The story begins with a stain on the ground. In 1871 the prospector Tom O'Brien found an outcropping gossan streaked with copper carbonate a few kilometres north-west of the new settlement of Cobar. A sample sent to Adelaide came back assaying a remarkable thirty-three percent copper, and the rush was on. The deposit took its name, as so many did, from the men who funded it: a Cornishman, a Scotsman, and an Australian, whose partnership gave the mine its enduring three-letter shorthand. It was a modest naming for what would become an extraordinary hole. The early decades were intermittent and hard, with serious production only really beginning around 1905.

The first era of the CSA ended the way many outback mines did, in disaster underground. The workings were mined on and off until about 1920, when a major fire forced the mine to close and ore extraction ceased. By then the early CSA had produced something over a hundred thousand tonnes of ore. A small settlement called Elouera had grown nearby between roughly 1906 and 1930, its hotel and houses tied to the mine's fortunes; when the copper stopped, that community drifted away too. For four decades the deep ground beneath Cobar lay quiet, its shafts flooding, its name fading toward the historical footnotes.

Then, in 1962, Broken Hill South began the work of bringing the CSA back, and on the eighth of October 1966 the reopened mine poured its first new production. What followed was a roll-call of owners that reads like a history of the global resources industry in miniature. CRA took it over in 1980. Golden Shamrock Mines bought it in 1993, only to be swallowed by Ghana's Ashanti Gold in 1996. The mine slid into receivership in 1997 and sat in care and maintenance, before the commodities giant Glencore restarted it in 1999 and ran it for more than two decades. In June 2023 it changed hands again, sold to Metals Acquisition. In October 2025 Harmony Gold, South Africa's largest gold producer, acquired Metals Acquisition for approximately US$1 billion, adding CSA to its portfolio as its first copper asset. Each owner inherited the same stubborn, deepening orebody and the same three borrowed initials.

What sets the CSA apart is sheer vertical ambition. The mine now reaches roughly 1.9 kilometres below the surface, deep enough to rank among the deepest underground operations anywhere in Australia and, by some reckonings, the second-deepest copper mine on the continent. Miners ride a long way into hot, hard rock to win high-grade ore that is hauled up, processed, and railed to the Port of Newcastle for export at a rate measured in the tens of thousands of tonnes of copper a year. With reserves still being proven, the mine's life has been extended into the 2030s, an unusual span for a deposit first pegged in the days of horse teams and hand drills.