metamorphic

Likely serpentinized ultramafic rock (serpentinite)

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

AI-generated identification · may be incorrect

Dark olive-green, mottled, and waxy to slightly sparkly with a granular fractured surface; serpentine hardness is about 2.5–4 Mohs, nonmetallic luster, and commonly massive rather than visibly crystalline. The image is insufficient for a definitive identification;…

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 magnetite, brucite, and pyroxene
Category: metamorphic
Identified: September 3, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a common hand specimen; $30–$150+ for polished, unusually patterned, or locality-labeled 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 convergent-plate boundaries and oceanic fault zones. Serpentinization occurs from the Paleozoic to the present, depending on the host terrane.

Uses & applications

Used as decorative and architectural stone, carvings, countertops, and historically as a source of ornamental “verde antique”; attractive pieces are collected but usually have modest value.

Geological facts

Serpentinite is often associated with chromite, asbestos-forming minerals, and unusual high-pressure rocks. It may feel unusually dense and can show a greasy or waxy surface when freshly broken.

Field identification & locations

Common in ophiolites and major fault zones, including California, the Appalachians, New Zealand, and Greece. A streak, magnet, hardness, and acid test help distinguish it from greenstone; avoid cutting or sanding unknown material because some serpentinite contains fibrous asbestos.