Lightning Ridge in New South Wales is a small mining town, 75 km north of Walgett on the rim of the Outback. The surrounding hills are full of gtemstones, and there are the famous opal fields of Grawin, Glengarry and Sheepyard. The opal is found in a certain clay, so this is the only place on Earth where the opal is separated from the surrounding rock in a process called wet pudding. This area is world famous for its black and blue opals. Black opal is set apart by the presence of carbon and iron oxide trace elements which produce a very dark stone, flecked with the traditional blue, green and red flashes.
Today the village of 6,000 inhabitants depends as much torism as it does on opals. There are numerous gem shops, museums and show mines. The tourist center is called Opal Cave Tourist Centre. Visitors can explore the mining fields and fossick for opal, but - as always in Australia - you have to obtain a permit first.