Lithium Mineralization in Basement Rocks of the Kusaki Area, North-Central Nigeria

Abstract

Lithium mineralization within the Nigerian Basement Complex remains underexplored despite increasing global demand for lithium resources. This study investigates the lithological characteristics and lithium enrichment of basement rocks in the Kusaki area, North-Central Nigeria (Southeastern part of Federal Capital Territory), using an integrated petrographic and spectroscopic approach. Fifteen representative samples, comprising gneiss, calc-silicate rocks, and pegmatites, were analyzed through thin-section petrography, Fourier Transform Infrared Spectroscopy (FTIR), and Ultraviolet–Visible (UV–Vis) spectroscopy. Field relationships have shown that the pegmatites are hosted by high-grade metamorphic rocks. Petrographic study, on the other hand reveals that the pegmatites are, as expected characterized by very coarse grains dominantly of quartz, feldspars, and ubiquitous muscovite, indicative of crystallization from volatile-rich, highly evolved granitic melts. FTIR spectra show consistent absorption bands between ~600 and 1502 cm⁻¹, including prominent features at ~670–672 cm⁻¹ and 710–712 cm⁻¹, corresponding to Li–O vibrational modes reported for lithium-bearing silicate phases. UV–Vis analyses further reveal systematic absorption bands in the 254–260 nm range across all pegmatite samples, consistent with electronic transitions associated with lithium incorporation in silicate and oxide matrices. The uniformity of the petrographic and spectroscopic signatures indicates pervasive lithium enrichment rather than localized mineralization, suggesting a common magmatic–hydrothermal origin linked to late-stage fractionation of Pan-African granitic magmas. These results provide new evidence for lithium-bearing pegmatites within the southeastern FCT and highlight the Kusaki area as a prospective target for rare-metal exploration within Nigeria’s crystalline basement.