Opals are a type of gemstone that are prized for their unique and beautiful colors, which are caused by the diffraction of light by the gemstone's microstructure. Opals are formed when silica gel seeps into cracks or spaces in rock and hardens over time. As the silica gel hardens, it forms a matrix of tiny silica spheres, which diffract light to create the characteristic colors of an opal.
Australia is the top producer of opals, accounting for around 95% of the world's supply. The majority of Australian opals are mined in the outback in the state of South Australia, where the town of Coober Pedy is known as the "opal capital of the world." Coober Pedy is a small town located in the desert region of South Australia, and it is home to a number of opal mines that produce some of the most valuable and sought-after opals in the world.
In addition to Coober Pedy, the Lightning Ridge region of New South Wales is also a significant producer of opals, and it is known for producing black opals, which are among the most valuable and sought-after type of opals. Black opals are characterized by their dark body color and vibrant play-of-color, and they are only found in a few places in the world, with the majority coming from Lightning Ridge.
Other significant opal-producing regions in Australia include Andamooka in South Australia, which is known for producing white opals, and Queensland, which is home to boulder opals, which are characterized by their unique appearance, with the opal forming a thin layer on top of a boulder-like rock. Opals from Australia are highly prized for their unique and beautiful colors, which can range from pale pastels to bright and vibrant hues.