Africa contains an enormous wealth of mineral resources, including some of the world’s largest reserves of fossil fuels, metallic ores, and gems and precious metals. This richness is matched by a great diversity of biological resources that includes the intensely lush equatorial rainforests of Central Africa and the world-famous populations of wildlife of the eastern and southern portions of the continent. Although agriculture (primarily subsistence) still dominates the economies of many African countries, the exploitation of these resources became the most significant economic activity in Africa in the 20th century.