Minrom Consulting was contracted by a manganese mine in the Northern Cape to scope, plan and execute a Mine Works Programme. Geologically, the project is situated within the Maremane Dome which is mainly comprised of dolomitic units of the Campbellrand Subgroup. The western edge of the Maremane Dome is overlain by the Gamagara quartzites and shales of the Olifantshoek Group. In this region, the Gamagara Formation unconformably overlies the Reivilo Formation dolomites (part of the Campbellrand Subgroup) which make up the karstic basement. Further to the west, the older Transvaal Supergroup occurs on top of the rocks of the Gamagara Formation which have been thrusted along what is termed the Black Ridge thrust fault.
The ferromanganese ore units form part of the Gamagara Formation and occur as brecciated karstic potholes along the unconformity between shales of the Gamagara Formation shales and dolomites of the Reivilo Formation. High-grade ore is primarily found on top of this ridge and along the western side
As part of the MWP, a resource delineation and partial definition drilling programme was undertaken which consisted of 42 RC drill holes with 900 metres drilled over the aream2. Two (2) areas were targeted for the drilling programme based on the geological mapping previous performed by Minrom. The purpose of the drilling programme was to delineate the manganese mineralisation and delineate mineable ore based on the mine’s current production and economic requirements. The RC drilling was used to estimate the grade and tonnage of material, with grades typically exceeding 26% manganese, resulting in a sellable product for the mine’s client. The contribution of the exploration project was in the order of 3c per mtu, ensuring adequate volume and on-spec production. This ensured optimal use of available resources. By supporting your local mine geologist with his exploration and ore definition process, you will be instrumental in unlocking value and increasing the project’s NPV.
It was concluded that the area contained significant manganese mineralisation of mineable grades with several pockets or “potholes” containing high-grade manganese. The drilling also identified areas strongly affected by dolomitic dilution, assisting in dilution control.
