metamorphic
Serpentinite with carbonate and iron-oxide alteration
Serpentinite; chiefly antigorite/lizardite Mg₃Si₂O₅(OH)₄, with magnetite, calcite, and chromian minerals
AI-generated identification · may be incorrectTypically dark green, brown, black, and reddish, with waxy to greasy luster and mottled veining; hardness about 2.5–4, massive rather than visibly crystalline, and variable specific gravity around 2.5–2.7. The rusty red-brown areas likely reflect iron oxidation, while pale patches may be carbonate.
Identified More metamorphic →
Explore Serpentinite with carbonate and iron-oxide alteration in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Typically dark green, brown, black, and reddish, with waxy to greasy luster and mottled veining; hardness about 2.5–4, massive rather than visibly crystalline, and variable specific gravity around 2.5–2.7. The rusty red-brown areas likely reflect iron oxidation, while pale patches may be carbonate.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite are hydrated during metamorphism, commonly along oceanic crust and subduction zones; alteration may occur from Paleozoic to modern tectonic settings. The specimen may also contain brecciated or partly altered host rock.
Uses & applications
Used as decorative stone, carving material, aggregate, and historically as a source of asbestos-bearing minerals; attractive pieces are collected, though fibrous material should not be cut or powdered.
Geological facts
Serpentinite often contains magnetite and can be weakly magnetic. Its name comes from its snake-like mottled appearance, and some varieties host chromite, nickel, and talc deposits.
Field identification & locations
Look for a relatively soft, green-black waxy rock with slick surfaces, mottling, and possible magnetism; a steel nail may scratch it. Common occurrences include California, Italy, New Zealand, Canada, and oceanic ophiolites.
More like this
