Using Moessbauer spectroscopy to clarify the bond of gold in gold-bearing sulfide minerals from selected deposits in Slovakia

The Moessbauer spectroscopic study of gold-bearing arsenopyrites and pyrites containing ''invisible'' gold showed that the predominant fraction of 121Sb in sulfides is characterized by the isomeric shift IS = 11.90 mm.s-1 , which is close to the value of 10.0 mm.s-1 for Sb in gudmundite. The structure of gudmundite resembles closely the arsenopyrite lattice, where Sb is in a tetrahedral coordination with respect to 1 sulfur atom and 3 iron atoms, like As in arsenopyrite. It is concluded that, in addition to the Au-Fe substitution, the occurrence of the Sb-Au substitution can also be assumed. ICP/MS laser analysis confirmed a not very pronounced negative Au-Sb correlation. 6 figs., 22 refs