igneous
Snowflake Obsidian
Volcanic glass with Spherulite inclusions (SiO2)
Hardness: 5-5.5 (Mohs); Color: Black with white/grey 'snowflakes'; Luster: Vitreous/Glassy; Structure: Amorphous (glassy) with radiating Cristobalite crystals; No cleavage.
- Hardness
- 5-5
- Color
- Black with white/grey 'snowflakes'
- Luster
- Vitreous/Glassy
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); Color: Black with white/grey 'snowflakes'; Luster: Vitreous/Glassy; Structure: Amorphous (glassy) with radiating Cristobalite crystals; No cleavage.
Formation & geological history
Formed when felsic lava cools rapidly, preventing significant crystal growth. The white patches (snowflakes) are inclusions of the mineral Cristobalite that formed as the glass devitrified over time.
Uses & applications
Used primarily in jewelry (beads, cabochons), carvings, meditation tools, and as a popular specimen for rock collectors and lapidary beginners.
Geological facts
Unlike most rocks, obsidian is naturally occurring volcanic glass. The snowflakes are actually internal radiating patterns of needles, a process called devitrification where the glass begins to turn into crystalline quartz.
Field identification & locations
Identify by its smooth, glassy texture and distinctive white circular patterns against a dark black base. It is commonly found in areas of recent volcanic activity such as Iceland, Mexico, and the Western USA.
