metamorphic
Serpentine (likely serpentine-rich pebble)
Serpentine-group minerals, chiefly antigorite and/or lizardite; commonly associated with magnetite and chlorite
AI-generated identification · may be incorrectGreen to yellow-green, mottled and waxy to greasy luster; typically massive with no visible crystals. Mohs hardness about 2.5–4, specific gravity roughly 2.5–2.6; often scratches with a steel blade and may show a smooth, soapy feel.
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Physical properties
Green to yellow-green, mottled and waxy to greasy luster; typically massive with no visible crystals. Mohs hardness about 2.5–4, specific gravity roughly 2.5–2.6; often scratches with a steel blade and may show a smooth, soapy feel.
Formation & geological history
Forms when ultramafic rocks such as peridotite undergo low-temperature hydrothermal alteration (serpentinization), commonly in ancient oceanic crust and subduction zones. The image cannot establish a precise age.
Uses & applications
Used decoratively, as ornamental stone, carvings, beads, and occasionally countertops; historically used as a jade substitute. Avoid dust from cutting because some serpentinites may contain fibrous asbestos minerals.
Geological facts
Its mottled green color resembles jade, but serpentine is generally softer and less tough. Magnetite formed during serpentinization can make some pieces weakly magnetic.
Field identification & locations
Common in serpentinite belts worldwide, including California, Italy, New Zealand, and the Himalayas. Confirm with hardness, waxy feel, low density, and petrographic or chemical testing; visual identification is not definitive.
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