Sublimate residue of ammonium formate (17 wt%) mixed with pyrrhotite sub-micrometer sized grains at 173 K inside the sample holder (48 mm in diameter and 5 mm deep) in the CARBONIR simulation chamber on 05/09/2018.

Fragment of the sublimate residue of ammonium formate (17 wt%) mixed with pyrrhotite grains imaged with an optical microscope outside the simulation chamber on 18/09/2018. The sublimate residue is made of fluffy aggregates of opaque pyrrhotite grains, the ammonium salt probably playing the role of a cement/coating between the pyrrhotite grains.

Zoom on a fragment of the sublimate residue of ammonium formate (17 wt%) mixed with pyrrhotite grains measured by Scanning Electron Microscopy outside the simulation chamber on 05/10/2018. The sub-micrometric to micrometric pyrrhotite grains are arranged in a porous structure as a result of the freezing and sublimation processes. The ammonium salt probably coats and/or cements the pyrrhotite grains.

Zoom on a fragment of the sublimate residue of ammonium formate (17 wt%) mixed with pyrrhotite grains measured by Scanning Electron Microscopy outside the simulation chamber on 05/10/2018. The sub-micrometric to micrometric pyrrhotite grains are arranged in a porous structure as a result of the freezing and sublimation processes. The ammonium salt probably coats and/or cements the pyrrhotite grains.