Spectroscopic Characterizations of Sand Dunes Minerals of El-Oued (Northeast Algerian Sahara) by FTIR, XRF and XRD Analyses

Abstract

This paper investigates the chemical and crystal structural properties of sand dunes of El-Oued region from the northeast Sahara of Algeria. By using of Fourier-transform infrared (FT-IR) spectroscopy, X-ray fluorescence (XRF) and X-ray diffraction (XRD) we show that El-Oued sand dunes are composed mainly of 97.6% α-quartz (SiO2) and 0.56% calcite (CaCO3). Very low concentrations of some oxides as Al2O3, Fe2O3, MgO and trace elements impurities were also found. The calculated crystallinity index CI = 0.975 confirm the highly crystalline nature of quartz. From the X-ray diffraction data, structural parameters of quartz and calcite minerals were determined. Quartz grains were found to have a hexagonal crystal structure with lattice parameters of a = b = 4.907 A and c = 5.401 A and calcite grains have a trigonal crystal structure with a = b = 4.977 A and c = 17.04 A. The calculated lattice parameters were similar to those of standard references. The crystallite sizes of quartz and calcite were estimated to be nanometric.