Raman spectroscopic investigation on Jarosite–Yavapaiite stability

The stability of synthetic Jarosite (KFe3(SO4)2(OH)6) at low temperature and reduced atmospheric pressure has been studied by Raman spectroscopy. Jarosite remains stable between 8 and 295 K, provided that the sample is not exposed to reduced atmospheric pressure. When exposed to reduced atmospheric pressure (2.0 × 10−2 Torr), however, the conversion of Jarosite into a different mineral is readily detected at room temperature by the appearance of a new Raman peak. The Raman shift of this peak (1032 cm−1) matches with that of Yavapaiite (KFe(SO4)2), which can be obtained by thermal decomposition of Jarosite above 473 K. These studies provide a better understanding of the stability of Jarosite subjected to conditions similar to that on the surface of Mars.