By Digifin Pty Ltd · About this coverage
Key Points
- Ore Reserve 1,100Mt at 0.39% total copper, on a 100% basis; South32 holds a 45% interest
- Total Mineral Resource up 8% to 1,870Mt at 0.37% total copper, inclusive of the Ore Reserve
- Initial reserve life extended about five years to 2045, including the fourth grinding line
- Update reflects infill drilling and assumptions from the approved processing capacity expansion
- Fourth grinding line approved in July is expected to lift copper output about 30% from 2031
About South32 (ASX:S32)
South32 Limited is an ASX-listed mining and metals company headquartered in Perth. Its producing assets include the Cannington silver, lead and zinc mine in north-west Queensland, manganese operations in the Northern Territory and South Africa, and a 45 per cent interest in the Sierra Gorda copper mine in Chile, while the Hermosa zinc, lead and silver project in Arizona is under development. The company reports in US dollars and its shares are also quoted in London and Johannesburg.
South32 Limited (ASX:S32) announced updated Ore Reserve and Mineral Resource estimates for the Sierra Gorda copper mine in the Antofagasta region of northern Chile, prepared in accordance with the JORC Code (2012) and reported on a 100 per cent basis. Measured against the estimates as at 30 June 2026, the Ore Reserve estimate as at 31 July 2026 increased 61 per cent to 1,100 million tonnes averaging 0.39% total copper, 0.016% total molybdenum and 0.06 g/t gold, at a total copper equivalent grade of 0.46%, and the total Mineral Resource estimate increased 8 per cent to 1,870 million tonnes averaging 0.37% total copper, 0.016% total molybdenum and 0.06 g/t gold, at a total copper equivalent grade of 0.44%. The copper equivalent grades are calculated using Sierra Gorda's internal price forecasts, which the announcement says are commercially sensitive and not disclosed. The announcement states that the Measured and Indicated Mineral Resources are inclusive of those Mineral Resources modified to produce the Ore Reserves. South32 acquired a 45 per cent interest in Sierra Gorda in February 2022 and has joint control alongside 55 per cent joint venture partner KGHM Polska Miedź.
South32 said the updates reflect enhanced orebody definition following infill drilling of approximately 85,000 metres from about 200 drillholes completed between 2023 and 2025. It said the Ore Reserve update reflects the updated Mineral Resource estimate and also includes assumptions from the recently approved expansion in processing capacity through the fourth grinding line project. On that basis the initial reserve life extends by approximately five years to 2045, which the announcement describes as a 19 year reserve life at forecast throughput rates including the expanded capacity from the fourth grinding line project. Chief Executive Officer Matt Daley said the update highlights the scale, quality and long-life orebody at Sierra Gorda, that the fourth grinding line project approved in July is expected to increase copper production by approximately 30 per cent from 2031, and that the orebody remains open at depth, offering potential for further growth. He added that exploration holes at the Catabela Northeast exploration project have intersected significant copper mineralisation.
Source: South32 Limited (ASX:S32), 25 August 2026. Summary content supplied by Digifin Pty Ltd.
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