Igneous
Snowflake Obsidian
Volcanic Glass with Cristobalite inclusions (70–75% SiO2)
Hardness: 5–6 (Mohs). Color: Black with white or gray flower-like spots. Luster: Vitreous/Glassy. Structure: Amorphous (glass) with radial crystals (spherulites). Specific Gravity: 2.35–2.60.
- Hardness
- 5–6 (Mohs)
- Color
- Black with white or gray flower-like spots
- Luster
- Vitreous/Glassy
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Physical properties
Hardness: 5–6 (Mohs). Color: Black with white or gray flower-like spots. Luster: Vitreous/Glassy. Structure: Amorphous (glass) with radial crystals (spherulites). Specific Gravity: 2.35–2.60.
Formation & geological history
Formed through the rapid cooling of felsic (silica-rich) lava. The 'snowflakes' are inclusions of cristobalite, a type of quartz that crystallized as the glass partially devitrified over time. Usually found in Quaternary volcanic areas.
Uses & applications
Primarily used for jewelry (beads, cabochons), ornamental carvings, and metaphysical collecting. Historically used for making sharp cutting tools like arrowheads due to its conchoidal fracture.
Geological facts
Unlike minerals, obsidian is a 'mineraloid' because it is a glass and lacks a crystalline structure. The white patches are called spherulites. It is considered a stone of 'purity' in various cultural folklore.
Field identification & locations
Identify by its glassy texture, conchoidal (shell-like) fracture patterns, and distinctive white radiating crystal patterns. Commonly found in volcanic regions of Utah, Oregon, Mexico, and Iceland.
