Mineralized pegmatites in Nasarawa area, have been studied in order to evaluate their geochemical features and economic potential. The pegmatites consist of microcline-microperthite, quartz, muscovite, minor plagioclase and accessory minerals. Some samples show replacement of microcline by albite and formation of gilberite. Samples of the pegmatites and their constituents, namely albite, K-feldspar and muscovite were analyzed for major, minor and trace elements. Indicator elements such as, Li, K, Rb, Cs, Nb, Ta, Sn and Ga have higher abundances in K-feldspar and muscovite than in pegmatites and albite. Compared with the K-feldspars, albite is depleted in Rb, Cs, F and Ga but enriched in the ore elements Nb, Ta, and Sn. Rb and Cs show high positive correlation coefficient of 0.911 and 0.805 respectively for K-feldspar and muscovite. The correlation coefficient of Rb and Cs for albite, is also positively high, with a value of 0.848. K/Rb versus Cs shows high negative correlation coefficients of -0.928 and -0.816, correspondingly for K-feldspar and muscovite, as characteristic of mineralized pegmatites. Contrasts between samples of the pegmatites and albite on one hand and K-feldspar and muscovite on the other, are essentially reflected by the element indicators, Rb, Cs and K. Consesquently, Rb, Cs and K contents of K-feldspar and muscovite can be used as reliable exploration aids for rare-metal pegmatites. © Nigerian Mining and Geosciences Society (NMGS).
