Claystone. 421 Geographic Situation. It occurs along with floetz-porphyry in the Pentland Hills; in a similar situation in the Island of Arran ; on the mountain of Tinto ; in the Ochil Hills ; and in many °ther places in Scotland. It occurs frequently on the Continent of Europe; and it has been observed asso ciated with the porphyries of Asia and America. 6. Adhesive-Slate. . -1 Klebschiefcr, Werner. Ce Schiste a polir, Broch. t. i. p. 376-—Klebscliiefer, Reuse, b. iv. s. 159.—Polierschiefer, Leonhard, 'label, s. 22—Kleb- schiefer, Karslen, Tabel. s. 26. Id. Steffens, b. i. s. 151. Id: Bent, b. ii. s. 560. ( * ' External Characters. Its colour is intermediate between greenish and yel- Wish, and also smoke-grey. It occurs massive. It is dull. I he fracture is straight slaty, I he fragments are tabular. It exfoliates on exposure to the air, but becomes com- P a ct again when immersed in water. It becomes shining in the streak. It is soft, passing into very soft. It is sectile. It splits very easily. It adheres strongly to the tongue. I I eels somewhat greasy. Specific gravity, 2.080, Klaproth. D d 3 Chemical