60 MINERALS OF CHILE. 



inch in length. Its color is crimson-red; specific gravity 5.8. 

 Its composition is the same as the last described mineral. 



TEN0R1TE OR BLACK OXIDE OF COPPER. 



This is found massive, almost always mixed with other min- 

 erals of copper. It has a black metallic luster, and when pure 

 contains 



Copper 79.86 



Oxygen 20.14 



t^ * i • n rx 100.00 



Its formula is Cu O. 



ATACAMITE. 



This mineral was first discovered in the sands of the desert 

 of Atacama, and hence its name. It is crystallized in modified 

 rectangular prisms and rectangular octahedrons. Its color is 

 of a dark emerald-green, almost black at times. It is translu- 

 cent; has a hardness of from 3 to 3.5, and a specific gravity of 

 about 4. It consists of water, chloride, and oxide of copper, 

 and contains, according to analysis of Ulex — 



Chlorine 16.12 



Oxide of copper 56.23 



Water 11.99 



Copper 14.56 



Silica 1.20 



100.00 

 Corresponding to the formula Cu Cl-f 3 Cu+3 H. 



This mineral is also found in the district of Tarapaca. It 

 is ground up in Chile, and is used as powder for letters under 

 the name of arsenillo. 



COPPER GLANCE. 



The specimens of this mineral examined were all massive, 

 of a black metallic luster, soft, and easily cut with a knife, 

 having a specific gravity of 5.7. It commonly has green 

 and blue carbonate disseminated through the mass. It is 

 composed of 



Copper 79.8 



Sulphur 20.2 



Havins: for its formula Cu 2 S. 



