Muscovite from McCoy prospects, Cotopaxi Pegmatite area, Cotopaxi, Cotopaxi Mining District, Fremont County, Colorado, USA
USA | |
| 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 |