mineral

Polished Ocean Jasper (orbicular jasper)

Microcrystalline quartz/chalcedony (SiO₂) with iron oxides and other inclusions

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; multicolored brown, cream, gray-green, and reddish areas with a waxy to vitreous luster. It is cryptocrystalline, opaque, and lacks cleavage, commonly displaying orbicular or brecciated patterns.

Identified August 16, 2026More mineral →

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Physical properties

Formation & geological history

Formed when silica-rich fluids replaced or cemented volcanic material, with iron and other minerals creating the colors and patterns. Classic ocean jasper formed in Miocene volcanic rocks of Madagascar, roughly 5–25 million years old.

Uses & applications

Used for cabochons, beads, carvings, polished specimens, and ornamental objects. Common-quality pieces generally have modest jewelry and collector value.

Geological facts

The green portion may contain celadonite, chlorite, or other alteration minerals; the reddish-brown colors commonly reflect iron oxides. True orbicular ocean jasper is especially prized for distinct circular patterns.

Field identification & locations

Identify it by its opaque, fine-grained silica body, curved fractures, lack of cleavage, and patterned orbs/brecciation; it should not show large exposed crystals. Commonly found in Madagascar, with similar jasper occurring worldwide.