metamorphic
Serpentine-rich rock (likely serpentinite)
Serpentinite; chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), commonly with magnetite, talc, or carbonate
AI-generated identification · may be incorrectTypically waxy to greasy luster, mottled yellow-green to dark green color, uneven fracture, and Mohs hardness about 2.5–4; this specimen’s rounded, weathered form and pattern are consistent with serpentine, though image-only identification is not definitive.
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Physical properties
Typically waxy to greasy luster, mottled yellow-green to dark green color, uneven fracture, and Mohs hardness about 2.5–4; this specimen’s rounded, weathered form and pattern are consistent with serpentine, though image-only identification is not definitive.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite undergo low-temperature hydrothermal metamorphism and hydration, commonly along oceanic crust and fault zones; ages range from ancient Precambrian to modern tectonic settings.
Uses & applications
Used as decorative stone, carvings, countertops, and historically for tools; some varieties are collectible. Serpentinite has also been used as a source or host rock for asbestos minerals, so avoid cutting or generating dust without testing.
Geological facts
Its green color reflects iron-bearing serpentine and associated minerals; magnetite may make pieces weakly magnetic. Similar-looking green rocks include nephrite, chlorite schist, and weathered ultramafic rocks.
Field identification & locations
Field clues include a soft, smooth or soapy feel, mottled green coloration, low hardness, and occasional magnetism; common occurrences include California, Italy, New Zealand, Canada, and the Appalachian region. A scratch test, streak, magnet test, and laboratory analysis can confirm it.
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