Geochemical evaluation of the Lueshe niobium deposit (Zaire) by Rietveld quantitative X-ray diffraction

The Lueshe Nb deposit is used as an example to show that a modal analysis of fine-grained samples can readily be obtained by X-ray powder diffraction and the Rietveld method. This permits applications such as the visualisation of the weathering profile, the calculation of enrichment factors and estimation of the amount of nondiffracting material. This quantification method is based on the knowledge of the structural parameters of all the phases present in the sample and, in the case of geological material (especially secondary minerals), it sometimes requires structure refinement to optimize the results.