Broken Hill is an isolated historic mining town in the far west outback of the Australian state, New South Wales. It is located near NSW’s border with South Australia along the Barrier Mountain Range. It is 220 m (722 ft) above sea level, has an average rainfall of 235 mm (9 in) and Summer temperatures that reach well over 40 °C (104 °F). The closest major city is Adelaide, the capital of South Australia, which is more than 500 km (311 mi) south-west. It is built on an orebody that formed about 1,800 million years ago, containing one of the world's largest silver-lead-zinc mineral deposits.