Snowflake Obsidian
Obsidian with Spherulitic inclusions of Cristobalite · Semi-Precious Gemstone / Decorative Stone
Crystal System
Amorphous (Glassy); inclusions are Tetragonal (Cristobalite). Typically occurs in massive habit with spherulitic inclusions.
Mineral Group
Silicates (Tectosilicate variety); Extrusive Igneous Rock / Volcanic Glass
Chemical Formula
SiO2 (70–75%) + MgO, Fe3O4 (Volcanic glass containing localized devitrification centers of Cristobalite)
Formation Process
Igneous/Volcanic. Formed by the rapid cooling of felsic (silica-rich) lava. The white 'snowflakes' form via devitrification, where the glass starts to crystallize into Cristobalite spherulites.
About This Crystal
A black, opaque volcanic glass featuring white or grey radiating clusters (snowflakes). It has a vitreous (glassy) luster and a smooth, conchoidal fracture surface where the inclusions are not present.
Physical Characteristics
Color: Black with white patches; Streak: White; Cleavage: None; Fracture: Conchoidal; Specific Gravity: 2.3–2.6; Tenacity: Brittle; Fluorescence: Generally none.
Optical Properties
Refractive Index: 1.48–1.51 (Isotropic); Birefringence: None; Luster: Vitreous; Transparency: Opaque to translucent on thin edges.
Hardness & Durability
Origin Region
Western United States (Utah, Oregon), Mexico, Iceland, and Italy (Lipari Islands). Forms in rhyolitic volcanic regions.
Hardness & Durability
Mohs Hardness: 5.0–5.5; Toughness: Poor (brittle and prone to chipping/cracking); Stability: Sensitive to sudden temperature changes.
Care & Maintenance
Clean with warm soapy water and a soft brush; avoid ultrasonic cleaners and steam. Store separately to prevent scratches from harder minerals like quartz or beryl.
Rarity & Value
Common; Value is generally low, determined by the contrast and pattern of the snowflakes. Often sold as tumbled stones or cabochons.
Special Characteristics
Distinctive devitrification pattern of radial Cristobalite crystals forming 'snowflakes' against a dark background; sharp conchoidal fracture.
Lore & History
Historically used for making extremely sharp arrowheads and tools. Metaphysically, it is regarded as a stone of purity and balance, believed to shield against negativity and represent the 'yin and yang' balance of light and dark.