Mineralogy of the RBT 04262 Martian meteorite as determined by micro‐Raman and micro‐X‐ray fluorescence spectroscopies

Abstract

Martian meteorites and terrestrial analogs represent the only samples available on Earth for studying mineralogy features of our neighbor planet Mars. This work characterizes the Roberts Massif (RBT) 04262 Martian meteorite by using mainly Raman spectroscopy. By means of this technique, it was confirmed that the meteorite matrix is composed by pyroxene and plagioclase (converted to maskelynite due to the shock pressure). Olivine-coarse grains embedded in the matrix were also observed. These grains were coated by hydrated magnesium and calcium sulfates, which would belong to the Mars sulfate deposits or to the terrestrial weathering. Although the sulfates could be formed on Mars due to the oxidation of sulfides or elemental sulfur along the sulfur Mars cycle, their distribution along cracks and fractures confirm that are weathering products. However, other S-bearing compounds that belong to Mars were found, such as elemental sulfur and a thermally transformed iron sulfide.Finally, the calcium phosphate merrillite and titanomagnetite were also detected. Taking this into account, the minerals found were classified into primary minerals that belong to Mars (pyroxene, olivine, elemental sulfur, and titanomagnetite), secondary ones that are alteration products of the primary minerals (maskelynite, iron sulfide, and merrillite), and terrestrial weathering products (sulfates gypsum and epsomite).

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

“…36 Figure 3E shows the Raman bands of marcasite and elemental sulfur, which are 319 (vs) and 381 (s); and 149 (m), 219 (m), 244 (w), and 471 (m), respectively. 6,13 Moreover, in this meteorite, it was observed that the oxidation in an anaerobic environment persisted. Sulfides and elemental sulfur continued to oxidize to anhydrous sulfates, which can hydrate through hydrothermal activity, leading to the formation of hydrated sulfates.…”

“…Subsequently, the transfer of S to the crust occurred through volcano degassing, magmatism, and hydrothermal processes, which resulted in a considerable amount of S at the surface. According to Huidobro et al, 6 photochemical activity and the presence of oxidizing agents led to rapid formation of S‐bearing minerals, such as sulfides. If oxidation continued on Mars without the presence of atmospheric oxygen (anaerobic conditions), the primary sulfides may have oxidized to secondary sulfides, 32 elemental sulfur, and sulfates.…”

“…As mentioned above, anaerobic oxidation of primary sulfides with high sulfur input can produce secondary oxides or FeS 2 (pyrite or marcasite, FeS 2 , stable, and metastable, respectively 6 ), elemental sulfur [S 8 ] 6 and Fe 2+ sulfates. 36 Figure 3E shows the Raman bands of marcasite and elemental sulfur, which are 319 (vs) and 381 (s); and 149 (m), 219 (m), 244 (w), and 471 (m), respectively.…”

“…Both techniques were selected in order to prove that the first in situ analytical technique on Mars (XRF spectroscopy), on board de Viking lander, 6 and the most novel technique to reach Mars (Raman spectroscopy), on board the Mars 2020 rover, 4 are a combination of techniques that give better results when used together 7 . In fact, both techniques are implemented in the last rover mentioned above.…”

GeoRaman

“…Huidobro et al [ 9 ] proposed the characterization of the Roberts Massif (RBT) 04262 Martian meteorite. It was confirmed that the meteorite matrix is composed of pyroxene and plagioclase (converted to maskelynite due to the shock pressure).…”