50 



PHYSIOGRAPHY. 



JVJispickel. 



Fig. 308. 



Fig. 309. 



Fig. 310. 



Franconia. 



Franconia. 



Fig. 304. r on r = 145 26'. (ditetraedre. H.) Fig. 

 305. / on Z=80 8'. (unit air e. H.) Fig. 306. z on *= 

 118 32'. Zon z = 16049 / . (unibinaire. H.) Fig. 308. 

 a on a=J21 52'. M on a^=136 20 7 . Fig. 309. g on 

 g = 118 32'. g on I = 131 48'. Fig. 310. g on a = 

 149 16'. 



Cleavage, parallel with M and M' pretty perfect ; traces 

 parallel with P. Surface, r deeply streaked parallel to its 

 own edges ; g sometimes rough, or striated in the direc- 

 tion of its edges of combination with Z; the remaining faces 

 are smooth. 



Lustre metallic. Color silver-white, inclining to steel- 

 grey. Streak dark greyish-black. 



Brittle. Hardness = 5-5 . . . 6-0. Sp. gr. = 6- 127, of 

 a crystallized variety. 



Compound Varieties. Twin-crystals : face of compo- 

 sition parallel, axis of revolution perpendicular to a face of 

 M; the composition often taking place parallel to both faces, 

 or being repeated in parallel layers. Massive : composi- 

 tion columnar, individuals of various sizes, generally straight 

 and divergent, or irregular. The faces of composition are 

 irregularly streaked. Individuals joined in a granular com- 



