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The word "matrix" comes from the Latin word mater, for "mother". That's a good way to think of this type of opal formation since the matrix contains little babies of opal. In Queensland material this matrix is usually ironstone ranging in color & density from a light ochre to hard black hematite. Some mothers have more babies than others, and some are given to flamboyance in their own appearance, while others prefer the more somber dignity of a solid chocolate brown.

The most outrageous matrix comes from the Yowah and Koroit opal fields of southwest Queensland. These mothers present an intricate patterning of various shades and are apparently quite fertile, judging from the multitude of opal babies.

These are 2 of the oldest opal mines in Australia, but in the old days they were only interested in finding the extremely rare examples of solid opal from these fields. The matrix wasn't bothered with. When richer solid opal fields like Lightning Ridge, Coober Pedy, and Andamooka were discovered the miners packed their swags & moved to richer pastures, leaving Koroit & Yowah to a few diehards and the occasional rockhound. The only other people interested in Yowah Nuts were the Aborigines. Yowah Nuts occur in almond-to-apple size nodules with hollow centers. Sometimes these centers get filled up with opal and are super beautiful and valuable . . . but it's the empty ones that interested the Australian Aboriginal.


Aborigines used these natural little bowls as paint pots to store the different colored ochres they need for body paint. They were easily transportable and tradable items for these nomads.

This material has been our favorite for the 30 years we've been involved in opal. The most Frequently Asked Question from those who see it for the first time is "have they been painted?" or "have they been enameled?" It's remarkable how many times these gems are mistaken for cloissone enamel. In a way, they are nature's own enamel work, as opal is composed mainly of silicon . . . just like enamel. Cloissonnature.

None of our stones have been treated in any way. This material naturally occurs with small cavities, where the opal has not filled the matrix. We don't fill these, for those of us who can appreciate the beauty of the void.

Other Opal Formations
Opal is basically a hydrated form of silica with bits of organic matter and trace minerals (the water it contains is in molecular form). Like window glass, it's a liquid and seeks a place to rest in cracks and cavities of the host rock . . . which differs from field to field. The "white" opal from Coober Pedy refers to its limestone matrix (an old reef from the days of the inland sea. Almost all opal in Australia is found on what was the ancient shoreline of this sea). The "black" opal

from Lightning Ridge can attribute its body color to organic carbon and oxides of manganese. Queensland boulder opal forms in cracks in dark ironstone boulders, a background that makes the opal color vivid.

Rather than try to improve upon the best, we've decided to refer those who want in-depth knowledge of the stone to the site of Peter Brusaschi: www.opalmine.com who has put together the most comprehensive explanation to be found on the web. Other top info sources can be found by clicking the Links button.

Doublets and Triplets

Sorry, we don't deal in these.

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