| Deposit ID | 10310345 |
|---|---|
| MRDS ID | M242087 |
| Record type | Site |
| Current site name | Tonopah Divide Gold and Silver Project |
| Alternate or previous names | Divide Mine, Tonopah Divide Mine, Gold Mountain, Gold Hill Mine, Falcon Exploration Mine and Mill |
| Related records | 10046865 |
| Geographic coordinates: | -117.24008, 37.99688 (WGS84) |
|---|---|
| Elevation | 1880 |
| Relative position | The Tonopah Divide Gold and Silver Project lis located six miles south of the town of Tonopah. |
Political divisions (FIPS codes)
Esmeralda(county)
Nevada(state)
United States(country)
North America(continent)
Land(continent)
USGS map quadrangles
Mud Lake NW(quadrangle 1:24,000 scale)
Goldfield(quadrangle 1:100,000 scale)
Goldfield(quadrangle 1:250,000 scale)
Hydrologic units (watersheds)
Ralston-Stone Cabin Valleys(hydrologic unit)
Central Nevada Desert Basins(hydrologic accounting unit)
Central Nevada Desert Basins(hydrologic subregion)
Great Basin(hydrologic region)
| Country | State | County |
|---|---|---|
| United States | Nevada | Esmeralda |
| Meridian | Township | Range | Section | Fraction | State |
|---|---|---|---|---|---|
| Mount Diablo | 002N | 042E | 26 | NW, SW, 26 | Nevada |
| Commodity | Importance |
|---|---|
| Silver | Primary |
| Gold | Primary |
| Molybdenum | Tertiary |
| Copper | Tertiary |
| Lead | Tertiary |
| Zinc Critical | Tertiary |
| Materials | Type of material |
|---|---|
| Gold | Ore |
| Cerargyrite | Ore |
| Argentite | Ore |
| Molybdenite | Ore |
| Powellite | Ore |
| Ferrimolybdite | Ore |
| Sphalerite | Ore |
| Chalcopyrite | Ore |
| Galena | Ore |
| Tetrahedrite | Ore |
| Sericite | Ore |
| Pyrite | Ore |
| Adularia | Ore |
| Quartz | Ore |
| Kaolinite | Ore |
| Limonite | Gangue |
| Model code | 150 |
|---|---|
| USGS model code | 25c |
| Deposit model name | Epithermal vein, Comstock |
| Mark3 model number | 16 |
| Host or associated | Host | ||
|---|---|---|---|
| Rock type | Volcanic Rock (Aphanitic) > Felsic Volcanic Rock | ||
| Rock type qualifier | rhyolitic | ||
| Rock unit name | Fraction Breccia | ||
| |||
| Host or associated | Host | ||
|---|---|---|---|
| Rock type | Volcanic Rock (Aphanitic) > Felsic Volcanic Rock | ||
| Rock type qualifier | rhyolitic | ||
| Rock unit name | Siebert Tuff | ||
| |||
| Host or associated | Associated | ||
|---|---|---|---|
| Rock type | Volcanic Rock (Aphanitic) > Felsic Volcanic Rock | ||
| Rock type qualifier | rhyolitic | ||
| Rock unit name | Oddie Rhyolite | ||
| |||
| Host or associated | Associated | ||
|---|---|---|---|
| Rock type | Volcanic Rock (Aphanitic) > Felsic Volcanic Rock > Rhyolite | ||
| Rock type qualifier | intrusive | ||
| Rock unit name | Oddie Rhyolite | ||
| |||
| Host or associated | Associated | ||
|---|---|---|---|
| Rock type | Volcanic Rock (Aphanitic) > Felsic Volcanic Rock > Rhyolite | ||
| Rock unit name | Oddie Rhyolite | ||
| |||
| Host or associated | Associated | ||
|---|---|---|---|
| Rock type | Volcanic Rock (Aphanitic) > Pyroclastic Rock > Volcanic Breccia (Agglomerate) | ||
| |||
| Host or associated | Associated | ||
|---|---|---|---|
| Rock type | Volcanic Rock (Aphanitic) > Intermediate Volcanic Rock > Andesite | ||
| Rock unit name | Divide Andesite | ||
| |||
| (1) | -117.24008, 37.99688 |
|---|
| Type of structure | Local |
|---|---|
| Structure description | A conspicuous set of northwest trending, high angle, right-lateral strike-slip faults bisect the Tonopah Divide district. The Tonopah Divide shaft developed the Divide lode which occupies the large Divide fault (Boden, 1992). On the west side of Gold Mountain the Mormon Girl fault appears to be a parallel right lateral fault of this set. Between these major faults are transcurrent north-northeast trending faults which accommodated minor right-lateral strike-slip motion. These fault sets clearly postdate earlier gold mineralized faults of the E-W trending and north dipping Gold Zone. The Gold Zone is parallel to and an easterly extension of the N 80?E listric Kernick fault on Hasbrouck Mountain. Gold-silver mineralization is known to occur almost exclusively in the hangingwall of the Gold Zone-Kernick fault system in the Divide district. Many of the mineralized faults found in the hangingwall of the Gold Zone are WNW trending high angle faults which may have fed the basal Siebert tuff unit. Interestingly Erdman (1992) noted a 'NW striking (more westerly?) gold bearing silicified fault was mapped that offset the Divide lode at the south end of the Falcon Pit'. This further suggests that at least some Gold Mountain mineralization occurred after the Divide fault ceased its right lateral motion. |
| General form | TABULAR |
|---|
| Operation type | Surface-Underground |
|---|---|
| Development status | Producer |
| Commodity type | Metallic |
| Deposit size | Small |
| Significant | Yes |
| Discovery year | 1901 |
| Discoverer | H.C. Brougher (silver discovery); Runge and Rochelle (gold discovery) |
| Year of first production | 1918 |
| Year of last production | 1980 |
| District name | Divide District |
|---|---|
| District name | (Gold Mountain District) |
| Ownership category | Private |
|---|---|
| Ownership category | BLM Administrative Area |
| Area name | Tonopah BLM Administrative District |
| Type | Owner-Operator |
|---|---|
| Owner | Tonogold Resources Inc. |
| Year | 2006 |
Albers, J.P. and Stewart, J.H., 1972, Geology and Ore Deposits of Esmeralda County, NV; NBMG Bull. 78.
Knopf, Adolph, 1921, The Divide Silver District, Nevada; USGS Bull. 715, p. 147-170.
State Inspector of Mines, 1981, Directory of Nevada Mine Operations Active in Calendar Year 1981
NBMG Report 33, p. 124.
Garside, L.J. and Tingley, J.V., 1982, Field Examination, NBMG, 26 Mar 82
NBMG Bull 92, p. 121-128
Smith, A.M., and Carpenter, Jay, 1931, Unpublished notes on inspection trip to Tonopah Divide Mine; NBMG File 87, item 1.
The Mining Record Newspaper, Aug. 26, 1981, "Falcon Exploration Reopens Nevada Gold Hill Mine."
Tonopah Times Bonanza, Aug. 6, 1981
The Northern Miner, 1980.
Tonopah Times Bonanza, Oct 25, 1974.
Eureka Sentinel, 1972.
Weed, W.H., Ed., 1920, The Mines Handbook, Vol XIV, p. 1162-1164
| Subject category | Comment text |
|---|---|
| Deposit | The geology of the Divide District has been described in some detail by Knopf (1921), Alpers and Stewart (1972), Bonham and Garside (1979) and Erdman (1992). Erdman (1992) mapped and compiled the geology of the Divide district near Gold Mountain at the center of the Tonopah Divide property). Erdman (1992) describes the volcanic succession locally as being underlain by the Fraction tuff. Bonham and Garside (1972) described the lower Fraction tuff locally as the Tonopah Summit member consisting of poorly welded to unwelded vitric-lithic quartz latite to rhyolite. The Tonopah Summit member exceeds one thousand feet in thickness in the Tonopah district; its base is not exposed in the Divide district. Bonham and Garside (1972) stated that the upper Fraction tuff, the King Tonopah member is missing in the Divide district; however, Boden (1992) indicated it was present. Phelps Dodge drilled a 610m core hole east of the Falcon pit entirely within the Fraction tuff (Boden, 1992). The Fraction tuff is overlain by the Siebert Formation which consists of a variety of interbedded volcaniclastic sedimentary and air fall tuffaceous debris. The Siebert has been estimated at 180 meters thick on Siebert Mountain near Tonopah; however, Erdman (1992) describes a 300m section at Gold Mountain. The basal portion of the Siebert consists of tuffaceous sandstone to bouldery conglomerate derived largely of underlying Fraction tuff (Bonham et al, 1979). This basal unit is frequently silicified where exposed in the Divide district. The middle unit consists of 275 meters of ash flow and air fall tuff intercalated with epiclastic, volcaniclastics and lacustine sediments (Erdman, 1992). The upper unit was described by Erdman (1992) as a heterolithic tuff. The Oddie Rhyolite was intruded into the Siebert tuff on Gold Mountain, High Divide and other locations in the Divide district. It consists of flow banded rhyolite containing 10 to 15% quartz, sanidine, sodic plagioclase and minor biotite phenocrysts. The Divide andesite was also intruded farther to the southeast, roughly contemporaneously with the Oddie Rhyolite. The Brougher rhyolite is exposed in the northern Divide district and is believe to post date the previous two units. |
| Deposit | Critical ages relations between mineralization and various units: The known mineralizing event at Tonopah Divide post-dates the intrusion of the Oddie Rhyolite K-Ar dated at 16.4-16.9 Ma. (Silberman, et. al., 1975). The post-mineral Brougher rhyolite at 16.1-16.3 Ma crosscuts veins on the north-side of the Tonopah Divide district. Adularia from Hasbrouck Mountain returned K-Ar dates at 16.1-16.4 Ma (Graney, 1985) and is believed to accurately represent the timing of the Tonopah Divide mineralizing event. The Tonopah Divide mineralizing event is considered contemporaneous with the second mineralizing (Three Hills) event in the Tonopah District. The Siebert Formation, dated at 16.9-17.1 Ma, is mineralized at the Tonopah Divide district and is best known as the host for mineralization at Hasbrouck Mountain (Silberman, et. al., 1975). The basal Siebert 'bouldery conglomerate' appears to have absorbed silica flooding during the 16.1-16.4 Ma mineralizing event. Since Tonopah district mine working closed before dating methods were perfected, very few dates of main stage Tonopah veins have been attempted. However, the best available data suggest this early stage occurred between 18.1-19.1 Ma. The upper Tonopah King member of the Fraction tuff, which unconformably underlies the Siebert Fm. in the Tonopah district, was dated at 18.7 Ma and is thought to be entirely pre-mineral relative to the early stage Tonopah productive veins. The earliest Fraction tuff was deposited as early as 20.5 Ma and is clearly pre-main Tonopah vein stage. Early stage veins were exclusively mined from the underlying Mizpah andesite dated at 22(?)- 20.5 Ma. One important ramification of these dates is that mineralized structures hosting the main stage Tonopah veins would not necessarily be expressed in units younger than the Tonopah King member of the Fraction tuff. If an older stage of mineralization underlies Tonopah Divide district, one would be well advised to scrutinize the Tonopah King and Tonopah Summit members of the Fraction tuff for a evidence of this event. |
| Deposit | Gold Mountain Au-Ag mineralization and Exploration Potential: Previous drilling has been skewed heavily toward the east flank of Gold Mountain in the vicinity of the Falcon pit. The Tonopah Divide mine was centered on the NW trending Divide fault at its point of intersection with the north-dipping Gold Zone fault system. Knopf (1921) felt that much of the Divide lode ore body was attributable to supergene enrichment. Sooty acanthite was noted coating pyrite along this fault to a depth between the 300 and 400 foot levels on the Divide Fault (Knopf, 1921). Below this level very little Ag-Au mineralization was mined, although the Tonopah Divide shaft was extended to a depth of over 400m. A second cluster of holes on Gold Mountain was drilled on a westerly spur known as Sealy Ridge. Fewer holes penetrated the intervening segment of the Gold Zone lying between the Divide pit and Sealy Ridge and on the northern flank of Gold Mountain. Cross sectional resource calculations by Johnson (2002) and Cartwright (1998) indicate that the density of drilling is not sufficient to adequately define the Gold Mountain resource. In the East Gold Zone greater drill hole density suggests the continuity of gold mineralization within the Oddie Rhyolite and associate breccias is questionable. Gold is associated with both silicification and potassic alteration in veins and breccia bodies along the Gold Zone fault system. Overall, the gold grade appears to be low (<.02 opt Au) and many of the intercepts are narrow. The Gold Zone dips moderately to steeply to the north and appears to widen where crosscut by northerly trending structures. There is minor evidence that the Gold Zone fault may flatten on its west end with depth in a fashion similar to the Kernick fault (Boden, 1992). The basal Siebert tuff has not been adequately drill tested above the Gold Zone fault at Gold Mountain. Hole GM_10_90 cut 18.3m @ 0.015 opt Au interpreted to lie near the top of the basal Siebert tuff at a vertical depth of about 130m. As the Siebert dips gently to the south on the north flank of Gold Mountain, potential exists to outline a sizeable oxide tonnage of gold mineralized basal Siebert in this area. The old Highway 95 Gap area: Drilling by Echo Bay (1990), Corona Gold (1992) and Euro Nv (1996) cut significant thicknesses of low grade gold mineralization above the Siebert-Fraction contact along a WNW trending normal faults on the Eliza Jane patent. In 1997, Phelps Dodge drilled three shallow rotary holes on the Amazon Patent which returned gold mineralization at and below the Siebert-Fraction tuff contact. Up to 49m of low grade gold mineralization was encountered and oxidation was found to extend from 76m to 107m below surface. TONOPAH-DIVIDE LODE HAS WELL-DEFINED WALLS. 13 CLAIMS COVERING 150 ACRES IN 1921 GOLD MOUNTAIN GOLD VEIN IS ON TONOPAH-DIVIDE PROPERTY. GOLD VEIN IS 0.5 FT WIDE, CARRYING $40/TON AU (1921) |
| Type | Date | Name | Affiliation | Comment |
|---|---|---|---|---|
| Reporter | 01-JUN-2002 | LaPointe, D.D. | Nevada Bureau of Mines and Geology | |
| Editor | 01-SEP-2007 | Schruben, Paul G. | U.S. Geological Survey | Converted from S&A FileMaker format to Oracle. Edit checks on rocks, units, and ages with Geolex search, and other fields. |
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