metamorphic
Polished serpentine pebble
Serpentinite; chiefly serpentine-group minerals (antigorite, lizardite, chrysotile), commonly with magnetite and carbonate
AI-generated identification · may be incorrectTypically olive-green to yellow-green, mottled and waxy to greasy-lustrous; Mohs hardness 2.5–4, massive rather than visibly crystalline, with poor cleavage. The specimen appears tumbled or naturally water-smoothed and may include pale carbonate veins or altered inclusions.
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Physical properties
Typically olive-green to yellow-green, mottled and waxy to greasy-lustrous; Mohs hardness 2.5–4, massive rather than visibly crystalline, with poor cleavage. The specimen appears tumbled or naturally water-smoothed and may include pale carbonate veins or altered inclusions.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite hydrate during hydrothermal alteration, commonly in oceanic crust and subduction-zone mélanges. Serpentinization spans many geological ages, from Precambrian terranes to active tectonic settings.
Uses & applications
Used as ornamental stone, carvings, beads, countertops, and occasionally architectural facing; historically used for heat-resistant objects. Fibrous chrysotile varieties were formerly used as asbestos but are hazardous when airborne.
Geological facts
Its green color and slick feel reflect serpentine minerals, while dark specks may be magnetite. Serpentinite is also associated with unusual soils and ecosystems enriched in nickel and chromium.
Field identification & locations
Identify by green mottling, low hardness, waxy texture, and a pale streak; avoid assuming jade, which is generally harder and tougher. Common sources include California, Italy, New Zealand, Canada, and the Appalachian and Alpine belts.
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