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cut
cabochon for use in pins, or beads or buttons. Triclinic and occurs in
crystals or compact masses. Hardness = 5-5. Specific gravity = . Colour i rose-red or
pink; also yellow, green or brown. Lustre: Vitreous to pearly. Mean refractive index = .
Composition: MnSiOa. It is found in many manganese mines in the Central
Provinces, Central India, Bombay and Madras. It occurs in a massive
form. Colour: brownish-red, flesh-red or rose-pink. It is also obtained
from the Ural Mountains and from Franklin, New Jersey.
19. Serpentine.—It
is a hydrated silicate of magnesia with iron. It is used for ornamental
purposes and cut cabochon for gems. Monoclinic but never occurs in
crystals and forms platy or fibrous masses. Hardness = to 4. Specific gravity =  .
Colour: various shades of green, also yellowish, greyish, reddish,
brownish or black. Lustre: dull, resinous, greasy or waxy. Feel is
smooth to greasy or waxy. Mean refractive index variable, to
Precious serpentine is translucent and green or yellow in colour.
Varieties:—Bowenite—granular and resembles jade; Williamsite—blackish
green; Verde antique— massive green; Chrysotile—fibrous. Good material
is found in Sweden, Scotland, Silesia, Saxony, Rhode Island, Vermont,
Massachusetts, Pennsylvania and California. Some material of attractive
colour is found in the asbestos mines near Pulivendla, Cuddapah
district, Madras.20. Smithsonite.—Though usually unattractive, those of yellow-green or blue may be cut cabochon or used for ornamentation. Composition— It is formed by the alteration of zinc sulphide and occurs in limestone and dolomite.
21. Sodalite is
polished as an ornamental stone or sometimes cut cabochon. It is deep
blue in colour and resembles lazurite. Cubic. Isotropic. Hardness = 5
to 6. Specific gravity = 2-24. It is found in the Ural Mountains
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