metamorphic
Polished dark-green stone, likely serpentinite
Serpentinite; predominantly serpentine-group minerals, commonly antigorite, lizardite, or chrysotile, with possible magnetite and minor pyroxene
AI-generated identification · may be incorrectTypically Mohs 2.5–4, dark green to black, waxy or dull luster, very fine-grained and massive, with no visible cleavage; specific gravity commonly about 2.5–2.6. The rounded, smooth surface appears naturally water-worn or polished.
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Physical properties
Typically Mohs 2.5–4, dark green to black, waxy or dull luster, very fine-grained and massive, with no visible cleavage; specific gravity commonly about 2.5–2.6. The rounded, smooth surface appears naturally water-worn or polished.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite undergo hydration and metamorphic alteration, commonly in oceanic lithosphere and subduction zones. Individual pieces may be geologically ancient, but the specimen’s exact age and locality cannot be determined from the image.
Uses & applications
Used as ornamental stone, carvings, beads, countertops, and historically as a jade substitute; some varieties are collected. It is generally unsuitable for high-wear applications because it is relatively soft.
Geological facts
Serpentinite often has a greasy or waxy feel and may contain magnetic magnetite. It can resemble nephrite jade, but is usually softer and less tough.
Field identification & locations
Common in ophiolite belts and metamorphic terrains worldwide, including California, Italy, New Zealand, and Canada. Confirm with hardness, streak, density, magnetism, and ideally microscopy or chemical testing; image identification is provisional.
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