South32 Limited has lifted the Ore Reserve estimate for the Sierra Gorda copper mine in northern Chile by 61% compared to its previous position, expanding the total to 1,100 million tonnes averaging 0.39% total copper, 0.016% total molybdenum and 0.06 g/t gold, at a copper equivalent grade of 0.46%.

The updated reserve estimate reflects enhanced orebody definition from infill drilling programs completed between 2023 and 2025, comprising approximately 85,000 metres across 200 drillholes. The expansion extends the initial reserve life by approximately five years to 2045.

Alongside the reserve upgrade, South32 reported a Mineral Resource estimate of 1,870 million tonnes averaging 0.37% total copper, 0.016% total molybdenum and 0.06 g/t gold, representing an 8% increase from the total reported at 30 June 2026.

South32 acquired its 45% interest in Sierra Gorda in February 2022, holding joint control alongside 55% joint venture partner KGHM Polska Miedź. The operation is located in the Antofagasta region and benefits from established infrastructure, including renewable power, a seawater pipeline and transport connections to local ports.

“This update highlights the scale, quality and long-life orebody at Sierra Gorda, which we expect will be a significant source of copper for decades to come.”

“It follows the approval in July to proceed with execution of the fourth grinding line project at Sierra Gorda, which is expected to increase copper production by approximately 30 per cent from 2031.” — Matt Daley, Chief Executive Officer

The reserve expansion builds on operating plans at the site. In July 2026, the joint venture approved execution for the fourth grinding line project, which is scheduled to achieve first production in mid-FY30 and reach full output in FY31 to increase plant throughput and lift annual average payable production.

At Sierra Gorda, South32 notes that the current orebody remains open at depth, offering potential for further resource conversion and mine life extensions beyond the current 2045 horizon. 

Read the full announcement: 61% Increase in Sierra Gorda Ore Reserve Estimate