Precious Opal from selected localities.
USA | |
| NBMG Spec. Pub. 31 Minerals of Nevada; USGS Bull 1538D |
Christopher Wentzell | |
Eckert, Allen W. (1997) The World of Opals. (John Wiley & Sons, New York). p. 312,310. | |
Rocks & Min.:13:56.; USGS Bull 1538D | |
Christopher Wentzell collection. | |
USGS Bull 1538D U.S. Geological Survey (2005) Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia. | |
Christopher Wentzell | |
NBMG Spec. Pub. 31 Minerals of Nevada | |
USGS Bull 1538D | |
Rocks & Min.: 8:16; 19:13.; USGS Bull 1538D | |
Keith Hodson, (1994) personal communication to Christopher Wentzell | |
[var: Black Opal] | |
NBMG Spec. Pub. 31 Minerals of Nevada | |
Christopher Wentzell; | |
| Christopher Wentzell collection. |
Sinkankas, John (1959) Gemstones of North America. Figure 30 at page 116. | |
Christopher Wentzell, dug 2013 October; known since 1994,C. Wentzell collection | |
Christopher N. Wentzell | |
various contributors (2013) Nevada-Jackpot! Mineral Monograph 18, Lithographie LLC, 59 |
Stonetree Opal Mine, WRT Stonetree group, Virgin Valley, Humboldt County, Nevada, USA