CHAPTER V 

 USEFUL METALS CONTINUED (GROUP II, SUBGROUP A) 



BISMUTH, COPPER AND CADMIUM 

 Bismuth : Its Properties, Occurrence and Uses 



Properties of Bismuth. Bismuth, symbol Bi, is a silvery 

 white metal with a reddish tinge. Unlike the other metals, 

 save antimony, it is extremely brittle. It is unoxidized at the 

 ordinary temperature in dry air while it is slowly oxidized in 

 moist atmosphere. The reddish tinge on the exposed surfaces 

 of the metal is the result of such oxidation. It expands 2 per 

 cent, upon cooling and this property is responsible for its exten- 

 sive use in the manufacture of safety plugs for boilers. Chem- 

 ically it is closely allied to arsenic and antimony. It is soluble in 

 HC1; specific gravity, 9.8, melting point, 269 atomic weight, 

 208, and crystallizes in the hexagonal system. 



Ores of Bismuth. Native bismuth, Bi, 100 per cent. It is 

 often associated with gold, silver, and several of the useful 

 metals. 



Bismuthinite, Bi 2 S 3 , 81.2 per cent, bismuth. 



Guanajuatite, Bi 2 Se 3 , 63.7 per cent, bismuth. 



Tetradymite, Bi 2 Te 3 , 51.9 per cent, bismuth when sulphur 

 free. 



Bismutite, Bi 2 O 3) H 2 CO 3 , 80.6 per cent, bismuth. A basic 

 carbonate of doubtful composition. 



Bismutosphaerite, Bi 2 3 ,Bi 2 (C0 3 ) 3 . 



Bismite, Bi 2 O 3 , 96.6 per cent, bismuth. 



There are also arsenates of bismuth, a tellurate, a vanadate, 

 a silicate and an oxychloride of the same base, but these are 

 rare minerals. The native metal and the sulphide, bismuth- 

 inite, are the most widely distributed of the bismuth minerals 

 and therefore the most important ores. 



Origin of the Ores. Native bismuth results from the reduction 

 of other ores of the metal. The important deposits of bismuth 

 in Bolivia may be primary. The bismuth is intergrown with 



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