sedimentary

Polished orbicular jasper (likely ocean jasper)

Silicified volcanic rock; chiefly microcrystalline quartz (SiO₂), with feldspar and iron-rich alteration minerals

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; blue-green to gray matrix with pale rounded orbicules, vitreous to waxy luster, and no obvious cleavage. The rounded, polished shape obscures its original texture and makes exact identification uncertain.

Identified August 8, 2026More sedimentary →

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At a glance

Common name: Polished orbicular jasper (likely ocean jasper)
Scientific name: Silicified volcanic rock; chiefly microcrystalline quartz (SiO₂), with feldspar and iron-rich alteration minerals
Category: sedimentary
Identified: August 8, 2026
Method: Standard

AI Estimated Value

About $5–$25 for a small tumbled or polished specimen; $25–$100+ for larger pieces with vivid, well-defined orbicules.

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 replace and cement volcanic material, producing orbicular patterns; commonly associated with Oligocene–Miocene volcanic rocks of Madagascar. Similar orbicular jaspers occur worldwide.

Uses & applications

Used for cabochons, beads, carvings, and decorative polished stones; occasionally sold as a lapidary collectible rather than a construction stone.

Geological facts

Ocean jasper is prized for concentric or spherical orbicules, though the trade name is applied broadly to patterned jasper. A quartz-rich composition gives it good polish and durability.

Field identification & locations

Look for rounded pale or colored orbs within a fine-grained opaque matrix, high polish, and lack of visible glassy transparency; verify with a scratch test only on an unimportant area. Common sources include Madagascar, Mexico, Oregon, and Australia.