mineral

Polished orbicular jasper (likely ocean jasper)

Silica-rich microcrystalline quartz/chalcedony with iron oxides and accessory minerals; SiO₂-dominant

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; polished, vitreous to waxy luster with red-brown, cream, gray, and dark orbicular patterns. It is cryptocrystalline, massive, and lacks visible cleavage; specific gravity is typically 2.55–2.70.

Identified August 28, 2026More mineral →

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Physical properties

Formation & geological history

Forms as silica-rich volcanic material or hydrothermal replacement, with iron-oxide and mineral inclusions producing the rounded patterns; most ocean jasper formed in ancient volcanic rocks of Madagascar, commonly Mesozoic to Paleozoic in age.

Uses & applications

Used for cabochons, beads, carvings, tumbling, and ornamental objects; durable but less valuable than fine agate or jasper varieties.

Geological facts

Orbicular patterning results from concentric mineral growth or alteration around nuclei, not fossils. “Ocean jasper” is a trade name rather than a distinct mineral species.

Field identification & locations

Identify it by its opaque polished body, multicolored concentric orbs, and absence of transparency or cleavage; confirm with a hardness test on an inconspicuous spot. Comparable orbicular jasper also occurs in Mexico, Australia, and the United States.