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Earthy Quartz. 3^7 Sometimes it is fo cariated by calx of iron and argill that penetrates, as to refemble flig;titly compafted ruft, as in R. 28. Its colour is reddifh brown. It is friable betvveen the fingers. Sometimes overlaid by calx of iron, as in Lefke O. 35 c, which exhibits quadrangular im- preflions öf fluorcryftals antiently contained in ir. Sometimes it has the »ppearance of a reddifh grey, or greyifh red, or yellow mortar, as in O. 1021 and 1733 ; or yellowifh red, as in S. 2-0. Sometimes it appears as if pafiing into fand- ftone, as in Lefke S., whofe colour \s greyifh red; its luftre, 1; tranfparency, o; hardnefs 10; fradture, fine fplintery, nearly even. See Lefke S. 1120. Earthy Quartz. This is often fo difguifed as to be eaftly mif- tskcn« The fpecimen, Lefke O. 360, is almoft per- feäly white. Its luftre fcarcely 1; tranfparency, 1 ; its ftrufture as loofe as that of mols, which it'refembles; exceedingly brittle, and light as 1 2d The fpecimen, O. 414, is dark grey; luftre and tranfparency, nearly o ; confifts of nn- nute grains compafled together with numerous miputc interftices ; yetits hardnefs ts 10; refem- bles fandftone, and N. 434 ™ more - , 3 d, ln the fpecimen, Ü. ,383, we find quartz deftitute of luftre and hardnefs, and of a yellow. A grey colour, and fplintery trafture; n dillers from filiceous fhiftus in having no tendency to a flaty ftrufture. , , 4.th, The olive green quartz, Lefke 744, very little luftre, but ferne tranfparency; ns rac- ; C c a ture >