Merensky Reef

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Mines in the Merensky Reef

The Merensky Reef is a 1 to 3 meter thick layer of igneous rock , a plagioclase pyroxenite , in the Bushveld complex in the Transvaal . Together with another 20 to 330 meters below horizon, the 15 to 250 cm thick UG2 chromite layer (UG2 = Upper Group 2) and the Platreef mined near Potgietersrus , the largest known reserves of platinum group metals (PGMs) are located here , such as platinum , palladium , rhodium , iridium and osmium . The PGM content fluctuates between 4.0 and 10.6 g / t in the rock.

The UG2 layer, the composition of which is relatively constant over the entire Bushveld complex, is rich in bronzite and chromite . However, it lacks the gold , copper and nickel by- products of the Merensky Reef, whereas its PGM reserves are likely to be almost twice as high. Rare minerals of these metals such as braggite , laurite , sperrylite , stibiopalladinite and cooperite occur.

The chromite banks often arise in large intrusions pervaded by mafic aggregations . A common theory is that chromite is a result of the initiation and mixing of simple magma with differentiated magma . Chromite becomes oversaturated in the mixture, which in turn leads to the formation of an almost mono-mineral layer on the floor of the magma chamber .

Platinum-bearing horizons in the Bushveld complex were discovered in 1924 by Hans Merensky in the Lydenburg district , who followed them for a few hundred kilometers in his research until 1930. Extensive mining on the reef was not carried out until the 1950s saw a sudden surge in demand for platinum group metals used in catalytic processes . This made commercial mining economical. Only after significant metallurgical advances in the 1970s was it possible to smelt the UG2 chromite in an economically viable manner.

Several companies are involved in the extraction of platinum metals from the Merensky Reef. They include the Anglo American Platinum Corporation Ltd. (formerly Rustenburg Platinum Holdings Ltd. ), Impala Platinum , Lonmin Platinum (including Western Platinum) and Northam Platinum. The Royal Bafokeng Nation took legal action for a share of the mining interest, which made them the richest tribe in Africa. The platinum supplies are expected to be depleted by 2040.

Web links

literature

  • René A. Pelletier: Mineral Resources of South-Central Africa. Oxford University Press, Cape Town / London / New York / Toronto 1964.
  • Wolfhard Wimmenauer : Petrography of igneous and metamorphic rocks. Enke, Stuttgart 1985, ISBN 3-432-94671-6 , pp. 101-102.

Individual evidence

  1. ^ Rodney T. Jones: Platinum Smelting in South Africa. at www.pyrometallurgy.co.za (English).
  2. ^ Pelletier: Mineral Resources of South-Central Africa. 1964, p. 95.
  3. ^ Wimmenauer: Petrography of igneous and metamorphic rocks. 1985, p. 101.
  4. ^ Rodney T. Jones: An overview of Southern African PGM smelting. 2005, p. 4. On www.mintek.co.za (English; PDF; 255 kB).

Coordinates: 24 ° 42 ′ 47.8 "  S , 28 ° 28 ′ 26.4"  E