igneous
Snowflake Obsidian
Volcanic Glass (SiO2 + impurities)
Hardness: 5-5.5 on Mohs scale; Color: Black with white or grey 'snowflake' patterns; Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline); Cleavage: Conchoidal fracture; Specific Gravity: 2.3 - 2.6.
- Hardness
- 5-5
- Color
- Black with white or grey 'snowflake' patterns
- Luster
- Vitreous/Glassy
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Physical properties
Hardness: 5-5.5 on Mohs scale; Color: Black with white or grey 'snowflake' patterns; Luster: Vitreous/Glassy; Structure: Amorphous (non-crystalline); Cleavage: Conchoidal fracture; Specific Gravity: 2.3 - 2.6.
Formation & geological history
Formed from the rapid cooling of silica-rich rhyolitic lava. The 'snowflakes' are inclusions of phenocrysts (spherulites) of the mineral cristobalite. Most specimens are relatively young geologically (Cenozoic era) because glass eventually devitrifies.
Uses & applications
Commonly used in jewelry (beads, cabochons), ornamental carvings, and as a healing stone in metaphysical practices. Historically, obsidian was used for making sharp tools like arrowheads and knives.
Geological facts
Obsidian is technically not a mineral because it is amorphous glass, not a crystal. The white 'snowflakes' are actually crystals of cristobalite—a type of quartz—that grew within the glass as it cooled and aged.
Field identification & locations
Identify by its glassy luster, sharp conchoidal edges, and distinct white spots against a black background. Commonly found in volcanic regions such as Utah (USA), Mexico, and Iceland. Collectors should look for balanced patterns and lack of surface scratching.
