In North Western Queensland, Australia, there are numerous small cobalt deposits of which Mount Cobalt is the largest. Recent work has shown that cobalt is also a significant constituent of the Mount Isa copper ores. The cobalt-bearing minerals cobaltite, alloclasite, (?) glaucodot and cobaltian arsenopyrite have been identified. The cobaltites from Mount Isa and Mount Cobalt are compared and although they possess cubic morphology, their anisotropy and X-ray properties indicate orthorhombic symmetry. The origin of cobalt mineralization in the Mount Isa and Mount Cobalt deposits is discussed in terms of the sedimentary theory.