Katanga Copperbelt
The Katanga (Shaba) Copperbelt, DR Congo: copper-cobalt ore, oxidised-zone malachite crystals and heterogenite, the Kolwezi species, and the Congo label trap.
The Katanga Copperbelt, also called the Shaba Copperbelt, is the Democratic Republic of the Congo part of a 700 km copper-cobalt arc that the USGS calls the greatest sediment-hosted copper-cobalt province in the world. Handbook sheets place malachite, heterogenite and kolwezite in the Katanga Copperbelt, and Katanga Copperbelt ore runs about 4.5% copper.
In short
- One belt, two countries. The USGS assessment by Zientek and co-authors (SIR 2010-5090-T) describes the Central African Copperbelt as a 700 km arc from the southeastern Democratic Republic of the Congo into Zambia. The Congolese part is the Katangan or Shaban Copperbelt. The border was set in 1894 at the Congo–Zambezi watershed.
- What the ore is. In the Congo, economic ore is fine-grained chalcocite with some bornite and carrollite in dolomitic rock, about 4.5% copper and 0.2% cobalt. Weathering reaches 400 m and enriches the top to as much as 20% copper and 5% cobalt. Heterogenite sits near the surface and malachite below it.
- What the Handbook places there. The Handbook of Mineralogy sheets name Katanga for malachite (large crystals from the Mashamba West mine), heterogenite (the Star of the Congo mine), carrollite (Kambove, Kamoto, Musonoi), dioptase (Tantara, Mashamba West) and torbernite (Musonoi, Shinkolobwe). Kolwezite is named for Kolwezi.
- The Congo Republic trap. Several sheets also name Mindouli, Renéville, Pimbi, M’Passa or Mfouati, which they place in the Congo Republic, a different country. A label reading only “Congo” does not tell you which. The libethenite sheet lists Mindouli inside its Katanga sentence, while the dioptase, plancheite and pseudomalachite sheets put Mindouli in the Congo Republic.
- Worked numbers. The USGS lists 10 Congolese giant deposits (over 2 Mt contained copper) totalling 48.0 Mt; the Kamoto–KOV–Musonie–Mupine group alone is 19 Mt, 39.6%. Heterogenite, CoO(OH), is 64.10% cobalt by mass and carrollite, CuCo2S4, 38.06%.
| Species | Formula (Handbook) | Hardness | Density | Katanga places on the sheet | IMA status, year, country |
|---|---|---|---|---|---|
| Malachite | Cu2(CO3)(OH)2 | 3.5–4 | 4.05 | Lubumbashi; Musonoi mine near Kolwezi; large crystals from the Mashamba West mine | G, year and country not given |
| Heterogenite | Co3+O(OH) | 3–5 | 3.07–4.32 | Star of the Congo mine near Lubumbashi; Shinkolobwe; Mindigi | A, 1967 s.p., Germany |
| Carrollite | Cu(Co,Ni)2S4 | 4.5–5.5 | 4.5–4.8 | Large crystals from Kambove; Kamoto and Musonoi mines near Kolwezi | G, 1852, USA |
| Kolwezite | (Cu,Co)2(CO3)(OH)2 | ~4 | 3.97 | Musonoi and Kamoto Cu–Co mines near Kolwezi; Mupine; Mashamba West | Rn, 1979-017, DR Congo |
| Cuprite | Cu2O | 3.5–4 | 6.14 | Likasi, Ruwe, Mashamba West mine, Kolwezi | G, 1845, Germany |
| Dioptase | CuSiO3·H2O | 5 | 3.28–3.35 | Tantara; Mashamba West mine, Kolwezi | G, 1798, Kazakhstan |
| Cornetite | Cu3(PO4)(OH)3 | ~4.5 | 4.10 | Star of the Congo mine near Lubumbashi; Kalabi and Lukini mines | G, 1916, DR Congo |
| Pseudomalachite | Cu5(PO4)2(OH)4 | 4.5–5 | 4.15–4.35 | Kakanda and M’sesa, near Kambove | — |
| Plancheite | Cu8Si8O22(OH)4·H2O | 6 | 3.65–3.80 | Tantara, Mindigi and M’sesa, near Kambove | — |
| Chrysocolla | (Cu,Al)2H2Si2O5(OH)4·nH2O | ~2–4 | 1.93–2.4 | Star of the Congo mine, Lubumbashi; Likasi; Kakanda | — |
| Torbernite | Cu(UO2)2(PO4)2·12H2O | 2–2.5 | 3.22 | Large crystals at the Musonoi mine; rich specimens from Shinkolobwe | A, 1980 s.p., Czech Republic |
| Curite | Pb3(UO2)8O8(OH)6·3H2O | 4–5 | 6.98–7.4 | Shinkolobwe | G, 1921, DR Congo |
Katanga, Shaba, Zaire: one belt, several names
The names. The USGS assessment calls the Congolese part of the belt the Katangan or Shaban Copperbelt and the Zambian part the Zambian Copperbelt. The Handbook sheets mostly write Katanga Province, Congo (Shaba Province, Zaire), giving both the present and the older names. Specimens labelled Shaba or Zaire are from the same ground.
The geology in one paragraph. The deposits are sediment-hosted stratabound copper in the Neoproterozoic Roan Group of the Katanga Basin. In the Congo many lie in fault sheets or salt structures, while the Zambian deposits are in place near the basement contact. The richest mineralisation sits at the first upward change from red or purple to grey strata. In the Congo most deposits lie in the lower part of the Mines Subgroup, around the R.S.C. member of the Kamoto Formation; the Kamoto and Kambove dolomites are named units. For this deposit type the USGS describes ore-mineral zoning from pyrite to chalcopyrite to bornite to chalcocite to hematite.
The Congo Republic trap. Method: a script reads the Distribution field (from Distribution: to the next Name:) of each sheet named here, as pdftotext -layout text, strips diacritics, expands ligatures, joins line breaks and matches case-insensitively. The pattern matched the Katanga places in the table, and also these, which the sheets place in the Congo Republic: Mindouli (dioptase, plancheite, pseudomalachite), Renéville and Pimbi (dioptase), Tshiniama (plancheite), M’Passa (chalcocite, germanite, reniérite) and Mfouati (wulfenite). The libethenite sheet lists Mindouli inside its Katanga sentence, so the sheets themselves disagree on Mindouli. Frondelite’s Kobokobo pegmatite is in Kivu, also not Katanga. Other localities are on the localities index.
Sulfides below, malachite and heterogenite above
The weathering profile. The USGS describes weathering to depths of 400 m, with sulfides just below the water table. Copper is more mobile than cobalt, so it moves down and precipitates at the water table, while heterogenite stays near the surface. From the top down the report lists:
- barren leached material, up to a few metres;
- heterogenite in siliceous clay;
- malachite and heterogenite in siliceous clay;
- malachite, heterogenite, copper silicates, cobalt carbonate and traces of copper sulfides in dolomite, where chalcocite breaks down and copper re-precipitates as malachite and chrysocolla;
- copper sulfides, malachite and heterogenite in dolomite, where carrollite quickly alters to heterogenite;
- unweathered copper and cobalt sulfides.
Worked composition. On standard atomic weights heterogenite, CoO(OH), is 64.10% cobalt; carrollite, CuCo2S4, is 38.06% cobalt and 20.52% copper; malachite is 57.48% copper. The primary ore’s 4.5% copper and 0.2% cobalt is 45 kg of copper and 2 kg of cobalt per tonne, a ratio of 22.5 to 1. The malachite-versus-chrysocolla question is on is chrysocolla the same as malachite.
Which minerals the Handbook places in Katanga
Copper and cobalt. Beyond the table, the sheets name Katanga for libethenite (Kakanda, Likasi), chalcocite (Mashamba West mine), calcite (the Mupine mine) and turquoise (good crystals from Katonto, north of Kolwezi). Shattuckite is named from Tantara and M’Sesa, near Kambove; its type locality is at Bisbee. The heterogenite sheet also names Bou Azzer.
Kipushi and Shinkolobwe. The sheets place aurichalcite, germanite, briartite and reniérite at Kipushi, 28 km southwest of Lubumbashi; briartite and reniérite are marked [TL] at the Prince Leopold mine. A paper the USGS cites describes Kipushi as a Cu, Zn, Pb deposit of the Copperbelt of Central Africa. Uranium minerals are named from Shinkolobwe: becquerelite, curite, kasolite, sklodowskite, cuprosklodowskite, uraninite, vandenbrandeite and torbernite. Several also name the Musonoi mine. This page gives no handling advice; see is my mineral radioactive and how to store radioactive mineral specimens, HSE EH40, COSHH 2002 or a clinician. That is not advice.
Named for the belt. Kolwezite is named for its occurrence at Kolwezi. Cornetite honours Jules Cornet (1865–1929), the Belgian geologist whom the USGS credits with publishing the basic stratigraphy of the Katangan sequence in 1894. The IMA list gives the Democratic Republic of the Congo as the country for kolwezite, cornetite, briartite and reniérite, and for becquerelite, curite, kasolite, sklodowskite, cuprosklodowskite and vandenbrandeite. It gives Germany for heterogenite, the USA for carrollite and the Czech Republic for torbernite. The species index has the species pages.
The giant deposits, by the USGS numbers
Table 3 of the assessment lists deposits with more than 2 million t of contained copper. In the Congo: DIMA 7.8 Mt, Fungurume 2.8, Kambove Principal–Kambove West 3.1, Kamoto–KOV–Musonie–Mupine 19, Kansalawile–Mambilima 2.8, Kimbwe 2.0, Kinsevere 2.1, Kwatebala 2.2, Mutanda Ya Mukonkota 3.7 and Tenke 2.5. Worked: 10 deposits, 48.0 Mt.
Zambia for comparison. The same table lists 8 Zambian giants totalling 81.3 Mt, led by Konkola–Musoshi at 22 Mt. The USGS abstract gives 152 Mt of copper in more than 80 deposits across the belt, and Table 1 gives 150 Mt for the Katanga Basin. Of the 48.0 Mt in Congolese giants, the Kamoto–KOV–Musonie–Mupine group is 39.6%.
Spelling. The USGS table writes Musonie; its map caption and the Handbook sheets write Musonoi. They are the same Kolwezi mine. For specimens the Handbook form is the one older labels carry.
From the 4th century to Gécamines: the dates
- 4th century AD: archaeological finds suggest malachite outcrops were mined (Bisson 2000, cited by the USGS).
- 1880s–1890s: German and Belgian expeditions visit precolonial mines, including Mount Kambobe, now Kambove.
- 1894: Jules Cornet publishes the basic Katangan stratigraphy; the Congo–Northern Rhodesia border is set.
- By 1906: Tanganyika Concessions prospectors locate more than 100 old copper workings on the Belgian side. The ancient pit at the Etoile (Star of the Congo) mine was 1,200 m long. The report says Union Minière du Haut Katanga was formed to work the deposits, without a year.
- 1960: independence. 1967: Union Minière nationalised, creating Gécamines.
- 1986: Congolese copper production, all by Gécamines, peaks at about 475 thousand t; it falls to 35 thousand t in 1994 and reaches nearly 500 thousand t in 2010 (USGS, country totals).
On a label. Mine, district town and province: Mashamba West mine, Kolwezi, Katanga, Democratic Republic of the Congo. “Shaba” or “Zaire” on an older label is the same place; “Congo” alone is not enough. We say nothing about present access or collecting. Nothing here is offered for sale; the wanted list is the only commercial route.