COMPOSITIONAL DATA FOR IKUNOLITE FROM REDZINY, RUDAWY JANOWICKIE, LOWER SILESIA, POLAND

摘要

The chemical composition of ikunolite and the distribution of Se among various sulfides and sulfosalts at Redziny, in the metamorphic cover of the Variscan Karkonosze pluton, in Lower Silesia, Poland, have been documented by electron-microprobe analysis. At Redziny, selenium becomes concentrated at the lower-temperature stages of mineralization. Its main carrier is ikunolite, Bi_4(S,Se)_3, with Se contents up to ca. 11 wt. percent. Some grains of Ag-bearing galena and aikinite also may be enriched in Se (above 1 wt. percent). The chemical composition of ikunolite shows a wide variability, never reported from any other locality. Results of our analyses document a full range of Se-for-S substitution in ikunolite and the existence of a complete solid-solution series from the sulfur end-member to a composition with a S:Se ratio ca. 1:1. According to data available in the literature, ikunolite also forms a continuous solid-solution series with laitakarite, Bi_4(Se,S)_3. Some ikunolite compositions reveal substantial amounts of Pb substituting for Bi, in the range 0-0.46 apfu. One sample has the composition PbBi_3(S,Se)_3, indicating a compositional trend towards babkinite, Pb_2Bi_2(S,Se)_3.