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Tellurium-rich stibiogoldfieldite and Se-bearing dantopaite from Goldfield, Nevada, USA: new crystal chemical data
Mineralogical Magazine ( IF 2.7 ) Pub Date : 2023-10-16 , DOI: 10.1180/mgm.2023.77
Silvia MUSETTI , Jiří SEJKORA , Cristian BIAGIONI , Zdeněk DOLNÍČEK

Cotype material of stibiogoldfieldite from the Mohawk mine, Goldfield, Nevada, USA, has been examined in order to collect single-crystal X-ray diffraction data of Te-rich stibiogoldfieldite and to characterise the associated Ag–Bi–(S,Se) phase. Tellurium-rich stibiogoldfieldite, with empirical formula (Cu11.30Ag0.03)Σ11.33(Sb0.80As0.57Bi0.06Te2.57)Σ4.00(S12.83Se0.20)Σ13.03, is cubic, space group I$\bar{4}$3m, with unit-cell parameters a = 10.2947(3) Å and V = 1091.04(10) Å3. Its crystal structure has been refined to R1 = 0.0161 for 397 unique reflections with Fo > 4σ(Fo) and 25 refined parameters. The structure refinement confirmed the occurrence of a vacancy at the M(2) site, in agreement with the substitution M(2)Cu+ + X(3)(Sb/As)3+ = M(2)□ + X(3)Te4+. The Ag–Bi–(S,Se) phase was identified as the 6P homologue of the pavonite series, namely dantopaite. Its empirical formula is Cu1.36Ag4.39Pb0.12Bi12.62Sb0.06(S14.01Se7.91Te0.08), showing an exceptionally high Se content. Unit-cell parameters of Se-bearing dantopaite are a = 13.518(2), b = 4.0898(6), c = 18.984(3) Å, β = 106.816(6)°, V = 1004.7(3) Å3 and space group C2/m. The crystal structure was refined to R1 = 0.0504 for 1230 unique reflections with Fo > 4σ(Fo) and 82 refined parameters. The metal excess (~0.55 atoms per formula unit) of this pavonite homologue is mainly due to the accumulation of Ag and Cu in the thin slab of the crystal structure, whereas the high Se content is related to the partial replacement of S occurring preferentially in the thick PbS-like slab. Domains richer in Se and Pb in dantopaite, with empirical formula Cu0.89Ag4.50Pb0.49Bi12.53Sb0.07(S11.26Se10.74), were also identified, as grains up to 30 μm in size intimately intergrown with bohdanowiczite, indicating the possibility of a wide Se-to-S substitution in dantopaite.



中文翻译:

来自美国内华达州金田的富碲锑金矿和含硒丹托白石:新的晶体化学数据

对来自美国内华达州戈德菲尔德莫霍克矿的锑金矿共型材料进行了检查,以收集富碲锑金矿的单晶 X 射线衍射数据并表征相关的 Ag-Bi-(S,Se) 相。富碲锑金矿,经验式 (Cu 11.30 Ag 0.03 ) Σ11.33 (Sb 0.80 As 0.57 Bi 0.06 Te 2.57 ) Σ4.00 (S 12.83 Se 0.20 ) Σ13.03为立方体,空间群I $\bar{ 4}$ 3 m,晶胞参数a = 10.2947(3) Å 和V = 1091.04(10) Å 3。其晶体结构已被细化至R 1 = 0.0161,具有 397 个独特的反射,且F o > 4σ( F o ) 和 25 个细化参数。结构精修证实了M (2) 位点处存在空位,与取代M (2) Cu + + X (3) (Sb/As) 3+ = M (2) □ + X (3 )4+。Ag-Bi-(S,Se) 相被鉴定为钙磷矿系列的6 P同系物,即丹托磷矿。其经验式为Cu 1.36 Ag 4.39 Pb 0.12 Bi 12.62 Sb 0.06 (S 14.01 Se 7.91 Te 0.08 ),显示出极高的Se含量。含硒丹托白石的晶胞参数为a = 13.518(2), b = 4.0898(6), c = 18.984(3) Å, β = 106.816(6)°, V = 1004.7(3) Å 3和空间C组2/。对于F o > 4σ( F o ) 的 1230 次独特反射和 82 个细化参数,晶体结构被细化为R 1 = 0.0504 。该钠长石同系物的金属过量(每个分子式单元约 0.55 个原子)主要是由于 Ag 和 Cu 在晶体结构的薄板中积累,而高 Se 含量则与 S 优先发生在晶体结构中的部分取代有关。类似 PbS 的厚板。丹托白石中富含 Se 和 Pb 的区域,经验式 Cu 0.89Ag 4.50 Pb 0.49 Bi 12.53 Sb 0.07 (S 11.26 Se 10.74 ) 也被鉴定为尺寸达 30 μm 的颗粒与博丹诺威石紧密共生,表明丹托白石中存在广泛的 Se-S 替代的可能性。

更新日期:2023-10-16
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