POLIER, OR POLISHING-SLATE. 7. Polier, or Polishing-Slate. Polierschiefer, Werner. Polierschiefer, Mohs, b. i. s. 451. Id. Karsten, Tabel. S. 26. Id. Steffens, b. i. s. 149. Id. Lots, b. ii. s. 562. Id. Oken, b. i. s. 279- It Is divided by Karsten into three subspecies, Common Polier-Slate, Earthy Polier-Slate, and Fna e I’olier-Slate. First Subspecies. I Common Polier-Slate. Gemeiner Polierschiefer, Karsten. Id. Lem, b. ii.’ s. 562. External Characters. Its colours are snow and yellowish white; also straw, cream, and ochre yellow. It occurs massive. It is dull. The principal fracture is thin slaty; the cross fracture even. The fragments are tabular. It is opaque. It is semi-hard. Feels meagre; and soils strongly. It is very brittle; and easily frangible. It is so light as to swim on the surface of water. D d 4 Constituent