Manufactured goods (such as automobiles and some iron and steel products) and mined commodities (such as coal, platinum and gold) form the backbone of South Africa's economy. These industries employ a high number of workers and constitute the bulk of South Africa's exports, and consequently they can significantly affect the value of the South African rand. Any degradation in the health of these sectors indirectly affects other economic sectors. For example, coal, one of South Africa's largest exports, is used to generate roughly 70 percent of the country's primary energy and roughly 90 percent of its electricity. High Production Costs On Aug. 13, labor negotiations broke down between unions and the Chamber of Mines, which represents the major coal mining companies. Now the negotiations are being mediated, and the unions can legally strike if an agreement is not reached. The major points of contention involve wage increases and housing allowances.