Mössbauer and Reflectance Spectroscopy of Synthetic Jarosite with Variable Compositions and Temperatures

Introduction: The Mars Exploration Rover Mössbauer spectroscopy team identified jarosite, a sulfate which forms in the presence of water, in spectra of a layered outcrop in Meridiani Planum [1]. They made this assignment based on a doublet with quadrupole splitting of ~1.22 mm/s at T=200-280K that was assigned to either Kor Na-jarosite with the possibility of some Al substituting for Fe in octahedral sites. In order to further characterize this jarosite at Meridiani and search for jarosite elsewhere, careful spectroscopic characterization of the Mössbauer parameters of jarosite over a range of compositions and temperatures is needed, which is the goal of this study. Table 1. Compositions of Synthetic Jarosites