Abstract
Three sulphosalts from the cuprobismutite homologous series have been found in a hydrothermal Ni-Bi-As mineralization at Čierna Lehota (Slovakia). Kupčíkite (second world occurrence) has a significant content of Pb (2.73 wt.%) and Fe (0.85 wt.%), with the structural formula (Cu3.92Fe0.24)Σ4.16(Bi4.60Pb0.19Ag0.04Sb0.01)Σ4.84S9.58. Hodrushite has a higher content of Ag (mean 1.27 wt.%), but less Fe (0.59 wt.%) and Pb (0.23 wt.%), with structural formula (Cu7.79Fe0.38)Σ8.17(Bi11.34Ag0.43Pb0.04Sb0.02)Σ11.83S22.13. Two varieties of cuprobismutite have the highest Ag content (3.8 and 2.3 wt.%), with Fe 0.6 and 0.2 wt.%, and Pb 0.1 and 6.7 wt.%, giving two formulas (Cu7.42Fe0.47)Σ7.87(Bi12.56Ag1.55Pb0.02)Σ14.13S24.68 and (Cu7.67Fe0.14)Σ7.81(Bi11.95Pb1.37Ag0.85Sb0.02)Σ14.19S24.13. Chemical variations between these sulphosalts are compared with published data, that emphasizes the role of minor cations. Associated sulphosalts are described: aikinite, and Bi-rich tennantite (Bi up to 9.7 wt.%).