Prominent Hill is an iron oxide copper gold deposit, the same broad geological family as the colossal Olympic Dam ore body about 130 km to the south-east. These deposits form where iron-rich fluids, surging up through the ancient crust of the Gawler Craton, leave copper and gold behind in vast haematite-stained masses. The resource here runs to more than 150 million tonnes of ore, grading around one per cent copper alongside gold and silver, plus a separate body of gold-rich rock. Unlike Olympic Dam, though, the uranium content stays low, never economical to recover. It is, in effect, Olympic Dam's quieter cousin: the same deep machinery of the earth, dialled to a different recipe.

The mine cost about 1.15 billion Australian dollars to build and went into production in February 2009, opened that May by the state premier. It began as a great open pit, but the richest ore lay deeper, and the operation followed it underground. The Malu mine drops vertically beneath the floor of the pit; the Ankata mine, opened in 2012, reaches a separate ore body about two kilometres to the west through a decline driven into the pit wall. Ankata takes its name from a word for dragon lizard in a local Aboriginal language, a small acknowledgement of whose country this is. Today the underground workings have largely replaced the open cut, chasing high-grade ore far below the desert floor.

Prominent Hill sits within the Woomera Prohibited Area, a vast tract of South Australian desert that doubles as one of the largest weapons-testing ranges on Earth. That setting once shaped the mine's fate dramatically. When its then-owner, Oz Minerals, sought to sell its assets to the Chinese state-controlled firm China Minmetals in 2009, the Australian government blocked the sale of this mine specifically, citing national security concerns over a foreign-owned operation inside a sensitive military zone. The rest of the company's assets changed hands; Prominent Hill was carved out and kept Australian. It was a rare moment when geopolitics reached down into a hole in the outback and changed who owned the rock.

Getting the metal out of this isolation is its own feat of logistics. Copper-gold concentrate is loaded into sealed containers and trucked roughly 120 km across the desert to a siding at Wirrida on the Adelaide-Darwin rail corridor, then railed south to Port Adelaide and onto ships bound for the world. A workforce of around 1,300 keeps the operation running, most of them flying in and out from a permanent village beside the pit, living for weeks at a time in the middle of nowhere. In 2023 the mine passed to BHP, the global resources giant, when it acquired Oz Minerals and folded Prominent Hill into a cluster of South Australian copper operations alongside Olympic Dam and the newer Carrapateena mine, part of a bet that this stretch of outback could anchor a copper province for decades to come. From a hill that barely rises above the plain, the copper that runs through the world's wiring and the gold that backs its vaults begins a journey of thousands of kilometres to reach the coast.