Hydrogen Geysers: Explanation for Observed Evidence of Geologically   Recent Volatile-Related Activity on Mercury's Surface
  High resolution images of Mercury's surface, from the MESSENGER spacecraft, reveal many bright deposits associated with irregular, shallow, rimless depressions whose origins were attributed to volatile-related activity, but absent information on the nature and origin of that volatile matter. Here I describe planetary formation, unlike the cited models, and show that primordial condensation from an atmosphere of solar composition at pressures of one atmosphere or above will lead to iron condensing as a liquid and dissolving copious amounts of hydrogen, which is subsequently released as Mercury's core solidifies and escapes from the surface, yielding the observed pit-like features with associated highly-reflecting matter. The exiting hydrogen chemically reduces some iron compound, probably iron sulfide, to the metal, which accounts for the bright deposits. 
J. Marvin Herndon
physics.gen-ph physics.geo-ph