metamorphic

Serpentinite (likely antigorite-rich)

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

AI-generated identification · may be incorrect

Dark green to black, waxy-to-submetallic luster, massive and strongly fractured; Mohs hardness about 2.5–4, with no obvious cleavage and a generally low-to-moderate specific gravity (about 2.5–2.7). The metallic sheen may reflect magnetite or polished serpentine surfaces.

Identified September 4, 2026More metamorphic →

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At a glance

Common name: Serpentinite (likely antigorite-rich)
Scientific name: Serpentinite; chiefly serpentine-group minerals, Mg₃Si₂O₅(OH)₄, with possible magnetite and minor chromite
Category: metamorphic
Identified: September 4, 2026
Method: Standard

AI Estimated Value

About $10–$50 for a common hand specimen; $50–$200+ for polished, large, or well-documented locality specimens.

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 ultramafic mantle rocks such as peridotite undergo hydration and metamorphic alteration, commonly along oceanic crust, subduction zones, and faults. Serpentinization occurs from the Precambrian to the present; the specimen’s exact age cannot be determined visually.

Uses & applications

Used as decorative and ornamental stone, carvings, countertops, and sometimes jewelry; massive material has limited industrial value compared with asbestos-bearing serpentinite. Collectible value is usually modest unless unusually attractive or locality-documented.

Geological facts

Serpentinite can contain magnetite and may be weakly magnetic. Some varieties contain fibrous chrysotile asbestos, so avoid cutting, drilling, sanding, or generating dust without proper controls.

Field identification & locations

Identify by its dark green-black color, waxy appearance, softness, slick feel, and possible magnetism; a steel knife may scratch it. Commonly found in California, Italy, New Zealand, Canada, and other tectonic belts; definitive identification requires hardness, magnetism, and ideally mineralogical testing.