An underground copper mine consisting of two shafts located in Mandan. The Mandan Mining Company was organized in 1863 after it discovered a rich vein of copper crossing the property. One shaft was sunk on the vein. According to company reports, mining was difficult due to several sand lenses around the vein. Because of this, the mine closed in 1866. In 1899, the mine was sold to the Keweenaw Copper Company and reorganized in 1905. A second shaft was sunk in 1907 in hopes of increasing copper output. By 1909, very little copper was recovered and the mine closed for good. Finding the piles today is very difficult. If found, they have been known to produce copper, silver, domeykite, tenorite, and epidote.