Nomenclature
Heterogenite is a compact or powdery black oxyhydroxide of cobalt. This is by far the most common secondary mineral found in the supergene alteration zones of the sulfide deposits of cobalt throughout the world.
In 1962, Max Hey came to the conclusion that the heterogenites all have a single formula, CoO.OH, analogous to that of manganite (MnO.OH) and goethite (FeO.OH).
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Mineralogy & Petrology
Heterogenite 3R, which occurs in the widest variety of appearances, is the heterogenite most commonly found in southern Katanga. The following habits are well known:
- Microgranular violet-gray, reniform nodules and irregular masses. They consist of a microgranular matrix that is often traversed by more coarse grained veinlets which have a metallic luster. Often these nodules contain a microgranular core, surrounded by fibroradial crystals evolving into concentric banded zones of coarser and more reflecting material. These crystallized masses were known in Katanga by the name "stainierite".
- Reniform or botryoidal banded masses or crusts with shiny jet-black surfaces. The banded structure is parallel to the bothryoidal surface or either concentric. Microscopically, in polarised light, these bands are without visible structure. Under crossed nicols it can be isotropic or weakly anisotropic in trapezohedral patches. The fracture resembles that of anthracite. In Katanga this type was known as "trieuite".
Uses
The cobalt extracted from heterogenite is mainly used in rechargeable batteries (mobile devices, hybrid cars) and in superalloys, which are used to make parts for gas turbine aircraft engines. It is also used to make magnets, tyre adhesives and catalysts for the petroleum and chemical industries. Cobalt fields of application in new technologies are so wide that is now considered as a strategic material in the modern industry.
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