Limestone. 485 Splendent, and is intermediate between pearly and v itreous. Fra&ure foliated, and fcmetimes, on 1 account of the finenefs of the grains, it appears fplintery. Fragments indeterminately angular blunt edged. It occurs almoft always in granular diftinft con ations, which are coarfe, fmall, and fine grained ; the latter paffes into compaft,i and fometimes is only diltinguilhed by its glimmering. Almoft always more or lefs tranfluoent, and the hlack variety is only tranflucent on the edges. Semi-hard. Brittle. Eafily frangible. Not particularly heavy. Specific gravity—1,700 to 2,80c. Chemical CharaBcr. It ufually effervefces with acids, and is purer than ^mmon limeftone. Gecgnostic Situation. It is peculiar to the primitive and tranfiticn moun- [ a >ns, and occurs but rarely, and only in fingle beds 111 the floetz formations. The oldeft granular lime- Hone in which the concretions are very diftinct, oc- Cur * in gneifs; but in the newer, which is found in 3 R the