Lightning flashes of color captured in stone! That can only describe precious opal, and 95% of precious opal mined today is found in the arid desert outback of Australia. Our story begins eons ago when a large inland sea stretched from the North of Australia down roughly two-thirds of the way across the continent. As the sea slowly receded, layers of sand and clay sediment were deposited until today the water is gone. As a result, the top one hundred feet or so below ground level consists of layers of shale, limestone and sandstone. Opals were formed when silica-rich water from weathered upper sediments trickled through the lower layers. A long, steady rate of deposition and evaporation results in the conditions necessary to form the consistent microscopic spheres needed for flashes of spectral color. Opals contain a significant percentage of water when mined and surface cracks referred to as crazing can be a problem that develops over time. We try to “season” rough, or let it sit for a few months to detect crazing prior to cutting. Since opals are relatively fragile it is best to wear them as pendants, earrings or special-occasion rings. Try to avoid extreme arid conditions and rapid changes in temperature.
Treatments: Assembled stones.