sedimentary

Polished ocean jasper (orbicular jasper)

Silicified volcanic rock; chiefly microcrystalline quartz/chalcedony (SiO₂), with iron oxides and other alteration minerals

AI-generated identification · may be incorrect

Typically hardness 6.5–7 Mohs, opaque gray to cream with rounded orbicular patterns, black/white inclusions, and a waxy to vitreous polish; no visible cleavage, conchoidal fracture, specific gravity about 2.5–2.7.

Identified September 12, 2026More sedimentary →

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At a glance

Common name: Polished ocean jasper (orbicular jasper)
Scientific name: Silicified volcanic rock; chiefly microcrystalline quartz/chalcedony (SiO₂), with iron oxides and other alteration minerals
Category: sedimentary
Identified: September 12, 2026
Method: Standard

AI Estimated Value

About $10–$40 for a small polished stone; $50–$150+ for unusually vivid, well-patterned 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 altered volcanic material, producing orbicular textures; most commercial material comes from Olegasqueira, Madagascar, generally of Mesozoic age. The pictured piece is a polished, shaped specimen.

Uses & applications

Used for cabochons, carvings, worry stones, spheres, and decorative objects; valued mainly by pattern, color, polish, and size.

Geological facts

“Ocean jasper” is a trade name rather than a single formally defined mineral. Orbicular rings and radiating patterns reflect repeated mineral growth during silica replacement.

Field identification & locations

Identify it by its opaque gray/cream base, rounded orbicules, fine-grained texture, and inability to scratch with a copper coin; glass should not scratch it, while quartz can. Common sources include Madagascar, Mexico, and Indonesia.