igneous
Snowflake obsidian
Volcanic glass (predominantly SiO₂) with spherulitic cristobalite or feldspar inclusions
AI-generated identification · may be incorrectBlack, glassy, commonly polished; white-to-gray snowflake patterns are radial crystalline spherulites. Mohs hardness about 5–5.5; amorphous, with conchoidal fracture and no cleavage.
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Physical properties
Black, glassy, commonly polished; white-to-gray snowflake patterns are radial crystalline spherulites. Mohs hardness about 5–5.5; amorphous, with conchoidal fracture and no cleavage.
Formation & geological history
Forms when silica-rich lava cools rapidly into natural volcanic glass; snowflake patterns develop as crystals grow during later cooling. It occurs in geologically recent volcanic deposits.
Uses & applications
Used for beads, cabochons, ornamental carvings, and mineral collecting; not generally used as a structural building stone.
Geological facts
The pale “snowflakes” are crystal aggregates within the otherwise glassy obsidian, not fossils or surface decoration.
Field identification & locations
Identify by its black glassy body, sharp conchoidal fracture, and distinctive pale radial patches; notable sources include Oregon and Mexico. The image shows a small polished piece, so locality and exact composition cannot be confirmed visually.
