igneous
Snowflake Obsidian
Obsidian with Spherulitic Cristobalite (SiO2)
Hardness: 5-5.5 (Mohs scale), Color: Black with white or gray flower-like patterns, Luster: Vitreous/Glassy, Crystal Structure: Amorphous (glassy) with cristobalite inclusions, 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 gray flower-like patterns, Luster: Vitreous/Glassy, Crystal Structure: Amorphous (glassy) with cristobalite inclusions, Specific Gravity: 2.3-2.6
Formation & geological history
Snowflake obsidian is an extrusive igneous rock formed when felsic lava cools rapidly with minimal crystal growth. The 'snowflakes' are inclusions of the mineral cristobalite (a polymorph of silicon dioxide) that formed as the glass began to devitrify over time.
Uses & applications
Primarily used for jewelry (cabochons, beads), decorative carvings, meditation stones, and metaphysical tools. In antiquity, it was used for sharp tools and weapons.
Geological facts
Unlike most rocks, obsidian is technically a 'mineraloid' because it is volcanic glass rather than a true crystal. The snowflake pattern signifies the transition of glass back into a crystalline state, a process known as devitrification.
Field identification & locations
Identify by its glassy texture, conchoidal fracture, and distinctive white radiator-shaped splotches. It is commonly found in volcanic regions of Utah, Mexico, and Iceland. To identify, look for a smooth, non-porous surface that feels like heavy glass.
