metamorphic
Serpentine-rich rock (likely serpentinite)
Serpentinite; chiefly antigorite, lizardite, or chrysotile Mg₃Si₂O₅(OH)₄
AI-generated identification · may be incorrectTypically olive-green to yellow-green, waxy to dull luster, fine-grained and massive; Mohs hardness about 2.5–4, with poor or absent cleavage and specific gravity around 2.5–2.6. The specimen’s mottled green, soft-looking appearance is consistent with serpentine, though the photo cannot confirm identity.
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Physical properties
Typically olive-green to yellow-green, waxy to dull luster, fine-grained and massive; Mohs hardness about 2.5–4, with poor or absent cleavage and specific gravity around 2.5–2.6. The specimen’s mottled green, soft-looking appearance is consistent with serpentine, though the photo cannot confirm identity.
Formation & geological history
Forms when ultramafic mantle rocks such as peridotite undergo hydration and metamorphism, commonly along tectonic plate boundaries and subduction zones. Serpentinite forms across many geological ages, from Precambrian terrains to modern oceanic settings.
Uses & applications
Used as ornamental stone, carving material, countertops, and historically for architecture; attractive pieces may be polished as cabochons or collected. Chrysotile-bearing material should not be cut, drilled, or powdered because inhaled fibers are hazardous.
Geological facts
Serpentine is a mineral group rather than one single mineral, and serpentinite commonly contains magnetite, producing weak magnetism. Green color can also result from chlorite, epidote, or weathered ultramafic rock.
Field identification & locations
Common in California, Italy, New Zealand, Canada, and oceanic ophiolites; field clues include greasy/waxy feel, low hardness, green mottling, and occasional magnetism. A hardness, streak, magnetism, or laboratory test is needed for confirmation.
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