metamorphic
Polished serpentine (likely serpentinite)
Serpentine-group minerals, chiefly Mg₃Si₂O₅(OH)₄; commonly lizardite, antigorite, or chrysotile
AI-generated identification · may be incorrectHardness about 2.5–4 Mohs; mottled olive-green, yellow-green, and dark brown-black with a waxy to greasy luster. Typically massive and fine-grained, with no obvious cleavage; specific gravity about 2.5–2.6.
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Physical properties
Hardness about 2.5–4 Mohs; mottled olive-green, yellow-green, and dark brown-black with a waxy to greasy luster. Typically massive and fine-grained, with no obvious cleavage; specific gravity about 2.5–2.6.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite hydrate during low-temperature metamorphism, often along oceanic crust and fault zones. Individual serpentinite bodies may range from Precambrian to modern tectonic settings.
Uses & applications
Commonly cut and polished as ornamental stone, cabochons, beads, and carvings; also used historically for architectural stone. It is generally a low-cost jewelry and collecting material.
Geological facts
The specimen’s rounded shape and glossy surface indicate tumbling or polishing. Serpentine can resemble jade, but is usually softer and less dense; chrysotile-bearing material should not be cut or abraded because its fibers can be hazardous if inhaled.
Field identification & locations
Identify by its greasy/waxy feel, green-black mottling, low hardness, and inability to scratch glass reliably. Common sources include California, Vermont, Italy, New Zealand, Russia, and Afghanistan.
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