igneous
Snowflake Obsidian
Volcanic Glass (SiO2 rich with Cristobalite inclusions)
Hardness: 5 to 5.5 Mohs scale. Color: Black with grayish-white snowflake-like patches. Luster: Vitreous to glassy. Structure: Amorphous (glassy matrix) with radial spherulitic inclusions. Cleavage: None, exhibits conchoidal fracture. Specific Gravity: ~2.35-2.6.
- Hardness
- 5 to 5
- Color
- Black with grayish-white snowflake-like patches
- Luster
- Vitreous to glassy
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Physical properties
Hardness: 5 to 5.5 Mohs scale. Color: Black with grayish-white snowflake-like patches. Luster: Vitreous to glassy. Structure: Amorphous (glassy matrix) with radial spherulitic inclusions. Cleavage: None, exhibits conchoidal fracture. Specific Gravity: ~2.35-2.6.
Formation & geological history
Formed when felsic lava cools rapidly with minimal crystal growth, creating natural volcanic glass. Over time, partial devitrification occurs, causing cristobalite (a silica mineral) to crystallize into spherulites that form the characteristic white 'snowflake' patterns.
Uses & applications
Widely used in lapidary arts, tumbled stones, jewelry (cabochons, beads, pendants), ornamental carvings, and metaphysical collections.
Geological facts
The white patches are inclusions of the mineral cristobalite. Because obsidian is a natural glass rather than a true mineral, it lacks a crystalline structure, though the snowflake inclusions within it are fully crystalline.
Field identification & locations
Identified by its shiny, black volcanic glass base filled with distinctive white or light gray flower-like or star-like inclusions. Commonly found in volcanic regions worldwide, including USA (Oregon, California, Utah), Mexico, Iceland, and Japan.
