igneous
Snowflake Obsidian (Flower Jasper variant)
Vitreous volcanic silicate with cristobalite inclusions
Hardness: 5-6 (Mohs scale); Color: Black or dark green with white or light green 'patches'; Luster: Vitreous/Glassy; Structure: Amorphous (glassy) with radiating crystal spherulites; Cleavage: None (conchoidal fracture).
- Hardness
- 5-6 (Mohs scale)
- Color
- Black or dark green with white or light green 'patches'
- Luster
- Vitreous/Glassy
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Physical properties
Hardness: 5-6 (Mohs scale); Color: Black or dark green with white or light green 'patches'; Luster: Vitreous/Glassy; Structure: Amorphous (glassy) with radiating crystal spherulites; Cleavage: None (conchoidal fracture).
Formation & geological history
Formed when lava cools rapidly (extrusive igneous) before crystals can grow. The 'flowering' or 'snowflake' patterns are clusters of cristobalite spherulites formed through devitrification over geological time.
Uses & applications
Primarily used in jewelry (cabochons, beads), decorative carvings, and as a popular collector's stone for tumbling and polishing.
Geological facts
While commonly called 'snowflakes', the white patches are actually a form of quartz known as cristobalite. Despite its appearance, obsidian is not technically a mineral because it lacks a crystalline structure; it is considered a 'mineraloid'.
Field identification & locations
Identify by its glassy, smooth texture and distinct white/gray patterns against a dark background. Often found in areas with recent volcanic activity such as Iceland, Mexico, and the Western USA (Utah/Oregon).
