A Preliminary Description of the Nkamouna Cobalt-Manganese-Nickel Laterite Deposit, Southeast Cameroon
Gideon Dzemua Lambiv, Sarah A. Gleeson, W. Buckovic, Benard Abei Ayongaba, Emmanual Simo, Lin Christophe Thierry Omgba Ahanda, Pierre Christain Mikolebeh, 2009. "A Preliminary Description of the Nkamouna Cobalt-Manganese-Nickel Laterite Deposit, Southeast Cameroon", Supergene Environments, Processes, and Products, Spencer R. Titley
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Seven Co mineralized laterite deposits have been identified in southeast Cameroon. The deposits are developed over serpentinite bodies of unknown age and origin. This paper focuses on one deposit, Nkamouna, which currently has delineated proven and probable reserves of 52 million tonnes of 0.24 percent Co and 0.72 percent Ni (43-101 compliant), making it the first Co laterite deposit with economic potential.
The weathering profile at Nkamouna is thick and company geologists have identified the following units in the profile (from the base): protolith (serpentinite), saprolite, silcrete, ferralite, ferricrete breccia unit, and the granular unit. The ore zone at Nkamouna is found at the top of the ferralite and at the base of the ferricrete breccia unit and has an average thickness of 8 m. The ore mineralogy is dominated by very coarse absolane that contains significant concentrations of Co. The coarse nature of the asbolane allows for physical upgrading of the ore before processing, which has a significant impact on the economics of the deposit.
The deposit is different from most Ni laterite deposits in that it has a very high Co/Ni ratio and very low Mg contents. The profile at Nkamouna is complex and, in particular, in the ferricrete breccia unit there is evidence for multiple phases of profile formation. This, along with a potential pre-enrichment of the protolith, may have resulted in the high Co endowment seen at Nkamouna.