metamorphic

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

Serpentinite, commonly dominated by serpentine-group minerals; exact identification requires testing

AI-generated identification · may be incorrect

Dark olive-green, fine-grained, rounded and polished with a subdued waxy-to-satiny luster; serpentine has Mohs hardness 2.5–4 and no visible crystal structure or strong cleavage. The image alone cannot distinguish it confidently from chlorite schist, greenstone, or weathered basalt.

Identified September 16, 2026More metamorphic →

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At a glance

Common name: Tumbled greenstone (likely serpentinite or chlorite-rich metamorphic rock)
Scientific name: Serpentinite, commonly dominated by serpentine-group minerals; exact identification requires testing
Category: metamorphic
Identified: September 16, 2026
Method: Standard

AI Estimated Value

About $2–$15 for a small common tumbled piece; $20–$100+ for attractive patterned, polished, or provenance-rich specimens.

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 hydrate during metamorphism, often along tectonic plate boundaries and ophiolites; formation ages vary widely from Precambrian to recent tectonic settings.

Uses & applications

Used as decorative stone, carvings, beads, and small lapidary pieces; some serpentinite is quarried for architectural stone, though fibrous asbestos-bearing varieties require caution.

Geological facts

Serpentinite may show a greasy or waxy feel and can contain magnetite, producing weak magnetism. Avoid cutting or grinding unknown material because some varieties contain chrysotile asbestos.

Field identification & locations

Look for olive-green mottling, low hardness, waxy luster, and possible magnetism; a steel nail may scratch it, while vinegar usually produces little reaction. Common in California, Italy, New Zealand, Canada, and ophiolite belts worldwide.