CHAPTER VIII 

 USEFUL METALS CONTINUED (GROUP IV) 



COBALT, NICKEL, MANGANESE, ZINC 

 Cobalt: Its Properties, Occurrence and Uses 



Properties. Cobalt, symbol Co, is a hard, bluish-white metal 

 somewhat suggestive of nickel, but without its characteristic 

 yellowish tinge. At a high temperature, unlike iron and nickel, it 

 retains its magnetism. The metal is malleable, sectile, and ve,ry 

 ductile when heated. In the massive form it is permanent in 

 ordinary atmosphere but when in the pulverulent state it is 

 rapidly oxidized. Its specific gravity varies from 8.54 to 8.7. 

 Its melting point 1530 C. Its atomic weight is 58.97. 



Ores of Cobalt. Cobalt occurs in the native state in very small 

 quantities in meteoric iron. 



Jaipurite, CoS, 64.6 per cent. Co. Used in enameling various 

 shades of blue on gold and silver. 



Linnceite, Co 3 S 4 , 21.34 per cent. Co. If none of the cobalt 

 were replaced by nickel the theoretical per cent, of cobalt 

 would be 57.9. 



Smaltite, CoAs 2 , 28.2 per cent. Co. Usually with some nickel 

 present. 



Safflorite, CoAs 2 , 28.2 per cent. Co. Nickel and iron present 

 in varying amounts. 



Skutterudite, CoAs 3 , 20.7 per cent. Co. With traces of iron. 



Cobaltite, CoS 2 , CoAs 2 , 35.4 per cent. Co. 



Erythrite (cobalt bloom), 3CoO,As 2 O6,8H 2 O, 37.47 per cent. Co. 



Asbolite (black cobalt ocher). Composition variable. 



Cobalt is widely diffused in the igneous rocks but in much 

 smaller quantities than its associate nickel. It is present also in 

 both the meteoric and terrestrial iron. It has been found also 

 in the ashes of sea weeds. 



Origin of the Ores. The sulphides of cobalt may be formed 

 by either the wet or the dry processes. The arsenides of cobalt 



235 



