mineral

Tumbled green-yellow chalcedony (likely prehnite or serpentine)

Cryptocrystalline quartz (chalcedony), SiO₂; identification is uncertain from the photograph

AI-generated identification · may be incorrect

Translucent olive-green to yellow, smooth tumbled surface, vitreous-to-waxy luster, and no visible crystal faces or cleavage. Likely hardness about 6–7 Mohs if chalcedony; the rounded shape is human-processed.

Identified August 25, 2026More mineral →

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At a glance

Common name: Tumbled green-yellow chalcedony (likely prehnite or serpentine)
Scientific name: Cryptocrystalline quartz (chalcedony), SiO₂; identification is uncertain from the photograph
Category: mineral
Identified: August 25, 2026
Method: Standard

AI Estimated Value

About $1–$10 for a small ordinary tumbled stone; $10–$50 if confirmed as attractive natural chrysoprase or high-quality 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

Chalcedony forms when silica-rich groundwater fills cavities and fractures, commonly in volcanic rocks; deposits range from ancient to geologically recent. Similar green material may instead be prehnite or serpentine, requiring hardness and refractive tests.

Uses & applications

Used as a decorative tumbled stone, cabochon, carving material, and inexpensive jewelry stone; chalcedony is also used for ornamental objects.

Geological facts

Green chalcedony is often marketed as chrysoprase when its color is strong and nickel-related. The image alone cannot reliably distinguish it from dyed agate, prehnite, or serpentine.

Field identification & locations

Test an inconspicuous area: chalcedony scratches glass and does not scratch easily with steel; serpentine is much softer. Common sources include Brazil, India, Madagascar, Australia, and the United States.