Raman spectral peak positions of olivine (Fo‐Fa) as fast methodology for classifying chondrites

Abstract

AbstractChondrites are the most common meteorites in the world. However, the carbonaceous chondrites represent only a small fraction of those. Among them, Allende meteorite is one of the most studied carbonaceous chondrites. The main objective of this paper is to use the Raman spectral peak positions of olivine as a parameter to chondrite classification, here, specifically, Allende meteorite. Although these correlations are not new in the literature, this approach has not been used to classify carbonaceous chondrites yet. To develop the olivine calibration, only the peak positions of the doublet in the 700–1100 cm−1 region were analyzed in this study. The typical Raman spectrum of olivine displays two major peaks, here called Peak A, with Raman shifting in the 814–824 cm−1 range, and Peak B, in the 836–857 cm−1 range. The results of measurements found were perfectly matched to a linear correlation between Peak A and Peak B. The peak position versus composition plot shows a good correlation between the samples used as reference. The correlation curve obtained from the reference olivines is consistent with the data found in literature, as well as the peak versus peak plot. Finally, from the analysis of the olivine Raman spectral peak positions present in Allende meteorite, it is possible to conclude that there is little Fe in its matrix. Actually, the proportion of metallic Fe is less than 3% when the range of fayalite content is between Fa26–32.Thus, although the exact amount of iron present in the sample is not entirely clear, this kind of methodology quickly and effectively provides a response regarding the Fa ratio in the meteorite.