metamorphic

Serpentinized ultramafic rock (serpentinite)

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

AI-generated identification · may be incorrect

Typically green to yellow-green, mottled, waxy to greasy luster, and massive rather than visibly crystalline; Mohs hardness about 2.5–4, with uneven fracture and variable density. The rounded specimen appears heavily weathered and may contain darker relic ultramafic minerals.

Identified September 6, 2026More metamorphic →

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At a glance

Common name: Serpentinized ultramafic rock (serpentinite)
Scientific name: Serpentinite; chiefly serpentine-group minerals, Mg₃Si₂O₅(OH)₄, with possible magnetite, olivine, pyroxene, and brucite
Category: metamorphic
Identified: September 6, 2026
Method: Standard

AI Estimated Value

About $10–$75 for a common rounded specimen; $100–$500+ for large, polished, unusually patterned, or documented 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 or other ultramafic rock is hydrated and metamorphosed by fluids, commonly along tectonic plate boundaries and ophiolites. Serpentinization can occur from the Precambrian to the present; this specimen’s age cannot be determined from the image.

Uses & applications

Used as decorative stone, carvings, countertops, and historically as a source of asbestos-bearing serpentine; attractive varieties are collected, though fibrous material should not be cut or powdered.

Geological facts

Often feels unusually smooth or soapy and may leave a pale green streak; magnetite can make some pieces weakly magnetic. Common associated minerals include chromite, talc, and carbonate veins.

Field identification & locations

Common in ophiolite belts, alpine regions, California, Italy, New Zealand, and parts of Canada. Confirm with a hardness test, streak, weak magnetism, and mineralogical analysis; visual identification is not definitive.