Ch. 2: Gems in Ceylon

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	GEMS IN CEYLON.	125

	bluish light occasionally plays upon it. Werner called it " Diamond Spar." It is said that some crystals found near St. Gothard, exhibit two colours, and that some of these are in dolomite, but mere commonly they are found in mass. Some in Styria have grown in with the granite, and so firmly that it is difficult, if not impossible, to remove them without damage. The crystals may be from the size of a pea to that of a hazel nut, of a greenish-blue or duck's-neck violet. Some pieces display several colours. In Bohemia they are found embedded in pebbly masses of hercinite. In Rhodes, Sweden, and the Urals, they may also be found with tourmaline in schist, with platinum and magnetic iron ore. In Ceylon, China, and India, they are found in beautiful green crystals, possessing characteristic stri pes, with black hornblende. Pleonaste. This mineral received the name of ceylanite from Rome d' L'Isle, who analyzed it with a number of others brought from Ceylon, Haiiy, seeing its crystal was like that of the spinel, desired to give it a special position in the system of minerals, and named it pleenaste, which signifies superfluity. Further investigation shewed that it was in reality a black variety of the spinel. The specific gravity of, this stone rises from 3'5 to 3'8- It consists principally of alumina, and about 10 per cent of protoxide af iron. Its in-i*sibility before the blow-pipe, and its formation with borax into an iron-coloured glass, are the surest indications of pleonaste. Acids have but little influence upon it. It is found in Russia and' other cold climates, but it is also found in Ceylon, as well as in the dolomite region in Ratan. Spinel, in consequence of its lustre, colour, and hardness, is used for personal ornament, and for objects of luxury; but it is only when the crystals are fine and large that they are considered gems. In cutting, it receives the same form as the ruby. Spinal ruby for balas ruby varies in value according to its cut and colour. In the inventury of the French Crown Jewels, in the year 1791, we find the following :—

	At the present time, small stones range from 5s. to 10s. a carat. Medium stones of fair colour 20s. to 40s. a carat. Large stones 60s. to 100s, a carat. Specimen stones attain even a higher value. The Cat's-Eye. Much confusion exists concerning this very curious and valuable gem, a confusion arising partly from the ignorance of many in the trade as to its true nature, .but principally from the mistake of those who have written about it. In mineralogical treatises it is usually confounded with, and described as a particular variety of quartz, which somewhat resembles it, but which is of little or no mercantile value, although it has occasionally been sent to Europe by unscrupulous merchants as the true cat's-eye. This chatoyant quartz is found in Ceylon (also the home of the true cat's-eye) in large quantities, and occurs chiefly of various shades of yellow or brown. It is semi-transparent, and when cut in a convex form (en cabochon) shews a more or less defined band of light with a silky lustre, resulting from a reflection of the fibrous-like grain of the stone itself, or more probably from an intimate admixture of asbestos. This quartz cat's-eye, even when most perfect,' cannot be compared for beauty with the real cat's-eye, for which it would not be mistaken, even by the uninitiated, It is at once distinguished by its inferior hardness and want of brilliancy,

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