The population of LIGHTNING RIDGE, 74km north of Walgett on the Castlereagh Highway, is a transient one, where people in their hordes pitch up, lured by the promise of opal. Amid this harsh landscape scarred by holes and slag heaps, Lightning Ridge’s opal fields are the only place in the world where black opal is found. Against their dark background, these “black” stones display a vivid spectrum of colours, and command top dollar.

Opal galleries and mines proliferate in town, among them the Walk-in Mine, which has tours to an underground mine and the opportunity to go fossicking; and the Chambers of the Black Hand, a 100-year-old mine  5km south of town, where owner/miner Ron Canlin has hand-chiselled over 450 surreal life-size carvings – everything from Egyptian tombs to superheroes – in the mine’s soft sandstone walls and installed an underground opal shop.

You can try your luck at finding opals in clearly demarcated fossicking areas (in 2007, a tourist unearthed a $20,000 black opal), but don’t do it anywhere else, or you may stray onto others’ claims and infringements are taken very seriously. Recover afterwards in the 42 °C water of the hot artesian bore baths on Pandora Street , which tap into the great Artesian Basin, an underground lake of fresh water about the size of Queensland.