Geophysical Prospecting Management for Gemstone Resources in Taraba State

This study examines the management of geophysical prospecting programmes for gemstone resources in Taraba State, North East Nigeria. Taraba State hosts some of Nigeria's most valuable gemstone occurrences including sapphire, zircon, aquamarine, and tourmaline in its basement complex, but the sector is dominated by unguided artisanal mining that yields far below its potential due to resource wastage and environmental damage. This study designs and implements a managed geophysical prospecting programme at two gemstone occurrences in Wukari and Jalingo local government areas. Ground magnetic profiling at 10-metre station spacing and VES surveys delineate the structural and lithological context of gem-bearing pegmatites. Programme management aspects documented include prospecting licence compliance, artisanal miner engagement protocols, health and safety management, and results communication to community stakeholders. Gemological sampling from prospecting excavations validates the geophysical interpretation. Findings reveal that pegmatite bodies hosting the highest gemstone grades consistently coincide with northeast-trending magnetic lows of 200 to 500 nanotesla amplitude at depths confirmed by VES to be between 5 and 25 metres. Geophysically-guided artisanal excavation encounters gem-grade material in 68 percent of guided excavations versus 31 percent in unguided pits, a 119 percent improvement in discovery rate. The programme demonstrates that professional geophysical management creates tangible economic benefits for artisanal miners while significantly reducing environmental disturbance per unit of gem material recovered. The study recommends scaling the programme through the Taraba State Mineral Resources Development Agency.

Keywords: gemstone prospecting, geophysics, Taraba State, pegmatite, artisanal mining management.