The present-day Martian atmosphere is oxidizing and likely cannot sustain surficial liquid water due to its low average pressure (Vázquez & Hanslmeier, 2006). The geomorphic and mineralogical record, however, requires that the Noachian (4.1-3.7 Gyr) Martian atmosphere had higher pressures, or a different composition, to allow the presence of liquid water on the surface. Initially the Martian atmosphere was likely reducing, as based on climate modeling and geochemical analyses on ancient Martian meteorites (Catling & Moore, 2003;Ramirez et al., 2014). The redox state of the Noachian atmosphere was likely primarily dictated by volcanic activity (e.g., Sholes et al., 2017) and hydrodynamic escape, although the timing of the evolution to present-day oxidizing conditions is not well constrained. Redox sensitive iron-bearing minerals present in Noachian terrains may be key in evaluating the timing of atmospheric evolution since they are sensitive to changes in oxidant concentration. Effective interpretation of present-day Martian mineral assemblages to constrain atmospheric redox history requires experimental evaluation of potential iron oxidation mechanisms.