Tuff from Grant County, New Mexico, USA
USA | |
| Ratté, J. C. (2008). The Early Oligocene Copperas Creek Volcano and geology along New Mexico Higway 15 between Sapillo Creek and the Gila Cliff Dwellings National Monument, Grant and Catron Counties, New Mexico. |
(2005) Mineral Resources Data System (MRDS), US Geological Survey. | |
| Wright, Ira (1919) Private report to Black Hawk mines. |