This cobaltoan dolomite is from the Mashamba West Mine in the Kolwezi District, Lualaba, DR Congo. This is an interesting piece that consists a large rhombohedral crystal assumed to be dolomite (possibly calcite?) that has been partially replaced by cobaltoan dolomite (Ca, Mg, C, O, H trace Co). The cobaltoan dolomite shows well defined orientation patterns. There are exposed portions of the original dolomite that contain inclusions of goethite just under the surface. This piece appears to be a floater that is covered on all surfaces with terminated crystalline surfaces. There are also secondary deposits of minor malachite and heterogenite. It measures 2 5/16 x 1 3/8 x 7/8 inches or 59 x 35 x 22 mm.