Ruby (Fa., .Rubis; GER., Rubin).—Composition, varies from about pure alumina, to a compound containing 10-20 per cent. of magnesia ; hardness, 9; sp. gr., ; colour, various shades of red. The ruby is essentially an Eastern gem. One celebrated mine is situated about 20 miles from Ish-kashm, in a district called Gharan, on the right bank of the Oxus. The formation is either red sandstone or magnesian limestone, easily worked ; tho stones occur encased in nodules in seams and spots in the rook. Superior gems are found at Mo-gast and Kyat-pyan, 5 days S.-E. of Ave, the workings being a monopoly of the King of Burmah. Perhaps the finest come from a district between the north-east of Mandalay and the west of the Upper Solween River. Another noted locality is at the foot of the Capelan Mountains, near Sirian, in Pew; where fine rubies are not rare ; also near Kandy, in Ceylon, where good stones are very scarce. One has been found near Mount Eliza, on Port Philip Bay, Victoria ; also one in Queensland ; and another in New Zealand. Rubies of pure colour and fair size are the most valuable of all gems.
Sapphire (FR., Saphir GER., Saphir).—Composition, about 98.5 per cent. of alumina, with oxide of iron and other colouring matter ; hardness, 9; sp. gr., 4.6-4•8 ; colour, from traneluceut yellow or white, to violet. Sapphires of great beauty are found in and near the Iser Mountains, in Bohemia, and in the bed of the River Iser, mostly in quartz sand and granite detritus. In Ceylon, good sapphires are not rare. Quite a rush has recently taken place to the mines of Battambong and Chantubong, in Siam, whence a stone of the finest water, weighing 370 carats in the rough, is credibly reported. Blue and white stones of some value have been found in Dandenong Creek, Victoria; at Ballarat, S. Australia; and in the Hanging-rock caves, near the Pearl River, New South Wales.
Topaz (Fa, Topaz's ; GEa., Topas). — Composition, 34 per cent. silica, 57 alumina, 15 fluorine; hardness, 8; sp. gr., 3.5 ; colours, yellow, blue, and white. In Saxony, is found a pale violet variety ; and in Bohemia, a sea-green. Many occur in the Urals, north of Katharinburg, in granite and albite ; and in E. Siberia. In the Brazilian province of Minas Gems, numbers are met
with in the aurifbrous gravels, especially at Capao. Some fine specimens have been got at Beech worth, Victoria, in Flinders' Island, and in Tasmania.
Turquois (FR., Turquoise, Agaphite ; GER., Agaphit, Kalait).—Composition, 47 alumina, 27 phosphoric acid, 3 phosphate of lime, 2 oxide of copper, 1 oxide of iron, 19 water; hardness, 6; ap. gr., 2.6-2.8 ; oolour, blue to blue-green. The Land of Midian possesses three turquois mines : one at Aynuneh, a second near Ziba, and a third, known to the Bedouins as Jebclshehsyk. But the atones comes principally from the mountainous district of Nishabor (Neehapore), in N.-E. Persia ; the oldest mine is in the Bari Madan bullik, and a second has recently been discovered in the bilk to the south, separating Nishabor from Turshiz. Mashhad is the headquarters of the trade. Better stones at lower figures are said to be procurable at Shikarptir, in Sind.
Baliography.—J. Mawe, 'Diamonds and Precious Stones' (London : 1815, 2nd ed. 1831); C. Barbot, 'Traitd des Pierres Prdoieusee ' (Paris: 1858) ; L. Fruchtwanger, 'Treatise on Gems' (New York: 1859) ; Kluge, Edeleteinkunde ' (Leipzig : 1860); J. J. Bleasdale, 'Gems and Precious Stones found in Victoria' (Essay in Off. Reo. Int:Col. Exhib. Melbourne : 1867); H. Emanuel, Diamonds and Precious Stones' (London : 1867, 2nd ed.) ; D. Page, Economic Geology' (London : 1874); L. Dieulafait, ' Diamonds and Precious Stones' (London : 1874) ; T. Shepstone, Geographical and Physical Characters of the Diamond-fields of S. Africa' (Jour. See. Arts, Vol. xxii., No. 1113, London : 1874); W. A. Ross, Pyrology ' (London : 1875); R. J. Mann, 'Commercial Aspects of the S. African Diamond-fields' (Ditto); Frdmy and Feil, ' Artificial Production of Precious Stones' (Jour. Soc. Arts, Vol. xxvi., No. 1319, London : 1878); E. W. Streeter, Precious Stones and Gems' (London : 1879, 2nd ed.) ; J. B. Hannay, Artificial Formation of the Diamond ' (Proo. Roy. Soc. Vol. xxx., No. 204, London; 1880).