metamorphic
Polished green serpentine (likely antigorite-rich)
Serpentinite; chiefly serpentine-group minerals, Mg₃Si₂O₅(OH)₄, with possible chlorite, magnetite, and talc
AI-generated identification · may be incorrectDark green to olive, mottled and waxy with a polished luster; typically massive rather than visibly crystalline. Hardness is about 2.5–4 Mohs, with poor cleavage and specific gravity near 2.5–2.6.
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Physical properties
Dark green to olive, mottled and waxy with a polished luster; typically massive rather than visibly crystalline. Hardness is about 2.5–4 Mohs, with poor cleavage and specific gravity near 2.5–2.6.
Formation & geological history
Forms when ultramafic rocks such as peridotite undergo hydration and alteration, commonly in oceanic crust and subduction-zone mélanges. Its age depends on the host terrane; the specimen appears tumbled or polished.
Uses & applications
Used as an ornamental and carving stone, beads, cabochons, and decorative objects; massive serpentinite is also used locally as dimension stone. Avoid prolonged exposure to dust from cutting, because some serpentinites may contain asbestos-form minerals.
Geological facts
The contrasting green patterns and white vein are characteristic of serpentine alteration and veining. It can resemble nephrite jade, but is generally softer and less tough.
Field identification & locations
Identify by its greasy/waxy feel, mottled green color, low hardness, and white-green veins; a steel scratch test should mark it, unlike jade. Common occurrences include California, Italy, New Zealand, Canada, and the Himalaya.
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