The Prominent Hill iron oxide copper gold (IOCG) deposit is located in the northeastern portion of the Archaean to Mesoproterozoic Gawler Craton, South Australia. Copper-gold-silver mineralisation at Prominent Hill is mostly hosted within hematitematrix breccia containing fragments of sandstone, siltstone, dolostone, and mafic to intermediate volcanic rocks. Copper mineralisation occurs as disseminations of chalcocite, bornite and chalcopyrite in the matrix of the breccia.

The Prominent Hill Open Pit Mineral Resource was fully depleted, with the Open Pit mining operations completed in March 2018.

Since 2 quarter 2018, previously stockpiled ore is processed.

The ROM stockpiles have been classified as Measured because they have been mined from zones which have been drilled to grade-control spacing. Mining production and reclaim records in conjunction with ROM surveys have supported the construction of open pit ROM stockpile block models at a monthly level of definition.

Prominent Hill is a copper, gold and silver mine located 650 km northwest of Adelaide in South Australia and comprise:
-Open pit mine (Malu) - which concluded operations in Q1 2018;
-Stockpiles - being in operation since Q2 2018;

Surface operations to rehandle stockpiles are carried out by mining contractor.

Ore in stockpiles is enough to operate until 2025

The Prominent Hill processing plant has been operating since February 2009 and comprises a conventional crushing, grinding and flotation circuit to recover copper, gold and silver to produce a high-quality concentrate. The plant can process approximately ten million tonnes per annum subject to the ore blend.

The current life of mine schedule has the plant running at that capacity approximately eight to nine million tonnes per annum until the end of quarter one 2025 with a high proportion of stockpiled open pit gold and lower grade ore. On exhaustion of these gold and marginal ore stocks the plant will be fed with underground ore alone.

Optimisation studies indicate that the plant can be configured to run at four to six million tonnes per annum dependent on the blend of copper and gold ores for minimal capital expenditure. If necessary, lower throughputs can be processed in batches providing the ability to process ore at a range of underground production rates.