igneous
Snowflake Obsidian
Volcanic Glass with Spherulitic Cristobalite Inclusion
Hardness: 5-5.5 on Mohs scale; Color: Black with white-to-gray 'snowflake' blotches; Luster: Vitreous (glassy); Structure: Amorphous (non-crystalline glass); Specific Gravity: 2.35-2.6
- Hardness
- 5-5
- Color
- Black with white-to-gray 'snowflake' blotches
- Luster
- Vitreous (glassy)
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Physical properties
Hardness: 5-5.5 on Mohs scale; Color: Black with white-to-gray 'snowflake' blotches; Luster: Vitreous (glassy); Structure: Amorphous (non-crystalline glass); Specific Gravity: 2.35-2.6
Formation & geological history
Formed when felsic lava cools rapidly with minimal crystal growth. The 'snowflakes' are inclusions of the mineral cristobalite, which form through a process called devitrification, where the glass begins to transform into crystalline quartz/feldspar.
Uses & applications
Used primarily in jewelry (cabochons, beads), decorative carvings, and as a popular specimen for metaphysical collectors and lapidary hobbyists.
Geological facts
Snowflake obsidian is not technically a mineral because it is a glass and lacks a crystalline structure, though the white 'snowflakes' are actual crystals. Ancient cultures used obsidian for surgical-grade blades due to its conchoidal fracture which creates edges thinner than steel.
Field identification & locations
Identified by its signature white radial patterns against a jet-black glassy base. Commonly found in volcanic regions such as Utah (USA), Mexico, and Iceland. Collectors should look for sharp color contrast and absence of air bubbles.
