FLINT GENUS. In the floetz rocks it forms the principal conftituerit part of the different great fandftone formations, and occurs alfo in the gyps and limeftone formations. Even in the neweft of all the formations, the allu vial, it is found in boulders and as Ioofe fand. Several varieties, as we have already mentioned, are by no means fo common; thus the quartz, with date-fhaped diftinft concretions, is only found in Si* lefia : the larger cellular variety only at Schneeberg in Saxony; the fmall cellular only in the Harz and Hungary; and laftly, the fine angular grained, flaty and flexible variety has been hitherto found only i n the Brazils. The pifture of the quartz fpecies which has been defcribed in the preceding pages is one of the mod highly finifhed in the Wernerian oryclognofie. Wi e ' denman and other mineralogifts by attending only t° a few of its leaft chara&eriftic features, have failed underftanding it. twentieth
