Contribution of X-ray diffraction (XRD) to the identification of mineral phases in the gold systems of the Kouroussa Gold Mine site, Republic of Guinea

This study evaluates the contribution of X-ray diffraction (XRD) to the identification and quantification of mineral phases within the gold-bearing systems of the Kouroussa permit, located in the Birimian domain of the West African Craton. Seventy samples collected from outcrops and drill cores from eight boreholes (>1400 m) were investigated, among which ten representative samples were selected for detailed analyses. After fine grinding to 75 µm, particle-size reduction and addition of a calcined ZnO internal standard (5 wt.%), analyses were performed using XRD diffractometry (Bruker D2 Phaser, 5–80° 2θ). Mineral phases were identified using DIFFRAC.EVA software and quantified through Rietveld refinement with PROFEX 5.The results reveal strong variability in mineral assemblages. Quartz dominates highly silicified zones, reaching 49 wt.% (C036) and 69 wt.% (C050). Feldspars and plagioclases characterize magmatic lithologies with cumulative contents up to 73 wt.% (C009). Carbonates, particularly abundant in sample C014 (48 wt.%), indicate carbonation related to CO₂-rich fluids. Ferromagnesian minerals, mainly chlorite and biotite, reflect greenschist-facies hydrothermal alteration. Sulfides, especially pyrite and arsenopyrite, are concentrated within mineralized zones, with local occurrences of native gold.The interpretation highlights three successive evolutionary stages: an initial magmatic phase, a hydrothermal phase marked by silicification, chloritization and carbonation, followed by a sulfide-gold mineralization stage. The most prospective mineralized zones are associated with intense silicification, strong hydrothermal alteration and high sulfide concentrations, confirming the effectiveness of XRD as a mineralogical vectoring tool in Birimian gold systems of Kouroussa.