Original and alteration mineral phases in the NWA 10628 Martian shergottite determined by micro‐Raman spectroscopy assisted with micro‐energy dispersive X‐ray fluorescence imaging

Abstract

NorthWest Africa 10628 (NWA 10628) is a shergottite found in Tindouf (Algeria) in 2014. Little is known on this meteorite apart from the Meteoritical Bulletin report. In this work, original and altered mineral phases of NWA 10628 were characterised by micro‐Raman spectroscopy assisted with micro‐energy dispersive X‐ray fluorescence imaging. The matrix of the meteorite is dominated by high‐Ca pyroxenes, augite ((Ca,Na)(Mg,Fe,Al,Ti)(Si,Al)2O6) and diopside (CaMgSi2O6). Olivine and feldspars appeared as small crystals all along the matrix. Merrillite (Ca9NaMg(PO4)7) was found as big crystals in inclusions. As whitlockite (Ca9NaMg(PO4)6(HPO4)) can be transformed into merrillite at high temperature and pressure, we suggest that merrillite in the meteorite was originally whitlockite, before its ejection from Mars. Gypsum (CaSO4·2H2O) was found as small crystals and in fractures; this last one could come from terrestrial weathering because it was associated with calcite (CaCO3). Small anhydrite (CaSO4) crystals are shown in the bulk together with gypsum, probably from the partial dehydration of original Martian gypsum by the high‐pressure/temperature of ejection. Pyrite and marcasite (FeS2 polymorphs) minerals were detected, as well as their oxidation products, goethite (α‐FeO (OH)) and rozenite (FeSO4·4H2O), due to their terrestrial weathering. The identification of hematite (Fe2O3), magnetite (Fe3O4), ilmenite (FeTiO3) and anatase (TiO2) suggested that ulvospinel (Fe2TiO4) was the precursor on Mars, because ulvospinel is transformed into ilmenite by pressure and later ilmenite can be altered to magnetite/hematite and anatase by oxidative weathering on Earth. This non‐destructive analytical methodology provides deep mineralogical characterisation adequate for scarce samples like those returning from the Mars Sample Return mission.

Raman spectroscopy, assisted by X‐ray fluorescence and laser‐induced breakdown spectroscopy, to characterise original and altered mineral phases in the NWA 2975 Martian shergottite

“…For instance, the characteristic peaks of calcite CaCO 3 34 (281, 711 and 1087 cm −1 ) and apatite (956 cm −1 ) were also detected in one spot of analysis each. As shown in Figure 9, iron oxides were detected in form of haematite Fe 2 O 3 34 (292 404, 507, 605, 659 and 1318 cm −1 ) and magnetite Fe 3 O 4 35 (broad band at 658 cm −1 ). To conclude, the iron sulfide (pyrrhotite, 209, 273 and 378 cm −1 ) was found associated with the characteristic double band of amorphous glass around 650 and 1250 cm −1 .…”

“…11 Besides the primary mineral phases, multiple secondary minerals were found. For instance, the characteristic peaks of calcite CaCO 3 34 (281, 711 and 1087 cm À1 ) and apatite (956 cm À1 ) were also detected in one spot of analysis each. As shown in Figure 9, iron oxides were detected in form of haematite Fe 2 O 3 34 (292 404, 507, 605, 659 and 1318 cm À1 ) and magnetite Fe 3 O 4 35 (broad band at 658 cm À1 ).…”

GeoRaman

“…Prieto‐delaVega et al [ 8 ] also studied a NWA meteorite, in this case the Northwest Africa 10628 (NWA 10628), which is a shergottite found in Tindouf (Algeria) in 2014. As little was known on this meteorite, they performed a deep Raman characterization complemented by Micro‐energy dispersive X‐ray fluorescence imaging (μ‐ED‐XRF).…”

Raman spectroscopy and X‐ray diffraction of diphenylphosphoryl azide under high pressures

“…[6][7][8][9][10][11][12] As pressure can directly change the molecular structures and bonding patterns, high-pressure techniques provide an excellent route to synthesize energetic polymeric nitrogen materials. [13][14][15][16] The highpressure studies of azides show that the electron orbital hybridization of the azide ions in inorganic azide leads to the occurrence of nitrogen polymerization. [17][18][19][20][21][22] However, the electron orbital hybridization in symmetric and linear azide ions is difficult to occur, which limits the researches and applications of polymeric nitrogen.…”