metamorphic
Polished greenstone (likely serpentinite)
Serpentinite, chiefly antigorite/lizardite Mg₃Si₂O₅(OH)₄, possibly with magnetite
AI-generated identification · may be incorrectDark olive-green, fine-grained, opaque, and waxy to greasy-lustrous with polished surfaces; typically Mohs 2.5–4, no visible crystals, and irregular fracture. The image alone cannot confirm composition; jade or nephrite are possible but less likely.
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Physical properties
Dark olive-green, fine-grained, opaque, and waxy to greasy-lustrous with polished surfaces; typically Mohs 2.5–4, no visible crystals, and irregular fracture. The image alone cannot confirm composition; jade or nephrite are possible but less likely.
Formation & geological history
Forms when ultramafic mantle rocks undergo hydration and metamorphism, commonly in ancient oceanic lithosphere and tectonic mélanges; ages vary widely from Paleozoic to modern tectonic settings.
Uses & applications
Used as ornamental stone, carved objects, countertops, and lapidary material; higher-quality jade-like pieces may be used in jewelry.
Geological facts
Serpentinite often contains magnetite and may be weakly magnetic; its green color comes from serpentine minerals. It is commonly confused with jade, which is generally tougher and denser.
Field identification & locations
Common in California, Italy, New Zealand, Canada, and ultramafic mountain belts. Test cautiously: serpentinite is relatively soft and may scratch with a steel knife, whereas jade resists scratching; hardness, density, and microscopic testing are needed for a firm identification.
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