metamorphic

Polished greenstone (likely serpentinite or chlorite-rich schist)

Serpentinite/chlorite-rich ultramafic metamorphic rock; composition commonly dominated by serpentine-group minerals, chlorite, magnetite, and minor amphibole or pyroxene

AI-generated identification · may be incorrect

Mohs hardness typically 2.5–5.5, mottled dark green, olive, brown, and black; waxy to glassy polished luster, fine-grained massive texture, and generally indistinct cleavage. The rounded shape and high sheen indicate tumbling or polishing.

Identified August 13, 2026More metamorphic →

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At a glance

Common name: Polished greenstone (likely serpentinite or chlorite-rich schist)
Scientific name: Serpentinite/chlorite-rich ultramafic metamorphic rock; composition commonly dominated by serpentine-group minerals, chlorite, magnetite, and minor amphibole or pyroxene
Category: metamorphic
Identified: August 13, 2026
Method: Standard

AI Estimated Value

About $5–$25 for a common polished palm stone; $30–$100+ for unusually attractive, large, or locally collectible 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 magnesium-rich ultramafic rocks are hydrated and metamorphosed, commonly in oceanic crust and subduction-zone mélanges; ages vary from ancient Precambrian to modern tectonic settings.

Uses & applications

Used as decorative stone, carvings, cabochons, worry stones, and occasionally architectural facing; generally modest lapidary value.

Geological facts

The photograph cannot distinguish serpentinite confidently from chlorite-rich schist or altered basalt; a streak, hardness, density, and thin-section test would help.

Field identification & locations

Look for green-black mottling, very fine texture, waxy feel, and possible magnetism from magnetite. Common sources include California, New Zealand, Italy, Canada, and major ophiolite belts.