What is Serpentine?
Serpentine is a family of hydrated magnesium silicates and an important ornamental and geological material formed by alteration of ultramafic rocks.
Mineralogy and crystal structure
Reference formula: Mg3Si2O5(OH)4. Serpentine includes several polymorphs and habits, including lizardite, antigorite and chrysotile. The existing structure is preserved as the group's representative model; fibrous material requires careful handling. Serpentine is classified with silicates and has a monoclinic crystal system. Typical hardness is 2.5–5 on the Mohs scale and specific gravity is approximately 2.5–2.7.
Colour, lustre and habit
Typical colours include green, yellow-green, black, white, brown. The usual massive, fibrous, platy habit and waxy, greasy, silky lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Serpentine forms in or is associated with low-temperature hydration and metamorphic alteration of olivine- and pyroxene-rich ultramafic rocks. Important documented localities include Italy, Canada, the United States, Russia, New Zealand, South Africa and Afghanistan.
Green stone from the oceanic mantle
Serpentine sells as both a sculptural stone and a geological record of mantle-rock alteration. Colour, veining, polish and whether fibres are present should be stated clearly.
Collecting and care
Do not cut, grind or generate dust from fibrous material. Protect polished surfaces from scratches and clean compact pieces gently.
