igneous
Orbicular Rhyolite (Rainforest Jasper)
Orbicular Rhyolite
Hardness: 6.5-7 (Mohs scale), Color: Green, cream, and brown with circular patterns, Luster: Vitreous to dull, Structure: Cryptocrystalline with spherulitic inclusions, Specific Gravity: 2.6-2.7
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Green, cream, and brown with circular patterns, Luster: Vitreous to dull, Structure: Cryptocrystalline with spherulitic inclusions, Specific Gravity: 2.6-2.7
Formation & geological history
Formed from rapid cooling of silica-rich volcanic lava where gas bubbles or crystals seeded the growth of radial mineral patterns (spherulites). Most commercial specimens date from the Tertiary period.
Uses & applications
Primarily used for ornamental purposes, lapidary art such as cabochons, metaphysical practices, and collector specimens.
Geological facts
Despite being called a Jasper, it is technically a volcanic rock (Rhyolite). The 'eyes' or circles are often composed of feldspar and quartz that grew outward from a central point.
Field identification & locations
Identify by its unique 'orbicular' or circular patterns against a dark green or earthy background. Common in volcanic regions, notably Western Australia and parts of Mexico.
