492 



MEASUREMENTS OF CRYSTALS. 



CORUNDUM. (Continued.) 

 Fig. 254, a secondary form. 



SPINELLE. Figs. 255 to 364 inclusive. Page 315. 



Fig. 255. The primary, a regular octa- 

 hedron. 



P onP' 109°28'16" 



Figs. 256 and 257. 



Pono 144°48'8" 



o ono 120 



Figs. 260 and 261. Groups of crystals. 



Orange county. 

 Fig. 262. A twin consisting of two equal 

 and similar portions of a crystal 

 similar to 256. 

 Fig. 263. A twin composed of about 

 equal parts of the primary octahe- 

 dron, of which one half is turned 

 round. 



SPINELLE. 



Fig. 264. Three nearly equal parts of the 

 same crystal variously turned upon 

 each other. The faces of composi- 

 tion in the latter case project. 



AUTOMOLITE. Fig. 265. Page 319. 



Fig. 265. The primary, a regular octahe- 

 dron. 

 P onP' 109O28'16" 



IDOCRASE. Figs. 266 to 269 inclusive. Page 321 . 

 Fig. 266. The primary, a right square 



prism. 

 Figs. 267 and 268. 



Monc 115°15' 



MoncZ 135 



P one 142 54 



c ond 127 6 



