Quantitative X-ray powder diffractometry was applied to the phase analysis of a mineral specimen containing two sulfur-rich isomorphous mineral phases, beudantite [PbFe3(AsO4)(SO4)(OH)6] and osarizawaite [PbFeAlCu(SO4)2(OH)6], together with goethite (FeOOH) and some hematite (Fe2O3). The application of the Rietveld method was extended to provide elemental as well as phase analysis.
