metamorphic
Likely serpentinite or chlorite-rich metamorphic rock
Serpentinite, mainly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), possibly with chlorite, magnetite, and carbonates
AI-generated identification · may be incorrectDark olive-green, mottled, fine- to medium-grained, with a dull to subtly waxy luster; likely Mohs 2.5–4, massive rather than visibly crystalline, and lacking obvious cleavage. The photograph is insufficient for a definitive identification.
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Physical properties
Dark olive-green, mottled, fine- to medium-grained, with a dull to subtly waxy luster; likely Mohs 2.5–4, massive rather than visibly crystalline, and lacking obvious cleavage. The photograph is insufficient for a definitive identification.
Formation & geological history
Typically forms when ultramafic mantle rocks such as peridotite hydrate during hydrothermal alteration, commonly in oceanic crust and subduction zones; ages vary widely. It may also be a chlorite-rich greenschist or altered basalt.
Uses & applications
Used as decorative stone, carvings, aggregate, and historically as a source of asbestos-bearing serpentine; ordinary pieces have little commercial value.
Geological facts
Serpentinite commonly contains magnetite and may be weakly magnetic. Some varieties contain chrysotile asbestos, so avoid cutting, sanding, or creating dust until tested.
Field identification & locations
Look for a green, dense, smooth or waxy surface and occasional slickensides; a streak, hardness, magnetism, acid reaction, and petrographic/X-ray testing can distinguish it from basalt, greenstone, or chlorite schist. Common in ophiolites and mountain belts.
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