| Popis: |
TheBi-bearing sulfosalts and chalco gen ides, ikunolite, babkinite, joseite-A, izoklakeite, cannizzarite, lillianite-gustavite and heyrovskyite, previously unknown in Kosovo, were identified in the Stan Terg deposit by means of electron microprobe analyses in samples from skarn and skarn-free mineral assemblages. Phase relationships among the minerals in the system Bi-Te-Pb-Ag- Cu indicate that they formed at different times with successive replacement of one mineral assemblage by the next, and do not represent decomposition products of high temperature Bi-bearing phases. The following replacement sequence is considered: lillianite/ gustavite+heyrovskyite+galena -izoklakeite-giessenite+cannizzarite -∗ bismuthinite+native bismuth -bismuth chalcogenides (joseite-A, ikunolite, babkinite) - chalcopyrite. Ikunolite and babkinite show a low degree of S and Se substitution and higher content of Pb for Bi substitution, suggesting a potential ikunolite-babkinite solid solution. Joseite-A is the first tellurium mineral described from this locality. Lillianite homologues include lillianite (N=4) and heyrovskyite (N=7) of low degree of AgBi for 2Pb substitution and average substitution coefficients x = 0.21 and 0.17, respectively. Izoklakeite-giessenite from Stan Terg has an average Sb/(Sb+Bi) ratio of about 0.43. Other identified Bi-bearing minerals include cannizzarite, native bismuth, and bismuthinite. All described minerals are associated with galena with elevated Bi and Ag contents (0.02 Bi+Ag apju). Native gold is spatially related with Bi mineralization. The bismuth-bearing phases at Stan Terg were formed during the retrograde evolution of the hydrothemial system under generally low-sulfidation and reduced fluid states in the temperature range from 350° to 250°C. ©2015 E. Schweizerbart'sche Verlagsbuchhandlung, Stuttgart, Germany. |
