metamorphic
Serpentinite
Serpentinite (composed primarily of mineral group (Mg,Fe,Ni,Al)3Si2O5(OH)4)
Hardness: 3-6 (variable), Color: olive green to dark green with brown mottled patches, Luster: waxy or greasy when polished, Crystal structure: Monoclinic, Cleavage: poor, SG: 2.2-2.9.
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Physical properties
Hardness: 3-6 (variable), Color: olive green to dark green with brown mottled patches, Luster: waxy or greasy when polished, Crystal structure: Monoclinic, Cleavage: poor, SG: 2.2-2.9.
Formation & geological history
Formed through serpentinization, a low-temperature metamorphic process where ultramafic rocks from the Earth's mantle are hydrated by seawater or hydrothermal fluids at tectonic plate boundaries.
Uses & applications
Used as decorative stone, for carvings, as a source of asbestos in the past, and as a shield in nuclear reactors due to its high water content.
Geological facts
Serpentinite is the official state rock of California. It is often associated with the presence of rare flora because soils derived from it are high in heavy metals and low in essential nutrients.
Field identification & locations
Identify in the field by its characteristic 'snake-skin' appearance, greenish hue, and waxy texture. Commonly found in ophiolite complexes and along fault zones, particularly in California and Vermont (USA) and the Alps.
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