SLATY GLANCE-C0A1. 393 It is shining and glistening, and the lustre is interme diate between metallic and semi-metallic. The principal fracture is more or less perfect slaty; the cross fracture small and flat conchoidal. The fragments are pretty sharp-edged, and sometimes trapezoidal. It is soft; in some rare varieties, viz. those passing in to graphite, it is very soft. It is easily frangible. It is intermediate between sectile and brittle. It is light. Specific gravity, 1 530, Klaproth. 1.800, Hatty. 1.415, Thomson. 1.300, La Metheris~ 1.468, Groess. 1.526, Kirwan. Chemical Characters. According to Dolomieu, when reduced to powder, and heated in a crucible, it does not give any sulphureous or bituminous odour, and, on distillation, it affords neither sulphur nor bitumen. By exposure to a considerable heat, it burns without flame, and at length is consumed, leaving a greater or lesser portion of ash, according to its purity. Constituent Parts. Panzenberg. Dolomieu. Carbon, 90 72.05 Silica, 4 to 2 13.19 Alumina, 4 to 5 3.29 pxide of iron, 2 to 3 3.47 Loss, 8.00 100 100.00 Geognostic