1162 A TREATISE ON METAMORPHISM. 



tiou of bornite by the direct reactions of the cupric salts may be supposed 

 to be as follows: 



For ferrous sulphide in the presence of oxygen the reaction is: 



(1) 4FeS+3CuS0 4 +20=Cu 3 FeS 3 +3FeS0 4 +S0 2 



For iron bisulphide the reaction is : 



(2) 3FeS 2 +3CuS0 4 +40=Cu 3 FeS 3 +2FeS0 4 +4S0 2 



or, if oxygen be supposed to be absent, the reaction for cupric salt maybe: 



(3) 13FeS 2 +21CuSO 4 +20H 2 O=7Cu 3 FeS 3 +6FeSO 4 +20H 2 SO 4 



The production of bornite by the direct reaction of cuprous sulphate 

 on the bisulphide of iron in the presence of oxygen may be written: 



(4) 5FeS 2 +3Cu 2 S0 4 +80=2Cu 3 FeS 3 +3FeS0 4 +4S0 2 



or, if no oxygen be present, the reaction is : 



(5) 23FeS 2 +21Cu 2 S0 4 +16H,0=14Cu 3 FeS 3 +9FeS0 4 +16H,S0 4 



However, the bornite may also be produced by the reaction of the 

 cupric salt on the chalcopyrite itself. For instance, in the presence of 

 oxyg-en, for cupric sulphate, the reaction might be: 



(6) 20uFeS 2 4-CuSO 4 4-20=Cu 3 FeS 3 +FeSO 4 +SO 2 



If oxygen be absent the reaction for cupric sulphate would be: 



(7) 13CuFeS 2 +llCuS0 4 +8H 2 0=8Cu 3 FeS 3 +5FeS0 4 +8H 2 S0 4 



The reaction for cuprous sulphate in the presence of oxygen may be 

 written : 



(8) 4CuFeS 2 +0u 2 SO 4 +6O=2Cu 3 FeS 3 +2FeSO 4 +SO 2 

 and in the presence of oxyg-en : 



(9 ) 23CuFeS 2 + 1 10u 2 SO 4 4-4H 2 = 15Cu 3 FeS 3 +8FeS0 4 +4H 2 S0 4 



Further reactions might be written by combining corresponding 

 equations for cupric and cuprous salts, as a result of which the bornite is 

 produced by the reaction of both cuprous and cupric compounds. Reac- 

 tions might also be written by which the bornite is partly produced from 

 bisulphide of iron and partly from chalcopyrite. These reactions would be 

 merely the combination of corresponding equations, and it seems hardly 

 necessary to write them out, since no new principle is illustrated. 



