igneous
Orbicular Rhyolite
Spherulitic Rhyolite
AI-generated identification · may be incorrectHardness of 6-7 on the Mohs scale, vitreous to dull luster, and microcrystalline structure featuring distinct spherulitic orbicular patterns. Colors typically range from brownish-gray to tan and black.
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Physical properties
Hardness of 6-7 on the Mohs scale, vitreous to dull luster, and microcrystalline structure featuring distinct spherulitic orbicular patterns. Colors typically range from brownish-gray to tan and black.
Formation & geological history
Formed by rapid cooling of silica-rich lava, causing spherical crystallization or spherulites to grow within the glassy groundmass during the volcanic process.
Uses & applications
Used primarily as a decorative stone, in lapidary arts for cabochons, and by mineral collectors.
Geological facts
The distinctive circular patterns, known as spherulites, form when minerals precipitate radially from a central point during cooling.
Field identification & locations
Easily identified by its polka-dot or orbicular structures embedded in a fine-grained volcanic matrix. Commonly found in volcanic regions worldwide.
