metamorphic
Polished serpentine
Serpentinite; chiefly serpentine-group minerals (lizardite, antigorite, chrysotile), Mg₃Si₂O₅(OH)₄
AI-generated identification · may be incorrectTypically olive-green to brown with black veining, waxy to greasy luster, and mottled patterns; hardness about 2.5–4 Mohs, noncleavable to fibrous, with a fine-grained texture and specific gravity around 2.5–2.6.
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Physical properties
Typically olive-green to brown with black veining, waxy to greasy luster, and mottled patterns; hardness about 2.5–4 Mohs, noncleavable to fibrous, with a fine-grained texture and specific gravity around 2.5–2.6.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite hydrate during hydrothermal alteration, commonly along tectonic plate boundaries; ages vary from Precambrian to modern. The pictured piece is polished and likely tumbled.
Uses & applications
Used as ornamental stone, carvings, cabochons, tiles, and decorative objects; historically used as a low-cost jade substitute. Fibrous chrysotile-bearing material should not be cut or abraded because its dust can be hazardous.
Geological facts
Serpentinite’s green color and veining result from alteration of iron- and magnesium-rich mantle minerals. It may resemble nephrite jade but is generally softer and less tough.
Field identification & locations
Identify by its greasy/waxy surface, green-black mottling, low hardness, and lack of strong translucency; common localities include California, Vermont, Italy, New Zealand, and Canada. A scratch test and professional microscopy can distinguish it from jade.
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