Opal from selected localities.
USA | |
| NBMG Bull 78 Geology and Mineral Deposits of Esmeralda County, Nevada |
NBMG Bull 78 Geology and Mineral Deposits of Esmeralda County, Nevada | |
| Page, L. R.; Stocking, H. E.; Smith, H. B. (1956) Contributions to the geology of uranium and thorium by the United States Geological Survey and Atomic Energy Commission for the United Nations International Conference on Peaceful Uses of Atomic Energy, Geneva, Switzerland, 1955. USGS Professional Paper 300 pp351-359 |
| [Opal-A var: Opal-AN] NBMG Spec. Pub. 31 Minerals of Nevada |
[Opal-A var: Opal-AN] NBMG Spec. Pub. 31 Minerals of Nevada |