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Ch. 20: Digests

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PRECIOUS STONES
139
DIOPSIDE
A variety of pyroxene; is found in the mountains of Europe, and the United States.
Crystallization monoclinic; in modified oblique rhombic prisms, usually thick, of six or eight sides, and terminating in two faces meeting at an edge.
Hardness, 5 to 6; brittle; specific gravity, 3.1 to 3.3, higher as the proportion of iron is greater.
Lustre vitreous to greasy; transparent to translucent.
Cleavage perfect, parallel to the sides of the prism; dis­tinct, parallel with the diagonals.
It is composed of silica, 55.3; lime, 27; magnesia, 17; ferrous oxide, and slight proportions of alumina, soda, and water.
Doubly refractive; dichroism in the finest color, very weak.
It cannot be dissolved by acids, but melts under the blow­pipe to a colorless glass; with soda or borax, to a transparent glass.
Colors, gray, greenish gray, bottle-green to blue. The finest resemble, when cut, a fine green tourmaline, and are very lustrous. Neither of the colors shows any trace of yellow.
Sahlite, named after Sahla, where it is found, is a coarser form of diopside, with less lustre and a more dingy color.
Alalite is a diopside from Piedmont.
Fassaite is a variety of rich green color, with a smooth, bright exterior.
Coccolite is the name given to granular varieties of the same general character.
Very fine diopside is now being found in New York State. They are cut brilliant, and rival in appearance the best green tourmaline.
Ch. 20: Digests Page of 237 Ch. 20: Digests
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