metamorphic

Serpentine-rich ultramafic rock (likely serpentinite)

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

AI-generated identification · may be incorrect

Pale green-gray, massive, smooth and waxy to dull luster, with rusty brown alteration and sparkling granular patches. Typically Mohs 2.5–4, low to moderate specific gravity, and no obvious cleavage; composition and hardness vary with accessory minerals.

Identified September 21, 2026More metamorphic →

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At a glance

Common name: Serpentine-rich ultramafic rock (likely serpentinite)
Scientific name: Serpentinite; chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), with possible magnetite, carbonates, and relict olivine/pyroxene
Category: metamorphic
Identified: September 21, 2026
Method: Standard

AI Estimated Value

About $5–$30 for a common palm-sized specimen; $30–$150+ for especially colorful, polished, or well-patterned 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 mantle-derived peridotite is hydrothermally hydrated during seafloor alteration or subduction. It commonly represents ancient oceanic lithosphere, ranging from Precambrian to modern tectonic settings.

Uses & applications

Used as decorative stone, carvings, countertops, and occasionally as a source of magnesium or asbestos-bearing material; attractive pieces are collected. Avoid cutting or dust-producing work because some serpentinite contains chrysotile asbestos.

Geological facts

The green color results from serpentine minerals formed by adding water to olivine- and pyroxene-rich rocks. Dark metallic grains may be magnetite, while pale sparkling areas may be carbonate or quartz veins.

Field identification & locations

Common in ophiolites and tectonic shear zones, including California, Italy, New Zealand, and the Appalachians. A waxy green surface, relatively low hardness, and possible weak magnetism help distinguish it from ordinary greenstone.