HERFD-XAS and XES study of Ag in PbS

In natural deposits, the majority of the Ag enriches sulphide minerals or forms its own phases. The contents of Ag and Sb(or Bi) in galena are often positively correlated. Up to 1.5 wt% of Ag concentrates in the pure PbS, and up to 5 wt% solutes in galena in the presence of Sb(or Bi). Based on the HRTEM, EPMA, and SEM/EDS analyses, in the absence of Sb and Bi, Ag most likely forms solid solution, Ag2S inclusions, or nano-sized inclusions of Ag°. In the presence of Sb and Bi, in most sources, the incorporation of Ag into the PbS structure is accounted for by the coupled isomorphous substitution mechanism 2Pb2+ = Ag+ + Sb(or Bi)3+. However, up to date, there is no spectroscopic data on the state of Ag in galena.
We propose to study natural samples of Ag-Sb and Ag-Bi-bearing galena by recording Ag L3-edge HERFD-XANES and XES spectra of 10 samples, and Sb L3-edge HERFD-XANES spectra for a few selected samples to study the mechanism of Ag-enrichment of galena.