Bonanza Opal workings (Virgin Opal; Bonanza Opal Mine; Virgin Opal Mine; Bon 1-5 lodes; Defiance Mine), Virgin Valley, Humboldt Co., Nevada, USAi
|Regional Level Types|
|Bonanza Opal workings (Virgin Opal; Bonanza Opal Mine; Virgin Opal Mine; Bon 1-5 lodes; Defiance Mine)||Workings|
|Latitude & Longitude (WGS84):||41° 50' 0'' North , 119° 4' 37'' West|
|Latitude & Longitude (decimal):||41.83361,-119.07722|
|Köppen climate type:||Dsb : Warm, dry-summer continental climate|
The Bonanza Opal workings are a precious opal deposit and mine group, located primarily in the SW¼ section 6, T45N, R26E, MDM, at an elevation around 5,200 feet. The patented portion of the mine is 103 acres. The early history of the Virgin Opal-Bonanza deposit is vague, but was one of the earliest claims in Virgin Valley.
The original discovery of opals in the area is reported to have occurred about 1905-1906 at what is now the nearby Opal Queen Mine just S-SE of the Bonanza Mine. The Bonanza deposit was discovered, staked and became the second major location in Virgin Valley. Ivan Dow, George Mathewson, Alfred Thompson and others were the original owners (1908). The deposit was first officially reported by J.C. Merriam in 1907.
The early workings at the Bonanza were shallow surface cuts, and the tendency of the opals to craze upon exposure to atmospheric conditions after mining caused disappointment and abandonment in their early commercial mining. Some years later, after 1916, Flora Loughead (pronounced "Lockheed") acquired the Bonanza group claims, which was one of the ten major groups she owned during her mining efforts in Virgin Valley.
In January, 1943 Flora Lockheed died and the Bonanza deposit was relocated on April 3, 1943, as the Virgin Opal Placer by Mark M. Foster, Frank L. Garaventa, and others, being 2,640 feet by 2,640 feet, or 160 acres. Mark Foster located a 40 acre addition measuring 2,640 feet by 660 feet on July 1, 1953, known as the Virgin Opal #2 Placer, on the southerly side of the existing Virgin Opal, bringing the amount of ground claimed to 200 acres. The work consisted of a cut to begin tunnel near the north side center line of the new claim.
On December 11, 1954, Mark Foster sold the Virgin Opal group placer claims (Virgin Opal & Virgin Opal #2) to the Hodson family. The Virgin Opal claims were downplayed in their importance by their new owners to discourage highgrading due to the remoteness of the location and the valuable nature of the gems in the exposed deposits, and in literature was purported to "be only a localized enrichment" (Eyles, 1964, p.122), which was not the actual case.
In 1973, while working on the Virgin Opal claim, Keith Hodson accidentally discovered the 7.25 pound "Bonanza" Opal, which was broken into 5 large pieces and numerous smaller chunks by the bulldoer blade. During 1974-1975, the United States Geological Survey examined the Virgin Opal-Bonanza deposit (among other mines in the area) as part of their study of the mineral potential of Virgin Valley and the Sheldon Range (U.S.G.S., 1984, p.1,131-134). On June 15, 1979, Keith Hodson located the Bon #1-5 Lode mining claims over his existing Virgin Opal Group placers and filed a patent application. A mineral survey was conducted on the Bon #1-5 lode claims between June 25-28, 1979. On September 7, 1982, Keith Hodson received a mineral patent to the Bon #1-5 lode claims, patent # 27-82-0024, covering 103.305 acres. The mine was worked for many years by owner Keith Hodson, and in the early 1980's produced a 3,853 carat limb replacement precious opal discovered by Hodson's wife, Agnes, known as the "Crowning Glory" which was valued at $50,000.00 (USA) as a wet specimen. On July 15, 1988, Keith Hodson (dba Rainbow Ridge Opal Mines Inc) sold the patented Bon #1-5 lode mining claims ("Bonanza Opal Mine") to Richard Leger and Lloyd Olds, who in turn formed a limited partnership selling 1% digging right shares in the mine. Initially the shares sold for $6,000.00 each, and averaged $9,000.00 or so in later years. On September 15, 1989, Richard Leger and Lloyd Olds filed the Virgin Opal #1 and #1A placer claims, claiming ground on either side of and buffering the patented Bonanza Opal mine. On October 22, 1991, the Bonanza shareholder partnership formed Bonanza Opal Mines, Inc., a Nevada corporation. On July 9, 1992, Lloyd Olds and Richard Leger quitclaimeed their interests in the Virgin Opal #1 and #1A placers to the Bonanza corporation, as well as the patented mine. The Virgin Opal placer claims on either side of the patented Bonanza Opal mine were apparently so valuable that Lloyd Olds stipulated in the deed that the claims were to remain with Bonanza Opal Mines Inc forever or be returned to him upon dissolution of the corporation. The corporation subsequently filed buffer lode claims on both sides of the patented mine.
For some time afterwards, the Bonanza corporation and shareholders were involved in lawsuits over management, ownership and share disputes, among other issues. However, after initiating a shareholder plan for the patented mine, considerable amounts of precious opal was recovered, of which 1/2 went to the corporation and 1/2 to the discovering shareholder; exceptional specimens remained property of the corporation. After legalities were settled, the tailings portion of the mine was open for public fee digging.
The Virgin Opal-Bonanza deposit is underlain by in-place, nearly horizontal to 45 degree dipping ash, tuff, and tuffaceous sandstone beds. The opal bearing horizon can generally be traced and averages more than 4 feet (1.2 m) thick and consists primarily of light colored bentonite containing varying amounts of petrified wood, rhyolite pebbles, ash, and opal. Precious opals are usually found in the upper half of the horizon. The Bonanza mine is quite developed and active, with many large trenches, open cuts, pits and workings. The original float (placer) deposits are exhausted; the lode deposit is being actively mined. The mine has produced large precious opals, the most noteworthy weighing 7.25 pounds ("The Bonanza Opal"); 8 pounds ("Irene's Delight"); and other smaller pieces too numerous to mention.
Bonanza Opal Mines Inc., sales for 1995 totaled $47,566 (11/30/1995) and the patented mine yielded a total of 79 gallons of opal from the 1995 season (the corporation's 50% share was 49 gallons of opal, or approximately ten 5-gallon buckets, which was considered to be a "bad" season). Heylmun (1987, p.44) notes that "In places, precious opal has been involved with slumping and landsliding; undoubtedbly, some valuable opal deposits lie buried beneath the landslides." The Virgin Opal-Bonanza deposit was noted as being one of several mines in Virgin Valley having opal reserves worth millions of dollars (USGS, 1984, p.7).
The patented mine, along with the other adjoining claims, transferred by Lloyd Olds and Richard Leger to the Bonanza Corporation, were estimated to be worth not less than $5,000,000.00 (five million dollars USA) in 1987 and 1994 (Defendants, 1996). The Bonanza deposit has also been noted as being one of the two most important mines in the area (Zeitner, 1986 p.44).
Regions containing this locality
|North America Plate||Tectonic Plate|
Select Mineral List TypeStandard Detailed Strunz Dana Chemical Elements
Detailed Mineral List:
| ⓘ Opal|
Formula: SiO2 · nH2O
Reference: USGS Bull 1538D
| ⓘ Opal var: Precious Opal|
Formula: SiO2 · nH2O
Reference: Rocks & Min.:13:56.; USGS Bull 1538D
| ⓘ 'Petrified Wood'|
Reference: USGS Bull 1538D
List of minerals arranged by Strunz 10th Edition classification
|Group 4 - Oxides and Hydroxides|
|ⓘ||Opal||4.DA.10||SiO2 · nH2O|
|ⓘ||var: Precious Opal||4.DA.10||SiO2 · nH2O|
|Unclassified Minerals, Rocks, etc.|
List of minerals arranged by Dana 8th Edition classification
|Group 75 - TECTOSILICATES Si Tetrahedral Frameworks|
|Si Tetrahedral Frameworks - SiO2 with H2O and organics|
|ⓘ||Opal||22.214.171.124||SiO2 · nH2O|
|Unclassified Minerals, Mixtures, etc.|
|ⓘ||var: Precious Opal||-||SiO2 · nH2O|
List of minerals for each chemical element
|H||ⓘ Opal (var: Precious Opal)||SiO2 · nH2O|
|H||ⓘ Opal||SiO2 · nH2O|
|O||ⓘ Opal (var: Precious Opal)||SiO2 · nH2O|
|O||ⓘ Opal||SiO2 · nH2O|
|Si||ⓘ Opal (var: Precious Opal)||SiO2 · nH2O|
|Si||ⓘ Opal||SiO2 · nH2O|
This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.
Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org
|Holocene - Pliocene|
0 - 5.333 Ma
|Landslide deposits, colluvium, and talus|
Age: Cenozoic (0 - 5.333 Ma)
Description: Unit is mixed on the Washoe North map with basalt, tuff, diatomite, and tuffaceous sediments. It includes the units mapped as Qls from the 1978 State map. It is present in Churchill, Washoe, Nye, Esmeralda, Elko, Eureka, Humboldt, Lander, Lincoln, Mineral, and Pershing Counties.
Comments: Original map source: Crafford, A.E.J., 2007, Geologic Map of Nevada: U.S. Geological Survey Data Series 249, 1 CD-ROM, 46 p., 1 plate; Scale 1:250,000.
Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. 
2.588 - 23.03 Ma
|Cenozoic volcanic rocks|
Age: Neogene (2.588 - 23.03 Ma)
Stratigraphic Name: Columbia River Basalt
Comments: Columbia Plateau
Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529.