igneous
Snowflake Obsidian
Volcanic Glass with Cristobalite inclusions (SiO2)
Hardness: 5-5.5 (Mohs scale), Color: Black with white or grey snowflake-like patches, Luster: Vitreous/Glassy, Crystal Structure: Amorphous (glass) with internal quartz spherulites, Cleavage: None (conchoidal fracture), Specific Gravity: 2.3-2.6
- Hardness
- 5-5
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Physical properties
Hardness: 5-5.5 (Mohs scale), Color: Black with white or grey snowflake-like patches, Luster: Vitreous/Glassy, Crystal Structure: Amorphous (glass) with internal quartz spherulites, Cleavage: None (conchoidal fracture), Specific Gravity: 2.3-2.6
Formation & geological history
Formed through rapid cooling of felsic lava, preventing crystal growth and creating natural glass. The white 'snowflakes' are inclusions of the mineral cristobalite, which is a type of quartz that crystallized as the glass cooled.
Uses & applications
Mainly used for ornamental purposes, jewelry (beads, cabochons), tumbled stones for collectors, and metaphysical practices.
Geological facts
Unlike most rocks, obsidian is technically a glass and not a true mineral because it lacks a crystalline structure. The 'snowflakes' are technically radiating clusters of crystals called spherulites.
Field identification & locations
Identify by its distinctive white-on-black pattern and glass-like surface. It is commonly found in areas of recent volcanic activity such as Iceland, Mexico, and the western United States (Oregon, Utah).
