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

Abstract

Chondrites 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.

Characterization of primary silicate minerals in Earth‐like bodies via Raman spectroscopy

“…do Nascimento‐Dias et al 37 established a linear correlation between peak position and Fa (fayalite) content. This study hypothesizes that this linear relationship persists, even with the incorporation of Mn and Ca.…”

Overview about Raman spectroscopy of types of olivine group minerals: A brief review

“…The studies about the range of κ 1 and κ 2 values are a very important point to understand the different types of olivine group minerals [43]. It was possible to see through to use κ 1 and κ 2 values some subtle points between endmembers, Co‐ and Ni‐olivine.…”

Analytical method for stable background reduction for Raman spectra of carbon‐containing meteorite and terrestrial samples suffering from intense fluorescence

“…The first‐ to third‐order polynomial fittings were then applied with using the data points at 800, 950, 1800, and 2000 cm −1 . These wavenumbers were chosen because D and G bands were expected to appear at 1000–1800 cm −1 and other minerals on the carbonaceous chondrites such as olivine (doublet at 820–880 cm −1 ) and enstatite (singlet at 1000 cm −1 ) were often observed together with the carbon‐rich compounds (Catalano et al., 2015; Mouri & Enami, 2008; Nascimento‐Dias et al., 2021; Reynard et al., 2008; Sharygin, 2020; Zhang et al., 2018). After the background subtraction, the resulting spectra were normalized at the apparent peak of G band (~1600 cm −1 ) for comparison.…”