480 CALC GENUS. Ohfervation. The bluilh grey variety often paffes into marie. b. Roeftone. Roogenftein.—Werner. St 1 .fLt-s-ZVithns var. b. c. d. Wall. t. 2. p. 384.-* Roo^enflein, Wtd f 511 —Oviform limeftone, Kiris'- vol. 1. p. 91—Roogenftein, E/lner, b. 2. f. 918.-*“ Id. Emm b. 1. f. 442.-~-Tufo oolitico, Nap. p. 353-'*“ L’oolite, Broch. t. i. p. 3 19. ■ External Cbaraders. r Its colour is hair brown and chefnut brown, but the confiderable quantity of marie which it contains makes it yellowifh grey and alh grey. Is maffive. Internally dull. Frafture fine fplintery, but it is very difficult to obferve, on account of the imallnefs of the diftin# concretions. The