• journal_title：The Canadian Mineralogist
• Contributor：Dan Topa ; Emil Makovicky
• Publisher：Mineralogical Association of Canada
• Date：2006-
• Format：text/html
• Language：en
• Identifier：10.2113/gscanmin.44.2.481
• journal_abbrev：Can Mineral
• issn：0008-4476
• volume：44
• issue：2
• firstpage：481
• section：Articles

The crystal structure of Ag-bearing paděraite, ideally Cu₇(Ag_0.33Pb_1.33Bi_11.33)_∑13 S₂₂, a 17.585(4), b 3.9386(9), c 28.453(7) Å, β 105.41(1)°, V 1899.8(8) ų, space group P2₁/m and Z = 2, from a skarn deposit at Băiţa Bihor in Romania, has been solved by direct methods and refined to an R₁ index of 7.72% for 2429 unique reflections [F_o ≥ 4σ(F_o)] measured with MoKα X-radiation on a three-circle diffractometer equipped with a CCD detector. The crystal structure of Ag-free, Cu-enriched paděraite, ideally Cu₇(Cu_0.33Pb_1.33Bi_11.33)_∑13S₂₂, a 17.573(2), b 3.9426(4), c 28.423(3) Å, β 105.525(2)°, V 1897.3(6) ų, space group P2₁/m and Z = 2, from a rare-metal granitic pegmatite at Swartberg, South Africa, has been solved by direct methods and refined to an R₁ index of 5.04% for 3200 unique reflections [F_o ≥ 4σ(F_o)]. In the crystal structures, there are 12 Bi sites, one Pb site, seven triangular and flat-tetrahedral Cu sites and 22 S positions. The crystal structure, in most features corresponding to that described earlier, can be represented as a intergrowth of kupčíkite-like “K slabs” and “Q slabs”, which on their own make up a structure related to nordströmite or kobellite. We provide the chemical formulae and unit cells of potential KQⁿ homologues of paděraite, as well as of regular intergrowths of paděraite and cuprobismutite homologous series.