To support the data analysis for the MErcury Radiometer and Thermal Infrared Imaging Spectrometer (MERTIS) instrument on the ESA-JAXA BepiColombo mission, we have measured the thermal infrared emissivity of finely grained silicates (<25 μm grain size) at different temperatures under vacuum to simulate the daytime conditions on the surface of Mercury. The silicates were selected to represent the mineralogy of Mercury as closely as possible (Helbert et al., 2007; Namur and Charlier, 2017; Vander Kaaden et al., 2017). The set includes one olivine (a Mg-rich forsterite), three pyroxenes (diopside, enstatite, and hypersthene), five feldspars (plagioclase group; anorthite, labradorite, andesine, oligoclase, and K-feldspar; microcline) and a feldspathoid (nepheline). The emissivity measurements for each mineral was carried out within the MERTIS spectral range of 7-14 μm with temperatures increasing from 100 C up to 500 C under vacuum (~0.1 mbar). The relationships between the spectral parameters such as the Christiansen Feature (CF) position, first Reststrahlen band (RB1) position, RB1 emissivity, and RB spectral contrast and temperature were investigated for all silicates. The study shows that the RB1 position shifts to longer wavelengths, RB1 emissivity decreases, and RB spectral contrast increases with increasing temperatures for all silicates studied. We apply the plot of CF vs RB1 as a tool to discriminate the major silicate groups such as feldspars, pyroxenes, and olivine, regardless of the temperatures at which they were measured. The CF vs RB1 plot can facilitate the first order discrimination of the mineralogy of Mercury’s surface with MERTIS. Moreover, this approach can be more widely used to map the igneous surface mineralogy of silicate targets such as the Moon, Mars, and S-type asteroids in the 7-14 μm spectral region with remote sensing from orbit and ground-based telescope observations.