Rietveld Refinement Based Quantitative Phase Analysis (QPA) of Ouargla (Part of Grand Erg Oriental in Algeria) Dunes Sand

In this paper, XRD Rietveld refinements by using MAUD (Materials Analysis Using Diffraction) software have been performed to determine the quantitative identification of the crystalline phases in the dunes sand of Ouargla (Algeria). The main XRD reflections were related to quartz (SiO2), gypsum (CaSO(4)2(H2O)) and bassanite (CaSO(4)0.67(H2O)). Structural (space group, lattice parameters and unit cell volume), microstructural (crystallite size and microstrain) and percentages have been determined for each constituting phase. The XRD patterns of natural sample of Ouargla dunes sand indicated that the quartz in this sand has high crystalline nature and (101) is the preferred orientation of quartz growth. It has been appeared that quartz has the hexagonal structure at alpha- phase. The crystallite sizes of quartz, gypsum and bassanite were 970.57 nm, 522.70 and 99.98 nm respectively. Some comparisons have been made with other recent works. The refined XRD patterns show that quartz and gypsum were the main components in this sand, with 72.11% and 23.77% respectively, in addition to 4.34% of basanite. All this was done with goodness of fit (GOF) 1.70.