GOLD IN ARSENOPYRITES FROM THE PEZINOK DEPOSIT (WESTERN CARPATHIANS, SLOVAKIA)

Two types of arsenopyrite are found in the Pezinok deposit: fine-grain ed gold-bearing arsenopyrite I with average gold content 110 ppm and y ounger coarse-grained arsenopyrite II without gold or with a low gold content (on the average 0.17 ppm). Arsenopyrite I is the most signific ant gold-bearing mineral in the Pezinok-Kolarsky Vrch Mt. Sb-Au deposi t (ICP/MS analyses by laser-beam ablation revealing gold grades at hig h as 378 ppm). Au-197 Mossbauer study of two arsenopyrite separates sh owed that gold is present exclusively in a chemically bound state with isomer shift values of 3.25 mm.s(-1) and 3.62 mm.s(-1), respectively. The gold-bearing arsenopyrites exhibit strong zonation patterns. Gene rally two extreme types of growth zones with different compositional t rends can be distinguished. The first zone has antimony, sulfur and ar senic contents around 0.6-1.0 wt. % and 40-41 wt. % respectively. This zone is followed by the second one, which is also strongly zoned and has arsenic and sulfur contents around 43-45 wt. % and 19-21 wt %, res pectively Antimony contents are 0.2 wt. % within the second zone, whic h is considered to be the most probable carrier of chemically bound go ld.