PLASMA. 218 Third Subspecies. Plasma. Plasma, Werner. id. Emm. b. iii. s. 322. Id. Brock, t. i. p. 278. Id. Rcuss, b. 2. s. 286. Id. Lud. Suck. Bert. Moks, b. i. s. 308. Id. Karst. Tabel. Id. Leonhard. Tabel. Id. Hab. Id. Kid, vol. i. p. 205. Id. Steffens, b. i. s. 159. Id. Lenz, b. i. s. 395.—Quartz- agathe calcedoine vert obscur, Lucas, t. ii. p. 110.—Plasma, Hoff. b. ii. s. 103. External Characters. Its most common colour is a variety intermediate be tween grass-green and leek-green, and sometimes ap proaching to pale mountain-green. It frequently occurs greenish-white and ochre-yellow: the latter colour is in •lots ; the first in spots, or clouded. Internally its lustre is glistening, inclining to glimmer ing. The fracture is perfect, and rather flat conchoidal. The fragments are angular, and very sharp edged. It is translucent, inclining to semi-transparent. It is hard. It is brittle. Rather easily frangible. Rather heavy. Specific gravity, 2.553, Klaproth. 2.445, Karsten. Chemical Characters. It is infusible before the blowpipe, but loses its colour. 0 3 Constituent