metamorphic
Serpentinized ultramafic rock (likely serpentinite)
Serpentinite; chiefly lizardite, antigorite, and/or chrysotile, commonly with magnetite, chromite, and residual olivine/pyroxene
AI-generated identification · may be incorrectTypically green, brown, black, or mottled with a waxy to greasy luster; hardness about 2.5–4 Mohs, uneven fracture, and massive or fibrous texture. The specimen appears polished or wet, so exact mineral identification is uncertain from the image alone.
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Physical properties
Typically green, brown, black, or mottled with a waxy to greasy luster; hardness about 2.5–4 Mohs, uneven fracture, and massive or fibrous texture. The specimen appears polished or wet, so exact mineral identification is uncertain from the image alone.
Formation & geological history
Forms when mantle-derived peridotite is chemically altered by water during hydrothermal metamorphism, commonly along oceanic crust and fault zones; ages range from Precambrian to modern tectonic settings.
Uses & applications
Used as decorative stone, carvings, countertops, and historically as a source of asbestos-bearing material; attractive pieces are collected, though fibrous varieties should not be cut or abraded.
Geological facts
Serpentinization increases rock volume and releases hydrogen, supporting unusual deep-earth microbial ecosystems. Some specimens contain valuable chromite, magnetite, or nickel minerals.
Field identification & locations
Field clues include low density, green-brown mottling, waxy surfaces, and occasional magnetism; a streak, hardness, magnet test, and thin-section or Raman/XRD analysis can confirm it. Common in ophiolites and subduction-related belts.
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