Others had seen the place and missed it. The explorer Charles Sturt sketched the area in 1844 and noted iron-stained rock on an isolated hill. In 1866 the Mount Gipps station named the paddock that held the outcrop Broken Hill, but dismissed the ridge itself as mullock, useless waste. So when Rasp staked his claim on 5 September 1883, the conventional wisdom said he was wasting his time. He pegged the outcrop anyway, then brought in six others to peg the entire length of it. They became known as the Syndicate of Seven. Rasp had found a gossan, the rusty weathered cap of a buried sulphide body, and he reported masses of galena, the lead ore he prized most. His claims of lead lying in heaps in the desert were thought exaggerated. They were, if anything, understated.

The find proved real, and a lead rush followed in the manner of a gold rush. In 1884 the syndicate reorganised as the Broken Hill Mining Company, and when horn silver was discovered in 1885, they incorporated the Broken Hill Proprietary Company Limited. That name, soon shortened to BHP, would grow over the following century into one of the largest mining companies in the world. It was born here, in the dust, on the strength of a deposit that one man mistook for tin. Early prospectors hacked easily won galena from the surface, and ore was hauled away to South Australia by camel trains, wagons, and pack mules, the cameleers and their animals doing the work no railway yet could. Then the assays came back with extraordinary silver grades, including pockets of native silver, and the desert hill revealed just how rich it truly was.

The scale is hard to hold in the mind. The orebody runs as a long, curving lens of massive sulphide, a buried boomerang of metal pitching down at each end and continuously mineralised for more than three miles, the feature miners came to call the Line of Lode. Through 1946 alone, the mines drew from it 63.8 million tons of ore, yielding 8.6 million tons of lead, 5.2 million tons of zinc, 538 million ounces of silver, and 165,000 ounces of gold, and the lode kept giving for decades after. The central section was worked out by 1940, pushing production to the north and south ends, where successive companies sank their shafts. This single deposit underwrote a city, seeded one of Australia's great corporations, and helped fund the industrialisation of the country. Few holes in the ground have ever paid out so much.

Wealth could not conjure water, and in this desert water was the constant enemy. By the early 1950s an eight-year drought had brought the mines to the edge of shutdown. The owners responded with one of the most audacious feats of improvisation in Australian mining: they ran water in by train. Over several months, tanker trains carried more than 250 million gallons of water some forty miles, pumped from the Darling River near Horse Lake to a siding at Mount Gipps, where it was stored, then sent flowing downhill by pipe to the city's reservoir and on to the mines. A railway built to carry metal out was pressed into service to carry survival in. It worked, and the lode kept producing.

Beneath the economics lies a geological wonder. The deposit formed in Proterozoic time, hundreds of millions of years ago, then was caught up in waves of intense metamorphism that squeezed and folded the sulphides into their distinctive curved shape and split them into separate lead-rich and zinc-rich lodes. The forces that reworked it also seeded it with an astonishing variety of minerals: more than 1,500 species have been identified at Broken Hill, including several dozen found nowhere else on the planet, among them the namesake mineral brokenhillite. Specimens of rhodonite and spessartine garnet set in galena are prized by collectors worldwide. Broken Hill is so distinctive that geologists named an entire class of deposits after it. To stand above the Line of Lode is to stand over a place that gave the world both a great mining company and a corner of the periodic table all its own.