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Ch. 6: Ruby, Sapphire, Spinel etc.

Ch. 6: Ruby, Sapphire, Spinel etc. Page of 295 Ch. 6: Ruby, Sapphire, Spinel etc. Text size:minus plus Restore normal size   Mail page  Print this page
Chalcedony, Mocha-stones, etc. 169
pure quartz, with opal disseminated through it. This stone is usually of a greyish colour, but sometimes oc­curs milky-white, pinkish, or of a smalt-blue: in the latter case it is called sapphirine. It is never found crystallized. Some Indian varieties are yellowish, which is owing to the presence of oxide of iron. It is often found lining agate geodes, in trap rocks, and sometimes stratified, various tints alternating; it is semi-transpa­rent, translucent (to nearly opaque) and as hard as quartz, but much less fragile, being very tough, and breaking with an even fracture, exhibiting little or no lustre. Before the blowpipe it becomes an opaque white. It is found in flints in most chalk-pits and in Europe is met with in Cornwall, Transylvania, and Iceland. From its hardness and toughness, this stone is well adapted for engraving, and has been used for this purpose from the most ancient period. White chalcedony, with minute blood-red spots, is called St. Stephen's-stone.
The chalcedonyx is a variety of chalcedony, having alternate stripes of white and grey. Plasma is a faintly-translucent variety which was much used in ancient times for engraving. Many fine gems are extant in this material; it is of a grass- or olive-green colour, sprinkled with minute yellow and white specks, and possesses a resinous sort of lustre; it is found among the ruins of Rome, in the Schwarzwald, in India and China. The name is derived from the Greek " image."
Ch. 6: Ruby, Sapphire, Spinel etc. Page of 295 Ch. 6: Ruby, Sapphire, Spinel etc.
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