igneous
Snowflake Obsidian
Volcanic Glass with Spherulite Inclusions (primarily SiO2)
Hardness: 5-5.5 (Mohs scale); Color: Black with grayish-white 'snowflake' patches; Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline glass); Cleavage: None (conchoidal fracture); Specific Gravity: 2.35-2.6
- Hardness
- 5-5
- Color
- Black with grayish-white 'snowflake' patches
- Luster
- Vitreous/Glassy
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Physical properties
Hardness: 5-5.5 (Mohs scale); Color: Black with grayish-white 'snowflake' patches; Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline glass); Cleavage: None (conchoidal fracture); Specific Gravity: 2.35-2.6
Formation & geological history
Formed when felsic lava cools rapidly with minimal crystal growth. The 'snowflakes' are spherulites, which are radiating clusters of needle-like cristobalite (a type of quartz) crystals formed through devitrification during cooling.
Uses & applications
Used primarily in jewelry (cabochons, beads), decorative carvings, and as a popular specimen for rock collectors and metaphysical practitioners.
Geological facts
Because it is a glass rather than a true mineral, it is technically a mineraloid. Native Americans and other ancient cultures used variety of obsidian to craft sharp arrowheads, knives, and surgical tools.
Field identification & locations
Identify by the smooth, glassy black surface broken by distinct white or gray flowery patterns. Found in volcanic regions like the American West (Utah, Oregon), Mexico, and Iceland. Surfaces are very sharp when broken.
