The formation of Fe silicides in surface ripple patterns, generated by erosion of a Si surface with keV Ar and Xe ions and simultaneous co-deposition of Fe, was investigated with conversion electron Mossbauer spectroscopy, atomic force microscopy and Rutherford backscattering spectrometry. For the dot and ripple patterns studied, we find an average Fe concentration in the irradiated layer between 6 and 25 at.%. The Mossbauer spectra clearly show evidence of the formation of Fe disilicides with Fe content close to 33 at.%, but very little evidence of the formation of metallic Fe particles. The results support the process of ion-induced phase separation toward an amorphous Fe disilicide phase as pattern generation mechanism. The observed amorphous phase is in agreement with thermodynamic calculations of amorphous Fe silicides. (C) 2015 Elsevier B.V. All rights reserved.