metamorphic
Serpentine (likely serpentinized ultramafic rock)
Serpentine-group minerals, chiefly antigorite, lizardite, or chrysotile; commonly derived from peridotite
AI-generated identification · may be incorrectTypically olive-green to gray-green, waxy to dull luster, Mohs hardness about 2.5–4, massive rather than visibly crystalline, with irregular fractures and occasional fibrous veining. The specimen’s mottled green color and smooth weathered surface fit serpentine, though image-only identification is provisional.
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Physical properties
Typically olive-green to gray-green, waxy to dull luster, Mohs hardness about 2.5–4, massive rather than visibly crystalline, with irregular fractures and occasional fibrous veining. The specimen’s mottled green color and smooth weathered surface fit serpentine, though image-only identification is provisional.
Formation & geological history
Forms when mantle-derived peridotite or pyroxenite reacts with water during hydrothermal alteration and low-temperature metamorphism, commonly along oceanic crust and tectonic fault zones. It can range from Precambrian to modern tectonic settings.
Uses & applications
Used as an ornamental and carving stone, architectural facing, countertops, and historically for decorative objects; fibrous chrysotile varieties are asbestos-bearing and hazardous when disturbed.
Geological facts
Serpentinite commonly contains magnetite and may be weakly magnetic; its name refers to a snake-like appearance. It is California’s state rock.
Field identification & locations
Common in California, the Appalachians, the Alps, New Zealand, and ophiolite belts worldwide. Confirm with a streak, hardness, density, acid test, and ideally Raman/XRD analysis; avoid generating dust.
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