Oxides and Reduced Phases in the Mid-IR: Data for the BepiColombo Mission to Mercury

Introduction: The MERTIS (MErcury Radiometer and Thermal Infrared Spectrometer) onboard of the BepiColombo ESA/JAXA mission to Mercury is a mid-infrared instrument that will allow mapping the hermean surface from 7 m to 14 m 1,2. After arrival in 2025, a database for the interpretation of the data is needed. As part of this effort, we have studied rock samples like impact rocks and meteorites e.g,. 3. A second field of interest are analogs synthesized based on data by MESSENGER e.g., 4.Based on recent modeling of the oxidation state of the hermean surface, a highly reducing environment can be expected 5,6. Likewise past volcanism or impact experiments suggest the presence of extremely reduced phases, e.g., Si-metal (e.g, 7, 8]). This implies that in addition to common minerals (pyroxene, plagioclase), also oxides (corundum, spinel, periclase), metallic phases, halides, and reduced variations e.g. of olivine (Ca-olivine Larnite) are possible. As part of our database project, we cover this type mineral phases.Samples and Techniques: We characterized the materials first with EMPA. Samples were ground and sieved into grain four size fractions (