Petrographic Studies, Geochemical Characterization and Mineralization Potential of Pegmatite at Awo, Southwestern Nigeria

Pegmatites are known to host industrial minerals, rare metals and gemstones of economic values. They occur across various formations in Nigeria but mostly in granitoids and occur mostly as intrusions in Ilesha schist belt of which the study area is situated. The studies of petrography, geochemical characterization and mineralization potential of pegmatites at Awo, Southwestern Nigeria was carried out in order to classify and deduce the tectonic setting as well as the type of ore mineralization in the area. The study employed petrographic studies of nine pegmatite samples. Four whole pegmatite rock samples were analyzed using X-Ray Diffraction while Five tantalo-columbite ore samples and four whole rock samples were further analyzed using Energy Dispersive X-Ray Fluorescence. Petrographic studies of the Awo pegmatite showed quartz to range from 20.0% to 34.1%, microcline ranges from 20.6% to 44.7%, plagioclase play characteristic albite twinning and ranges from 14.8% to 23.2%, biotite ranges from 2.7% to 21.8%, hornblende ranges from 4.1% to 19.4% while muscovite ranges from 2.2% to 6.1%, with less than 1% accessory opaque minerals. X-ray diffraction results indicated that quartz ranges from 25% to 51% while feldspar is from 53% to 88% indicative of peraluminous composition of Awo pegmatites. Niobium oxide ranges from 2.86% to 5.29% while tantanium oxide ranges from 1.08% to 1.49% for whole pegmatite rock samples. Major oxides, trace and rare earth elements results show niobium oxide ranges from 24.76% to 31.43% while tantanium oxide ranges from 22.57% to 27.36% for ore samples, which revealed preference for niobium in pegmatite of the studied area. Awo pegmatite belongs to rare earth element class in NYF family as shown from progressive accumulation of Nb, Y and F from 0.63wt% to 1.22wt%, 0.61wt% to 1.00wt% and 0.27wt% to 0.73wt% respectively for whole rock samples as well as 15.62wt% to 21.40wt%, 0.45wt% to 0.85wt% and 0.28wt to 1.10wt% for ore samples. This pegmatite is of magmatic origin, peraluminous in composition from NYF family and the metal ore is columbite.