Crystal structure of mattheddleite: a Pb, S, Si phase with the apatite structure

Abstract

The crystal structure of mattheddleite (Pb 5 (Si 1.5 S 1.5 )O 12 (Cl 0.57 OH 0.43 ), P6 3 /m, a = 10.0056(6), c = 7.4960(9) A Ê ) from Leadhills, Scotland has been determined to R = 0.065. The structure is that of apatite where Pb replaces Ca, equal amounts of S and Si replace P and the X anion is OH + Cl. The composition deduced from the structural refinement differs from that of microprobe analyses by giving full occupancy of the tetrahedral site and equal Si and S to preserve charge balance. We conclude that the microprobe analysis is incorrect possibly due to large and inaccurate absorption corrections. For the crystal analysed, the X anion position is zoned from an OH-rich interior to a Cl-rich exterior. The Pb(2) atom is disordered which may be analogous to the disordering of the Ca(2) site in Cl-rich, Ca apatites.

The production of a lead glaze with galena: Thermal transformations in the PbS–SiO2 system

“…Type I crystals contain 86.1 wt% Pb and 13.6 wt% S and no O, corresponding to galena. Type II and Type III crystallites are identified by SR‐μXRD as lanarkite, PbO·PbSO 4 , and mattheddleite, a lead silicate sulfate chloride of composition Pb 10 (SiO 4 ) 3.5 (SO 4 ) 2 Cl 2 , respectively, as shown in Figure . The chemical composition obtained for the Type II crystals is also in good agreement with those of lanarkite, PbO·PbSO 4 .…”

Other Minerals from the Supergroup of Apatite

“…Mattheddleite [131], [132], [133], [134] is a mineral with the composition Pb 10 (SiO 4 ) 3 (SO 4 ) 3 Cl 2 (LIVINGSTONE et al [131]) or Pb 5 (Si 1.5 S 1.5 )O 12 (Cl 0.57 OH 0.43 ) (STELLE et al [134]) which is a lead member of apatite supergroup where phosphorus is totally replaced by sulfur and silicon: Si 4+ + S 6+ ↔ 2P 5+ . Mattheddleite was first recognized in typical Pb mineral region at Leadhills, Scotland and named after Scottish mineralogist MATTHEW FORSTER HEDDLE (1828-1897).…”

“…Mattheddleite is a colorless or white hexagonal mineral belonging to the space group P6 3 /M. The unit cell parameters are a = 9.963 (10.0056 [134]) and c = 7.464 (7.4960 [134]) Å, Z = ½ (Z = Apatites and their Synthetic Analogues -Synthesis, Structure, Properties and Applications…”

“…[134]) and V = 641.63 (649.9[134]) Å3 . Calculated density is 6.96 (6.822[134]) g⋅cm−3 . The hardness of the mineral on the Mohs scale is 4½.Other Minerals from the Supergroup of Apatite http://dx.doi.org/10.5772/62210…”