Gossans on Mars

Abstract

The appearance of rusty iron-rich oxidized cappings over sulfide-bearing rocks on earth indicates that similar gossans may have formed on the surface of Mars. Electrochemical processes and thermodynamic relationships linking acidity to oxidation-reduction reactions between primary sulfide minerals and their oxidative weathering products present in the regolith of Mars are discussed. Remote-sensed visible spectra of the Martian surface are in keeping with the presence of poorly-crystalline FeOOH, jarosite, silica, and clay silicates found in gossans, while incompletely weathered pyrrhotite may represent the magnetic material observed in Martian regolith.