metamorphic

Serpentinite

Serpentinite; chiefly serpentine-group minerals (lizardite, antigorite, chrysotile), often with magnetite and relict olivine/pyroxene

AI-generated identification · may be incorrect

Dark green to black, mottled and waxy to greasy luster, commonly showing fibrous or streaked textures; Mohs hardness about 2.5–4, with variable cleavage and specific gravity around 2.5–2.7. The specimen’s appearance is consistent with serpentinite, though a photo alone cannot confirm it.

Identified September 6, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when ultramafic mantle rocks such as peridotite undergo hydration and metamorphism, commonly along oceanic crust, subduction zones, and faults; ages range from Precambrian to recent tectonic settings.

Uses & applications

Used as decorative and architectural stone, carving material, aggregate, and historically as a source of asbestos when chrysotile-rich; attractive pieces may be collected or polished.

Geological facts

Often feels unusually smooth or waxy and may leave a pale green streak; magnetite can make some specimens weakly magnetic. Chrysotile-bearing material should not be cut, drilled, or powdered because fibers can be hazardous.

Field identification & locations

Common in ophiolites and metamorphic belts, including California, Italy, New Zealand, Canada, and the Appalachians. Distinguish it from jade by its lower hardness and waxier texture; acid reaction is generally absent.