Delos (Del) Flint was born in Pasadena, California in 1918, attended Pasadena public schools, and majored in geology at Caltech, graduating with a B.S. in 1939. After earning an M.S. at Northwestern University in 1941, he joined the U.S. Geological Survey and mapped chromite deposits in Montana, Oregon, California, and Camagüey, Cuba. (The Camagüey chromite mapping studies were published as USGS Bulletin 954-B in 1948.) He joined the U.S. Army in 1944, was commissioned as Second Lieutenant after completing basic field artillery and officer training, and his unit shipped out to Japan after V-J Day as part of the occupation army. He was transferred from the 89th Field Artillery Battalion in Nagoya to the U.S. Army Corps of Engineers Tokyo Office, and went to Okinawa as the fourth (final) chief of the Pacific Geological Mapping Program field party assigned to map and analyze military geology of Okinawa and the Ryukyu Islands. In 1947, after overseeing completion of these field activities, he was discharged from military service, rejoined the U.S. Geological Survey, and returned to Washington, DC. As a member of the Military Geology Branch, he coauthored several Okinawa project reports (later published by the Army as Military Geology of Okinawa-Jima, Ryukyu-Retto, Volumes I, II, and V.)
In 1954, Del was transferred to Santiago de Cuba to lead a Point Four program studying chromite deposits in Camagüey and Oriente. While in Cuba, Del came in contact with Freeport Sulphur Company, which was opening a nickel mine at Moa Bay in Oriente. When Freeport offered him a position as a geologist, he accepted, and the Flints moved to New Orleans in 1957 shortly before Castro took power. Del spent the remainder of his professional career as an exploration geologist with Freeport and its successor companies. He moved to Nevada in 1975 when Freeport Exploration Company (the exploration arm of Freeport McMoRan Minerals Company) relocated its headquarters to Reno. He retired on January 1, 1984 as Vice-President and Chief Geologist of Freeport Exploration Company.
Del’s exploration activities with Freeport took him all over the world. He worked on sulfur deposits and prospects in the U.S., Mexico, Poland, Egypt, Argentina, China, Chile, and the Canadian Arctic; potash and sour gas deposits in the U.S. and Canada; kaolin in France; asbestos in Mexico; and metallic mineral deposits in the U.S., Canada, Mexico, Australia, Chile, Spain, the Philippines, and Indonesia. He contributed to the discovery and development of the Nepean and Mount Keith nickel mines in Australia, the Reid Lake mixed sulfides deposit in Canada, the Jerritt Canyon gold deposits in Nevada, and – most importantly – the Ertsberg-Grasberg copper-gold district in Irian Jaya.
In 1960, Forbes Wilson, Freeport’s manager of minerals exploration, organized and led an exploration and sampling expedition to Dutch New Guinea to locate and evaluate the Ertsberg, an almost inaccessible copper ore mountain in the Carstensz Range which had not been revisited since its discovery in 1936. Del spent 76 days in the remote jungles and rugged mountains of New Guinea (now Irian Jaya) as a member of the expedition advance team. They traveled more than 60 miles in canoes through the coastal swamps, walked over 150 miles, and climbed from sea level to over 13,000 feet, relying on air drops for supplies and locally recruited mountain people for porterage and support, and communicating with the outside world only with a bicycle-powered portable radio. Del described this expedition as “a trip into the Stone Age”, and the huge magnetite-chalcopyrite skarn ore deposit as “all one could hope for”. The 300 kg of ore samples collected by the expedition averaged 3.5% copper by weight.
In 1967, Freeport negotiated a contract of work with the Indonesian government to develop the Ertsberg (the largest aboveground copper ore deposit ever discovered) and adjacent area. Del returned to Irian Jaya, where he was involved in drilling, sampling, and training Indonesian geologists and professional personnel. In 1968, he identified and field mapped the grossularite garnet-bornite skarn extension that was later developed as Ertsberg East deposit. He revisited Irian Jaya many times after the Ertsberg mine went into production in 1973.
Del was a long-time member of the Society of Economic Geologists (Councilor, 1966-67; Vice President, 1974) and American Institute of Mining, Metallurgical and Petroleum Engineers (National Nominating Committee Chairman, 1973), and a Senior Fellow of the Geological Society of America. His memoirs and additional writings, compiled as Recollections of a Hard-Rock Geologist, were published privately in hardcover in 2013 as a gift to family and friends. Del served as president of the Geological Society of Nevada in 1976-1977, was elected an Honorary Member in 1992, and remained an active member until his death at age 95 in November, 2014.