igneous
Polished snowflake obsidian
Obsidian (volcanic glass), likely with cristobalite or feldspar spherulites
AI-generated identification · may be incorrectBlack, glossy volcanic glass with a white branching snowflake-like pattern; hardness about 5–5.5 Mohs, no cleavage, and conchoidal fracture. The pictured piece is a small polished sphere.
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Physical properties
Black, glossy volcanic glass with a white branching snowflake-like pattern; hardness about 5–5.5 Mohs, no cleavage, and conchoidal fracture. The pictured piece is a small polished sphere.
Formation & geological history
Obsidian forms when silica-rich lava cools rapidly, preventing crystals from growing; snowflake patterns develop as crystals form within the glass during devitrification. It is geologically young volcanic material, commonly Quaternary in age.
Uses & applications
Used for cabochons, beads, carvings, and decorative objects; historically, obsidian was shaped into sharp tools and blades.
Geological facts
The white “snowflakes” are typically radiating aggregates of cristobalite, not mineral inclusions shaped like actual snowflakes.
Field identification & locations
Identify it by the glassy black surface, sharp conchoidal fracture on unpolished pieces, and contrasting pale radial patches. Snowflake obsidian is found in volcanic regions, notably Mexico and the western United States.
