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. 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.