earthy polier-slate. 425 Constituent Parts. Silica, 83.50 Alumina, 4.00 Lime, 9.50 Oxide of Iron, 1.50 Water, 9.00 Bucholz, Gehlen’s Journal, b. ii. s. 34. Third Subspecies. Friable Polier-Slate. Zerreiblicher Polierschiefer, Karsten, Id. Lenz, b. ii. s. 563. External Characters. Same colours as preceding. It occurs massive. The principal fracture is thin slaty; the cross fracture fine earthy. It is very soft. It is friable, and sectile. Constituent Parts. Silica, - - 87.00 Alumina, - - 0.50 Lime, - - 0 50 Oxide of Iron, - 1.50 Water, - - 10.00 Bucholz, Gehlcn’s Journ. b. ii. s. 34. Geognostic