igneous
Snowflake Obsidian
Spherulitic Volcanic Glass (SiO2)
Hardness: 5-5.5 (Mohs scale); Color: Black with white or gray flower-like spots; Luster: Vitreous/Glassy; Structure: Amorphous with spherulitic inclusions; Fracture: Conchoidal.
- Hardness
- 5-5
- Color
- Black with white or gray flower-like spots
- Luster
- Vitreous/Glassy
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Physical properties
Hardness: 5-5.5 (Mohs scale); Color: Black with white or gray flower-like spots; Luster: Vitreous/Glassy; Structure: Amorphous with spherulitic inclusions; Fracture: Conchoidal.
Formation & geological history
Formed when felsic lava cools rapidly with minimal crystal growth, followed by partial devitrification where cristobalite crystals grow in radial 'snowflake' patterns within the glass.
Uses & applications
Used primarily in jewelry (cabochons, beads), decorative carvings, meditation stones, and as a lapidary material.
Geological facts
The 'snowflakes' are actually internal clusters of the mineral cristobalite. Unlike most rocks, obsidian is technically a volcanic glass because it cools too fast to form a crystalline structure.
Field identification & locations
Identified by its distinctive white radial patterns against a jet-black glassy background. High-quality specimens have well-defined, non-overlapping snowflakes. Common in volcanic regions like Utah (USA), Mexico, and Iceland.
