Bale, RBBayewu, OOFolorunso, IOOloruntola, MO2023-01-052023-01-052011http://www.aensiweb.com/old/jasr/jasr/2011/1402-1410.pdfhttps://uilspace.unilorin.edu.ng/handle/20.500.12484/8130The geophysical and geotechnical assessment of the granite deposit at Idi-Osan Ofagada village near Abeokuta, southwestern Nigeria, have been undertaken and the exploitation suitability of the deposit established. The area is underlain by the granite gneiss rocks of the Precambrian Basement complex of southwestern Nigeria. Fourteen Vertical Electrical Soundings (VES) of Schlumberger array were carried out on the areas covered with overburden to determine their resistivity characteristics, overburden thickness and the reserve tonnage of the basement rock. The compressive strength and the specific gravity of the rock were measured to determine its competency and density respectively. The area is gridded into 5 by 6 blocks for more accurate calculations of the parameter for the estimation of the reserve. The reserve is estimated for elevation datum of 150m, 160m and 170m. Taking into account the economic implication for the removal of overburden, a minimum ratio of overburden to basement thickness of 1:1 and a limiting 10m overburden is considered to be the economically exploitable area. The VES results showed a two to three geoelectric layers; the sandy weathered layer, clayey layer and the basement. The isopach and geoelectric sections revealed that the overburden thickness varies from 1.5m to 23.6m with the thickest overburden of 10m and above occurring in the north-western and south-eastern parts. Geotechnically, the deposit has an average compressive strength of 47.68N/mm2 Young Modulus of 633N/mm2 and specific Gravity of 1.615. The reserve estimates obtained for 170m, 160m and 150m elevation datum are 4.42 x 105, 17.17 x 105 and 37.09 x 105 tons respectively. The results showed that the exploitation of rock in the area is economically viable most especially at 160 and 150m datumenVES, Reserve Estimation, Specific Gravity, Overburden ThicknessArticle