First Spectroscopic Characterization of Silicate Mineral in the St. Severin LL6 Chondrite: Diffuse Reflectance and FTIR Spectroscopic Studies

We report here for the first time the spectroscopic investigations on St. Severin meteorite using Fourier transform infrared spectroscopy, focusing on its mineralogical phases. The St. Severin LL6 chondrite is dominated by Mg-rich olivine, with whole-rock composition of SiO2 (40.50-40.75 wt%), MgO (25.40-25.58 wt%), and FeO (18.60-18.80 wt%). Minor oxides include Al2O3, CaO, Cr2O3, TiO2 and MnO. Infrared spectroscopy shows characteristic olivine bands near 980, 885, 835, 600, and 500 cm−1, with positions reflecting the Mg/Fe ratio. Diffuse reflectance spectra in the 10 and 20 μm regions are analogous to Fo-rich dunite and consistent with interplanetary dust and astrophysical silicate observations, confirming Mg-rich olivine dominance. Minor variations in band widths and intensities likely arise from Fe content, grain size, and crystallinity. These results demonstrate the mineralogical similarity between St. Severin, terrestrial dunites, and cosmic silicates, highlighting the extensive occurrence of Mg-rich olivine in meteoritic and astrophysical environments.