Most of the opals in the world, and that 97 per cent is produced in Australia. Ninety percent are called 'light opal' or white crystalline opal. White opals are 60 percent of the total production of the precious stones in the world. He is on all deposits of opals. Crystal opal or hydrated silica is 30 percent of total production, the black opal 8 percent, and only 2 percent of the boulder opal.
One of the major sources for the extraction of opal is the city of Coober Pedy, located in South Australia. The most valuable and largest opal in the world, "Australian Olympic", was found in 1956 in the field of opals in Kober Pedy, with a surprising name "Eight Mile". Weighs Olympic Australian opal 17 000 carats, a length of 28 centimeters and a height of 12 cm, width 11 cm.
Mine in Australia Mintabie Opal is located approximately 250 kilometers north-west of Coober Pedy. In this field, too, we found a lot of crystal opal is rarely found and black opals. However, selling them abroad, arguing that it opals Coober Pedy. In any case, black opals found in Australia are the best in the world.
In South Australia there is a city and the region Andamooka, where many black opals and opal crystal. Another Australian town of Lightning Ridge is located in New South Wales, it is considered a major deposit of black opals and opals based on black stone, jet black and dark gray. Boulders opal found in the western part of Queensland, north of Kynuna. Most boulder opal in the south-west Queensland, Australia.
The rarest type of Australian opal called Pipe, it is closely connected with the boulder opal, which is formed in the sandstone with iron oxide and fossilized tree roots.
In the Valley of Virginia, in northern Nevada and in the areas of Humboldt, is a black fire opal, an official stone Nevada. Most of the precious opal with partial impregnation of wood is also found in Australia. Opals are often found in the bones and fish heads long since dead snakes, some opals very high water content, and they crack when dry.
The largest unpolished black opal is now kept at the Smithsonian Institution, and he is known as Opal Roebling, was found in 1917, weighing 2585 carats. The largest polished black opal is found in Australia, known as the Black Peacock, and is also located at the Smithsonian Institution, the stone weighs 160 carats.
In the US state of Idaho is a deposit of light opal, opal many here are in thin layers.
Other significant deposits of precious opal around the world are in Slovakia, Czech Republic, Turkey, Hungary, Brazil, Indonesia, Honduras, Nicaragua, Guatemala, Ethiopia.
In 2008, NASA announced that it discovered opal deposits on Mars.