Donnel Foster Hewett (June 24, 1881, Irwin, Pennsylvania – February 5, 1971) was an American geologist and mineralogist, known for his leading role in the 1905 discovery of the Minas Ragra vanadium ore deposit in Peru.[1] This ore deposit was the world's principal source of vanadium for more than 30 years.[2][3] Hewett, with Earl V. Shannon, described and named orientite, a mineral rich in manganese.[4][5]