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Ch. 5: Tourmaline

Ch. 5: Jade Page of 296 Ch. 5: Tourmaline Text size:minus plus Restore normal size   Mail page  Print this page
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PRECIOUS STONES.
work it into objects of great beauty. A sceptre of white jade was sent as a present from the Emperor of China to Prince Albert of England.
TOURMALINE.
The tourmaline holds but a secondary rank among those gems that are used for ornament, but, from a scientific point of view, it is well worth attention.
The modern tourmaline is the lyncurium of the ancients. It is also called schorl, especially in Germany, from the name of a village in Saxony, where it is very abundant.
Its composition is very complex; there are, how­ever, certain elements which are characteristic of it, namely, boracic acid, silica, and alumina. In all tourmalines, also, there is an alkaline base, some­times potash, sometimes soda, sometimes lithia, or a mixture of all. There is found in it also mag­nesia, lime, oxide of iron, and oxide of manganese.
The tourmaline is always crystallized, and its crystals appertain to the rhombohedral system. The crystals are in the form of longish prisms, sometimes with six faces, sometimes with nine, and in this case, in consequence of the obliteration or partial obliteration of faces, they terminate in such forms as shown in Fig. 82.
Ch. 5: Jade Page of 296 Ch. 5: Tourmaline
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