metamorphic
Serpentinized ultramafic rock (serpentinite)
Serpentinite; chiefly serpentine-group minerals, Mg₃Si₂O₅(OH)₄, with possible magnetite, chromite, talc, and carbonate
AI-generated identification · may be incorrectTypically green, gray, black, or mottled with waxy to greasy luster; Mohs hardness about 2.5–4, poor cleavage, massive or fibrous crystal texture, and specific gravity roughly 2.5–2.7. The image’s rounded, pale green mottling and dark veins are consistent with weathered serpentinite, though exact identification require…
Identified More metamorphic →
Explore Serpentinized ultramafic rock (serpentinite) in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Typically green, gray, black, or mottled with waxy to greasy luster; Mohs hardness about 2.5–4, poor cleavage, massive or fibrous crystal texture, and specific gravity roughly 2.5–2.7. The image’s rounded, pale green mottling and dark veins are consistent with weathered serpentinite, though exact identification requires testing.
Formation & geological history
Forms when mantle-derived peridotite is hydrated and metamorphosed during seafloor alteration or mountain-building, commonly along plate boundaries and fault zones. Formation ages vary widely, from Precambrian to modern tectonic settings.
Uses & applications
Used as decorative and architectural stone, carvings, aggregates, and historically as a source of asbestos-bearing material; gem-quality varieties may be polished as ornamental stone.
Geological facts
Serpentinite can contain magnetite and may be weakly magnetic; some varieties contain hazardous chrysotile asbestos. It is California’s state rock.
Field identification & locations
Common in ophiolites and tectonic mélanges, especially California, Italy, New Zealand, and parts of Canada. Field clues include a smooth waxy surface, green-black mottling, low hardness, and occasional magnetism; avoid cutting or sanding unknown specimens.
More like this
