mineral

Tumbled ocean jasper (orbicular jasper), probable

Microcrystalline quartz (SiO₂) with iron oxides and accessory minerals

AI-generated identification · may be incorrect

Opaque, polished/tumbled stone with gray, cream, brown, and dark blue-green patches; vitreous to waxy luster. Mohs hardness 6.5–7, cryptocrystalline quartz structure, no visible cleavage, specific gravity about 2.6.

Identified August 23, 2026More mineral →

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Physical properties

Formation & geological history

Forms when silica-rich fluids replace or fill volcanic rock, commonly producing orbicular patterns through rhythmic mineral growth; many ocean jasper specimens formed in Miocene volcanic environments of Madagascar. Exact age depends on locality.

Uses & applications

Used for cabochons, beads, carvings, tumbling, and decorative objects; common pieces have modest collector value.

Geological facts

“Ocean jasper” is a trade name rather than one strictly defined mineral species; its patterns may include quartz, chalcedony, feldspar, zeolites, and iron oxides.

Field identification & locations

Identify by its opaque, fine-grained texture, glassy polish, hardness, and resistance to scratching by a steel knife; it should not show the translucent banding typical of agate. Common sources include Madagascar, Australia, Mexico, and the western United States.