igneous
Snowflake Obsidian
Volcanic glass with Cristobalite inclusions (mostly SiO2)
Hardness: 5-5.5 (Mohs scale); Color: Black with white or gray flower-like 'snowflakes'; Luster: Vitreous (glassy); Crystal structure: Amorphous (non-crystalline glass) with crystalline inclusions; Cleavage: None (conchoidal fracture); Specific gravity: 2.35-2.6.
- Hardness
- 5-5
- Color
- Black with white or gray flower-like 'snowflakes'
- Luster
- Vitreous (glassy)
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Physical properties
Hardness: 5-5.5 (Mohs scale); Color: Black with white or gray flower-like 'snowflakes'; Luster: Vitreous (glassy); Crystal structure: Amorphous (non-crystalline glass) with crystalline inclusions; Cleavage: None (conchoidal fracture); Specific gravity: 2.35-2.6.
Formation & geological history
Formed when felsic lava (rich in silica) cools rapidly, preventing crystal growth. The 'snowflakes' are spherulites of cristobalite, a type of quartz, which localized crystallization during the cooling process. Commonly found in areas with geologically recent volcanic activity.
Uses & applications
Primarily used for jewelry (beads, cabochons), ornamental carvings, and decorative stones. Historically used by various cultures to create sharp tools and arrowheads, though snowflake obsidian is more brittle than plain obsidian.
Geological facts
The 'snowflakes' are actually internal crystals of cristobalite that grew in a radial pattern within the glass. Because it is glass and not a true mineral, it is technically a 'mineraloid'. It is often associated with protection and grounding in metaphysical practices.
Field identification & locations
Identify by its distinct conchoidal (shell-like) fracture edges and the characteristic white blotches against a deep black glassy background. It is commonly found in the Western United States (Utah, Oregon), Mexico, and Iceland. Collectors should look for sharp color contrast and well-defined 'snowflake' patterns.
