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USA | |
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| [var. Black Opal] Betts, John (n.d.) John Betts website listing. |
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| Castor, Stephen B., Ferdock, Gregory C. (2004) Minerals of Nevada. Special Publication 31. Nevada Bureau of Mines and Geology
USGS Bull 1538D |
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| Christopher Wentzell |
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| Eckert, Allen W. (1997) The World of Opals. (John Wiley & Sons, New York). p. 312,310. |
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| Rocks & Min.:13:56.
USGS Bull 1538D |
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| Christopher Wentzell collection. |
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| (2005) Mineral Resources Data System (MRDS), US Geological Survey.
USGS Bull 1538D |
|
| Christopher Wentzell |
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| Castor, Stephen B., Ferdock, Gregory C. (2004) Minerals of Nevada. Special Publication 31. Nevada Bureau of Mines and Geology |
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| USGS Bull 1538D |
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| Rocks & Min.: 8:16
19:13.
USGS Bull 1538D |
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| Keith Hodson, (1994) personal communication to Christopher Wentzell |
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| [var. Black Opal] |
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| Castor, Stephen B., Ferdock, Gregory C. (2004) Minerals of Nevada. Special Publication 31. Nevada Bureau of Mines and Geology |
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| Christopher Wentzell |
- WRT Stonetree group ("Dominion Opal Mine")
| Christopher Wentzell collection. |
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| Sinkankas, John (1959) Gemstones of North America Vol. 1. Van Nostrand Reinhold Co., New York. |
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| Christopher Wentzell, dug 2013 October
known since 1994,C. Wentzell collection |
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| Christopher N. Wentzell |
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| various contributors (2013) Nevada-Jackpot! Mineral Monograph 18, Lithographie LLC, 59 |
Virgin Valley, Humboldt County, Nevada, USA