mineral

Polished ocean jasper (orbicular jasper)

Silica-rich chalcedony/quartz aggregate; chiefly microcrystalline SiO₂ with iron-oxide inclusions

AI-generated identification · may be incorrect

Typically hardness 6.5–7 Mohs, opaque, orange-yellow with white rounded orbicules and small cavities, and a vitreous to waxy luster after polishing. It has no visible cleavage and a cryptocrystalline structure; density is about 2.6 g/cm³.

Identified August 22, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich fluids fill volcanic cavities and fractures, producing chalcedony, quartz, and iron/mineral orbicules; Madagascar ocean jasper is mainly Cretaceous volcanic material. The specimen is tumbled and polished.

Uses & applications

Used for cabochons, beads, carvings, display stones, and lapidary collections; it is not generally used as a construction stone.

Geological facts

Ocean jasper is famous for concentric orbicular patterns and is strongly associated with Madagascar’s northwestern coast. Small vugs or pits may remain visible after polishing.

Field identification & locations

Identify it by its opaque orange, cream, and orbicular pattern, waxy polish, and quartz-like hardness; glass will scratch more easily. Common sources include Madagascar, Mexico, Brazil, and Australia.