Raman, MIR, VNIR, and LIBS spectra of szomolnokite, rozenite, and melanterite: Martian implications

Different sulfates have been extensively detected on the Martian surface. The presence of ferrous sulfates provides valuable clues about the redox environment, hydrological processes, and climate history of ancient Mars. In this study, three hydrated ferrous sulfates were prepared in the laboratory using heating dehydration reactions. The samples were analyzed using X-ray Diffraction (XRD) to confirm their phase and homogeneity. Subsequently, Raman, mid-infrared (MIR) spectra, visible near-infrared (VNIR) spectra, and laser-induced breakdown spectroscopy (LIBS) were measured and analyzed. The results demonstrate that the spectra of three hydrated ferrous sulfates exhibit distinctive features that can offer new insights for identifying different ferrous sulfates on Mars and aid in the interpretation of in-situ data collected by instruments such as the Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals (SHERLOC), SuperCam, and ChemCam, etc.