mineral

Polished orbicular jasper (likely ocean jasper)

Jasper, microcrystalline quartz (SiO₂), with iron-oxide and other silicate inclusions

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque blue-gray body with yellow-orange orbicular patches and a smooth polished surface. Waxy to vitreous luster; cryptocrystalline quartz with no visible cleavage and conchoidal fracture.

Identified August 21, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich fluids cement volcanic ash or replace volcanic rock, with concentric mineral growth producing the orbicules; ocean jasper formed mainly in Oligocene–Miocene volcanic rocks of Madagascar. Exact identification is uncertain from the photograph alone.

Uses & applications

Used for cabochons, beads, carvings, polished stones, and collectibles; too variable and nonuniform for major construction use.

Geological facts

The circular patterns result from rhythmic replacement or radiating growth of quartz, feldspar, zeolites, and iron oxides—not fossils. “Ocean jasper” is a trade name rather than a single precisely defined mineral species.

Field identification & locations

Look for high opacity, rounded orbicules, a quartz-like polish, and inability to scratch it with a steel knife; it should not fizz in dilute acid. Common material comes from Madagascar, while orbicular jasper also occurs in Oregon, Mexico, and Australia.