  We present the compositional analysis of three terrestrial analogues of
Martian olivine-bearing rocks derived from both laboratory and flight-derived
analytical instruments. In the first step, state-of-the-art spectroscopic (XRF,
NIR and Raman) and diffractometric (XRD) laboratory systems were complementary
used. Besides providing a detailed mineralogical and geochemical
characterization of the samples, results comparison shed light on the
advantages ensured by the combined use of Raman and NIR techniques, being these
the spectroscopic instruments that will soon deploy (2021) on Mars as part of
the ExoMars/ESA rover payload. In order to extrapolate valuable indicators of
the mineralogical data that could derive from the ExoMars/Raman Laser
Spectrometer (RLS), laboratory results were then compared with the molecular
data gathered through the RLS ExoMars Simulator. Beside correctly identifying
all major phases (feldspar, pyroxene and olivine), the RLS ExoMars Simulator
confirmed the presence of additional minor compounds (i.e. hematite and
apatite) that were not detected by complementary techniques. Furthermore,
concerning the in-depth study of olivine grains, the RLS ExoMars simulator was
able to effectively detect the shifting of the characteristic double peak
around 820 and 850 cm-1, from which the Fe-Mg content of the analysed crystals
can be extrapolated. Considering that olivine is one of the main mineral phases
of the ExoMars landing site (Oxia Planum), this study suggests that the
ExoMars/RLS system has the potential to provide detailed information about the
elemental composition of olivine on Mars.
