurgical results from its Mostaza copper-silver deposit in Chile, with recoveries exceeding 90% for copper and 85% for silver.
Testing on high-grade material averaging 5.09% copper and 279g/t silver produced a concentrate grading around 27% copper and 1,414g/t silver, using a conventional flotation process.
The company said the initial results indicate that standard sulphide flotation could provide an effective processing route for Mostaza, while further optimisation of grinding and regrinding could improve recoveries further.
Mineralogical work confirmed chalcocite as the dominant copper mineral, accounting for roughly 78% to 83% of copper in the tested samples. This helps explain the deposit’s high copper grades and favourable flotation response.
By comparison, initial leach testing achieved copper recovery of just under 50%, significantly below the flotation results, reinforcing flotation as the more promising processing route at this stage.
Great Southern plans further metallurgical work using drill-core samples across a broader range of copper and silver grades as part of its Phase IV drilling programme, due to begin within the next month.
For investors, the main significance is that Mostaza has now shown both high-grade mineralisation and potentially strong metallurgical recoveries, two important ingredients for future resource and economic studies. However, these are preliminary sighter tests on selected high-grade material, and broader drill-core testing will be required before recoveries can be considered representative of the deposit as a whole.
