Mineralisation Potential of Feldspar and Muscovite Extracts from Olode Pegmatite, Southwestern Nigeria
Publication Date : 17/05/2022
Rare metal mineralisation potential of pegmatites in different pegmatite fields of Nigeria are being studied to understand the type and level of rare metal mineralisation and provide guidelines for small and large scale mining in the pegmatite fields of Nigeria. The Olode pegmatites in the Ibadan- Osogbo field intrudes biotite gneiss and granite gneiss; they are characterized by large crystals of quartz, muscovite and k-feldspar with subordinate plagioclase, while schorl and beryl are accessory minerals. Samples of pegmatites were obtained during systematic geological mapping and minerals extracts were extracted from the samples and analyzed using Inductively Coupled Plasma Mass Spectrometry (ICPMS). Geochemical analysis results revealed high SiO values in feldspar extract compared to 2 muscovite extracts and higher Al O value in muscovite extracts compared to feldspars extracts. The muscovite 2 3 extracts are enriched in rare metals compared to the feldspar extracts; Na/K ratio low (less than 1.0), this indicates poor degree of albitization and this is responsible for poor mineralization of Sn. Average concentration (ppm) are 131, 24, 796 and 79 for Ba, Cs, Rb and Sr respectively in feldspar extracts and average values (ppm) are 120, 144, 42, 11 and 20 for Ga, Nb, Sn, Ta and W respectively in muscovite extracts. Plot of K/Rb against Rb showed that pegmatite has characteristics of a unmineralised muscovite class pegmatite and Nb is mineralized in preference to Ta in the muscovite extracts. Geochemical plots such as the Ta against Cs plot, Ta against Ga plot all show that Olode pegmatite is a rare metal depleted pegmatite as the mineral extracts plots below the limes of mineralisation.
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