1847-1931

American geochemist best known for his meticulous analyses and compilations of chemical and physical data. His Data of Geochemistry (1908) was a standard source on minerals in Earth's crust, and he proposed a theory of evolution of the heavier elements from the lighter. Clarke was simultaneously chief chemist of the U.S. Geological Survey and honorary curator of minerals of the U.S. National Museum (1883-1924). He was the first president of the national American Chemical Society (1901).