mineral
Polished botryoidal jasper/chalcedony (likely ocean jasper)
Microcrystalline quartz, SiO₂, with iron-oxide and other mineral inclusions
AI-generated identification · may be incorrectTypically Mohs 6.5–7, brown to honey-brown with purple, cream, yellow, and dark inclusions; vitreous to waxy luster and opaque to slightly translucent. The rounded botryoidal texture and tiny cavities are characteristic, though exact identification cannot be certain from an image.
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Physical properties
Typically Mohs 6.5–7, brown to honey-brown with purple, cream, yellow, and dark inclusions; vitreous to waxy luster and opaque to slightly translucent. The rounded botryoidal texture and tiny cavities are characteristic, though exact identification cannot be certain from an image.
Formation & geological history
Silica-rich fluids filled volcanic cavities and fractures, later depositing chalcedony and jasper with iron and other inclusions; many ocean-jasper specimens formed in Jurassic–Cretaceous volcanic rocks of Madagascar.
Uses & applications
Used as a lapidary stone for cabochons, carvings, polished specimens, and jewelry; valued mainly for attractive patterning rather than industrial use.
Geological facts
“Ocean jasper” is a trade name applied to orbicular or botryoidal jasper, especially material from Madagascar; similar brown material may instead be common jasper, agate, or slag-like chalcedony.
Field identification & locations
Look for a glassy/waxy surface, very fine-grained texture, curved botryoidal bumps, and inability to scratch it with a steel knife; acid testing and provenance help distinguish it from glass or slag. Common sources include Madagascar, Mexico, Indonesia, and Oregon.
