metamorphic

Tumbled greenstone (likely serpentine or chlorite-rich metamorphic rock)

Serpentinite, approximately Mg₃Si₂O₅(OH)₄, or chlorite-rich greenstone

AI-generated identification · may be incorrect

Dark green to black, fine-grained, mottled, and dull to waxy; likely Mohs hardness 3–5, with no visible cleavage and a compact crystalline texture. The rounded shape and smooth surface indicate tumbling or water wear.

Identified August 17, 2026More metamorphic →

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At a glance

Common name: Tumbled greenstone (likely serpentine or chlorite-rich metamorphic rock)
Scientific name: Serpentinite, approximately Mg₃Si₂O₅(OH)₄, or chlorite-rich greenstone
Category: metamorphic
Identified: August 17, 2026
Method: Standard

AI Estimated Value

Typically $3–$20 for a small tumbled stone; $20–$75 if unusually attractive, well-polished, or sold as collectible serpentine.

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

Serpentinite forms when ultramafic rocks such as peridotite are altered by hydrothermal fluids, commonly along tectonic plate boundaries; chlorite-rich greenstones form during low-grade metamorphism. Exact age and identity require testing.

Uses & applications

Used for carvings, beads, landscaping, and decorative stone; attractive pieces may be sold as ornamental or lapidary material rather than high-value gemstones.

Geological facts

The specimen resembles common serpentine/greenstone but cannot be identified conclusively from a photograph. Serpentine may contain magnetite and can show a characteristic waxy polish.

Field identification & locations

Look for a green-black color, fine mottling, waxy luster, low hardness, and possible white veining; a streak, hardness, density, magnetism, and acid test can distinguish it from jade or basalt. Common sources include California, Italy, New Zealand, Canada, and serpentinite belts worldwide.