THE CRYSTAL STRUCTURE OF PADĚRAITE,

详细信息   p://canmin.geoscienceworld.org/content/44/2/481.full">在线全文   p://canmin.geoscienceworld.org/content/44/2/481.full.pdf">PDF全文下载

• 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

摘要

<p id="p-1">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) Åp>3p>, 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) Åp>3p>, 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 KQp>np> homologues of paděraite, as well as of regular intergrowths of paděraite and cuprobismutite homologous series. p>