igneous
Snowflake obsidian
Volcanic glass with cristobalite spherulites (SiO₂-rich obsidian)
AI-generated identification · may be incorrectTypically black, glassy obsidian with pale gray-white, snowflake-like patches; hardness about 5–5.5 Mohs and conchoidal fracture. The patches are radial crystal aggregates, not separate inclusions of snow.
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Physical properties
Typically black, glassy obsidian with pale gray-white, snowflake-like patches; hardness about 5–5.5 Mohs and conchoidal fracture. The patches are radial crystal aggregates, not separate inclusions of snow.
Formation & geological history
Forms when silica-rich lava cools rapidly, preventing extensive crystal growth; snowflake patterns develop as cristobalite crystallizes within the glass during later cooling. Geological ages vary by volcanic deposit.
Uses & applications
Commonly cut and polished for jewelry, beads, carvings, and decorative or collectible pieces; not generally used as a structural stone.
Geological facts
The pictured specimen appears to be a small, roughly triangular cut or broken piece showing the characteristic contrasting snowflake pattern.
Field identification & locations
Identify by the black glassy matrix, sharp curved fracture surfaces, and pale radial spherulites. Notable deposits occur in volcanic regions including Oregon and Utah, USA, and Mexico; the image alone cannot confirm locality.
