194 PHYSIOGRAPHY. CLASS n. 



Tqpfstein. Grunerde. Chlorit. Talk. WEHN-. HofFm. 

 H. B. II. 2. S. 131. 134. 195. 267. Chlorit. Topf- 

 stein. Talk. HAUSM. II. S. 490. 496. 497. Chlorit. 

 Talk. Topfstein. LEONH. S. 4C5. 466. 467. Talc (in 

 part). HAT: Y. Traite, T. III. p. 252. Tabl. comp. p. 56. 

 Traite', 2de Ed. T. II. p. 489. 



Fundamental form. Scalene four-sided pyramid of 

 unknown dimensions. Vol. I. Fig. 9. Simple 

 forms. P oo ; P -f- oo = 120 (nearly) ; 

 Pr + CD ; Pr -|- oo ; in various combinations 

 presenting hexagonal, rhomboidal, and rectan- 

 gular plates. 



Cleavage, P oo, commonly highly perfect. Frac- 

 ture not observable. Surface P oo smooth. 

 The faces of the other forms streaked parallel to 

 the edges of combination with P oo. 



Lustre pearly upon P oo, both as faces of crys- 

 tallisation and of cleavage. The faces of the 

 other forms possess vitreous lustre, inclining to 

 adamantine, generally low degrees. 



Colour, various shades of green, as blackish-green, 

 leek-green, celandine-green, and apple-green, 

 passing into greenish-grey, greenish-white, and 

 greyish-white. Streak corresponding to the co- 

 lour, green . . . white. Semi-transparent . . . trans- 

 lucent. Different colours in different directions. 

 Some individuals are of a bright green colour if 

 viewed in a direction perpendicular to the la- 

 minae, while parallel to them they exhibit in 

 other directions a fine brown tinge. In the lat- 

 ter direction they are much more transparent 

 than in the former. 



