metamorphic

Serpentine-rich altered rock

Serpentinite, likely with chlorite and magnetite; exact identification requires testing

AI-generated identification · may be incorrect

Typically dark green to black, mottled, waxy to greasy luster, and massive rather than visibly crystalline; Mohs hardness about 2.5–4, with variable specific gravity around 2.5–2.6. The wet surface enhances its green coloration and luster.

Identified September 21, 2026More metamorphic →

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Physical properties

Formation & geological history

Forms when ultramafic mantle rocks, especially peridotite, are hydrated and metamorphosed by hydrothermal fluids; commonly Paleozoic to younger, depending on its tectonic setting.

Uses & applications

Used as decorative stone, carving material, countertops, and historically as a source of asbestos-bearing minerals; attractive pieces are collected as lapidary specimens.

Geological facts

Serpentinite is named for its snake-skin-like mottling and often contains antigorite, lizardite, or chrysotile. Chrysotile-bearing material should not be cut, drilled, or powdered because its dust can be hazardous.

Field identification & locations

Common in ophiolites and subduction-zone mélanges, including California, Italy, New Zealand, and the Appalachians. A relatively soft green stone that may scratch with a steel knife and can show a pale streak is consistent with serpentinite.