The Crystal Structure of Dadsonite

Abstract

Slovakia, has been refi ned to an R 1 index of 4.90% for 5263 unique refl ections [F o 2 ≥ 2 (F 2)] measured with MoK␣ radiation on a three-circle diffractometer equipped with a CCD detector. There are 10 pure Pb and 8 Sb sites, as well as three mixed (Pb,Sb) and (Sb,Pb) sites and three split coordinations of Sb in the crystal structure. Thirty S positions and one presumed Cl position, designated as "S1", constitute the anion part of the structure. The structure is of a rod-layer type, with two types of rod-layers alternating along the stacking direction b. Dadsonite is a desymmetrized OD structure with profuse twinning. The two types of layers present possess layer symmetries p1 and b2/m11, respectively. These layers respectively have a pseudoperiodicity equal to a/2 and a set of elements of pseudosymmetry which together cause a disorder process.

Focused Ion Beam and Advanced Electron Microscopy for Minerals: Insights and Outlook from Bismuth Sulphosalts

“…In contrast, the phases within the symplectites are compositionally relatively homogenous. If the amount of Cu is considered together with Ag, these compositions are very similar to the Ag-Bi-substituted heyrovskyite [74]. However, the two clusters are also positioned close to the compositional field for neyite (Cu6Ag2Pb25Bi26S68; [75]), cuproneyite (Cu7Pb27Bi25S68), and so-called 'Cu-enriched' cuproneyite (Cu11Pb25Bi25S68).…”

“…For comparative purposes, empirical formulae calculated on the basis of 17 apfu (as in heyrovskyite) are [(Cu 0. 90 9.09 ] for D. If the amount of Cu is considered together with Ag, these compositions are very similar to the Ag-Bi-substituted heyrovskyite [74]. However, the two clusters are also positioned close to the compositional field for neyite (Cu 6 [96].…”

“…Atoms are shown as balls: dark grey (smaller)-Bi; light grey (larger)-Pb; red-Cu; green-Ag; yellow-S. Coordination polyhedra are shown using the same colour code for each atom type; (b) Aikinite crystal structure [66] is built by Pb2S6 ribbons (dark grey) with 4 Cu atoms filling adjacent tetrahedral voids and BiS2+3 in monocapped prismatic polyhedra (light grey); (c) Ag-Bi-substituted heyrovskyite [74]. The bicapped trigonal prismatic PbS6+2 position is along the mirror planes (dark grey), the other cations (Ag, Pb, and Bi) are present in the octahedral MeS6 sites (light grey).…”

“…Gustavite is the Ag-bearing end-member of the same N = 4 homologue. Also reported are Ag-Bi-substituted heyrovskyites (Ag 1.31 Pb 3.37 Bi 3.32 S 9 ; [74], four discrete Ag-rich homologues (Figure 1a,c) [78,79], and a synthetic phase Ag 2.25 Pb 2.5 Bi 4.25 S 10 equivalent to N = 8 homologue ( 8 L); [81]). Natural Ag-free specimens are very rare, and are mostly found in young volcanic environments (e.g., [82]).…”

Ciriottiite, Cu(Cu,Ag)3Pb19(Sb,As)22(As2)S56, the Cu-Analogue of Sterryite from the Tavagnasco Mining District, Piedmont, Italy

“…Therefore, the characterization of sulfosalt assemblage could give interesting information about the ore geochemistry. In other cases, some structural features could indicate particular crystallization conditions, like the presence of chlorine site (e.g., dadsonite [24]), indicating the high chlorinity of the hydrothermal solutions, or localized S-S bonds, indicating high f (S 2 ) conditions (e.g., moëloite [25]). …”