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60.45 mm Opal Mountain Opal Thunderegg Rhyolite Sphere

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60.45 mm Opal Mountain Opal Thunderegg Rhyolite Sphere

Availability: In stock

Opal Mountain Rhyolite

Opal Mountain, Idaho, USA

Sphere Diameter : 60.45 mm
1 inch = 2.54 cm = 25.4 mm

With extreme care, this delicate opal filled material has been, painstakingly, polished to a mirror finish with the opal geode cavity preserved!

A very cool piece where you can see the interior structure and layering of the Opal Mountain Rhyolite with 3 completely round thunderegg geodes polished on the face.

We collected this material and hand selected each for its patterns and unique coloring. Every orb you see on the face of the sphere is filled with precious or common opal.

Each of our spheres is perfectly round with no pitting, cracking, or excessive use of glue to hide imperfections.


Opal Mountain Rhyolite is found from a single source deposit in Idaho.

6-4 million years ago, volcanic activity left rhyolite and perlite ash deposits with gas pockets (aka a thunderegg). Before and during our last Ice Age, roughly 1 million to 50,000 years ago, geysers seeped mineral (silica) rich solution up and through the ancient volcanic deposits and slowly filled the cavities left by the gas pockets with a combonation of both precious and common opal.