Witwatersrand Basin (Johannesburg, South Africa) Located in South Africa, the Witwatersrand Basin represents the richest gold field ever discovered. It is estimated the 40% of all of the gold ever mined has come out of the Basin. In 1970, South Africa's output accounted for 79% of the world's gold production. By 2009, South Africa's share of world gold production had dropped to less than 8%.