mineral

Polished ocean jasper (orbicular jasper)

Microcrystalline quartz (SiO₂) with chalcedony, iron oxides, and assorted silicate inclusions

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; opaque to slightly translucent, with a waxy to glassy luster and cream, blue-gray, yellow, orange, and red coloration. The specimen shows brecciated, orbicular-like patterns rather than visible crystal faces; no cleavage.

Identified August 12, 2026More mineral →

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Physical properties

Formation & geological history

Formed when silica-rich fluids replaced or cemented volcanic rock, with iron-oxide staining and mineral-rich cavities producing the colorful patterns. Classic Madagascar ocean jasper formed in Oligocene–Miocene volcanic sequences, roughly 5–30 million years old.

Uses & applications

Used for lapidary carvings, polished spheres, cabochons, jewelry, and ornamental objects; it has little industrial value.

Geological facts

Ocean jasper is strongly associated with remote coastal deposits near Marovato, Madagascar, and was historically collected from shoreline exposures. “Jasper” is a trade name for opaque, impure chalcedony or microcrystalline quartz.

Field identification & locations

Identify it by its high polish, quartz-like hardness, opaque multicolor body, and irregular or orbicular patterns; genuine pieces commonly show natural pits or seams. Common sources include Madagascar, Oregon, Mexico, India, and Brazil.