The Kalahari Manganese Field

The Kalahari Manganese Field (KMF), located in the Northern Cape province of South Africa, is the largest known, land-based deposit of high-grade manganese in the world and is estimated to contain approximately 4.2 billion tonnes of exploitable manganese. This is more than 77% of the world's total known land-based reserves.

The Kalahari Manganese Field is dominated by the Hotazel geological formation, comprising three sedimentary manganese layers interbedded with banded iron formations. The lower manganese orebody is the best developed and laterally continuous, with thicknesses of up to 45m in the southeast near the Tshipi Borwa Mine, compared to thicknesses of 5 to 8m along the north limit of the main Kalahari deposit.The other sedimentary manganese layers in the Hotazel geological formation are the middle manganese orebody, which is up to 3m thick (but often absent in the southern portion of the KMF) and of low manganese content, and the upper manganese orebody, which displays variable thickness from several metres to several tens of metres with minor increases in manganese content.

There are three main ore types in the Kalahari deposit, the primary Mamatwan-type ore (contains 30 to 38.5 weight per cent. (wt%) manganese metal ); the secondary Wessels-type ore (contains 42 to 60 wt% manganese metal) and high-grade supergene ore (with manganese metal content of 40 to 42 wt%).