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Mill City Tungsten Mine

Producer in Pershing county in Nevada, United States with commodities Tungsten, Molybdenum, Silver, Gold, Copper, Bismuth
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Sections on this page
  1. Identification information
  2. Geographic coordinates
  3. Site location context
  4. Geographic areas
  5. Public Land Survey System information
  6. Commodities
  7. Materials information
  8. Alteration
  9. Mineral occurrence model information
  10. Host and associated rocks
  11. Nearby scientific data
  12. Geologic structures
  13. Controls for ore emplacement
  14. Economic information about the deposit and operations
  15. Mining district
  16. Land status
  17. Ownership information
  18. Bibliographic references
  19. General comments
  20. Reporter information

Geologic information

Identification information

Deposit ID 10310494
Record type Site
Current site name Mill City Tungsten Mine
Alternate or previous names Springer Mine, Humbolt-Springer, Humbolt Mine, Nevada-Massachusetts Mine, Stank and Forge Lease, Summit Mine, Codd Mine, O'Byrne Mine, Keyes Shaft, Friedman, Constantine, Sutton, North Sutton, Sutton No. 2, Orphan, South Sutton, Baker Workings, Uncle Sam Midway
Related records 10042502

Comments on the site identification

  • This is a new record encompassing information from many earlier records for individual shafts or prospects on the tungsten deposits of the central Mill City District.

Geographic coordinates

Geographic coordinates: -118.1332, 40.78156 (WGS84)
Elevation 1500
Relative position The mine is located on the southeast flank of the Eugene Mountains, about 23 miles southwest of Winnemucca.

Site location context

Political divisions (FIPS codes)

Pershing(county)

Nevada(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Woody Canyon(quadrangle 1:24,000 scale)

Eugene Mountains(quadrangle 1:100,000 scale)

Lovelock(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Lower Humboldt(hydrologic unit)

Humboldt(hydrologic accounting unit)

Black Rock Desert-Humboldt(hydrologic subregion)

Great Basin(hydrologic region)

Geographic areas

Country State County
United States Nevada Pershing

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 34N 34E 26 27 34 35 Nevada

Comments on the location information

  • The mine workings are located about 8 miles NNW of Mill City spread out on the flanks of Stank Hill, Springer Hill and Humboldt Hill near the lower part of Springer Canyon.

Commodities

Commodity Importance
Tungsten Critical Primary
Molybdenum Secondary
Silver Tertiary
Gold Tertiary
Copper Tertiary
Bismuth Critical Tertiary

Comments on the commodity information

  • Ore Materials: scheelite, powellite
  • Gangue Materials: epidote, garnet, quartz, pyrite, wollastonite, tremolite, calcite, diopside, garnet, quartz

Materials information

Materials Type of material
Scheelite Ore
Powellite Ore
Garnet Ore
Quartz Ore
Pyrite Ore
Wollastonite Ore
Tremolite Ore
Calcite Ore
Diopside Ore
Garnet Ore
Quartz Ore
Epidote Gangue

Alteration

  • (Local) silicification, albitization

Mineral occurrence model information

Model code 42
USGS model code 14a
Deposit model name W skarn

Host and associated rocks

  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone
    Rock unit name Raspberry Formation
    Stratigraphic age (youngest) Late Triassic
  • Host or associated Host
    Rock type Metamorphic Rock > Skarn (Tactite)
  • Host or associated Associated
    Rock type Plutonic Rock > Granitoid > Granodiorite
    Rock type qualifier equigranular stock
    Rock unit name Springer Stock
    Stratigraphic age (youngest) Late Cretaceous
    Chronological age 78.4
    Dating method K-Ar
  • Host or associated Associated
    Rock type Volcanic Rock (Aphanitic) > Intermediate Volcanic Rock > Andesite
    Rock type qualifier hornblende-andesite dikes
    Stratigraphic age (youngest) Tertiary
  • Host or associated Associated
    Rock type
    Rock unit name Olsen Stock

Nearby scientific data

(1) -118.1332, 40.78156
ListMap

Economic information

Geologic structures

Type of structure Local
Structure description The Stank fault strikes N-S for 1.5 miles. Strata strike N20E. The strata on the west side of the fault dip east, while on the east side of the fault, beds dip 70 west. Post-mineral faults also present, in many cases off-setting mineralized skarn beds.
Type of structure Regional
Structure description Basin and Range faulting

Controls for ore emplacement

  • Ore formation was controlled primarily by proximity of limestone beds to igneous intrusive bodies, and secondarily by faulting.

Comments on the geologic information

  • The Stank orebody appears to be a pendant-like mass. Triassic sediments are intruded by granodiorite stocks and dikes, producing contact metamorphism (garnet-epidote-wollastonite-tremolite). These were followed by andesite dikes.

Economic information about the deposit and operations

Operation type Surface-Underground
Development status Producer
Commodity type Metallic
Deposit size Large
Significant Yes
Discovery year 1917
Discoverer Emil Stank
Year of first production 1918
Year of last production 1982
Production years 1918-1919; 1925-1958; 1982

Mining district

District name Mill City District

Land status

Ownership category Private
Ownership category BLM Administrative Area
Area name Winnemucca BLM Administrative District

Ownership information

  • Type Owner-Operator
    Owner General Electric
    Year 2005

Comments on the workings information

  • The mine area is developed by many underground workings: shafts, drifts, stopes, amswell as by open pits at the surface. The Stank mine workings connect at the 300 level with those of the Springer Mine.

Comments on other economic factors

  • Production from 1925-1944 totalled 1,049,714 tons of ore with an average grade of 1.17% WO3, yielding 1,100,773 units WO3. From 1944 to 1958, production totalled 2,073,565 tons of ore grading 042% WO3, for a total yield of 685,365 units WO3. The sharp drop in ore grade was due to a change from mining the richer ore of the Stank and Humboldt orebodies to the lower grade Sutton orebodies in 1944 and the addition of large low-grade tonnages from open pits in the 1950s which averaged 0.22-0.25% WO3. The total recorded production from the Mill City District mines for the productive year between 1917 and 1958 was 3,258,135 tons of ore yielding about 2.2 million units of WO3.
    In 1982, General Electric announced 13-15 years worth of ore reserves at the Mill City mines, which were not depleted before they closed operations in October of that year.

Comments on development

  • Although the Eugene Mountains were mined for silver and gold beginning in 1862, tungsten was not discovered there until Emil Stank had a sample analyzed that he had collected while silver prospecting a few years earlier. The onset of World War I had increased demand for tungsten, and Stank?s discovery was rapidly brought into production by three companies within months of the claim locations.
    Pacific Tungsten Company took over Stank?s claims, Thomas Sutton formed the Mill City Tungsten Mining Company to work his claims east of , and L. T. Friedman formed the Nevada-Humboldt Mining Company to mine the deposits on Humboldt Hill. Two of the companies were operating mills by the end of 1918, but the end of the war brought the cessation of tungsten mining at Mill City in 1919. By 1925, the Nevada-Massachusetts Company under Charles Segerstromhad purchased and consolidated all of the main district properties and was the sole operator at the Tungsten camp until 1958 when production ceased. The property was maintained on standby until 1962,after which it slipped into disrepair. In 1969, however, Segerstrom?s heirs, operating under Tungsten Properties Limited partnership, again acquired the property and in 1971 negotiated a deal with General Electric Co. to re-evaluate the property. After extensive explorration and development, GE constructed a $55 million mine, mill, and processing plant, which operated for less than a year in 1982, at which time depressed prices forced closure again. For more than 20 years, the mine has been kept in ?mothballs? with a caretaker to maintain equipment in working condition. A buyer was being sought (2005) to reopen the mine since it is in a ?turnkey? state ready to be brought back into production will minimal renovation.

Reference information

Bibliographic references

  • Deposit

    Kerr, P.F., 1934, Geology of the tungsten deposits near Mill City, Nevada, U. of Nev., Vol 28, No. 2 (NBMG Bull.21), 46 p.

  • Deposit

    Johnson, M.G., 1977, Geology and Mineral Deposits in Pershing County, Nevada: NBMG Bull. 89

  • Deposit

    Kerr, 1946, Tungsten Mineralization in the United States: GSA Memoir 15, 241 p.

  • Deposit

    Stager, H. K and Tingley, J.V., 1988, Tungsten Deposits in Nevada, NBMG Bull. 105.

  • Deposit

    King, W. H. and Holmes, G.H., Jr., 1950, Investigation of Nevada-Massachusetts Tungsten Deposits, Pershing County, NV; USBM Report of Investigations RI 4634, p. 3-4.

General comments

Subject category Comment text
Deposit The scheelite deposits of the district occur in roughly parallel limestone beds that have been altered to skarn. The main production has been from a few distinct beds that traverse the district with a general northerly trend. The main production zone is about a mile long and about 0.75 mile wide bounded on the north by the Olsen stock. The southern boundary is more gradational, governed by proximity to the Springer Stock. Virtually all district tungsten production has come from mines on five ore beds: the Humboldt, Springer, and Stank ore horizons, and the Sutton No. 1 and Sutton No. 2 mines on the Sutton horizon. The Summit-O'Byrne bed strikes NE, dips steeply SE and extends from the south rim of the George Mine pit across Stank Hill and into Stank Canyon, where it comes in contact with the small southwest stock. Ore in the tactite body was limited to a triangular segment of the bed lying between the surface and the plane of the Stank fault. Ore on the south was limited by the gradational limestone-tactite boundary.
Scheelite occurs as disseminations and fracture coatings in skarn bodies and as irregular blebs and crystal masses in quartz veins that cut through the skarn and granodiorite. Scheelite is the main ore mineral, accompanied in places by small amounts of molybdenite, chalcopyrite, rare bismuthinite, and up to several percent pyrite. Powellite occurs only as a secondary mineral associated with molybdenite.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-SEP-2005 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.

Beyond USGS

Supplemental information added by qvyshift.com. Not part of the original USGS MRDS record.

Maps centered on this site

Authoritative Nevada resources

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