Chalcopyrite with pyrite, dolomite, tetrahedrite: Colorado, Eagle County, Gilman, Eagle Mine 20-28 Level

Abstract

The mineral specimen comes from the Eagle Mine, located near Gilman in the Gilman mining district, Eagle County, Colorado. Rich silver-lead carbonate ores were discovered in the Gilman area around 1879. By the early 1880s a number of the area's mines were producing silver and gold. District production of these metals declined by the 1890s and lead and zinc became the district's primary products by the early 1900s. In 1912 the New Jersey Zinc Company consolidated some of the mines on Battle Mountain into the Eagle Mine, which became Colorado's major zinc producer. The Mine also became known for its attractive mineral specimens. The Eagle was operated by New Jersey Zinc until 1983 when it was purchased by the Battle Mountain Corporation. The Mine was closed in 1984 and subsequently flooded. Because of mine seepage, groundwater contamination and pollution from tailings the area of the Eagle Mine and the town of Gilman was declared a Superfund site in 1986.