igneous
Snowflake Obsidian
Obsidian with Cristobalite inclusions
Hardness: 5-5.5 on Mohs scale; Color: Black with white or gray flower-like patterns; Luster: Vitreous (glassy); Crystal Structure: Amorphous (volcanic glass); Specific Gravity: 2.35-2.6
- Hardness
- 5-5
- Color
- Black with white or gray flower-like patterns
- Luster
- Vitreous (glassy)
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Physical properties
Hardness: 5-5.5 on Mohs scale; Color: Black with white or gray flower-like patterns; Luster: Vitreous (glassy); Crystal Structure: Amorphous (volcanic glass); Specific Gravity: 2.35-2.6
Formation & geological history
Formed from the rapid cooling of felsic lava. The "snowflakes" are spherulites of white cristobalite crystals that formed through devitrification of the volcanic glass.
Uses & applications
Used primarily in jewelry (beads, cabochons), ornamental carvings, and as a popular specimen for rock collectors.
Geological facts
While it looks like a mineral, obsidian is actually a volcanic glass. The white patterns are a result of the glass starting to crystallize into minerals, specifically cristobalite, over geological time.
Field identification & locations
Identify by its glassy texture, conchoidal fracture, and distinct white star-shaped inclusions. It is found in volcanic regions, notably in the United States, Mexico, and Iceland.
