Kazakhstan has an abundant supply of accessible mineral and fossil fuel resources. Development of petroleum, natural gas, and mineral extractions has attracted most of the over $40 billion in foreign investment in Kazakhstan since 1993 and accounts for some 57% of the nation's industrial output (or approximately 13% of gross domestic product). According to some estimates, Kazakhstan has the second largest uranium, chromium, lead, and zinc reserves; the third largest manganese reserves; the fifth largest copper reserves; and ranks in the top ten for coal, iron, and gold. It is also an exporter of diamonds. Perhaps most significant for economic development, Kazakhstan also currently has the 11th largest proven reserves of both petroleum and natural gas.