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112 METALLOIDS. TIG. TIG. 89. TIG. 90. Forms and combinations, o, d, i, p, s , ao, ad, od, ai, oi, si, os os', aod aoi, ois, dos, aodpi. The faces d sometimes rough and curved; g, ip, s curved. Twins. Twin-face o. The twin-crystals are frequently hemihedral, and very thin in the direction of a normal to the twin-face. Cleavage, o, very perfect. Fractureconchoidal. Transparent.. .translucent. Lustre adamantine, p = 2-44. Colourless, white, grey, brown, green, yellow, red, blue, rarely black. Streak grey. u = lo-o ° = 3 5 l • ■ 3 ' 6 -, Acquires vitreous electricity by friction. Does not conduct electricity. Some varieties are phosphorescent for some time after exposure to the light of the sun. Burns away before the blowpipe on platinum foil When burnt in an atmosphere of oxygen, the product of combustion is carbonic acid. Is not acted upon by acids. C, carbon. In isolated and imbedded crystals and grains, rarely massive Is found in a quartz conglomerate, in strata of clay and sand containing iron oxide, and in alluvium, on the eastern boundary °Co E, ateau . of . the De ccan, between the parallels of n° and 2d . lhe principal localities are,—on the river Pennar be tween Cuddapah and Gandicotta; between the Pennar and a m i UCar nc ^ a ^ ! on lower Kistna near Ellore: umbhulpur on the Mahanadi; Pannah between the rivers Sonar and Sone m the Bundelkund. Diamonds are also found 4-l a( : ca w . est s ‘ ( l e °f tire Ratu mountains, rather to the north of Pulo Ari, Landak, Sekajam and Tajan in Borneo, in Celebes and Java. They are found in the Brazils in alluvium, accompanied by oxides of iron, quartz, kyanite, beryl, chrysoberyl, anatase, topaz, spinelle, corundum, garnet, &c ; m the district of Cero do Frio in Minas Geraes, in the Lo I “ "; 10 Jcqmtinhonha and Rio Arassuhay; on the right nf P- p i p- J’™ nclsco at Matto Grosso, and in the beds of R,io lardo, Rio \elhas, and various other rivers, all of which tali into the 8. Irancisco; in the mines of Riven and Cuithe;
