sedimentary

Polished orbicular jasper (likely kambaba jasper)

Silicified microcrystalline quartz/chalcedony, commonly sold as Kambaba jasper; composition varies and may include quartz, chlorite, and iron oxides

AI-generated identification · may be incorrect

Typically dark green-black to black with gray-green orbicular swirls; opaque, glossy after polishing, cryptocrystalline, and lacks visible cleavage. Mohs hardness is about 6.5–7; specific gravity approximately 2.5–2.7.

Identified August 30, 2026More sedimentary →

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At a glance

Common name: Polished orbicular jasper (likely kambaba jasper)
Scientific name: Silicified microcrystalline quartz/chalcedony, commonly sold as Kambaba jasper; composition varies and may include quartz, chlorite, and iron oxides
Category: sedimentary
Identified: August 30, 2026
Method: Standard

AI Estimated Value

Approximately $10–$40 for a palm-sized polished common specimen; unusually vivid patterning or fine carving may reach $50–$150.

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

Formed from silica-rich volcanic or sedimentary material later replaced and cemented by chalcedony, with orbicular patterns from contrasting mineral-rich zones. Kambaba jasper is commonly associated with Proterozoic rocks of Madagascar, though commercial labels are variable.

Uses & applications

Used as a lapidary stone for cabochons, carvings, worry stones, spheres, and polished ornaments; it has minor collector and jewelry value.

Geological facts

The specimen is clearly polished and wet-looking, which enhances its black-and-gray contrast. “Jasper” is a trade term for opaque, microcrystalline silica rather than one single mineral species.

Field identification & locations

Identify it by its opaque body, curved orbicular banding, glassy-to-waxy polish, and hardness sufficient to scratch ordinary glass; it should not show bubbles or uniform glassy translucence. Common sources include Madagascar, Indonesia, Mexico, and the western United States.