Heterogenite | |
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General | |
Category | Mineral |
Formula (repeating unit) | CoO(OH) |
IMA symbol | Htg [1] |
Strunz classification | 04.FE.20 |
Dana classification | 06.01.04.02 |
Crystal system | Trigonal or Hexagonal |
Identification | |
Color | Black, reddish, blackish-brown |
Cleavage | {0001} |
Mohs scale hardness | 4–5 |
Density | 4.13 – 4.47, Average = 4.3 |
Common impurities | Mn, Ni, Zn, Cu, Fe |
Heterogenite is a natural tri-valent cobalt oxyhydroxide mineral. [2] It is the most abundant oxidised cobalt mineral in the Katanga Copperbelt, a region in the Democratic Republic of the Congo. [3] About 70% of known heterogenite is located in the DRC. [4]
The name heterogenite came from Greek, "of another kind", as the mineral differs in composition from similar minerals. [5] Its formation is likely related to the weathering of carrollite (CuCo2S4). [6] In nature it is found coexisting with other minerals like smaltite, pharmacosiderite, calcite, linnaeite, sphaerocobaltite, malachite and cuprite. [2]
Heterogenite has an average grade of 64.1% cobalt, one of the highest rates among cobalt-containing minerals. [7]
Similar to most oxyhydroxides, heterogenite acts as a chemical 'sponge', trapping many trace elements such as Ni, Zn, V, As, Mo, and Pb. Amongst these trace elements is also uranium, whose concentration in the mineral can be as high as a few percent. [8]
Heterogenite contains cobalt in both Co2+ and Co3+ oxidation states. [6]
Heterogenite is formed by the oxidation of cobalt-sulfides and accumulated as residual deposits during a Pliocene weathering event. [6] Many studies highlight that heterogenite was formed in oxidizing conditions under the surface. [9] In several locations, primary sulfides have been oxidised due to surface weathering down to about 100 meters below the surface, which resulted in significant cobalt enrichment and transformation to oxidic ore minerals, such as heterogenite. [10]
The preferred concentration technique for treating heterogenite is surface sulfidation followed by flotation. Sulfidation typically requires sodium sulfide (Na2S), ammonium sulfide (NH4)2S), or sodium sulfydrate (NaSH) in order to make heterogenite suitable for collection with sulfydryl-type collectors [9]
Bioleaching is the extraction or liberation of metals from their ores through the use of living organisms. Bioleaching is one of several applications within biohydrometallurgy and several methods are used to treat ores or concentrates containing copper, zinc, lead, arsenic, antimony, nickel, molybdenum, gold, silver, and cobalt.
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Limonite is an iron ore consisting of a mixture of hydrated iron(III) oxide-hydroxides in varying composition. The generic formula is frequently written as FeO(OH)·nH2O, although this is not entirely accurate as the ratio of oxide to hydroxide can vary quite widely. Limonite is one of the three principal iron ores, the others being hematite and magnetite, and has been mined for the production of iron since at least 2500 BP.
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Iron(III) oxide-hydroxide or ferric oxyhydroxide is the chemical compound of iron, oxygen, and hydrogen with formula FeO(OH).
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A nickel mine is a mine that produces nickel. Some mines produce nickel primarily, while some mines produce nickel as a side-product of some other metal that has a higher concentration in the ore.
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