mineral

Polished orbicular jasper (likely ocean jasper)

Silicified volcanic rock; predominantly microcrystalline quartz/chalcedony (SiO₂) with iron oxides and possible feldspar/zeolite inclusions

AI-generated identification · may be incorrect

Black, cream, tan, and rust-colored orbicules in a polished surface; waxy to vitreous luster, opaque, no visible cleavage, Mohs hardness about 6.5–7, specific gravity roughly 2.5–2.7. The rounded cream spots are characteristic silica-rich spherulites or replaced cavities.

Identified August 30, 2026More mineral →

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At a glance

Common name: Polished orbicular jasper (likely ocean jasper)
Scientific name: Silicified volcanic rock; predominantly microcrystalline quartz/chalcedony (SiO₂) with iron oxides and possible feldspar/zeolite inclusions
Category: mineral
Identified: August 30, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a small polished stone; $30–$150+ for unusually vivid, well-patterned cabochons or specimens.

Not an official valuation

AI estimate for general interest only — not an appraisal. Actual value depends on condition, provenance, and market demand. Verify with a professional before buying, selling, or insuring.

This identification was generated by AI and may contain errors. Verify important details before relying on them — and never use an AI result to judge whether a specimen is safe to handle. Read the full disclaimer

Physical properties

Formation & geological history

Forms when silica-rich fluids silicify volcanic tuff or rhyolitic material, producing orbicular patterns; Madagascar ocean jasper is generally Cenozoic, commonly Miocene to Oligocene in age. Exact locality cannot be confirmed from the image.

Uses & applications

Used as a lapidary material for cabochons, beads, carvings, polished stones, and ornaments; it is not generally used as structural stone.

Geological facts

“Ocean jasper” is a trade name rather than a single strictly defined mineral species. Orbicular patterns vary greatly, and some similar material is sold as orbicular jasper from Mexico, Australia, or Indonesia.

Field identification & locations

Identify it by its hardness, opaque chalcedony matrix, and contrasting concentric or radiating orbicules; a steel file should barely scratch it, while glass may be scratched. Common sources include Madagascar, Mexico, Australia, and Indonesia.