metamorphic
Polished dark green stone, likely serpentine
Serpentinite; chiefly serpentine-group minerals, approximately Mg₃Si₂O₅(OH)₄
AI-generated identification · may be incorrectHardness about 2.5–4 Mohs; dark olive-green to black, waxy to greasy luster, massive rather than visibly crystalline, commonly with mottled or veined patterns. The smooth rounded form appears polished or naturally water-worn.
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Physical properties
Hardness about 2.5–4 Mohs; dark olive-green to black, waxy to greasy luster, massive rather than visibly crystalline, commonly with mottled or veined patterns. The smooth rounded form appears polished or naturally water-worn.
Formation & geological history
Forms when ultramafic mantle rocks undergo low-temperature hydration and metamorphism; serpentinite is commonly Paleozoic to younger, depending on its tectonic setting. It occurs especially in ophiolite belts and subduction-zone mélanges.
Uses & applications
Used as decorative stone, carvings, countertops, and ornamental or lapidary material; softer varieties are shaped into beads and sculptures. It has limited value as a gemstone compared with jade.
Geological facts
Serpentine is a mineral group, while serpentinite is the corresponding rock. Some varieties resemble jade, but serpentine is generally softer and has lower density.
Field identification & locations
Look for a dark green waxy appearance, low hardness, and fibrous or mottled veins; a steel nail may scratch it. Common localities include California, Vermont, Italy, New Zealand, and many ophiolite complexes worldwide.
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