igneous
Snowflake Obsidian
Spherulitic Obsidian (Volcanic Glass with Cristobalite)
Hardness: 5-5.5 (Mohs scale), Color: Black with white or grey spots, Luster: Vitreous/Glassy, Structure: Amorphous with radiator spherulites, Cleavage: None/Conchoidal fracture, Specific Gravity: 2.35-2.6
- Hardness
- 5-5
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Physical properties
Hardness: 5-5.5 (Mohs scale), Color: Black with white or grey spots, Luster: Vitreous/Glassy, Structure: Amorphous with radiator spherulites, Cleavage: None/Conchoidal fracture, Specific Gravity: 2.35-2.6
Formation & geological history
Formed from the rapid cooling of silica-rich lava. The white 'snowflakes' are inclusions of cristobalite, a type of quartz, which grew in the glass as it cooled over time.
Uses & applications
Primarily used for jewelry (beads, cabochons), ornamental carvings, and 'healing' stone markets/collecting.
Geological facts
Unlike most volcanic glass which is very stable, snowflake obsidian is actually 'devitrifying' - the glass is slowly turning into mineral crystals over millions of years.
Field identification & locations
Identify by its characteristic white radial patterns on a black background and glassy feel. Found in areas with past volcanic activity such as Utah, USA, and Mexico.
