The Merensky Reef has been the principal source of pgm since it was first worked in 1925. However, the other reefs have grown in importance, so that by 1999 the Merensky Reef accounted for just over 50 per cent of all the platinum-bearing ore processed in South Africa. The Platreef, briefly mined in the 1920s, was not exploited on a large scale until 1993.
Miners use hand-held pneumatic drills to bore holes which are then filled with explosive.
After blasting, ore is removed from the stope using scrapers attached to winches. It is then transported through a series of ore passes to the bottom of the shaft, and hauled to the surface. Open-pit methods are used to mine the Platreef, which is much wider than the other reefs, varying between 5 and 90 metres in thickness. Allowing for losses which occur during refining, this means that between 7 and 12 tonnes of ore must be processed to obtain a single ounce of platinum. The ore is crushed and milled to reduce the size of the rock particles and to expose the minerals which contain the pgm.