Chalcocite from selected localities.
||Grant, U. S. (1901), Preliminary report on the copper-bearing rocks of Douglas County, Wisconsin, 2nd Ed.: Wisconsin Geological and Natural History Survey Bull. VI Economic Series #3, 83 p. Dutton, C. E. (1972) Sampling of Copper-bearing Keweenawan Rocks of Northwestern Wisconsin: U.S. Geological Survey Open File Report 9.1267, 13p.|
||Cordua, W.S. (1990), Amygdule Minerals of the South Range Quarry, Douglas County, Wisconsin: Rocks and Minerals: 65: 412-415.|