metamorphic
Serpentinite
Serpentinite; chiefly serpentine-group minerals (chrysotile, lizardite, antigorite), commonly with magnetite, brucite, and relict olivine/pyroxene
AI-generated identification · may be incorrectTypically dark green to gray-green, waxy to greasy luster, massive or weakly fibrous, Mohs hardness about 2.5–4, and specific gravity roughly 2.5–2.6. The specimen’s mottled green-gray surface and rusty brown oxidation are characteristic, though image-only identification is provisional.
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Physical properties
Typically dark green to gray-green, waxy to greasy luster, massive or weakly fibrous, Mohs hardness about 2.5–4, and specific gravity roughly 2.5–2.6. The specimen’s mottled green-gray surface and rusty brown oxidation are characteristic, though image-only identification is provisional.
Formation & geological history
Forms when mantle peridotite is hydrated and metamorphosed by water, commonly along oceanic crust, faults, and subduction zones; ages range from Precambrian to modern tectonic settings. It commonly occurs in ophiolites and metamorphic belts.
Uses & applications
Used as decorative stone, carvings, countertops, and historically for ornamental objects; asbestos-bearing varieties require caution and are unsuitable for cutting or dust-producing work.
Geological facts
Often weakly magnetic because of magnetite and may show a waxy, slick feel. Some serpentinite varieties contain chrysotile asbestos, which cannot be confirmed from the photograph.
Field identification & locations
Common in California, the Appalachians, the Alps, New Zealand, and ophiolite complexes worldwide; distinguish it from greenstone by its waxy texture, mottled pattern, and possible magnetic response. A hardness, streak, magnetism, and asbestos-safe laboratory test would improve identification.
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