mineral

Polished orbicular jasper (likely ocean jasper)

Jasper, microcrystalline quartz (SiO₂), with iron-oxide and volcanic-mineral inclusions

AI-generated identification · may be incorrect

Hardness 6.5–7 Mohs; opaque brown, gray, cream, and reddish-orange colors; waxy to vitreous luster; cryptocrystalline quartz with no cleavage and conchoidal fracture. The rounded, polished form is a tumbled specimen.

Identified August 16, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich fluids replace or cement volcanic ash and rock, with iron oxides producing the colors and orbicular patterns. Ocean jasper formed mainly in Miocene volcanic environments of Madagascar, roughly 5–20 million years ago.

Uses & applications

Used for cabochons, beads, carvings, lapidary pieces, and decorative stone. Small tumbled pieces commonly sell for about $2–$10; unusually patterned specimens may reach $20–$50.

Geological facts

Jasper is a variety of opaque chalcedony and microcrystalline quartz rather than a separate mineral species. Orbicular jasper is prized for concentric or radiating inclusion patterns.

Field identification & locations

Identify it by its opaque, fine-grained body, glassy/waxy polish, hardness, and lack of visible cleavage; it should resist scratching by a steel blade. Common sources include Madagascar, Brazil, India, Mexico, and the western United States.