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Rio Tinto Mine

Past Producer in Elko county in Nevada, United States with commodities Copper, Silver, Gold, Zinc, Lead
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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. Ore body information
  14. Controls for ore emplacement
  15. Economic information about the deposit and operations
  16. Mining district
  17. Land status
  18. Ownership information
  19. Workings at the site
  20. Links to other databases
  21. Bibliographic references
  22. General comments
  23. Reporter information

Geologic information

Identification information

Deposit ID 10310316
MRDS ID M233366
Record type Site
Current site name Rio Tinto Mine
Alternate or previous names Mountain City Copper Mine, Mountain City Silver Mine, Mountain City Mercur, Mountain City Consolidated., Golden Copper, Golden Copper Nos. 1-3, Rio Grande Copper, Rio Grande North, Rio Grande Extension, Rio Grande Extension Nos. 1-7

Comments on the site identification

  • This record supersedes MRDS record #M233366 which should be deleted from the database. The current record includes all material from record #M233366

Geographic coordinates

Point of reference Ore Body
Geographic coordinates: -115.98172, 41.81242 (WGS84)
Elevation 1860
Location accuracy 100(meters)
Relative position The mine is located in Copper Gulch, about 70 air miles north of Elko. The lat/long are for the Rio Tinto adit visible in the satellite imagery. Mountain City mine is adjacent on the north, Rio Grande Copper claims on the east and west.

Site location context

Political divisions (FIPS codes)

Elko(county)

Nevada(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

Mountain City(quadrangle 1:24,000 scale)

Jarbidge Mountains(quadrangle 1:100,000 scale)

Wells(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Upper Owyhee(hydrologic unit)

Middle Snake-Boise(hydrologic accounting unit)

Middle Snake(hydrologic subregion)

Pacific Northwest(hydrologic region)

Federal lands

Humboldt-Toiyabe National Forest(National Forest)

National Forest FS(Type of land area)

FS(Federal land areas administered by FS)

Geographic areas

Country State County
United States Nevada Elko

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 045N 053E 11 NW 1/4 Nevada

Comments on the location information

  • The Rio Tinto mine is located in Copper Gulch, a few miles south of Mountain City.

Commodities

Commodity Importance
Copper Primary
Silver Secondary
Gold Secondary
Zinc Critical Tertiary
Lead Tertiary

Comments on the commodity information

  • Ore Materials: chalcopyrite, bornite, chalcocite, covellite, sphalerite, galena, malachite, cuprite
  • Gangue Materials: quartz, pyrite

Materials information

Materials Type of material
Chalcopyrite Ore
Bornite Ore
Chalcocite Ore
Covellite Ore
Sphalerite Ore
Galena Ore
Malachite Ore
Cuprite Ore
Azurite Ore
Copper Ore
Quartz Gangue
Pyrite Gangue

Alteration

  • (Local) Alteration types affecting the host rocks are chloritic, argillic, and silicic.

Mineral occurrence model information

Model code 91
USGS model code 24b
Deposit model name Massive sulfide, Besshi (Japanese deposits)
Mark3 model number 30

Host and associated rocks

  • Host or associated Host
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Shale
    Rock type qualifier dark
    Rock unit name Valmy Formation
    Stratigraphic age (youngest) Ordovician
  • Host or associated Host
    Rock type Metamorphic Rock > Metasedimentary Rock > Quartzite
    Rock unit name Valmy Formation
    Stratigraphic age (youngest) Ordovician
  • Host or associated Associated
    Rock type Plutonic Rock
    Rock type qualifier granitic
    Stratigraphic age (youngest) Cretaceous

Nearby scientific data

Ore Body (1) -115.98172, 41.81242
ListMap

Economic information

Geologic structures

Type of structure Regional
Structure description The Roberts Mountains Thrust fault is exposed at the surface less than 3 miles from the mine.
Type of structure Local
Structure description faults

Ore body information

  • General form tabular to irregular
    Strike N75W
    Dip 075N
    Thickness 60.96M
    Length 213.36M
    Width 152.4M
    Depth to top 69.19M
    Depth to bottom 152.4M
  • Strike N80W
    Dip 70N
    Thickness 37M
    Length 244M
    Width 244M
    Depth to top 61M
    Field Value
    Type of Orebody #1 REPLACEMENT
    Shape of Orebody #1 LENTICULAR
    Type of Orebody #2 DISSEMINATED
    Primary mode of Origin OXIDATION
    Secondary mode of Origin HYDROTHERMAL
    Primary Ore Control LITHOLOGY
    Secondary Ore Control FRACTURING
    Degree of Wallrock Alter. MODERATE
    Type of Wallrock Alter. #1 INTERM ARGILLIC
    Strike And Dip N80W:70N
    Minimum Depth to Top 61
    Avg. Thick. Unconsol. Mat. 0
    Min. Thick. Unconsol. Mat. 0
    Date of Last Modification 830316

Controls for ore emplacement

  • bedding

Comments on the geologic information

  • The Rio Tinto mine is developed in the Ordovician Valmy Formation. Several plutons of Cretaceous age intrude this and other Paleozoic formations; this sequence was eroded and covered with Miocene, Pliocene, and possibly older volcanic rocks. The primary mineralization of the area is believed to postdate the Mississippian Nelson Formation and pre-date the Cretaceous intrusives. The primary orebodies are lenticular in shape and are composed largely of quartz, pyrite, and chalcopyrite. The ore lenses, in general, strike northwestward and dip northward; they are in shales with associated minor quartzite lenses. The ore is epigenetic, and the principal orebody was leached to the 200-ft level; supergene copper sulfide ore was immediately below the barren gossan. The supergene enrichment of the ore may have required a large part of Tertiary time.
  • THE MOUNTAIN CITY MINE ORE VEIN IS A FISSURE FILLING, CEMENTING ANGULAR FRAGMENTS OF LIMESTONE. AT SOME SITES THE VEIN IS SHEETED, CONTAING LIMESTONE PARTITIONS BETWEEN.

Economic information about the deposit and operations

Operation type Underground
Development status Past Producer
Commodity type Metallic
Deposit size Small
Significant Yes
Discovery year 1919
Discoverer Samuel Franklin Hunt
Year of first production 1932

Mining district

District name Mountain City District

Land status

Ownership category Private
Area name Elko administrative district

Ownership information

  • Type Owner
    Owner Cominco
    First year 1976
  • Type Unknown
    Owner Rio Grande Copper Co.
  • Type Owner-Operator
    Owner Mountain City Consolidated
  • Type Owner-Operator
    Owner Cliffs Copper (Div Of Cleveland Cliffs Iron Co.) (early 1970's)
    ID 2600210
    Home office Denver, Colo
    Year 1974
  • Type Owner-Operator
    Owner E. I. Dupont Co.
    ID 2600210
    Interest 50
    Home office Delaware
    Year 1974
  • Type Operator
    Owner Mountain City Copper Co.

Workings at the site

  • Type of workings Underground
    Length 91.44M
    Overall depth 152.4M
  • Type of workings Underground
    Length 6000M
    Overall depth 137M
    Field Value
    MAS Development Schedule # 1
    Mining Record # 1
    Status of Mining Method PROPOSED
    Mining Method LEACHING IN PLACE (IN SITU) 10-89
    Hardness of Rock SOFT NONPLASTIC FISSURED MODERATE WATER
    Rock Characteristics ONE SYSTEM OF WEAKNESS PLANES
    Number of Shafts 2
    Avg. Length of Adits (m) 200
    Number of Adits 2
    1st Condition of Workings OPEN
    2nd Condition of Workings FLOODED
    3rd Condition of Workings PART ACCESSIBLE
    Capacity Units MT ORE/DAY
    Units of Production $/MT ORE
    Operating Days per Year 357
    Operating Shifts per Day 1
    Year of Information 1974

Comments on the workings information

  • The Rio Tinto mine was developed by underground workings on six levels.

Comments on other economic factors

  • In summary, underground copper mining at Rio Tinto commenced in 1932 and continued intermittently for approximately forty years. From 1932 until operations ceased in 1949 the Rio Tinto mine produced 1,109,878 short tons of ore averaging 9.74% copper, 0.274 ounces per ton silver, and .0057 ounces per ton gold. Of this 177,043 tons averaged 26.1 per cent copper. Ore was leached from old tailings in the 1960's and 1970's yielding an additional 7.7 million pounds of copper. The site has not produced since 1975.
    There is no report of remaining reserves at the mine.

Comments on development

  • In 1919, Samuel Franklyn Hunt, filed claims on some traces of copper a few miles south of Mountain City. He named his claims Rio Tinto after the famed copper mines in Spain and spent the next 12 years attempting to get financial backing to develop the claims. He was grubstaked during this time by Walt and Jack Davidson who ran a store in Mountain City. In 1931, Ogden Chase became interested in backing the venture, and Hunt and Chase organized the Rio Tinto Copper Company with Samuel Hunt as president and Ogden Chase as manager. In 1932 an inclined shaft was sunk and ore was hit at 227 ft. Production began in 1932. The ore assayed at 40% and gradually rose to 47%.On June 30, 1932, the International Smelting and Refining Company, a subsidiary of the Anaconda Copper Company, purchased the Rio Tinto Copper Company for $300,000. The company was renamed the Mountain City Copper Company. A flotation mill was built in 1937 to process the ore. It closed in 1949. In 1965, G.M. Wallace Co. of Denver leased the property from Bieroth, and leached copper from old tailings. Cliff's Copper Corp.of Rifle, Colo. purchased the mine in the early 1970s and continued leaching operations and did some underground work, investigating the feasibility of in-place leaching. The 1960s and early 1970s leaching operations yielded another 7.7 million pounds of copper. The mine closed again in 1975 with the fall in copper prices. Cominco bought the mine in 1976 but did not initiate any mining. The mill was dismantled for scrap by the Loveland Construction Company in 1979.
    Ore processing during historic mine operations included generated tailings that were emplaced in the Mill Creek drainage. In 1993, due to concerns about environmental damage to surrounding surface waters, four of the previous owners and operators of the site jointly formed the Rio Tinto Working Group (RTWG) to remediate the site in cooperation with the State of Nevada, Department of Conservation and Natural Resource and the Division of Environmental Protection (NDEP). The Rio Tinto Working Group consists of the Atlantic Richfield Company, Cleveland Cliffs Iron Company, E. I. DuPont de Nemours and Company, and Cominco American Inc. The RTWG was able to fast track site investigation and remedial designs, leading to a timely start up of remedial construction activities.
  • AFTER 2 YRS RIO TINTO PREPROD MINE WILL HAVE A TOTAL LIFE OF 20 YRS, C ARE FOR AN IN-SITU-LEACH, ALL COSTS FROM L. MOORES NOTES. REC-120 + 151 BASE YR OF COSTING 1970. PHASE 1 MINING OPERATION - IN SITU LEACHING OF MINE TO 500 ANNUAL PRODUCTION 4,800,000 LBS, LIFE- 10.4 YRS NOTE- PROD. STARTED 1972 , SINK WELL BETWEEN 300 TO 500 L ELARGE PRESENT CEMENTATION PLANT ACQ 0 EXP $ 0 DEV 0 EQPT 244,600 LEACH PLANT 180,000 WORK CAP 200,100 OP COST (ANNUAL DIRECT, IND, TAX, INS) $605,100 PHASE 2 MINING OP - IN SITU LEACHING OF LOW GRADE ORE BRO UNDERCUTTING ANNUAL PRODUCTION 4,000,000 LBS COPPER, 10 YR LIFE NOTE- NEW WORK CONSISTS OF UNDERCUTTING ORE BLOCK AND DRIL SOLUTION DISTRIBUTION HOLES ABOVE CAVED ORE. MINE EQPT AND DEVEL $6,077,400 245,900 OP COSTS (ANNUAL DIRECT, IND, TAX, INS) $821,30 RESERVE ESTIMATE GIVEN FOR INDICATED ONLY-75% PROB INTERVAL 50% P I = 25% P I = 10% P I = 1.33 X 75% P I
  • Mountain City mine: discovery year - 1820's, year first production - 1869, year last production - 1947, production years - 1869-1947.

Reference information

Bibliographic references

General comments

Subject category Comment text
Deposit The orebody is a hydrothermal exhalative massive sulfide replacement in the upper plate of the Roberts Mountains thrust fault. The original hypogene ore body consisted of quartz-chalcopyrite-pyrite and minor amounts of sphalerite and galena. The ore body is stratabound, it is limited to a particular sequence of black and gray shales with minor quartzite lenses. Supergene processes produced a gossan which was 400 feet by 100 feet at the surface and extends to a depth of 200 feet. Starting at approximately the 200 foot level and extending locally to below the 400 foot level secondary copper sulfides have formed. Locally these form a blanket from a few inches thick to 50 feet thick and in spots running as much as 50 percent copper. Below the zone of secondary sulfides is the primary quartz-chalcopyrite, pyrite ore. The ore body occurs in the upper plate of the Roberts Mountains thrust in eugeosynclinal rocks transported from the west.

The primary orebodies are lenticular in shape and are composed largely of quartz, pyrite, and chalcopyrite. The ore lenses, in general, strike northwestward and dip northward; they are in shales with associated minor quartzite lenses. The ore is epigenetic, and the principal orebody was leached to the 200-ft level; supergene copper sulfide ore was immediately below the barren gossan.
Deposit THE RIO GRANDE COPPER "WEST" CLAIM GROUP CONSISTS OF 4 CLAIMS: GOLDEN COPPER AND GOLDEN COPPER NOS. 1-3. THERE ARE CONTIGUOUS WITH THE WEST END OF THE RIO TINTO CLAIMS. THE RIO GRANDE COPPER "EAST" CLAIM GROUP CONSISTS 11 CLAIMS: RIO GRANDE NORTH, RIO GRANDE EXTENSION, RIO GRANDE EXTENSION NO. 1, RIO GRANDE, RIO GRANDE NOS. 1-7. THESE ARE CONTIGUOUS WITH THE EAST END OF THE RIO TINTO CLAIMS AND PARTLY WRAP AROUND THE EAST END. THE 1989 ELKO COUNTY MASTER TITLE PLATS SHOW THAT THE "WEST" CLAIMS ARE INCLUDED IN A MUCH LARGER CLAIM GROUP KNOWN AS THE PAT CLAIMS. THE PAT CLAIMS INCLUDE THE PAT NOS. 1-25, SPIRO CLAIMS, AND BJH CLAIMS. THE "WEST" CLAIMS ARE PARTLY INCLUDED IN THE LABERTA CLAIMS (ALBERTA-UTOPIA CLAIM GROUP) AND LUCKY NOS. 1-11 CLAIMS. PART OF THE "WEST" CLAIMS ARE NOW ON OPEN OR UNCLAIMED GROUND (1989).
Deposit ACCORDING TO EMMONS, P. 84, SEVERAL HUNDRED THOUSAND DOLLARS WORTH OF SILVER ORE, SOME LEAD, WAS TAKEN FROM THE MOUNTAIN CITY MINE IN THE 1870'S, THROUGH A SHAFT, NOW INACCESSIBLE.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-OCT-1979 Taylor, J. K. Nevada Bureau of Mines and Geology
Reporter 03-OCT-1991 Schmauch, Steven W. U.S. Bureau of Mines
Reporter 01-JUN-2003 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.

External references

Maps centered on this site

Authoritative Nevada resources

These are landing pages for further research — the state agencies don't currently expose per-mine deep links.