Serpentine
Serpentine, common, widely distributed mineral, composed of hydrated
magnesium silicate, Mg3Si2O5(OH)4, so called because of serpentlike
bands of green color occurring in massive varieties. It crystallizes
in the monoclinic system and occurs in two distinct forms: antigorite,
a massive variety, and chrysotile, a fibrous variety. The massive
variety has a greasy, waxy luster, and the fibrous variety is silky.
Both varieties are colored light and dark green, which in massive
formations of antigorite produce a beautiful, variegated coloring.
The term serpentine is also applied to a rock composed principally
of antigorite. The
hardness of the mineral ranges from 2 to 5, and the specific gravity ranges
from 2.2 for chrysotile to 2.65 for antigorite. Chrysotile is the
mineral from which asbestos is made. Antigorite, often used as an
ornamental stone, sometimes occurs as a collateral mineral in verd
antique marble.
Serpentine always occurs as an alteration product of another magnesium
silicate mineral, such as olivine, amphibole, or pyroxene. Large deposits
of chrysotile are located in Canada, in Russia, in Kazakhstan, in
South Africa, and in Vermont, New York, New Jersey, and Arizona in
the United States.
Source: (http://encarta.msn.com)
