South32 Raises Sierra Gorda Ore Reserve Estimate 61%, Extends Reserve Life to 2045
South32 has increased the Ore Reserve estimate at the Sierra Gorda copper mine in northern Chile by 61% to 1.1 billion tonnes, strengthening the long-term production outlook for the large-scale copper operation.
The updated Ore Reserve, effective as of July 31, 2026, averages 0.39% total copper, 0.016% total molybdenum and 0.06 g/t gold, with a total copper-equivalent grade of 0.46%. South32 said the increase followed improved definition of the orebody after approximately 85,000 metres of infill drilling across 200 drill holescompleted between 2023 and 2025.
The larger reserve base extends Sierra Gorda's initial reserve life by approximately five years to 2045. South32 also reported an updated Mineral Resource estimate of 1.87 billion tonnes, averaging 0.37% total copper, 0.016% total molybdenum and 0.06 g/t gold. The company noted that the orebody remains open at depth, providing potential for further resource and mine-life growth.
The reserve update follows South32's approval in July of a fourth grinding line project at Sierra Gorda, which is expected to increase copper production by approximately 30% from 2031. The combination of a larger reserve base and additional processing capacity supports a stronger long-term production profile for the operation.
South32 holds a 45% interest in Sierra Gorda, while its joint venture partner KGHM Polska Miedź holds the remaining 55%. Sierra Gorda is a large open-pit copper mine in Chile's Antofagasta region, producing copper concentrate for export to international markets.
The 61% increase in Ore Reserves provides greater visibility over Sierra Gorda's longer-term copper production and supports the recently approved expansion. With the orebody remaining open at depth, further exploration success could provide additional upside beyond the current reserve life to 2045.
