John Hays Hammond

John Hays Hammond (1855-1936), American mining engineer who helped create De Beers Consolidated Diamond Mines, the largest diamond producer in the world. Hammond was born in San Francisco, California. He studied at Sheffield Scientific School of Yale University in New Haven, Connecticut, and in 1876 he took a course at the Royal School of Mines in Freiburg, Germany. In 1880 Hammond became manager of the North Star and Empire mines in Grass Valley, California. In 1893 he met Cecil Rhodes, a British statesman and major proponent for British rule in southern Africa, as well as brothers Henry and Barney Barnato, who dominated the diamond industry after merging their mining companies into De Beers Consolidated Diamond Mines in 1888. As one of the leaders of a rebellion by British immigrants to overthrow the South African Republic, Hammond was arrested and condemned to death in January 1896. Hammond’s sentence was commuted, however, and he was released after paying a $125,000 fine. After returning to the United States in 1900, he became a consulting engineer for the Guggenheim Exploration Company and developed the Utah Copper and Nevada Copper companies. He was president of the Panama Exposition Commission to Europe in 1912 and chairman of the United States Coal Commission in 1922 and 1923.