New Mexico Mineral Symposium — Abstracts

 The mineralization of the Shaba deposit belongs to the South Equatorial cupro-cobaltiferous metallogenic province in Central Africa. This province extends about 500 km in width from the town of Kolwezi in Zaire to the town of N'Dola in Zambia. The northern zone called "Shaba Crescent" is entirely in southern Shaba; the southern zone called "Zambia Copper belt" is nearby in Zambia but overlaps the southern Shaba a bit. The mineralization in Shaba and Zambia have the same sedimentary origin. They are of the same Upper Proterozoic era. They have the same distribution of copper and cobalt in mineralized patches. In both deposits the primary sulfides of copper and cobalt are the same. They were probably deposited at the same time but are completely different in their lithology and their tectonic structure. In Shaba, dolomite is abundant in the gangues of the mineral deposit while it is almost entirely lacking in those in Zambia. The local rocks belong to the Katanga System, is divided into three supergroups: Roan, Lower Kundelungu, and Upper Kundelungu.

The lower part of the Katanga System, called Roan Supergroup, has been deposited in a lagoonal environment. In the lower third of the Roan Supergroup the Cu and Co minerals are concentrated generally in two orebodies. In Shaba, the lower orebody is in a siliceous dolomite 10 to 15 m thick and the upper orebody is in a sandy dolomitic shale 5 to 10 m thick. The two orebodies are separated by a 10- to 15-m massive barren dolomite bed. Uranium is also found locally in some deposits. Generally the patches of Co mineralization are smaller and inside the patches of Cu mineralization. The average grade of the Cu of the Shaba mines is generally 4 to 5% while the average grade of the Co is about 0.5%.

More than 200 minerals are reported in the South Shaba. The principal sulfide minerals are chalcocite for copper and carrollite for cobalt; the sulfide minerals have been altered to carbonates, silicates, and phosphates. The oxidized zone goes generally from 50 to 200 m. The principal oxide minerals for copper are malachite, cuprite, cornetite, libethenite, pseudomalachite, chrysocolla, plancheite; for cobalt the principal minerals are heterogenite and kolwezite, accessory mineral is sphaerocobaltite. In the Shaba mines one exception is the Kijushi mine, which is an hypogene "chimney" deposit similar to Tsumeb with mainly lead, zinc, and copper with accessory cobalt, germanium, cadmium, gallium, and arsenic. The mine of Shinkolobwe is not considered as an exception but as a particular case.

Minerals from the Shaba mines