Australian Opal Fields and The Great Aretesian Basin

Australia produces 95% of the precious opal on the global market.
The opal found in Australia is sourced mainly from three different regions 100s of kilometres apart from each other.
These three areas were once within a vast inland sea that existed 100 million years ago. The location and size of this sea corresponds roughly to The Great Artesian Basin on top of which it sat. As the sea dried up, hydrated silica that eventually became opal formed in rock crevices, hard clay or sand in these three areas and their different geological conditions created the three different types of natural Australian opal.

Types of Australian Opal I sell:


Black Opal is found mainly at Lightning Ridge N.S.W. 600km northwest of Sydney.  First noticed in the late 1800’s, it wasn’t until 1905 that the first shafts were dug and a layer of black “potch” (non-precious opal) was discovered. Within this layer of potch is found precious opal called Black Opal a name they have because of their dark body colour that ranges from light grey to dark black. Their rarity makes them the most valuable of all opals.

Australia Black Opal mining fields map
Australian Black Opal Mining Fields


Boulder opal is mined from the vast opal fields of central Queensland. The silica here formed in the crevices of very hard Ironstone boulders. When they are cut and polished, the natural Ironstone backing is retained.

Australian Boulder Opal Mining Fields map
Australian Boulder Opal Mining Fields


White Opal is found across a large area in South Australia and is mined mainly at Cobber Pedy, Andamooka and Mintabie. Also called Light Opal, their pale milky white background elicits usually subtle colours.

Australian White Opal Mining Fields map
Australian White Opal Mining Fields

Crystal OPAL

An opal that is translucent or transparent and has a play-of-colour within the stone is called a “Crystal opal”. They can come from a number of opal producing areas – if from Lightning Ridge they are called a “Black Crystal” and if from South Australia, a “White Crystal”.