IS* LIMESTONE FAMILY. It is dull, both externally and internally, and only glimmering when intermixed with foreign parts. The fracture is generally earthy, which approaches sometimes to splintery, sometimes to conchoidal; in the great inclines to slaty. The fragments are angular and blunt-edged, and some times tabular. It is soft. It is opaque. It is brittle. It is easily frangible. " It is not particularly heavy. Chemical Characters. Before the blowpipe, it intumesces, and melts into a greenish-black slag. It effervesces briskly with acids. Constituent Parts. Carbonatp of Lime, - 50 Silica, - - - 12 Alumina, - - 32 Iron and Oxide of Manganese, 2 Kirwan. Geo gnostic Situation. It occurs in beds in the floetz limestone and coal for mations ; also in the new floetz formations that rest up on chalk. Geographic Situation. It frequently occurs in the coal formations in Scotland and England, and in the new floetz formation which rests upon chalk in the south of England. On the Con- 4 S (i£>r\L