432 CLAY-SLATE FAMILY. It occurs massive, and sometimes in roundish balls, which are imbedded in the massive varieties. Its lustre is more or less glimmering. The fracture is nearly perfect straight slaty. The fragments are tabular. It is opaque. It retains its colour in the streak. It is soft. It is easily frangible, and rather brittle. Specific gravity, 2.384, Kir wan. 2.017, Karstm. Second Subspecies. Glossy Alum-Slate. % Gliinzender Alaunschiefer, Werner. Var. Alaunschiefer, Wid. s. 395—Glanzender Alaunschiefer, Emm. b. i. s. 297.—Alaunschiefer, Estner, b. ii. s. 651.—Va- riete de 1’Argile schisteuse, Hauy.—L* Schiste alumineux eda- tante, Broch. t. i. p. 38S._Glan*ender Alaunschiefer, Reuss, • n. s. 145. Id. Hab. s. 49. Id. Leonhard, Tabl. s. 22. Id. arst. Tabel. s. 36. Id. Steffens, b. i. s. 206'. Id. Lenz, ]>. ii- s- 572. Id. Oken, b. i. s. 362. External Characters. hi ^Ir COl ]° Ur ,S ’ ntermet *iate between bluish and iron ’ < son ietimes exhibits on the surface of fissures the pavonine or temper-steel tarnish. It occurs massive. Its lustre is semi-metallic and shining on the principal fracture, and glimmering or dull on the cross fracture. he fracture is partly straight', partly undulating curved slaty. J The