metamorphic

Serpentinite

Serpentinite; chiefly serpentine-group minerals (antigorite, lizardite, chrysotile), commonly with magnetite and minor chromite

AI-generated identification · may be incorrect

Typically dark green to black, mottled or waxy, with dull to greasy luster; Mohs hardness about 2.5–4, massive texture, and no obvious cleavage. The specimen’s green-black mottling is consistent with polished or naturally smoothed serpentinite.

Identified September 7, 2026More metamorphic →

Explore Serpentinite in the encyclopedia →

Identify your own rocks.

Get a report just like this from any photo, free.

App Store Google Play

Physical properties

Formation & geological history

Forms when ultramafic mantle rocks such as peridotite hydrate during metamorphism, commonly along tectonic plate boundaries and ophiolites. It can form from Precambrian to modern geological ages.

Uses & applications

Used as an ornamental and carving stone, architectural facing, countertops, and occasionally jewelry; asbestos-bearing varieties require health precautions. Common specimens generally have modest collector value.

Geological facts

Serpentinite is often magnetic because hydration reactions produce magnetite and can release hydrogen. Some varieties resemble jade, but serpentinite is generally softer and less durable.

Field identification & locations

Common in ophiolite belts and subduction-related terranes, including California, Italy, New Zealand, Canada, and the Appalachians. Field clues include green-black color, greasy feel, low hardness, veining, and possible magnetism; confirmation requires mineralogical testing.