USEFUL METALS 135 



Copper : Its Properties, Occurence and Uses 



Properties of Copper. Copper, symbol Cu, is a copper red to red- 

 dish brown, soft, ductile and malleable metal. Its color as copper 

 red is best seen by reflected light. It is extremely tough, there- 

 fore, capable of being drawn out into exceedingly fine wires or 

 hammered out into thin leaves. Its ductility and malleability 

 are greatly diminished by the presence of impurities. As an 

 electrical conductor it is second only to silver. The metal slowly 

 tarnishes in dry air but in a moist atmosphere it is readily coated 

 with a basic green carbonate. It is readily soluble in the mineral 

 acids. Its specific gravity is 8.9. It melting point is 1065. 

 Its atomic weight 63.57. 



Ores of Copper. Native copper, Cu, 100 per cent, copper but 

 often alloyed with gold, silver, lead and mercury. 



Chalcocite, Cu 2 S, 79.8 per cent, copper. A gray sulphide. 



Covellite, CuS, 66.4 per cent, copper. An indigo blue sulphide. 



Bornite, Cu 2 S,CuS,FeS, 55.5 per cent, copper. Known as 

 horseflesh ore by miners. 



Chalcopyrite, CuFeS 3 , 34.5 per cent, copper. The most im- 

 portant source of the metal. 



Tetrahedrite, 4Cu 2 S,Sb 2 S 3 , 30.4 per cent, copper. Often 

 argentiferous. 



Tennantite, 4Cu 2 S,As 2 S3, 57.5 per cent, copper. 



Enargite, 3Cu 2 S,As 2 Ss, 48.3 per cent, copper. 



Chalcanthite, CuSo4,5H 2 0, 25.4 per cent, copper. A natural 

 blue vitriol. 



Brochantite, CuSO4,(3CuOH) 2 , 62.4 per cent, copper. 



Cuprite, Cu 2 O, 88.8 per cent, copper. The red oxide of copper. 



Tenorite, CuO, 79.8 per cent, copper. The black oxide of 

 copper. 



Malachite, CuC0 2 ,Cu(OH) 2 , 57.4 per cent, copper. The green 

 carbonate. 



Azurite, 2CuC0 3 ,Cu(OH) 2 , 55 per cent, copper. The blue 

 carbonate. 



Nantokite, Cu 2 Cl 2 , 64.1 per cent, copper. 



Atacamite, CuCl 2 ,Cu(OH) 2 , 59.4 per cent, copper. 



Dioptase, CuSiO 3 ,H 2 O. 



Chrysocolla, CuSi0 3 ,2H 2 O. 



Origin of the Ores. Copper is widely distributed in nature. 

 The metal is easily oxidizable and also easily reduced. It there- 



