All of significant opal deposits in Australia during last 100 years are located within or surrounding Great Artesian Basin. The most important deposits are found in New South Wales, South Australia and Queensland.
Today, mining is carried out at following main areas and each area produces solid opal with specific characteristics and colour patterns.
Lightning Ridge, New South Wales
This is a town famous for its rich and rare black opal. Black opal gets its name from colour of “nobbies” or pieces of rough opal in which gems are usually found.
Black opal was first discovered here in late 1880’s, however its commercial value was not at first recognised by buyers. It wasn’t until early 1900’s that some opal nobbies were found and shafts dug.
Opal occurs either as “nobbies” or in seams and thin layers within a soft greyish clay stone. The opal dirt levels occur between six and eighteen metres from surface, but have been found at depths as deep as thirty metres. The fields also yield opalised shells, wood and reptilian bones.
Some of traditional fields around Lightning Ridge include Three Mile and Thorleys Six Mile.
White Cliffs, New South Wales
Located 295 kilometres northeast of Broken Hill, White Cliffs is Australia’s oldest opal field, where mining began about 1889. As with most towns with mining operations, population quickly soared, peaking at 5,000 in its heyday.
The light crystal opal found at White Cliff quickly became famous on world market. The opal fields produced first commercially accepted opal, far surpassing quality of Hungarian mines, as opal displaying such vivid colours had never been seen before.
Between 1903 and 1914, richer areas of opal field became exhausted and a decline in production resulted. The effects of World War 1 also affected area, contributing to decline.
The history of opal in Queensland dates back to early 1870’s, but it wasn’t until 1889 when gem was successfully marketed. The real development of vast opal deposits began in 1873 with discovery of fine quality opal north of Thargomindah.
During those early years production was low as there was no ready market for gem. It took efforts and determination of an entrepreneur named Tully Woolaston to establish industry.