metamorphic
Serpentinite (likely serpentinized ultramafic rock)
Serpentinite; chiefly serpentine-group minerals (antigorite, lizardite, chrysotile), commonly with magnetite and relict olivine/pyroxene
AI-generated identification · may be incorrectDark green to black, mottled and earthy-to-waxy luster with a massive texture; Mohs hardness about 2.5–4, generally low specific gravity, and no obvious cleavage. The reddish-brown patches may be iron oxides or weathered inclusions.
Identified More metamorphic →
Explore Serpentinite (likely serpentinized ultramafic rock) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Dark green to black, mottled and earthy-to-waxy luster with a massive texture; Mohs hardness about 2.5–4, generally low specific gravity, and no obvious cleavage. The reddish-brown patches may be iron oxides or weathered inclusions.
Formation & geological history
Forms when mantle-derived peridotite is hydrated and altered by hydrothermal fluids, commonly along ophiolites and plate boundaries; ages range from Precambrian to modern tectonic settings. A precise age requires locality information.
Uses & applications
Used as decorative stone, carving material, aggregate, and historically as dimension stone; fibrous chrysotile-bearing varieties have asbestos risks and should not be cut or powdered.
Geological facts
Often feels relatively soft and may leave a pale green streak or powder when scratched. Magnetite can make some specimens weakly magnetic.
Field identification & locations
Common in California, the Appalachian region, Italy, Greece, New Zealand, and ophiolite belts worldwide; identify by green-black color, waxy surface, softness, and possible magnetism. Confirmation requires thin-section or X-ray analysis.
More like this
