Serpentine is the name used for several different aggregate structures which are usually green, yellowish green, or brownish green in color. The finer serpentine is cut as cabochons for gemstones, or carved into decorative objects. Though serpentine is sometimes confused with jade, serpentine is usually spotted or veined.
The serpentine group includes as many as 20 different members. All the serpentines are a basic magnesium silicate, with many containing iron as well. Other elements may also be present in small quantities, including chromium, nickel and cobalt.
Two basic structures for serpentine are usually distinguished -- antigorite (leafy serpentine) and chrysotile (fibrous serpentine). The chrysotile minerals are more likely to form serpentine asbestos, while antigorite forms cryptocrystalline masses sometimes with a lamellar or micaceous character. Since asbestos fibers are a health hazard only the antigorite form is used for gemstones or carvings.
Most serpentine are opaque to translucent, with a hardness rating ranging from 2.5 to 5.5. Antigorite tends to be the harder variety. Serpentine is fairly light, with a density of 2.44 to 2.62, slightly lower than quartz. Luster ranges from greasy to waxy to silky. Serpentine is known to be susceptible to acids.
A number of trade names have been introduced to refer to serpentine variants, including bastite, bowenite, connemara, verd-antique and williamsite. You may also encounter terms such new jade, noble serpentine and precious serpentine. However the latter three terms are not used in gemology.
Serpentine varieties are found in many places in the world, including Afghanistan, Burma, China, New Zealand, the USA, Canada, UK, Greece, Italy and Norway.
- First Published: November-08-2010
- Last Updated: November-12-2010
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