Opal can be a confusing gem stone. For one thing, it’s not a mineral like most gems. Minerals have an identifiable crystal structure. Opal has a non-crystalline, amorphous structure, and so it’s labeled a mineraloid. Another unusual quality of opal is all its different variations. Most people think of opal as the stone that flashes different colors. Gemologists call that quality “play of color.” But that only happens with precious opal, which represents about 5% of all opal. Most opal is called “common opal” or “potch opal”, and it shows no play of color. These are just two reasons why opal is, well, complicated.
If you are really serious about your gem stones, you’ve probably heard of Black Opal, White Opal, Crystal Opal, Peruvian Opal, and Fire Opal. You know that most of the precious opal comes from Australia or Ethiopia. You understand that an opal doublet is really a layer of precious opal too fragile to survive alone in jewelry, so it’s backed with a non-precious material. An opal triplet is an even finer layer of precious opal, with both a backing and a protective clear quartz dome over the top.
But what is Boulder Opal? I describe it as ribbons or veins of opal that are embedded in the host rock it formed within. Because the host rock is tougher and harder than opal, boulder opal is considered more durable. And because the host rock is less valuable, you can get a big piece of boulder opal for much less money than a small piece of crystal or black opal. Boulder opal is mined in Queensland, which is the northeastern part of Australia. Mine fields in places like Quilpie, Bulgaroo, Koroit, and Yowah are yielding a lot of product. As Boulder Opal has become more popular, these mines have kept up with demand.
For the month of May, 2018, we’ve brought several beautiful pieces of boulder opal into our store, courtesy of our distributor, DuftyWeis Opals. They’re only here for a limited time so, if you have the chance, come in to be personally introduced to boulder opal.