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USA | |
| Roberts, Willard Lincoln, Rapp, George Jr. (1965) Mineralogy of the Black Hills. Bulletin 18. South Dakota School of Mines and Technology |
- Keystone Gold Mining District
| Roberts, Willard Lincoln, Rapp, George Jr. (1965) Mineralogy of the Black Hills. Bulletin 18. South Dakota School of Mines and Technology |
| Roberts, Willard Lincoln, Rapp, George Jr. (1965) Mineralogy of the Black Hills. Bulletin 18. South Dakota School of Mines and Technology |
| Roberts, Willard Lincoln, Rapp, George Jr. (1965) Mineralogy of the Black Hills. Bulletin 18. South Dakota School of Mines and Technology |
| American Mineralogist, Volume 73, pages 324-337, 1988 |
| Rocks & Minerals: 67(6): 380-388. USGS Bull 380D |
| Roberts, Willard Lincoln, Rapp, George Jr. (1965) Mineralogy of the Black Hills. Bulletin 18. South Dakota School of Mines and Technology |