Boulder Opal Collection

Precious opal deposits are found in ironstone. Australian Boulder Opals are distinguished by their layer of solid brown ironstone left on the back of the stone. They are mined from large ironstone boulders under the ground which contain natural veins of opal within their interior. Boulder Opals are found only in Queensland, Australia. The Boulder Opal stones in this collection, with their beautiful iridescence, are from the Winton mines.