igneous
Snowflake Obsidian
Spherulitic Volcanic Glass (primarily SiO2)
Hardness: 5-5.5 (Mohs scale); Color: Black with white or gray 'snowflakes'; Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline glass); Cleavage: None (conchoidal fracture); Specific Gravity: 2.35-2.6.
- Hardness
- 5-5
- Color
- Black with white or gray 'snowflakes'
- Luster
- Vitreous/Glassy
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Physical properties
Hardness: 5-5.5 (Mohs scale); Color: Black with white or gray 'snowflakes'; Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline glass); Cleavage: None (conchoidal fracture); Specific Gravity: 2.35-2.6.
Formation & geological history
Formed from rapidly cooling felsic lava. The 'snowflakes' are spherulites of needle-like cristobalite (a type of quartz) that occurred during the cooling or weathering process. It is typically from the Tertiary or Quaternary geological periods.
Uses & applications
Primarily used for jewelry (cabochons, beads), decorative carvings, meditation stones, or as a lapidary material for tumbling.
Geological facts
Ancient cultures used obsidian to create surgical-quality blades because it fractures to an edge only a few molecules thick. The 'snowflakes' are technically a partial crystallization of the glass, representing the stone's transition from glass to rock over time.
Field identification & locations
Identify by its glassy base, conchoidal (shell-like) fracture edges, and the distinct white radiating patterns. Commonly found in volcanic regions such as Utah and California (USA), Iceland, and Mexico.
