Agate from
USA | |
| P Cristofono collection |
| Simpson, B., and Mitchell, J. R. 1989 Gem Trails of Arizona: Gem Guides Book company, Baldwin Park, California, 124 p. |
| MRDS database Dep. ID #10023617, MRDS ID #I000805. |
| |
| [var. Fortification Agate] Northrop, Stuart A., LaBruzza, F.A. (1996) Minerals of New Mexico (3rd ed.) University of New Mexico Press, Albuquerque, NM. |
Black Hills Rockhound Area, Black Hills, Graham County, Arizona, USA