DsAwitf g ■Slate. 529 Fragments generally tabular, and fometimes fplin- tery. • ' • Opaque. Colours'and writes. v:,]rr: ? ■ Its ftreak is gliftening, but does not. alter the co lour. . . V ; - t':.* Soft, palling into very foft. Mild. Eafily frangible. Feels meagre but fine. Not particularly heavy, approaching to light. i. \ * ■ Chemical Char after s. According to Lelievre before the blow" pipe and without addition becomes covered with a flight var- xiifh. .‘to ssd'AT ■'<,! a ) m " L • Constituent Parts. Silica 64,0 Alumina 11.25 Carbone 11,0 Oxyd of iron 2,75 Water 7,5° t 96,35 % According to Wiegleb. Crclls. Ann. 1797- C 4S5. Gcognostie