270 PHYSIOGRAPHY. 



White Copperas White Iron-Pyrites. 



WHITE COPPERAS. 



Crystals, having six lateral faces terminated by pyra- 

 mids, with six truncated faces ; the angle which two faces 

 of the pyramid, form = 128 8', their inclination to the 

 lateral faces 119, and their angles with the truncature 

 = 151. 



Color white, with a pale tinge of violet. 



Compound Varieties. Massive: granular. 



1. It is wholly dissolved in cold water ; but in hot, it deposits oxide of 

 iron and silica. 



2. Analysis. 



By ROSE. 



0-37 

 4355 

 25-21 



Silica . 



Sulphuric acid 



Oxide of iron 



Alumina 



Lime 



Magnesia 



Water 



031 

 43-55 

 24 11 



0-92 



0-73 



032 



30-10 



0-78 



0-14 



0-21 



29 98 



3. It is found in abundance in the province of Copiapo, a province in 

 the north of Chili, near Bolivia ; and is apparently derived from the de- 

 composition of a bed of Iron and Copper Pyrites, mingled with Feldspar. 



WHITE IRON-PYRITES. Prismatic Chlorone- 

 Pyrites. 



Primary form. Right rhombic prism. M on M = 

 106 2'.* 



Secondary forms. 



Fig. 471. Fig. 472. 



Cornwall. 



