A special experimental setup for in-field applications was developed at Mainz. It incorporates hardware for automated positioning of the Mössbauer sensor head, a Plexiglas tube, and a modified version of the space proven Miniaturized Mössbauer Spectrometer MIMOS II (Klingelhöfer et al., Science, 306:1740–1745, 2004; Klingelhöfer et al., J. Geophys. Res., 108(E12):8067, 2003; Klingelhöfer et al., Hyperfine Interact. 144/145:371–379, 2002; Génin et al., Solid State Sci., 7:545–572, 2005). MIMOS operates in backscattering geometry, thus no sample preparation is required. Also dedicated software for running measurement sequences (e.g., different depth positions at different times etc.) was developed. The setup can work autonomously up to several weeks in the field. Preliminary results confirm that fougerite mineral found in hydromorphic soils is Fe^II–III hydroxycarbonate green rust.