rock

Orbicular jasper

Siliceous microcrystalline quartz (chalcedony), commonly sold as ocean jasper

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque blue-green, cream, orange, and gray orbicular pattern with a waxy to dull luster. It consists mainly of cryptocrystalline quartz with radiating or concentric inclusions and minor iron oxides, clay, or other silicates.

Identified September 20, 2026More rock →

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Physical properties

Formation & geological history

A silica-rich volcanic or hydrothermal rock formed when chalcedony and related minerals filled cavities or replaced material in volcanic rocks; many ocean-jasper specimens formed in Miocene volcanic terrains of Madagascar. Exact age and locality cannot be confirmed from the image.

Uses & applications

Used as a lapidary stone for cabochons, beads, carvings, polished slices, and decorative specimens; it is not generally used as a construction stone.

Geological facts

The distinctive orbs are produced by repeated mineral growth, replacement, and inclusion of contrasting materials. “Ocean jasper” is a commercial name rather than a single precisely defined mineral species.

Field identification & locations

Identify by its opaque body, multicolored concentric orbs, silica-like hardness, and lack of obvious cleavage; a scratch test and locality information help distinguish it from orbicular rhyolite or dyed material. Common examples come from Madagascar, Mexico, and Australia.