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Rhovan ( Rhombus Vanadium ) - Bushveld Complex
North West Province, South Africa
Main commodities: V Fe Ti

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The Rhovan iron-vanadium mine is located approximately 35 km ENE of Rustenburg in the North West Province of South Africa, and lies within the Western Lobe of the Bushveld Complex.

It exploits vanadium bearing titaniferous magnetite bands in the Upper Zone of the Bushveld Complex. The mafic component of the Bushveld Complex (known as the Rustenburg Layered Suite) has been subdivided into five zones, from the base, the Marginal, Lower, Critical, Main and Upper Zones respectively. For background on the regional geological and metallogenic setting see the Bushveld Complex record.

The Main Zone, which underlies the host Upper Zone, is composed of gabbros grading upwards into gabbronorites, with several anorthosites and a distinct Pyroxenite Marker two thirds of the way up the Zone. The base of the Upper Zone is defined by the first appearance of cumulus magnetite above the Pyroxenite Marker. This zone is composed of gabbro, anorthosite and a roof zone of olivine diorite, and has been divided into: i). Subzone A at the base, composed of 700 m of anorthosite and magnetite ferrogabbro, and more than 11 magnetite layers; ii). Subzone B, where cumulus Fe-rich olivine appears, composed of around 580 m of anorthosite, troctolite, and olivine and magnetite ferrogabbro containing 7 more magnetite layers; and iii). Subzone C where apatite is present as an additional cumulus phase in a 1000 m thick sequence of olivine diorite with anorthosite and magnetite rich diorite and a further 7 magnetite layers.

The Upper Zone layered mafic rocks carry approximately 8% magnetite disseminated in gabbroic rocks, plus a further cumulative 20 m of pure magnetite distributed in 25 discrete magnetite layers. The magnetite layers are concordant and of different thicknesses, V2O5 and TiO2 grade, but with persistence over considerable distances, both along strike and down dip. On the Eastern Lobe of the Complex there are also crosscutting plugs of almost pure magnetite in both the Main and Upper Zones (the largest had an ovoid plan dimension of 300x100 m).

Vanadium occurs in solid solution within the magnetite layers. The highest vanadium contents of around 1.6% V
2O5 occur in the lowermost layers, decreasing to about 0.25% in the uppermost part of the Upper Zone. Titanium varies in an inverse manner from around 11% TiO2 in the lower layers to 18% in the uppermost.

The magnetite is characteristically black, highly magnetic, commonly coarsely granular (often up to 1 cm across) and closely packed. The approximately 5% ilmenite grains are interspersed and more variable in size, shape and distribution, being present as individual grains, elongated intergranular bodies or exsolution lamallae parallel to the octahedral planes of magnetite. The magnetite comprises intergrowths of both Ti-poor and Ti-rich magnetite phases.

The highest V
2O5 grades over reasonable widths are confined to the Main Magnetite Layers which are approximately 130 m above the base of the Upper Zone, in Subzone A.   In the Western Lobe of the Bushveld Complex, the lower magnetite layers, which include the Main Magnetite Layer, extend from north of Pretoria, westward to Rustenburg, then northwestward towards the Pilanesberg before trending north-easterly towards Thabazimbi.   In the vicinity of Rhovan, the Main Magnetite Layer is actually three separate thick magnetite layers.   The lower two are separated by less than 5 m, whereas the upper may be anywhere between 28 and 200 m higher.   The lowest averages around 1 m in thickness with 1.8% V2O5, while the middle averages near 1.6 m at 1.3% V2O5, and the upper 1.6 m at 1.4% V2O5

Open pit reserves and resources at Rhovan in June 2005 included:

      Proved Ore Reserves - 44 Mt @ 0.5% V
2O5  +  Probable Ore Reserves - 6 Mt @ 0.7% V2O5
      Measured Mineral Resource - 77.5 Mt @ 0.5% V
2O5  +  Inferred Mineral Resource - 139.8 Mt @ 0.5% V2O5.

The most recent source geological information used to prepare this decription was dated: 2005.    
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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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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