mineral
Polished ocean jasper
Silicified rhyolite/chalcedony aggregate (primarily microcrystalline SiO₂)
AI-generated identification · may be incorrectTypically hardness 6.5–7 Mohs, opaque to slightly translucent, with a white, gray, cream, and dark green-brown orbicular pattern; vitreous to waxy luster and no visible cleavage. The rounded form is tumbled and polished rather than naturally crystalline.
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Physical properties
Typically hardness 6.5–7 Mohs, opaque to slightly translucent, with a white, gray, cream, and dark green-brown orbicular pattern; vitreous to waxy luster and no visible cleavage. The rounded form is tumbled and polished rather than naturally crystalline.
Formation & geological history
Formed when silica-rich volcanic fluids silicified and replaced cavities or portions of rhyolite, often producing orbicular textures; many commercial examples come from Madagascar and are Cenozoic in age. Exact identification is uncertain from the photograph alone.
Uses & applications
Used as a lapidary stone for cabochons, carvings, spheres, and tumbled specimens; it has minor decorative and jewelry use.
Geological facts
“Ocean jasper” is a trade name, not a single formally defined mineral species; orbicules may consist of chalcedony, quartz, feldspar, and iron oxides.
Field identification & locations
Identify it by its polished, opaque chalcedony-like body and irregular orbicular or landscape patterns; genuine material is cool, fairly heavy, and resists scratching by steel. Common sources include Madagascar, Mexico, and Indonesia.
