Freibergite Subgroup from Clear Creek County, Colorado, USA
USA | |
| Eckel, Edwin Butt , Cobban, Robert R., Mosburg, Shirley K., Foord, Eugene E. (1997) Minerals of Colorado. Fulcrum Publishing. |
| Eckel, Edwin Butt , Cobban, Robert R., Mosburg, Shirley K., Foord, Eugene E. (1997) Minerals of Colorado. Fulcrum Publishing. |
| Lovering, T.S., Goddard, E.N. (1950) Geology and ore deposits of the Front Range, Colorado. Professional Paper 223. US Geological Survey doi:10.3133/pp223 |