Quartz from selected localities.
USA | |
| [Chalcedony var: Agate] MacFall, P.M. (1951) Gem Hunter's Guide (1st ed.). Science and Mathematics Publishing Company, 187 pages. |
[Chalcedony] Tschernich, Rudy, 1992, Zeolites of the World | |
| U.S. Geological Survey, 2005, Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia. |