mineral
Polished ocean jasper cabochon
Orbicular jasper (microcrystalline quartz, SiO₂)
AI-generated identification · may be incorrectHardness about 6.5–7 Mohs; dark green to black matrix with pale green/cream orbicular patterns, opaque, waxy to vitreous luster, and no visible cleavage. The rounded triangular object is a polished, likely drilled or mounted cabochon.
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Physical properties
Hardness about 6.5–7 Mohs; dark green to black matrix with pale green/cream orbicular patterns, opaque, waxy to vitreous luster, and no visible cleavage. The rounded triangular object is a polished, likely drilled or mounted cabochon.
Formation & geological history
Forms when silica-rich volcanic material is altered and filled with concentric mineral growths, commonly in cavities of rhyolitic lava; most orbicular ocean jasper comes from Miocene-aged volcanic rocks near northwest Madagascar.
Uses & applications
Used for cabochons, pendants, beads, carvings, and lapidary display; valued mainly for attractive patterning rather than industrial applications.
Geological facts
“Ocean jasper” is a trade name, not a single mineral species; its orbicules may contain quartz, feldspar, chlorite, and iron oxides.
Field identification & locations
Identify by opaque chalcedonic material, rounded orbicules, strong polish, and inability to scratch with a copper coin; common sources include Madagascar, Mexico, and Australia. Exact identification is uncertain from the photograph alone.