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PORCELAIN-JASPER. 257 Observations. 1. The distinguishing characters of this mineral, are Its colour-delineations, its want of lustre, and its very flat conehoidal fracture, which sometimes inclines to earthy, and even to slaty. Its geognostic situation ah'o distin guishes it from all the other subspecies of this species. 2. It is allied to Conehoidal Hornstone and Claystone, and passes into both of these minerals. These transitions are to be observed in the Pentland Hills. It is distin guished from Conehoidal IJornstone by its colour, colour* delineations, want of lustre, its more perfect flat con- choidal fracture, and its opacity: from Claystone it is distinguished by its greater hardness. Third Subspecies. Porcelain-Jasper. Porzellan Jaspis, Werner. id. Wid. p. 314..—Porcellanite, Kirw. vol. i. p. 313.—Porzellan- Jaspis, Estner, b. ii. s. 613. Id. Emm. b. i. s. 240.—Diaspro porcellanico, Nap. p. 192 Jaspe porcelaine, Lam. t. ii. p. 1(16. Id. Broch. t. i. p. 166.—Thermantide porcellanite, Haw/, t. iv. p. 510.—Porzellan Jaspis, Reuss, b. ii. s. 307- Id. Litd. b. i. s. 94. Id. Suck, lr th. s. 351. Id. Bert. s. 22G. Id. Molts, b. i. s. 321. Id. Karsten, Tabel. s. 38. Id. Leonhard, s - 12. Id. Steffens, b. i. s. 184. Id. Iloff. b. ii. s. 168. Id. Lenz, b. i, £ 4.18. Id. Oken, b. i. s. 298. External Characters. Its colours are grey, blue, yellow, and seldom black Vol. I. H and
