metamorphic

Tumbled greenstone or serpentine pebble

Likely serpentinite, composed mainly of serpentine-group minerals (antigorite/lizardite); identification is uncertain from the image alone

AI-generated identification · may be incorrect

Pale green-gray, matte to waxy luster, rounded and naturally or artificially smoothed surface; hardness about 2.5–4 Mohs, generally massive with no visible crystal structure or cleavage, and specific gravity about 2.5–2.6.

Identified September 13, 2026More metamorphic →

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At a glance

Common name: Tumbled greenstone or serpentine pebble
Scientific name: Likely serpentinite, composed mainly of serpentine-group minerals (antigorite/lizardite); identification is uncertain from the image alone
Category: metamorphic
Identified: September 13, 2026
Method: Standard

AI Estimated Value

Approximately $1–$10 as a common small tumbled or naturally rounded specimen; $20–$100+ if confirmed as attractive carving-grade stone or jade-like 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

Serpentinite forms when ultramafic mantle rocks chemically alter through hydration, commonly during plate subduction; most examples are Paleozoic to Mesozoic or younger, depending on locality.

Uses & applications

Used as carving stone, ornamental material, and occasionally jewelry or tumbled-stone material; this small specimen has modest decorative value.

Geological facts

The green color results from hydrated magnesium silicate minerals and may vary from pale gray-green to deep mottled green. It can resemble nephrite jade, but is usually softer and less fibrous.

Field identification & locations

Common in ophiolites and tectonic zones, including California, Italy, New Zealand, and the Appalachians. A steel knife may scratch it; a vinegar test is usually ineffective, while waxy feel and green streaking favor serpentine.