78 MINERALS OF CHILE. 



lignites of Concepcion and Colcura are found. Breithaupt 



called a prismatic crystalline variety of this mineral from 



Chile Chileite, without, however, any just grounds of separating 



it from the gothite proper. The analysis of the Chileite, as 



given by Breithaupt, is 



Peroxide of iron 83.5 



Water.... 10.3 



Copper 1.9 



Silica 4.3 



Formula, Fe H. 100 -° 



PYRITES. 



The different varieties of iron pyrites are found in all parts 

 of Chile. They sometimes contain an appreciable amount of 

 gold. 



COQUIMBITE WHITE COPPERAS. 



The Tierra Amarilla, near Copiapo, is a seam of pyrites 

 that crosses compact feldspathic rocks, and from its decompo- 

 sition several minerals result. The one in question occurs in 

 regular hexagonal plates of a yellowish -white color and pearly 

 luster. It has a strong astringent taste, and is quite soluble in 

 water. It is a neutral sulphate of iron, as shown by Eose's 

 analysis : 



Peroxide of iron 24.11 



Sulphuric acid 43.55 



Alumina 92 



Lime .73 



Magnesia 32 



Silica 31 



Water 30.10 



Its formula is FS 3 +9 H. 100 - 04 



COPIAPITE — YELLOW COPPERAS. 



This occurs associated with the last, and is most commonly 

 found in fibrous masses, of a beautiful silky luster when the 

 fracture is fresh ; it, however, soon becomes of a rusty color. 

 It is not so soluble as the last, and is a basic salt. Its specific 

 gravity is 1.84. The analysis of a fine specimen furnished me 



Sulphuric acid 30.25 30.42 



Peroxide of iron 31.75 30.98 



S£=::::::::::::::::::::::::::::::::::::^54}^- ti ^ d - 



100.74 



The analyses correspond to the formula 3?e S 2 +ll IL 



