Fundamental Mvssbauer Parameters of Hydrous Iron Sulfates

Hydrous iron sulfates, which form as alteration products of sulfides, are rare on Earth. On Mars, the low temperature and pH found in the martian permafrost create ideal conditions for the formation of this group of minerals [1], which includes such phases as coquimbite (Fe2(SO4) 9H2O) and amarantite (FeSO4(OH) 3H2O). Viking, Mars Pathfinder, MER and OMEGA data [e.g., [2]] have all indicated the presence of high sulfur contents on the surface of Mars, but the mineralogy of the sulfur-rich phases has not been well constrained. Recent work by [3] suggests that hydrous iron sulfates might satisfy the Martian thermal emission, vis-near IR, and M ssbauer spectra. These data suggest that sulfide and sulfate minerals might be significant contributors to all types of spectra acquired on the Martian surface.