From Wikipedia, the free encyclopedia:
Serpentine is said to owe its name either to its serpent-like colors and patterns or from an old belief that the stones were effective protection from snake bites. They have their origins in metamorphic alterations of peridotite and pyroxene.
Colours range from white to grey, yellow to green, and brown to black, and are often splotchy or veined. Many are intergrown with other minerals, such as calcite and dolomite. Occurrence is worldwide; New Caledonia, Canada (Quebec), USA (northern California), Afghanistan, Cornwall, China, France, Norway and Italy are notable localities.
Rock composed primarily of these minerals is called serpentinite. Serpentines find use in industry for a number of purposes, such as railway ballasts, building materials, and the asbestiform types find use as thermal and electrical insulation (chrysotile asbestos). The more attractive and durable varieties (all of antigorite) are termed "noble" or "precious" serpentine and are used extensively as gems and in ornamental carvings.