Opal from Columbia River Plateau Basins, North America Plate
USA | |
| Dake, H. C. (1956) Northwest Gem Trails - A Field Guide for the Gem Hunter, Mineral Collector and Tourist (2nd ed.) Gembooks. |
| Dake, H. C. (1956) Northwest Gem Trails - A Field Guide for the Gem Hunter, Mineral Collector and Tourist (2nd ed.) Gembooks. |
| Tschernich, Rudy W. (1992) Zeolites of the World. Geoscience Press, Inc., Phoenix, Arizona. 567pp. |
| |
| Cannon, Bart (1975) Minerals of Washington. Cordilleran, Mercer Island, WA. |
| [var. Common Opal] T Douglas Schonewald Collection |
T Douglas Schonewald Collection | |
| www.mineralcouncil.org (n.d.) http://www.mineralcouncil.org/ |
| Jared Goguen |
| Micro Probe Volume VII Number 9 Spring 1994 |
Diatomite Mines, Frenchman Hills, Grant County, Washington, USA