RIOTINTO MINES

Spanish Minas De Riotinto, copper mines, located near the town of Nerva (formerly Riotinto), in Huelva provincia, in the autonomous community of Andalusia, southwestern Spain, on the Tinto River. Worked since Phoenician and Roman times, the mines (the name of which means stained river and refers to the pollution caused by working them) were leased to a Swede named Wolters in 1725 and to a British syndicate in 1872. Returned to Spanish control in 1954, they are considered to be among the world's most valuable copper mines.