Tumble Polished Opal - 1/2 Pound - Idaho

Opal from the Spencer Opal Mine is some of the most sought after in the world for it's rarity and color spectrum. A relatively modern mine, in comparison to those from Australia and Ethiopia, the opals present in Idaho span the entire color spectrum and offer their own unique additions to the world of opals in spectacular patterns and color combinations. The formation of these fantastic opals is one that was time consuming and took literally millions of years - beginning 6-4 million years ago, volcanic activity left rhyolite and perlite ash deposits with gas pockets. During our last Ice Age, roughly 50-20,000 years ago, geysers seeped mineral rich solution up and through the ancient volcanic deposit and slowly filled the cavities left by the gas pockets.