• An Australian boulder matrix opal is a naturally occuring precious opal mixed with the parent rock ( ironstone)
rather than having been deposited in seams or patches, like in boulder opal.
• The parent rock is a ferruginous rock ( containing iron ), and is called ironstone.
• It is found exclusively in Queensland, Australia, and does not need to be treated before cutting or polishing.
• The word boulder is used in its name, because it is always found in proximity or among deposits boulder opal, and the mother rock is the same as boulder opal.
• It is not to be confused with Andamoonka matrix stone from South Australia, of which the mother rock is of a different composition and must be treated before cutting and polishing to accentuate the opal colours
• When cut and polished, by world standards, boulder opal matrix stone is a "Natural opal,Type 3.