Synchrotron-based X-ray diffraction of the lead apatite series Pb₁₀(PO₄)₆Cl₂-Pb₁₀(AsO₄)₆Cl₂

A number of compounds of the pyromorphite-mimetite solid solution series were synthesized at room temperature and analyzed with infrared spectroscopy and powder X-ray diffraction. High-resolution high-quality powder diffraction data were obtained by means of the state-of-the-art instrument at the 11-BM beamline of the Advanced Photon Source at Argonne National Laboratory, Argonne, IL, USA. The unit-cell dimensions, atomic position and atomic displacement parameters, as well as site occupancy for analyzed phases, were refined by the Rietveld method and reported herein for the first time. The results of this study indicate that the pyromorphite-mimetite series is continuous in near-Earth-surface environments. Detailed structural changes caused by P⁵⁺-As⁵⁺ substitutions in minerals from the pyromorphite-mimetite solid solution series are reported.