metamorphic
Serpentinite
Serpentinite; chiefly serpentine-group minerals (antigorite, lizardite, chrysotile), with magnetite and remnants of olivine/pyroxene
AI-generated identification · may be incorrectTypically mottled green, black, cream, and yellow with waxy to greasy luster; massive, fine- to coarse-grained, Mohs hardness about 2.5–4, with poor or absent cleavage. This rounded specimen may also contain talc, carbonate, or chromite, producing the dark patches and pale areas.
Identified More metamorphic →
Explore Serpentinite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Typically mottled green, black, cream, and yellow with waxy to greasy luster; massive, fine- to coarse-grained, Mohs hardness about 2.5–4, with poor or absent cleavage. This rounded specimen may also contain talc, carbonate, or chromite, producing the dark patches and pale areas.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite undergo hydration and metamorphism, commonly along oceanic crust and subduction-zone faults. Serpentinization spans much of Earth history, from Precambrian rocks to active seafloor systems.
Uses & applications
Used as ornamental and lapidary stone, countertops, carvings, tumbled stones, and historically as a source of asbestos-bearing material; industrial use is limited because chrysotile may be hazardous when fibers become airborne.
Geological facts
Serpentinite can feel unusually smooth or greasy and is often weakly magnetic from magnetite. It commonly hosts chromite, nickel, platinum-group elements, and distinctive high-pressure minerals.
Field identification & locations
Identify it by green-black mottling, low hardness, waxy surface, and possible magnetism; a steel blade may scratch it. Common localities include California, Italy, New Zealand, the Alps, and many ancient ophiolite belts.
More like this
