Laboratory measurements of particulate samples of olivine and related planetological studies

In this work we present laboratory reflection measurements on olivine samples, analyzed in the wavelength range 0.2 - 2.5 microns. Our purpose is to study the influence of the grain size on the spectra and in particular on the variations of the absorption feature at about 0.64 microns, whose reflectance peaks at 0.56 microns and near 0.7 microns have relative strengths, which are size dependent and well correlated. The identification of such feature in the observed spectra of Mars would provide useful information about the characteristics of the regolith present on the Martian surface; for this purpose, we analysed some reflectance spectra collected by the VIS-IR imaging spectrometer OMEGA on board of Mars Express.