metamorphic

Polished orbicular jasper (likely kambaba jasper)

Silicified microcrystalline quartz/chalcedony, commonly with chlorite- or amphibole-rich orbicules; composition varies

AI-generated identification · may be incorrect

Hardness about 6.5–7 Mohs; dark green to black with brown-red patches and rounded green orbicules, a waxy-to-glassy luster, and no visible cleavage. The specimen is highly polished and its exact identity cannot be confirmed from appearance alone.

Identified August 13, 2026More metamorphic →

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At a glance

Common name: Polished orbicular jasper (likely kambaba jasper)
Scientific name: Silicified microcrystalline quartz/chalcedony, commonly with chlorite- or amphibole-rich orbicules; composition varies
Category: metamorphic
Identified: August 13, 2026
Method: Standard

AI Estimated Value

Approximately $10–$40 for a palm-sized polished specimen; $50–$100 for larger, high-quality examples.

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 by silica-rich fluids replacing or cementing volcanic material, with orbicules developing during alteration; commonly Precambrian or older, depending on locality. Kambaba jasper is especially associated with Madagascar.

Uses & applications

Used as a cabochon, lapidary ornament, worry stone, or decorative polished stone; not generally used as structural stone. Common polished pieces typically sell for about $10–$40, with larger or unusually patterned specimens reaching $50–$100.

Geological facts

The circular markings are orbicules, produced by concentric mineral growth or alteration rather than fossils. “Jasper” is a trade term for opaque, impurity-rich chalcedony and can encompass several visually similar materials.

Field identification & locations

Identify it by its opaque dark-green body, rounded mottling, fine-grained texture, and quartz-like hardness; a scratch test, streak test, and locality information help distinguish it from serpentine, basalt, or dyed stone. Common sources include Madagascar, South Africa, Australia, and Mexico.