metamorphic

Tumbled greenstone (likely serpentinite or green jasper)

Serpentinite, commonly dominated by serpentine-group minerals (Mg₃Si₂O₅(OH)₄); exact identification requires testing

AI-generated identification · may be incorrect

Olive-green, opaque, finely grained, and waxy to vitreous when wet or polished; typically Mohs 2.5–4, with no visible crystals or cleavage and moderate density. The rounded shape indicates tumbling or natural water wear.

Identified August 14, 2026More metamorphic →

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At a glance

Common name: Tumbled greenstone (likely serpentinite or green jasper)
Scientific name: Serpentinite, commonly dominated by serpentine-group minerals (Mg₃Si₂O₅(OH)₄); exact identification requires testing
Category: metamorphic
Identified: August 14, 2026
Method: Standard

AI Estimated Value

About $5–$25 for a common tumbled specimen; $25–$75 if unusually attractive, large, or locality-documented.

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 serpentinite, it formed when ultramafic mantle rock was hydrothermally altered, commonly during oceanic crust formation and later tectonic uplift. If green jasper, it is silica-rich microcrystalline quartz formed from mineral-rich sediment or volcanic fluids; age depends on locality.

Uses & applications

Used as a decorative stone, carving material, ornamental aggregate, and collectible; some varieties are made into cabochons or beads. It has limited industrial value as a small polished specimen.

Geological facts

The image alone cannot reliably distinguish serpentinite from green jasper or other greenstone. A streak, hardness, density, and acid/microscope examination would improve identification.

Field identification & locations

Common sources include California, Oregon, Washington, New Zealand, Italy, and many ophiolite belts for serpentinite; green jasper occurs worldwide. Serpentinite scratches with a steel knife, whereas jasper generally scratches glass.