metamorphic

Tumbled greenstone/serpentine pebble

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

AI-generated identification · may be incorrect

Pale green, rounded, opaque, and dull to waxy with a fine-grained massive texture; serpentine has Mohs hardness about 2.5–4 and no visible cleavage. The photograph is insufficient to confirm composition, and similar-looking greenstones include nephrite and altered volcanic rock.

Identified September 14, 2026More metamorphic →

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At a glance

Common name: Tumbled greenstone/serpentine pebble
Scientific name: Serpentinite, chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), possibly with chlorite or talc
Category: metamorphic
Identified: September 14, 2026
Method: Standard

AI Estimated Value

About $1–$10 for a common tumbled pebble; $20–$100+ if verified as attractive carving-grade serpentine 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

Typically forms when ultramafic mantle rocks are hydrated and metamorphosed, commonly in oceanic lithosphere and subduction-zone mélanges; ages range from Precambrian to modern tectonic settings.

Uses & applications

Used as decorative stone, carvings, beads, and minor architectural material; high-quality tougher varieties may be sold as greenstone, while ordinary pebbles have little commercial value.

Geological facts

Serpentinite often shows mottled green coloration and a slippery or waxy feel; some varieties contain magnetite and may be weakly magnetic.

Field identification & locations

Field clues include low hardness, pale green streak or powder, waxy luster, and reaction to neither dilute acid nor a steel knife strongly; hardness and density testing can distinguish it from jade. Common in ophiolites and tectonic fault zones.