X-ray Diffraction Mineralogy of Stream Sediments as a Tool for Gold Exploration: Evidence for Hydrothermal Alteration in the Lokoja Basement Complex, Nigeria

Abstract

This study applies X-ray diffraction (XRD) analysis of stream sediments to 
characterize hydrothermal alteration signatures linked to gold mineralization within 
the Lokoja Basement Complex, north-central Nigeria. Ten representative sediment 
samples were collected from active drainage channels incising the Precambrian 
crystalline rocks and analyzed using powder XRD to determine their mineralogical 
compositions and exploration significance. The results reveal quartz-dominated 
assemblages (48.9–79.0%) exhibiting strong diffraction peaks between 26.6° and 
26.99° 2θ, diagnostic of gold-bearing quartz veins. Muscovite contents range from 0.1
14.1%, with distinct peaks indicating sericitic alteration typically associated with 
shear-zone–hosted gold systems. Feldspar minerals (albite: 3.7–33.9%, orthoclase: 0
15.7%, anorthite: 0–22.8%) show variable alteration intensities, while higher 
muscovite/feldspar ratios correlate positively with known gold anomalies. Sample XRD
4 displays the most prominent gold-related mineralogical signature, characterized by 
quartz (74%), muscovite (0.71%), and altered feldspars, reflecting the mineralogical 
attributes of phyllic alteration zones. Peak intensity ratios and d-spacing variations 
further suggest systematic changes in quartz crystallinity and muscovite polytypes 
indicative of hydrothermal fluid–rock interactions. Integration of the mineralogical 
data with complementary geochemical results reveals that XRD-identified alteration 
assemblages coincide with zones of elevated Au–As–Pb concentrations. These findings 
confirm that XRD-based mineralogical characterization of stream sediments.