Koroit Opal (Australia, South West Queensland)
The Koroit opal field is an opal mining area in Paroo Shire in South West Queensland, Australia. It is known for the very distinctive type of boulder opal that is found in its mines. In Queensland boulder opal is found within a 300 km wide belt of sedimentary rocks in the Winton Formation. Here opal is found as a kernel in small concretions.