metamorphic
Serpentine (polished/tumbled)
Serpentinite; chiefly antigorite, lizardite, and chrysotile, commonly with magnetite and carbonate minerals
AI-generated identification · may be incorrectTypically olive-green to yellow-green, mottled, waxy to greasy luster, Mohs hardness 2.5–4, and fine-grained to fibrous texture; this rounded specimen appears polished. Its low density and dark magnetite flecks are characteristic.
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Physical properties
Typically olive-green to yellow-green, mottled, waxy to greasy luster, Mohs hardness 2.5–4, and fine-grained to fibrous texture; this rounded specimen appears polished. Its low density and dark magnetite flecks are characteristic.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite undergo hydration during low-temperature metamorphism, commonly along oceanic crust and subduction zones. Serpentinization occurs from the Precambrian to the present.
Uses & applications
Used as ornamental stone, carvings, beads, countertops, and historically as a source of asbestos where chrysotile is present; avoid cutting or abrading unknown material because asbestos fibers may occur. Common polished pieces generally have modest value.
Geological facts
The green color results from hydrated magnesium silicate minerals, while black flecks are often magnetite. Serpentinite is California’s state rock and commonly forms distinctive slickensides and serpentinite mélanges.
Field identification & locations
Look for mottled apple-green coloration, waxy luster, softness, and possible magnetism; it can resemble jade but is generally softer. Common localities include California, Italy, New Zealand, Canada, and the Appalachian Mountains.
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