Limpopo (Northern) Province, South Africa

Main commodities: Fe
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The Thabazimbi iron ore deposits are situated in the Northern Province of South Africa, 200 km north of Johannesburg.   #Location: 24°36'S, 27° 23'E.

These mines have been in production since 1932 and are currently owned and operated by Kumba Resources Limited. The operation produces around 2.4 Mt per annum of lump and fines iron ore in roughly equal proportions exclusively for Kumba's South African steel operations at the Vanderbijlpark Steel Plant, outside of Johannesburg and the Newcastle Steel Plant in northern KwaZulu-Natal.

The Thabazimbi deposits are hosted by the Palaeoproterozoic Transvaal Supergroup within the Transvaal sub-basin.   They occur in the basal Penge Formation, immediately above the lowest shale unit, a 10 m thick chert rich band which immediately overlies the thick dolomite and chert succession of the Malmani Dolomite.

The Penge Formation, is 350 m thick and is composed of thick iron formations alternating with thin units of orthochemical iron formation.   The iron ore lenses (+60% Fe) are restricted to the basal 80 m section of the Penge Formation rhythmites, occuring as irregular, tabular bodies distributed over a strike length of 12 km.   Individual bodies lens out along strike, separated by sterile gaps of un-economic iron formation and vary in thickness from 2 to 100 m, averaging around 20 m.   Both the host and ore dip at around 50°.

At depth the ore grades laterally down dip into talc-hematite and then to carbonate-hematite rocks, while lenses of primary iron formation are also found within the orebodies closer to surface.   The ore zones have a gradational upper boundary with the un-enriched overlying iron formation, while the degree of iron enrichment in the ore appears to be directly proportional to the amount of brecciation of the iron formation resulting from solution collapse in the underlying chert poor dolomites of the uppermost Malmani Dolomite.

Most of the ore is brecciated, occuring as primary hematite fragments (ie. the hematite, magnetite and martite of the ferhythmites in the original iron formation) set in a fine secondary hematite matrix.   The primary hematite clasts have a steel-grey to blue-grey colour, metallic lustre and a dense compact texture.   In contrast the fine seconday hematite matrix has a variable colour from steel-grey to black-grey, and is locally red-brown.

The brecciation and content of clasts versus matrix is variable as is the hardness and friability of the ore and the degree of removal of chert and replacement by goethite and hematite.   The iron enrichment is believed to be post (Palaeoproterozoic) Waterburg tectonism with a second post (late Mesozic) Karoo phase.

The mineral reserve and resource estimates for the deposit in 2001 were -   Proven: 16.3 Mt and Probable: 4.1 Mt.   The mineral resource estimates were -   Measured: 32.43 Mt, Indicated: 42.00 Mt and Inferred: 19.80 Mt.

Total production from 1932 to 2005 was 118 Mt of saleable ore.

The mineral reserve and resource estimates for the deposit in 2006 were -   Proven: 10.0 Mt and Probable: 4.0 Mt, for a total reserve of 14 Mt @ 64% Fe, 0.07% P.   The mineral resource estimates were -   Measured: 23 Mt, Indicated: 18 Mt and Inferred: 20 Mt, for a total resource of 61 Mt @ 61.3% Fe, 0.06% P (Kumba Resources website, 2009).

The most recent source geological information used to prepare this summary was dated: 2002.    
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.

  References & Additional Information
   Selected References:
Gutzmer, J., Chisonga, B.C., Beukes, N.J. and Mukhopadhyay, J., C.A.,  2008 - The geochemistry of banded iron formation-hosted high-grade hematite-martite iron ores: in Hagemann S, Rosiere C, Gutzmer J and Beukes N J, (eds.), 2008 Banded Iron Formation-Related High-Grade Iron Ore, Reviews in Economic Geology   v.15 pp. 157-183
Van Deventer J L, Eriksson P G and Snyman C P,  1986 - The Thabazimbi Iron Ore Deposit, North-Western Transvaal: in Anhaeusser CR, Maske S (Eds), 1986 Mineral Deposits of Southern Africa Geol. Soc. of South Africa, Johannesburg   v1 pp 923-929

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 takes no responsibility what-so-ever for inaccurate or out of date data, information or interpretations.

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