Hecla Mining Company is a gold, silver, and other precious metals mining company based in Coeur d'Alene, Idaho. Founded in 1891, it is the largest silver mining company in the United States and the 9th biggest mining company in the United States overall. This area is known as the Silver Valley. In 1983, this entire area was designated as a Superfund site by the Environmental Protection Agency, because of land, water, and air contamination resulting from a century of mostly unregulated silver and gold mining.