Quantitative analysis of the ore mineral parageneses in the Fe-Cu-S-O system at T = 400°C and P = 1 kbar

Abstract

It is carried out ore parageneses digital study of the iron and copper sulphides and oxides and native copper in the Fe-Cu-S-O system, open for the sulphur and oxygen at T = 400"C and P = I kbar. The system includes 10 minerals: pyrrhotite (Po), pyrite (Py), magnetite (Mt), hematite (Hem), chalcopyrite (Ccp), bornite (Bn), native copper (Cop), chalcocite (Cc), covellite (Cv) and cuprite (Cup). For the calculations is used Shvarov's (1992) database for the thermodynamical properties of the minerals and the sulphur and oxygen fugacities. Paragenetic incompatible are the minerals: Po - Hem, Po - Ce, Po - Cv, Po - Cup, Py - Cop, Py - Cup, Py - Cc, Mt - Cv, Mt - Cup, Cop - Bn, Cop - Ccp, Cop - Cv, Cup - Bn, Cup - Ccp, Cup - Cv, Cv - Ccp H Cc - Ccp. The simultaneous occur of some of these minerals indicates metastable state of the system. It is estimated the values of the sulphur and oxygen fugacity in the gas phase, that is in the equilibrium with the association of the ore mineral parageneses at T = 400ºC and P = I kbar. These values enable to draw monovariant lines, setting landmarks between the fields of the different ore mineral parageneses stability and chemical transform reactions. The results of the calculations are presented on the plot with coordinates IgfS2 - IgfO2.