PHYSIOGRAPHY. 



Red Silver. 



161 



Sectile. Hardness =2'5 . . . 3-0. Sp. gr. =5-787 . . . 

 5*844. BREITHAUPT. 



Compound Varieties. 1. Twin-crystals. Face of com- 

 position perpendicular, axis of revolution parallel, to an 

 edge of z. 



Fig. 382. 



This kind of regular composition is frequently repeated, 

 contiguous to all the terminal edges of z, as in 

 Fiff. 333. 



2. Face of composition parallel, axis of revolution per- 

 pendicular to g. 



