tenorite, copper oxide mineral (CuO) found as gray-to-black metallic crystals as a sublimation product on lavas. Melaconite, the massive variety, is common as earthy deposits in the oxidized zone of copper lodes. Crystals of tenorite have been identified at Mount Vesuvius and Mount Etna, Italy, and at Lostwithiel, Cornwall, Eng. Melaconite is abundant at Huerta de Arriba, Burgos, Spain, and at Bisbee, Ariz., where it was mined (1880–1902) as a copper ore. For detailed physical properties, see oxide mineral (table).