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122 FLINT GENUS. Internally its luftre is intermediate between filing and gliftening, and is vitreous. Its fracture is intermediate between imperfectly conchoida!, and fmall and coarfe grained uneven and inclines fometimes more to the one, fometiiD eS more to the other. x Fragments indeterminately angular. It very rarely prefents coarfe and fmall grained tinftconcretions; fometimesit occurs invfcrythin, thi fl > and but feldom in thick and ftraight prifmatic difti 11 ^ concretions.- Thefe concretions are fometimes ^ thin that they verge on the fibrous, and fuch varie^f are fometimes parallel, but mod frequently fc 0 ? 1 ” formly divergent, and are fometimes again collet into thick wedge-fhaped concretions, which rat £ ^ pafs into coarfe and fmall grained diltindt concretio^' Opaque, but a little tranducent on the etlg eS ’ when it paifes into tourmaline. Gives a grey ftreak. Hard, fiightly inferior to quartz. Very eafily. frangible. j Intermediate between not particularly heavy* heavy. Specific gravity—3,092, Brrffon 3,150, Ccrfji ir ^ 3,212, Kirvian. ' Chemical Characters. , Unlft Before the blow pipe it melts pretty cafdy ' VIt ^ addition into a blaskifh flag. Melted with botf* forms a grcenilh coloured glafs.