Nickel, with generally low concentrations (less than 2% NiO), is hosted by several secondary mineral phases (goethite, Mn-oxyhydroxides and smectite locally). Cobalt is generally of higher grade (up to 0.9% CoO), and is associated with cryptocrystalline and crystallized Mn-oxyhydroxides. SEM/microprobe observations suggest that nickel and cobalt concentration in secondary minerals is due to repeated remobilization. This has also favored the formation of mineral phases