mineral

Tumbled Ocean Jasper (likely)

Orbicular rhyolite/chalcedony aggregate; primarily microcrystalline quartz (SiO₂) with feldspar and iron-oxide inclusions

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; polished vitreous-to-waxy luster, pink, gray, white, and reddish zones, with irregular orbicular patterns. Massive, fine-grained structure with no obvious cleavage; specific gravity about 2.5–2.7.

Identified September 3, 2026More mineral →

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Physical properties

Formation & geological history

Forms from silica-rich volcanic lava, commonly with spherulitic or orbicular textures produced during cooling and later mineral-filled cavities. Classic material comes from Miocene volcanic rocks near Madagascar, though similar orbicular rhyolites occur elsewhere.

Uses & applications

Used as a low-cost lapidary stone for cabochons, beads, carvings, and tumbled specimens; mainly valued decoratively and by collectors.

Geological facts

The pictured piece appears polished and may be Ocean Jasper or a visually similar orbicular rhyolite; exact identification requires locality information or testing because several jaspers look alike.

Field identification & locations

Identify by its opaque multicolored body, rounded orbicular markings, and quartz-like hardness; it should not scratch easily with a steel knife. Ocean Jasper is chiefly associated with remote northwest Madagascar coastal deposits.