mineral

Tumbled ocean jasper (orbicular/chalcedony-rich jasper)

Microcrystalline quartz, SiO₂, with iron oxides and variable volcanic inclusions

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; rounded and polished, with pale green, cream, pink, gray, and dark patches. Waxy to dull luster, cryptocrystalline structure, no visible cleavage, and conchoidal fracture; specific gravity about 2.6.

Identified August 13, 2026More mineral →

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Physical properties

Formation & geological history

Typically formed when silica-rich fluids filled cavities and fractures in volcanic rock, later developing iron-oxide and other mineral patterns; many commercial ocean jasper specimens come from Oligocene–Miocene volcanic rocks of Madagascar.

Uses & applications

Used as a lapidary stone for cabochons, carvings, beads, spheres, and decorative objects; it has modest jewelry and collector value.

Geological facts

“Ocean jasper” is a trade name rather than a single formally defined mineral species. Orbicular patterns, if present, result from concentric silica and mineral growth around nucleation centers.

Field identification & locations

Identify it by its opaque waxy appearance, polished rounded form, fine-grained texture, and mottled or orbicular colors; it should not show glassy quartz crystals. Commonly found in Madagascar, especially coastal volcanic localities, as well as other jasper-producing regions.