Australian boulder
opals have exquisite shades of blue, purple, red, green and
aqua "fire".
Each boulder opal is unique. Boulder opals form in veins running
through ironstone which makes it more durable than other forms of
opal because of the hard ironstone base.
Boulder
opals , Yowah
opals, and Koroit
opals are each unique types of opal found in different opal
fields of Australia. Yowah and Koroit opals have interesting abstract
patterns on the surface of the cut stone.
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