Zaire is the world's largest producer of cobalt and diamond and fifth in mine production of copper. Copper is the country's most important product, accounting for 43% of the value of all exports and providing byproducts of cobalt, zinc, cadmium, gold, silver, and sulfur. Mineral industry exports provide 86% of Zaire's foreign exchange and a third of its gross domestic product. The industry's labor force is 10% of the industrial work force. The country's geologic heritage of ancient mineralized rock is the source of its mineral wealth and remains to be further developed. Information available to the Bureau of Mines indicates that output of gold, tin, and tin byproducts has declined owing to exhaustion of easily minable ore and deterioration of production facilities. Resources remain for exploitation but will require much capital and new infrastructure. The rugged environment, isolation of scattered deposits, and inadequate reinvestment may have lost some resources for development indefinitely. Low copper prices and higher cost for energy and transportation are balanced by relatively low wages and by government and international financial assistance.