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Resources & Reserves

Geology

Implats exploits platiniferous horizons within the Bushveld Complex in South Africa and the Great Dyke in Zimbabwe.These two layered intrusions are unique in terms of size and geological continuity. Mining mostly takes place as underground operations focusing on relatively narrow mineralised horizons with specific mining methods adapted to suit the local geology and morphology of the mineralised horizons.

The Bushveld Complex

The Bushveld Complex is an extremely large (66 000km2), two billion year-old layered igneous intrusion occurring in the northern part of South Africa. Rock types range in composition from ultramafic to felsic. The complex is not only unique in size, but also in the range and economic significance of its contained mineral wealth. In addition to the platinum group metals (PGMs) and associated base metals, vast quantities of chromite,vanadium and dimension stone are also produced.

 

Resource and Reserves

  Mineral resource and mineral reserve statement 2015

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The layered sequence, the Rustenburg Layered Suite, comprises five major sub divisions, ie the Marginal, Lower, Critical, Main and Upper zones. Two horizons within the Critical Zone, namely the Merensky Reef and the Upper Group 2 (UG2) Reef, host economically exploitable quantities of PGMs. These two horizons, along with other layers which can be traced for hundreds of kilometres around the complex, are the focus of Implats’ operations. The PGMs – platinum, palladium, rhodium, ruthenium and iridium – as well as the associated gold, copper, nickel, cobalt, chromite and other minor metals and compounds, are mined and recovered concurrently.

The Great Dyke

The Great Dyke is a 2.5 billion year-old layered mafic-ultramafic body intruded into Archaean granites and greenstone belts. It is highly elongated, slightly sinuous, 550km long, north-northeast trending with a maximum width of 12km and bisects Zimbabwe in a north-northeasterly trend and is divided vertically into a lower ultramafic sequence, comprising cyclic repetitions of dunite, harzburgite, pyroxenite and chromitite, and an uppermafic sequence consisting mainly of olivine gabbro, gabbronorite and norite. It is U-shaped in section with layers dipping and flattening towards the axis of the intrusion. Much of the mafic sequence has been removed by erosion and at the present plane of erosion the Dyke is exposed as a series of narrow,contiguous layered complexes or chambers. These are, from north to south, Musengezi, Hartley (comprising the Darwendale and Sebakwe sub-chambers) and a southern chamber comprising the Selukwe and Wedza sub-chambers.

The Main Sulphide Zone (MSZ), host to economically exploitable PGMs and associated base metal mineralisation, is located 10m to 50m below the ultramafic/mafic contact in the P1 pyroxenite. The PGMs, along with gold, copper and nickel, occur in the MSZ.  The grade profiles vary between areas and the platinum and palladium peaks are some what offset. Typically, the MSZ consists of a 2m to 10m-thick zone containing 2% to 8% of iron-nickel-copper sulphides disseminated in pyroxenite. The base of this nickel copper-rich layer is straddled by a 1 to 5m-thick zone of elevated precious metals (Pt, Pd, Rh and Au). The base metal zone contains up to 5% sulphides, while the sulphide content of the PGM zone is less than 0.5%.