Iron nanoparticles detection in Ordinary Chondrite samples

S-type asteroids are identified as the parent bodies of the Ordinary Chondrites (OCs): this association is based on comparison of their infrared spectra (0.4-2.5 m) [1, 2]. However, some differences between the asteroid spectra and the meteorite ones arise, since the former show a marked reflectance increase with increasing wavelength. This phenomenon, called reddening, is probably due to iron nanoparticles (npFe), produced on S-type asteroids by Space Weathering (SW) processes [3], such as vaporisation and re-deposit of iron silicates caused by micrometeoroid impacts [4], sputtering from solar wind particles [5] or shock-induced phase transformations on Fe-Ni alloys [6].