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Kalahari Mn - Mamatwan, Wessels, Middelplaats, Black Rock, Gloria, Nchwaning |
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Northern Cape, South Africa |
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Mn
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Super Porphyry Cu and Au
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The Kalahari Manganese deposits are located in the Griqualand West area of the Northern Cape Province of South Africa. The mines exploiting the field include: Mamatwan, Wessels, Middelplaats, Black Rock, Gloria and Nchwaning.
Mineralisation is developed in three braunite-kutnahorite lutite layers interbedded with iron formation in the Hotazel Formation of the Palaeoproterozoic (2400 to 2100 Ma) Transvaal Sequence which was deposited within an intracratonic basin on the Kaapvaal Craton. The relatively flat lying, concealed, mineralised, Hotazel Formation units of the Kalahari manganese field covers an area of some 30 x 10 km.
The Mamatwan mine exploits the lower most of the three layers which averages 45 m in thickness. This layer has been subdivided into: (1) an upper 19.5 m thick sub-economic layer with >30% Mn and an Mn:Fe ratio of 3, (2) a central 19.7 m thick economic layer with 38% Mn and an Mn:Fe ratio of >8, and (3) a lower 6 m thick subeconomic layer with 30% Mn and an Mn:Fe ratio of 5.
Proven economic reserves in 1986 were 300 to 400 Mt, although the total resource in 1982 was approximately 13 600 Mt of ore with a minimum 20% Mn. This includes 5940 Mt @ 20 to 30% Mn, 6284 Mt @ 30 to 38% Mn and 980 Mt @ 38 to 40% Mn.
The ore comprises very fine grained, banded braunite-kutnahorite lutite with concretionary ovoids, laminae and lenticles of Mn-calcite commonly with associated hausmannite.
A zone of higher grade ore known as Wessels-type is localised on the north-western margin of the exposed field and accounts for 3% of the total resource in the field. This ore is characterised by up to 60% Mn. Resource figures (1982) for Wessels-type ore were:
31 Mt @ 30 to 40% Mn (5 to 10% Fe), 18 Mt @ 36 to 40% Mn (60% Mn+Fe), 30 Mt @ 40 to 44% Mn (60% Mn+Fe), 330 Mt @ >44% Mn (60% Mn+Fe).
For detail see the reference(s) listed below.
The most recent source geological information used to prepare this decription was dated: 1986.
This description is a summary from published sources, the chief of which are listed below.
© Copyright Porter GeoConsultancy Pty Ltd. Unauthorised copying, reproduction, storage or dissemination prohibited.
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Selected References:
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Beukes N J, Burger A M and Gutzmer J, 1995 - Fault-controlled hydrothermal alteration of Palaeoproterozoic manganese ore in Wessels Mine, Kalahari manganese field : in S. Afr. J. Geol. v98 pp 430-451
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De Villiers J E 1983 - The Manganese deposits of Griqualand West, South Africa: some mineralogic aspects: in Econ. Geol. v78 pp 1108-1118
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Dixon R D, 1985 - Sugilite and associated minerals from Wessels Mine, Kalahari manganese field : in S. Afr. J. Geol. v88 pp 11-17
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Evans D A D, Gutzmer J, Beukes N J, Kirschvink J L 2001 - Paleomagnetic constraints on ages of mineralization in the Kalahari Manganese Field, South Africa: in Econ. Geol. v96 pp 621-631
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Gutzmer J and Beukes N J, 1996 - Mineral paragenesis of the Kalahari managanese field, South Africa: in Ore Geology Reviews v11 pp 405-428
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Gutzmer J, Beukes N J 1995 - Fault-controlled metasomatic alteration of early Proterozoic sedimentary Manganese ores in the Kalahari Manganese field, South Africa: in Econ. Geol. v90 pp 823-844
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Gutzmer J, Beukes N J and Yeh H W, 1997 - Fault-controlled metasomatic alteration of Early Proterozoic sedimentary manganese ore at Mamatwan Mine, Kalahari manganese field, South Africa: in S. Afr. J. Geol. v100 pp 53-71
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Gutzmer J, Beukes N J, 1997 - Effects of mass transfer, compaction and secondary porosity on hydrothermal upgrading of Paleoproterozoic sedimentary manganese ore in the Kalahari manganese field, South Africa: in Mineralium Deposita v32 pp 250-256
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Kleyenstueber A S E, 1984 - The mineralogy of the manganese-bearing Hotazel Formation, of the Proterozoic Transvaal Sequence in Griqualand West, South Africa : in S. Afr. J. Geol. v87 pp 257-272
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Luders V, Gutzmer J, Beukes N J 1999 - Fluid inclusion studies in cogenetic Hematite, Hausmannite, and gangue minerals from high-grade Manganese ores in the Kalahari Manganese field, South Africa: in Econ. Geol. v94 pp 589-596
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Miyano T, Beukes N J 1987 - Physicochemical environments for the formation of Quartz-free Manganese Oxide ores from the Early Proterozoic Hotazel Formation, Kalahari Manganese field, South Africa: in Econ. Geol. v82 pp 706-718
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Nel C J, Beukes N J, de Villiers J P R 1986 - The Mamatwan Manganese mine of the Kalahari Manganese Field: in Anhaeusser C R, Maske S, (Eds.), 1986 Mineral Deposits of South Africa Geol. Soc. South Africa, Johannesburg v1 pp 963-978
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Tsikos H and Moore J M, 1998 - The Kalahari manganese field; an enigmatic association of iron and manganese : in S. Afr. J. Geol. v101 pp 287-290
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Tsikos H, Beukes N J, Moore J M, HarrisÊC 2003 - Deposition, Diagenesis, and Secondary Enrichment of Metals in the Paleoproterozoic Hotazel Iron Formation, Kalahari Manganese Field, South Africa: in Econ. Geol. v98 pp 1449-1462
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Tsikos H, Moore J M 1997 - Petrography and geochemistry of the Paleoproterozoic Hotazel Iron-formation, Kalahari Manganese field, South Africa: implications for Precambrian Manganese metallogenesis: in Econ. Geol. v92 pp 87-97
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Porter GeoConsultancy Pty Ltd (PorterGeo) provides access to this database at no charge. It is largely based on scientific papers and reports in the public domain, and was current when the sources consulted were published. While PorterGeo endeavour to ensure the information was accurate at the time of compilation and subsequent updating, PorterGeo, its employees and servants: i). do not warrant, or make any representation regarding the use, or results of the use of the information contained herein as to its correctness, accuracy, currency, or otherwise; and ii). expressly disclaim all liability or responsibility to any person using the information or conclusions contained herein.
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