metamorphic
Serpentine-rich metamorphic rock
Serpentinite, chiefly serpentine-group minerals (Mg₃Si₂O₅(OH)₄), with possible chlorite, magnetite, and altered olivine/pyroxene
AI-generated identification · may be incorrectTypically green to yellow-green, mottled, and waxy to dull; this specimen appears fine-grained with rusty weathering. Hardness is about 2.5–4, generally massive with no obvious cleavage; specific gravity commonly 2.5–2.6.
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Physical properties
Typically green to yellow-green, mottled, and waxy to dull; this specimen appears fine-grained with rusty weathering. Hardness is about 2.5–4, generally massive with no obvious cleavage; specific gravity commonly 2.5–2.6.
Formation & geological history
Forms when ultramafic rocks such as peridotite undergo hydration and alteration by hot, water-rich fluids, commonly along tectonic plate boundaries and fault zones. Most examples range from Precambrian to modern tectonic settings.
Uses & applications
Used as decorative stone, carvings, countertops, and mineral specimens; historically some varieties were used as asbestos-bearing stone, so cutting or grinding should be avoided without testing.
Geological facts
The green color is produced by serpentine minerals, while red-brown patches commonly represent iron oxidation. It may be confused with greenstone, jade, or chlorite schist.
Field identification & locations
Look for low hardness, a greasy or waxy feel, green mottling, and possible magnetism from magnetite; a steel knife may scratch it. Common in California, the Alps, New Zealand, Canada, and oceanic ophiolite belts.
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