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International audienceWe report in situ NanoSIMS siderophile minor and trace element abundances in individual Fe-Ni metal grains in the unequilibrated chondrite Krymka (LL3.2). Associated kamacite and taenite of 10 metal grains in four chondrules and one matrix metal were analyzed for elemental concentrations of Fe, Ni, Co, Cu, Rh, Ir and Pt. The results show large elemental variations among the metal grains. However, complementary and correlative variations exist between adjacent kamacite-taenite. This is consistent with the unequilibrated character of the chondrite and corroborates an attainment of chemical equilibrium between the metal phases. The calculated equilibrium temperature is 446 ± 9 °C. This is concordant with the range given by Kimura et al. (2008) for the Krymka post-accretion thermal metamorphism. Based on Ni diffusivity in taenite, a slow cooling rate is estimated of the Krymka parent body that does not exceed ~1K/Myr, which is consistent with cooling rates inferred by other workers for unequilibrated ordinary chondrites. Elemental ionic radii might have played a role in controlling elemental partitioning between kamacite and taenite. The bulk compositions of the Krymka metal grains have non-solar (mostly subsolar) element/Ni ratios suggesting the Fe-Ni grains could have formed from distinct precursors of non-solar compositions or had their compositions modified subsequent to chondrule formation events

Physicochemical, mineralogical, and thermogravimetric characterizations were carried out to assess the potential technological benefits of natural sand deposits from El-Oued district (eastern Algeria). The use of granulometric analysis, FTIR spectroscopy, X-ray fluorescence (WDXRF), X-ray diffraction (XRD), scanning electron microscope (SEM/EDX), and thermogravimetric (TGA) analysis was necessary to further highlight the main physical and chemical properties of the studied sands. The grain size distribution suggests fine-to-medium sands with a mean grain size ranged from 207 to 261 μm. However, the grain micro-texture features indicate aeolian nature of El-Oued sand, and the chemical analysis reveals that all samples contain a high ratio of silica (SiO 2 ) reaching 94% with low content of CaO, Al 2 O 3 , Fe 2 O 3 , Na 2 O, and K 2 O oxides, which reflects the siliceous nature of El-Oued sand. The mineralogy of the El-Oued sand consists mainly of α-quartz (≤ 93% SiO 2 ) with minor calcite (CaCO 3 ) and very small amounts of feldspar mineral. Furthermore, the crystallite size of Quartz in all sand samples was determined to be in the range of nanometric scale. Thermal analysis (TGA) showed that El-Oued sand was relatively stable upon 800 °C. These characteristics corroborate the interesting and promising uses of El-Oued sand in the industry and nanotechnology. KeywordsSand • Mineralogical and chemical characterization • α-Quartz • Rietveld refinement • Industrial applications