Mineralogy of the LAR 12095 Martian shergottite as determined by micro-Raman and micro-X-ray fluorescence spectroscopies

In this work, the geochemical characterization of the olivine-phyric Martian shergottite LAR 12095 was performed by using two complementary analytical techniques: micro-Raman and micro-energy dispersive X-ray fluorescence spectroscopies. Thanks to this methodology, olivine, pyroxene, and ilmenite were detected as primary minerals from Mars. Maskelynite, hematite, anatase, chromite, merrillite, oxidized mackinawite, pyrrhotite, elemental sulfur, marcasite, jarosite, epsomite, and gypsum were classified as secondary minerals. The major novelty of this work is that alterations under anaerobic and aerobic conditions of S-bearing minerals can be appreciated. In this sense, primary sulfides were altered to secondary sulfides, elemental sulfur and sulfates under the oxygen-free Martian atmosphere. However, in the Earth's oxidizing atmosphere, primary sulfides are weathered to iron oxides, such as hematite. In addition, it should be highlighted that the presence of ilmenite, mackinawite, elemental sulfur, and jarosite has been reported for the first time in this meteorite.

Automated summary

In this study, the geochemical properties of Martian shergottite LAR 12095 were analyzed using micro-Raman and micro-energy dispersive X-ray fluorescence spectroscopies. Olivine, pyroxene, and ilmenite were identified as primary minerals from Mars, while secondary minerals such as maskelynite, hematite, and anatase, among others, were also detected. The main significance of this research lies in the ability to observe the alteration of sulfur-bearing minerals under both anaerobic and aerobic conditions. Furthermore, the presence of ilmenite, mackinawite, elemental sulfur, and jarosite in this meteorite was reported for the first time.