Biotite from Jefferson County, Montana, USA
USA | |
| The Lapidary Journal, May 1985 (W.C. van Laer) The Mineral News (several issues) many ID by x-ray diffraction (Jim Wilson, Weber State W.C. van Laer, Montana Tech U.S. National Museum some by physical characteristics, i.e.: crystal form, fluorescence, magnetic attraction, etc.) some yet to be published |
| USGS Bulletin 988-G(1953) |
| (2005) Mineral Resources Data System (MRDS), US Geological Survey. |
| Knopf, A. (1913) Ore Deposits of the Helen Mining Region, Montana. United States Geological Survey, Bulletin 527, 143 pages. |
| Barrick Gold Corporation |