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PEARLSTONE. 281 feet eonchoulal: it is rather heavier than semi-opal, and is differently affected by the blowpipe. 2. It is named Pilch stone, from the striking resem blance which some of its varieties have to pitch. 3. It was first discovered, about sixty years ago, by a mineralogist of Dresden, named Schulz ; but it was first established as a distinct species by Werner. L It appears to pass on the one hand into Obsidian, and on the other into Pearlstone, 3. Pearlstone. I’erlstein, Werner. he Perlstcin, Broch. t. i. p. 352.—Lave vitreuse perlee, Haw/, t. iv. p. 495.—I’erlstein, Iiaiss, b. ii. s. 349. Id. Lud. b. i. ■s. 99. Id. Suck. ]r th. s. 367. Id. Bert. s. 224. Id. Mohs, b. i. s. 353. Lave vitreuse perl6, Lucas, p. 231. Obsidienne perle, Brong. t. i. p. 340.—I’erlstein, Ilaus. s. 88.—l’earl- stein, Leonhard, Tabel. s. 14. Id. Karslcn, Tabel. s. 36— Pearlstone, Kid, Appendix, p. 38—Perlstein, Steffens, b. i. s - 378. hi. Hoff. b. ii. 208. Id. Lenz, b. i. s. 443. Id. Oken, b- i- s. 306. External Characters. It is generally grey, sometimes also bl..ck and red. 1 he varieties of grey are smoke, bluish, ash, yellowish, ai »d pearl grey : from dark ash-grey it passes into grey ish-black ; from yellowish-grey into a kind of straw-yel low : from pearl-grey into flesh and brick red, and red dish-brown. The colours are sometimes disposed in sl riped and spotted delineations.
