Mineral phase discrimination of the chelyabinsk meteorite by LIBS mapping/cluster analysis

The Chelyabinsk meteorite, resulting from one of the most extensively studied meteor events of the 21st century, was analyzed to investigate compositional heterogeneity across its inner matrix, fusion crust, and metallic inclusions using non-invasive techniques such as Laser-Induced Breakdown Spectroscopy (LIBS) and Raman spectroscopy, which allowed the preservation of the integrity of the sample. A high-resolution scanning micro-LIBS analysis was conducted to visualize the spatial heterogeneity of the meteorite at the micrometer scale. Unsupervised K-means clustering enabled segmentation of chemically distinct domains and correlation with major mineral phases identified by Raman spectroscopy, including olivine, pyroxene, chromite, and plagioclase. Calibration-Free LIBS (CF-LIBS) was applied to achieve semi-quantitative elemental analysis without the need for external calibration standards, yielding compositions consistent with LL-type ordinary chondrites and confirming the classification of the Chelyabinsk meteorite as an LL chondrite. The methodology demonstrated here highlights the utility of combining LIBS and Raman spectroscopy for non-destructive, high-resolution chemical and mineralogical characterization of meteorites, offering a valuable toolset for planetary science and meteoritic research.