CATIONIC COMPOSITION OF SULPHIDE, SELENIDE AND TELLURIDE MINERALS

Gorchakova O.E. and Smirnova N.L.

Dept. of Chemistry, All-Russian Inst. of Scientific and Technical Informatiion, Moscow, goe@viniti.msk.su

Minerals belonging to the sulphide class sre considered. The set of sulphide minerals can be divided into three subsets: sulphides, selenides and tellurides. Besides pure S, Se and Te mixed anions are also possible:

SeS, TeS, S.H₂ O (for example: NaFeS₂.2H₂O - erdite). Qualitative formulae of these minerals are considered. An ideal qualitative formula consists of main (species forming) chemical elements without isomorphic impurities, coefficients and charges of atoms. The cationic composition of sulphides, selenides and tellurides was established. 439 S - containing, 46 Se - containing and 55 Te - containing minerals were analyzed. The total number of cations in sulphide minerals is 939, in selenide minerals - 65, in telluride minerals - 72. All cations of selenide and telluride minerals were found in sulphide minerals, but some cations were met only in sulphides: Na (7 minerals), K (6), Cs (1), Be (3), Mg (4), Ca (3), Ba (1), Ti (1), V (8), Nb (1), Cr (7), W (2), Mn (6), Ru (2), Os (2), Ir (7), Al (2), Ga (1), In (3). Each of these cations has frequency not more than 5% of Cu maximal frequency. Cation frequency correlation was defined only for common cations of all three subsets.

Based on the difference (D) between the frequency of sulphide, selenide and telluride cations it was established that minerals containing Cu, Pb, Sb, Fe, Ag, As, Bi were leaders for sulphides, Ni, Cu, Ag minerals - for selenides, Pd, Ag, Sb, Bi - for tellurides. The frequency of Pd minerals in tellurides is three times more than in sulphides. Fe, As, Sn and Co cations in tellurides are 56, 56, 25 and 8%, correspondingly, of maximal frequency of Cu (144) cations in sulphides. Rare cations are Mo, Cd, Ge for selenides and Fe, Co, Rh, Sn, As - for tellurides, among these cations only Rh is rare for sulphide minerals. Analysis of qualitative formulae is an important characteristic of ore deposits.