sedimentary
Orbicular Jasper (Ocean Jasper)
Silica-rich Microcrystalline Quartz (SiO2) with various inclusions
Hardness: 6.5-7 (Mohs); Color: Tan/brown matrix with orbicular (circular) patterns of cream and white; Luster: Vitreous to waxy after polishing; Structure: Trigonal (microcrystalline)
- Hardness
- 6
- Luster
- Vitreous to waxy after polishing
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Physical properties
Hardness: 6.5-7 (Mohs); Color: Tan/brown matrix with orbicular (circular) patterns of cream and white; Luster: Vitreous to waxy after polishing; Structure: Trigonal (microcrystalline)
Formation & geological history
Formed primarily by the percolation and deposition of silica-rich fluids into cavities or fissures in volcanic or sedimentary rocks, often during the late stages of hydrothermal activity. The orbicular patterns result from radial growth of spherulites.
Uses & applications
Primarily used as a lapidary material for creating polished stones, cabochons for jewelry, and as a decorative collector's specimen.
Geological facts
Orbicular Jasper is known for its distinct 'circles' or 'eyes'. The most famous variety is found along the coast of Madagascar, but similar orbicular jasper can be found in several locations worldwide including Idaho and California.
Field identification & locations
Identify in the field by its hardness (will scratch glass), smooth waxy feel when worn by water, and characteristic circular patterns that do not follow linear bands. Often found in riverbeds or coastal deposits.
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