Abstract Exotic copper deposits, ferricretes, and manganocretes in Arizona, New Mexico, and Sonora are metal deposits in conglomerates that are spatially and genetically associated with porphyry Cu deposits. Deposits of this exotic class are typically zoned from ferricrete upgradient and extending into the bedrock leached capping, to black manganese oxides or Cu wad next downgradient, and to chrysocolla farther downgradient in the Cu-rich systems. Small deposits may lack zonation. Entire zoned systems vary from as little as 500 m long up to 6 km long (in Chile). In the Sonoran province, the El Pilar exotic Cu deposit exceeds 160 Mt at 0.4 percent Cu, but only one other known deposit was more than 10 Mt. Small tonnages of several percent Cu were selectively mined, between about 1880 and 1920, from chrysocolla zones. Average grades are typically 0.7 to 2 percent Cu in chrysocolla zones but mostly 0.5 percent or less in Cu wad zones. Solvent extraction-electrowinning (SXEW) will treat most exotic Cu ores. Ferricretes and manganocretes are not economic at present, although Mn deposits that may be of this class were mined in the past. Exotic Cu deposits form when a headward-eroding stream intersects a forming supergene enrichment profile of a bedrock porphyry Cu deposit ( Münchmeyer, 1996 ). Acidic metals-charged groundwater then discharges laterally into the alluvial aquifer and neutralizes and oxidizes while moving downgradient. It deposits metals in the conglomerates in the following order: first, hematite, then copper wad, and, finally, chrysocolla. Where the porphyry system is merely pyritic, upgradient goethitic

Abstract 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.