Professional Evaluation of Coal Resources in the Lafia-Obi Field, Nasarawa State

The Lafia-Obi Coal Field in Nasarawa State, North Central Nigeria, contains subbituminous coal seams within the Maastrichtian Lafia Formation that represent a significant domestic energy resource relevant to Nigeria's coal-to-power aspirations under the National Integrated Mineral Development Programme. This study undertakes a professional resource evaluation of the Lafia-Obi Coal Field, integrating borehole data, outcrop measurements, and laboratory coal quality analyses to estimate resources in compliance with JORC Code principles. Existing borehole records from the Nigerian Coal Corporation were compiled and geo-referenced, with seam intercepts correlated across the field using lithostratigraphic marker horizons. Measured sections at eight outcrop locations supplemented borehole data in areas of limited drill coverage. Proximate and ultimate analyses were performed on systematically collected channel samples from three principal seam horizons, with gross calorific value, total moisture, ash content, total sulphur, and vitrinite reflectance determined. Geostatistical kriging was applied to estimate seam thickness and quality variability, enabling resource classification into measured, indicated, and inferred categories. The study presents resource tonnes by seam at designated quality and thickness cutoffs and discusses the major modifying factors affecting economic extraction. Findings support the renewed investment interest in coal as a domestic thermal electricity generation feedstock. Keywords: coal resources, Lafia-Obi Field, Nasarawa State, JORC Code, proximate analysis.