Iron Mountain Mine

Iron Mountain Mine, also known as the Richmond Mine at Iron Mountain, is a mine near Redding in Northern California, US. Geologically classified as a "massive sulfide ore deposit", the site was mined for iron, silver, gold, copper, zinc and pyrite intermittently from the 1860s until 1963. The mine is the source of extremely acidic mine drainage which also contains large amounts of zinc, copper and cadmium. One of America's most toxic waste sites, it has been listed as a federal Superfund site since 1983.HistoryThe site was mined by the Mountain Copper Company, Ltd., both underground using open stope mining techniques and at the surface in the form of open pit and sidehill mining. As a result, the mountain fractured and mineral deposits were exposed to oxygen, water and certain bacteria, resulting in acidic mine drainage.Though mining operations were discontinued in 1963, underground mine workings, waste rock dumps, piles of mine tailings, and an open mine pit still remain at the site.