igneous
Snowflake obsidian
Volcanic glass (obsidian), chiefly silica-rich rhyolitic composition, with cristobalite or feldspar spherulites
AI-generated identification · may be incorrectTypically black, vitreous, and opaque with pale gray-white radial “snowflake” patterns; hardness about 5–5.5 Mohs, conchoidal fracture, no cleavage, and specific gravity about 2.35–2.าม5. The rounded shape indicates tumbling or polishing.
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Physical properties
Typically black, vitreous, and opaque with pale gray-white radial “snowflake” patterns; hardness about 5–5.5 Mohs, conchoidal fracture, no cleavage, and specific gravity about 2.35–2.าม5. The rounded shape indicates tumbling or polishing.
Formation & geological history
Forms when silica-rich lava cools rapidly, preventing crystal growth; the snowflakes develop from devitrification and spherulite crystallization. It is generally Quaternary to Cenozoic in age, depending on source volcanic flow.
Uses & applications
Used for cabochons, beads, carvings, ornaments, and lapidary collectibles; historically, obsidian was knapped into sharp blades and tools.
Geological facts
Snowflake patterns are not fossils or painted inclusions but mineral-rich crystallized zones within volcanic glass.
Field identification & locations
Identify by its glossy black glassy body, conchoidal fracture, and distinctive pale radial spherulites; common sources include Mexico, the western United States, and Armenia.
