Snowflake Obsidian
Obsidian var. Snowflake (containing Spherulites of Cristobalite) · Semi-Precious Gemstone / Mineral Specimen
Crystal System
Amorphous (Volcanic Glass); Spherulites are Tetragonal/Cubic
Mineral Group
Silicates (Tectosilicate class); Volcanic Glass
Chemical Formula
SiO2 (70–75%) + MgO, Fe3O4 / Spherulites: SiO2 (Polymorph)
Formation Process
Igneous: Rapid cooling of silica-rich rhyolitic lava. The 'snowflakes' form through devitrification, where the glass begins to crystallize into cristobalite spherulites.
About This Crystal
A dark, opaque black volcanic glass containing white or greyish orbicular patches (snowflakes). It has a vitreous (glassy) luster and a smooth, shell-like surface where fractured.
Physical Characteristics
Color: Black with white/grey radial inclusions. Streak: White. Cleavage: None. Fracture: Conchoidal. Specific Gravity: 2.35–2.60. Non-fluorescent usually, but cristobalite may show weak response.
Optical Properties
Isotropic (Singly refractive). Refractive Index: 1.48–1.51. No pleochroism. Opaque in mass, though thin edges may be translucent brown/grey.
Hardness & Durability
Origin Region
Utah (USA), Mexico, and Iceland; typically found in geologically young volcanic regions.
Hardness & Durability
Mohs Hardness: 5.0–5.5. Brittle tenacity. Sensitive to rapid temperature changes and physical impact due to conchoidal fracture patterns.
Care & Maintenance
Clean with warm soapy water and a soft cloth. Avoid ultrasonic or steam cleaners. Store separately from harder gemstones like quartz or topaz to prevent scratching.
Rarity & Value
Common. Generally inexpensive. Value is based on the aesthetic pattern of the flakes and the quality of the polish. Not typically treated.
Special Characteristics
Features Spherulitic Growth (radial clusters of cristobalite needle-like crystals) which creates the 'snowflake' visual effect against the black glass matrix.
Lore & History
Historically used by ancient cultures for making sharp tools and arrowheads. In lore, it is considered a stone of purity and balance, associated with the Root Chakra and used for 'grounding'.