igneous
Snowflake Obsidian
Hydrated Volcanic Glass with Cristobalite inclusions
Hardness: 5-5.5 (Mohs scale), Color: Black with white or grey splotches (snowflakes), Luster: Vitreous/Glassy, Crystal Structure: Amorphous (non-crystalline), Cleavage: None/Conchoidal fracture, Specific Gravity: 2.35-2.6.
- Hardness
- 5-5
Identified More igneous →
Explore Snowflake Obsidian in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness: 5-5.5 (Mohs scale), Color: Black with white or grey splotches (snowflakes), Luster: Vitreous/Glassy, Crystal Structure: Amorphous (non-crystalline), Cleavage: None/Conchoidal fracture, Specific Gravity: 2.35-2.6.
Formation & geological history
Formed when felsic lava cools rapidly with minimal crystal growth. The 'snowflakes' are inclusions of the mineral cristobalite (a type of quartz) that underwent radial growth during partial devitrification of the glass. Found in volcanic regions of any age.
Uses & applications
Primarily used for jewelry such as cabochons and beads, ornamental carvings, collection specimens, and metaphysical practices. Historically, obsidian was used for making sharp cutting tools and arrowheads.
Geological facts
The 'snowflakes' are called spherulites. While obsidian itself is a glass, Snowflake Obsidian is technically in the process of turning from a glass back into a crystalline rock.
Field identification & locations
Identified by its jet-black glassy base and distinctive white flower-like patches. Commonly found in locations with recent volcanic activity such as Utah (USA), Mexico, and Iceland. Feel for a smooth, glass-like texture and look for conchoidal (curved) fracture lines.
