sedimentary
Ocean Jasper
Orbicular Jasper (Silicon Dioxide with impurities, SiO2)
Hardness: 6.5-7 (Mohs scale), Color: Cream, tan, and orange-tinted with orbicular patterns, Luster: Vitreous to waxy (when polished), Crystal Structure: Trigonal (Microcrystalline), Specific Gravity: 2.58-2.91
- Hardness
- 6
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Physical properties
Hardness: 6.5-7 (Mohs scale), Color: Cream, tan, and orange-tinted with orbicular patterns, Luster: Vitreous to waxy (when polished), Crystal Structure: Trigonal (Microcrystalline), Specific Gravity: 2.58-2.91
Formation & geological history
Formed as a rhyolitic flow or through the precipitation of silica around a nucleus, creating distinctive spheres. This specific variety is unique to the coast of Madagascar, formed during the Mesozoic era.
Uses & applications
Primarily used for lapidary work, jewelry, ornamental carvings, and by crystal collectors for aesthetic and metaphysical purposes.
Geological facts
Ocean Jasper is technically a misnomer; it is more accurately a chalcedony or spherulitic rhyolite. It was rediscovered in the late 1990s after decades of being 'lost' because it can only be mined during low tide.
Field identification & locations
Identify by its unique 'orbicular' (eye-like) circular patterns and multicolored swirls. In the field, look for volcanic coastal outcrops in northwestern Madagascar; it is rarely found elsewhere.
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