igneous
Snowflake Obsidian
Obsidian with Cristobalite inclusions (SiO2)
Hardness: 5-5.5 on Mohs scale; Color: Black with white-to-gray splotches; Luster: Vitreous (glassy); Structure: Amorphous (glass); Cleavage: Conchoidal fracture; Specific gravity: 2.35-2.6.
- Hardness
- 5-5
- Color
- Black with white-to-gray splotches
- Luster
- Vitreous (glassy)
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Physical properties
Hardness: 5-5.5 on Mohs scale; Color: Black with white-to-gray splotches; Luster: Vitreous (glassy); Structure: Amorphous (glass); Cleavage: Conchoidal fracture; Specific gravity: 2.35-2.6.
Formation & geological history
Formed from rapidly cooling felsic lava where water or certain minerals trigger the crystallization of cristobalite 'snowflakes' within the black volcanic glass. Found in volcanic regions.
Uses & applications
Primarily used for jewelry (beads, cabochons), ornamental carvings, and as a popular collector's gemstone due to its unique pattern.
Geological facts
The 'snowflakes' are actually radial clusters of the mineral cristobalite, a high-temperature polymorph of silica. While it looks like a mineral, obsidian is technically a volcanic glass because it lacks a crystalline structure.
Field identification & locations
Identify by the distinctive white floral or snowflake-like patterns against a glassy black surface. Common in the USA (Utah, California), Mexico, and Iceland. Use caution as broken edges are razor-sharp.
