Search for a command to run...
This contribution presents a petrographic, microstructural, and micro-analytical approach developed for the comprehensive study of ordinary chondrites, as part of a master’s thesis aimed at defining an analytical protocol for the petrological and minerochemical characterization of extraterrestrial materials. The ultimate goal is the establishment of a dedicated laboratory for the petrological study of meteorites, exploiting available instrumentation and acquired micro-analytical expertise to achieve both a complete classification of chondrites and a deeper understanding of the processes governing their genesis and evolution.The study was carried out in collaboration with the Italian Museum of Planetary Sciences, where an internship allowed the examination of a reference collection of classified meteorite thin sections commonly used for educational purposes. Subsequently, three ordinary unclassified chondrites, provided by the “Museo del Cielo e della Terra” (San Giovanni in Persiceto, Bologna, Italy) and by a private collection, were investigated.The analytical workflow includes: (i) macroscopic measurements and photographic documentation; (ii) petrographic analysis by transmitted and reflected light optical microscopy for microstructural and mineralogical characterization; (iii) SEM-EDS X-ray compositional mapping on the whole petrographic thin section as well as on selected chondrules and microstructural sites; (iv) SEM-EDS quantitative microanalyses of mineral phases; and (v) micro-Raman spectroscopy.Preliminary results indicate that, from a chemical perspective, two of the unclassified samples can be assigned to the H group and one to the L group of ordinary chondrites. Petrographic observations classify the investigated meteorites as petrologic types 4 to 6. The most common chondrule textures observed include porphyritic and barred olivine, porphyritic olivine–pyroxene, granular olivine–pyroxene, radial pyroxene, and complex chondrules.SEM-EDS compositional maps of entire thin sections and selected microstructural domains enable visualization of textural relationships, estimation of modal mineral abundances relative to metallic phases, and the development of a comparative framework among ordinary chondrites. Mineral chemistry data are compared with literature values to refine classification criteria. Micro-Raman spectroscopy is performed on opaque phases or on selected minerals for the correct identification of the polymorphic phase which constrains proper ranges of P-T conditions. Moreover, micro-Raman analyses are employed to characterize solid and fluid/melt inclusions within primary minerals, assess surface alteration features, and investigate dust extracted from fractures, providing insights into secondary processes related to atmospheric entry and post-impact evolution.