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USA | |
| Richard Fretterd and Jean Cowman (2016) Exploring a topaz-bearing Pikes Peak pegmatite. in Second Eugene E. Foord Pegmatite Symposium July 15-19, 2016 Colorado School of Mines campus, Golden, Colorado |
| Hanley, J.B., Heinrich, E.W., Page, L.R. (1950) Pegmatite investigations in Colorado, Wyoming, and Utah, 1942-1944. Professional Paper 227. US Geological Survey doi:10.3133/pp227 |
| Eckel, Edwin Butt , Cobban, Robert R., Mosburg, Shirley K., Foord, Eugene E. (1997) Minerals of Colorado. Fulcrum Publishing. |
Devil's Hole Mine, Fremont County, Colorado, USA