metamorphic

Tumbled greenstone (probable serpentinite)

Serpentinite, chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), possibly with chlorite, magnetite, or talc

AI-generated identification · may be incorrect

Dark green to gray-green, mottled and waxy to dull luster; typically massive with no visible crystals, hardness about 2.5–4 Mohs, and specific gravity roughly 2.5–2.7. The rounded, polished shape indicates natural abrasion or tumbling.

Identified September 17, 2026More metamorphic →

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At a glance

Common name: Tumbled greenstone (probable serpentinite)
Scientific name: Serpentinite, chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), possibly with chlorite, magnetite, or talc
Category: metamorphic
Identified: September 17, 2026
Method: Standard

AI Estimated Value

About $2–$15 for a small tumbled specimen; $20–$100+ for well-carved, vividly patterned, or jewelry-grade material.

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

Forms when ultramafic mantle rocks, especially peridotite, undergo hydration during metamorphism in oceanic crust or subduction zones; formation ages vary widely from Paleozoic to modern tectonic belts.

Uses & applications

Used as carving stone, architectural facing, landscaping material, and ornamental jewelry; attractive dense pieces are sold as worry stones or pendants.

Geological facts

Serpentinite commonly contains magnetite, making some pieces weakly magnetic. Its green color and veining can resemble jade, but serpentinite is generally softer and less valuable.

Field identification & locations

Common in ophiolites and tectonic belts, including California, the Appalachian region, New Zealand, and the Alps. Test cautiously: it is softer than glass and may show a white streak; definitive identification requires hardness, density, and mineralogical testing.