gemstone

Green cabochon gemstone, likely prehnite or green quartz

Probable prehnite (Ca₂Al₂Si₃O₁₀(OH)₂); identification is uncertain because the specimen is enclosed and strongly flash-reflective

AI-generated identification · may be incorrect

Pale yellow-green, translucent, vitreous-to-waxy luster, polished cabochon with no visible crystal faces. Prehnite hardness is 6–6.5 Mohs, specific gravity about 2.80–2.95, and typically has poor cleavage; internal veils or fractures are visible.

Identified September 12, 2026More gemstone →

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At a glance

Common name: Green cabochon gemstone, likely prehnite or green quartz
Scientific name: Probable prehnite (Ca₂Al₂Si₃O₁₀(OH)₂); identification is uncertain because the specimen is enclosed and strongly flash-reflective
Category: gemstone
Identified: September 12, 2026
Method: Standard

AI Estimated Value

Approximately $5–$30 for a small common cabochon; $30–$100+ for unusually clear, attractive natural prehnite.

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

If prehnite, it formed in low-temperature hydrothermal cavities in basaltic volcanic rocks, commonly alongside zeolites; deposits are generally Cenozoic to older, depending on locality. The stone has been cut and mounted in a small transparent container or setting.

Uses & applications

Used for cabochons, beads, carvings, and mineral collecting; attractive translucent green material has modest jewelry value.

Geological facts

The olive-green color and cloudy translucence are compatible with prehnite, but glass, chrysoprase, green fluorite, or treated quartz are possible alternatives. A refractive-index, hardness, and specific-gravity test would be needed for reliable identification.

Field identification & locations

Common sources include Australia, South Africa, China, India, and the United States. Test only an inconspicuous edge: prehnite should resist a steel knife but be scratched by quartz; avoid testing the container or setting.