metamorphic

Likely serpentinized ultramafic rock (serpentinite)

Serpentinite; chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), with possible olivine, pyroxene, magnetite, and talc

AI-generated identification · may be incorrect

Dark olive-green to black, mottled and locally waxy or slightly greasy; typically Mohs 2.5–4, with variable luster and poorly visible crystals. The specimen’s granular, green-black appearance is consistent with altered peridotite, though the image is not diagnostic.

Identified September 3, 2026More metamorphic →

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At a glance

Common name: Likely serpentinized ultramafic rock (serpentinite)
Scientific name: Serpentinite; chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), with possible olivine, pyroxene, magnetite, and talc
Category: metamorphic
Identified: September 3, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a common hand specimen; $30–$150 for attractive polished or unusual pieces.

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 mantle-derived peridotite is hydrated and metamorphosed by water, commonly along plate boundaries and ancient oceanic crust; ages range from Precambrian to modern tectonic settings.

Uses & applications

Used as decorative stone, carving material, aggregate, and occasionally as a source of magnesium or asbestos-bearing material; generally not a jewelry gemstone unless polished.

Geological facts

Serpentinite commonly contains magnetite, making some pieces weakly magnetic, and may host chrysotile asbestos; avoid cutting, sanding, or generating dust without proper controls.

Field identification & locations

Common in ophiolite belts, subduction zones, and mountain cores, including California, Italy, New Zealand, and the Appalachians. Confirm with a hardness test, streak, magnet test, and ideally thin-section or X-ray analysis.