mineral

Polished ocean jasper

Orbicular jasper (microcrystalline quartz, SiO₂)

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque green, brown, cream, and reddish zones with a vitreous-to-waxy polish, orbicular patterns, cavities, and no visible cleavage. Specific gravity is typically 2.5–2.7.

Identified August 24, 2026More mineral →

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Physical properties

Formation & geological history

Formed when silica-rich volcanic fluids filled cavities and fractures in altered rhyolitic volcanic rock, producing chalcedony, quartz, and colorful iron- or manganese-rich patterns. Most classic material formed in Madagascar, likely during Mesozoic volcanic activity.

Uses & applications

Used for ornamental carvings, polished freeforms, cabochons, beads, and collector specimens; it has little structural or industrial use beyond decorative stone.

Geological facts

The name “ocean jasper” is a trade name, not a single formally defined mineral species. Its distinctive circles and flowing patterns result from repeated silica deposition, brecciation, and mineral replacement.

Field identification & locations

Identify it by its opaque multicolor orbicular or scenic patterns, smooth polish, and quartz-like hardness; common localities include northwest Madagascar, especially the remote Marovato region. Acid and scratch testing should be avoided on finished pieces.