sedimentary
Ocean Jasper
Orbicular Jasper (variety of Chalcedony/Quartz, SiO2)
Hardness: 6.5-7 (Mohs scale); Color: Variegated greens, white, cream, and brown; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.6-2.9.
- Hardness
- 6
- Color
- Variegated greens, white, cream, and brown
- Luster
- Vitreous to waxy
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Physical properties
Hardness: 6.5-7 (Mohs scale); Color: Variegated greens, white, cream, and brown; Luster: Vitreous to waxy; Crystal structure: Trigonal/Microcrystalline; Cleavage: None; Specific Gravity: 2.6-2.9.
Formation & geological history
Formed as a result of rhythmic precipitation of silica around a nucleus in volcanic or sedimentary environments. Specifically found in Cretaceous-age rhyolitic flows along the coast of Madagascar.
Uses & applications
Primarily used for lapidary work, jewelry (cabochons), interior decoration (spheres/carvings), and as a collector's mineral specimen.
Geological facts
Ocean Jasper is exceptionally rare because the original veins in Madagascar were only accessible by boat at low tide. This specific 'orbicular' pattern is created by the presence of radial clusters of acicular fibers (spherulites).
Field identification & locations
Identified by its distinctive multi-colored 'eye' or flower-like orbicular patterns and high hardness. It often contains small druzy quartz-filled vugs. Collectors look for high color contrast and well-defined circles.
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