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Cove - McCoy Gold Mine

Producer in Lander county in Nevada, United States with commodities Gold, Silver, Copper, Manganese, Arsenic, Mercury, Antimony, Thallium, Lead, Zinc, Tin
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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. Bibliographic references
  20. General comments
  21. Reporter information

Geologic information

Identification information

Deposit ID 10310331
MRDS ID W700450
Record type Site
Current site name Cove - McCoy Gold Mine
Alternate or previous names Cove, McCoy, Brown Zone, Cove East, East Brown Zone, Gold Dome Zone, Peacock Zone, Echo Bay Mine
Related records 10085018

Comments on the site identification

  • All material from earlier records M232459, W700450, M242946, M242947, for the Cove and McCoy mines has been incorporated into the current record. All material from earlier records the McCoy Gold Mine record 10310312 was merged into this record and deleted.

Geographic coordinates

Point of reference Geographic coordinates: Elevation UTM Precision Relative position Point location
-117.20233, 40.33629 (WGS84) 1520 The mine is located about 30 miles southwest of the town of Battle Mountain.
(click for info)
-117.22706, 40.33268 (WGS84) 1620 These coordinates are for the McCoy Gold Mine alone. It is located about 30 miles southwest of the town of Battle Mountain.

Site location context

Political divisions (FIPS codes)

Lander(county)

Nevada(state)

United States(country)

North America(continent)

Land(continent)

USGS map quadrangles

McCoy(quadrangle 1:24,000 scale)

Fish Creek Mountains(quadrangle 1:100,000 scale)

Winnemucca(quadrangle 1:250,000 scale)

Hydrologic units (watersheds)

Reese(hydrologic unit)

Humboldt(hydrologic accounting unit)

Black Rock Desert-Humboldt(hydrologic subregion)

Great Basin(hydrologic region)

Geographic areas

Country State County
United States Nevada Lander

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 029N 042E 36 Nevada
Mount Diablo 028N 042E 02 Nevada

Comments on the location information

  • The mine is located on the NE side of the Fish Creek Mountains. The original Cove Mine was approximately 1.5 miles NE of McCoy Mine, later merged as a single entity.

Commodities

Commodity Importance
Gold Primary
Silver Primary
Copper Secondary
Manganese Critical Tertiary
Arsenic Critical Tertiary
Mercury Tertiary
Antimony Critical Tertiary
Thallium Tertiary
Lead Tertiary
Zinc Critical Tertiary
Tin Critical Tertiary

Comments on the commodity information

  • Ore Materials: Cove mine - electrum, native silver, canfieldite, tetrahedrite, tennantite, acanthite. McCoy mine - native gold, cerargyrite, malachite, galena, cerussite, pyrite, chalcopyrite, chalcocite.
  • Gangue Materials: Cove mine - clay, sericite, calcite, iron oxides, manganese oxides, pyrite, sphalerite, galena, cassiterite, marcasite, chalcopyrite, stannite, pyrrhotite, arsenopyrite, digenite, covellite, chalcocite, chatkalite. McCoy mine - quartz, opalite, jasper, iron oxides, calcite, garnet, pyroxene, calcite, epidote, zeolite, chlorite, pyrite.

Materials information

Materials Type of material
Electrum Ore
Silver Ore
Canfieldite Ore
Tetrahedrite Ore
Tennantite Ore
Acanthite Ore
Galena Ore
Pyrite Ore
Chalcopyrite Ore
Cerargyrite Ore
Malachite Ore
Cerrusite Ore
Gold Ore
Chalcocite Ore
Clay Gangue
Sericite Gangue
Sphalerite Gangue
Cassiterite Gangue
Stannite Gangue
Pyrrhotite Gangue
Arsenopyrite Gangue
Digenite Gangue
Covellite Gangue
Chatkalite Gangue
Quartz Gangue
Jasper Gangue
Calcite Gangue
Garnet Gangue
Pyroxene Gangue
Epidote Gangue
Zeolite Gangue
Chlorite Gangue

Alteration

  • (Local) Upper ore zone alteration consists of argillization, silicification, amd manganese alteration. Alteration has resulted in the formation of clay and sericite along fractures and within the more permeable beds. Locally, complete replacement of the carbonate to form jasperoid has occurred along bedding and along some structures. Abundant manganese (as manganoan calcite) has been introduced into the rock, giving the clay and jasperoid a sooty brown appearance. Lower ore zone: base metal sulfides and pyrite were introduced into the host rock, filling fractures and partially replacing the host rock.

Mineral occurrence model information

Model code 75
USGS model code 19c
Deposit model name Distal disseminated Ag-Au
Mark3 model number 18
Model code 64
USGS model code 18f
Deposit model name Skarn Au
Mark3 model number 82

Host and associated rocks

  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone
    Rock unit name Favret Formation
    Stratigraphic age (youngest) Middle Triassic
  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Dolomite
    Rock type qualifier silty to sandy diagenetic
    Rock unit name Home Station Member of Augusta Mountain Formation
    Stratigraphic age (youngest) Middle Triassic
  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Dolomite
    Rock unit name Panther Canyon Member of Augusta Mountain Formation
    Stratigraphic age (youngest) Middle Triassic
  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone
    Rock type qualifier microcrystalline
    Rock unit name Panther Canyon Member of Augusta Mountain Formation
    Stratigraphic age (youngest) Middle Triassic
  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone
    Rock type qualifier silty
    Rock unit name Panther Canyon Member of Augusta Mountain Formation
    Stratigraphic age (youngest) Middle Triassic
  • Host or associated Host
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Sandstone
    Rock type qualifier calcite-cemented
    Rock unit name Panther Canyon Member of Augusta Mountain Formation
    Stratigraphic age (youngest) Middle Triassic
  • Host or associated Host
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Conglomerate
    Rock unit name Panther Canyon Member of Augusta Mountain Formation
    Stratigraphic age (youngest) Middle Triassic
  • Host or associated Host
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Conglomerate
    Rock unit name Panther Canyon Member of Augusta Mountain Formation
    Stratigraphic age (youngest) Middle Triassic
  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone
    Rock unit name Smelser Pass Member of Augusta Mountain Formation
    Stratigraphic age (youngest) Middle Triassic
  • Host or associated Associated
    Rock type Plutonic Rock > Granitoid > Granodiorite
    Rock type qualifier dikes
    Stratigraphic age (youngest) Middle Eocene
    Chronological age 39.5
  • Host or associated Host
    Rock type Plutonic Rock > Mafic Intrusive Rock > Diorite
    Rock unit name Augusta Mountain Formation
    Stratigraphic age (youngest) Late Triassic
    Stratigraphic age (oldest) Middle Triassic

Nearby scientific data

(1) -117.20233, 40.33629
ListMap
(2) -117.22706, 40.33268
ListMap

Economic information

Geologic structures

Type of structure Local
Structure description faults

Ore body information

  • General form replacement; stockwork; tabular to irregular or stratiform

Controls for ore emplacement

  • fractures, faults

Comments on the geologic information

  • The post-mineral Caetano Tuff (32-34 Ma) covers +/- 60% of the Cove deposit.

Economic information about the deposit and operations

Operation type Surface
Development status Producer
Commodity type Metallic
Deposit size Medium
Significant Yes
Discovery year 1914
Discoverer McCoy Mine - J.H. McCoy. Cove mine - Echo Bay Minerals Co. (David Emmons)
Year of first production 1925
Year of last production 2004
Production years McCoy mine 1914 - 2004, Cove mine 1988 - 1992

Mining district

District name McCoy District

Land status

Ownership category BLM Administrative Area
Area name Battle Mountain BLM Administrative District

Ownership information

  • Type Owner-Operator
    Owner Echo Bay Minerals Co.
    Year 2004

Comments on other economic factors

  • Cove -McCoy is a world-class gold-silver mine, with pre-mining reserves totaling 3.6 million ounces Au and 164.3 million ounces Ag.



    McCoy-Cove production:

    1986: 50,000 ounces of gold

    1987-98: 3,046,660 ounces of gold, 85.79 million ounces of silver

    1999: 124,500 ounces of gold, 8.43 million ounces of silver

    2000: 162,784 ounces of gold, 12,328,297 ounces of silver

    2001: 94,633 ounces of gold, 6,451,425 ounces of silver

    2002: 33,142 ounces of gold, 1,987,421 ounces of silver

    2003: 4,699 ounces of gold, 706 ounces of silver

    2004: 8,454 ounces of gold, 64,335 ounces of silver



    For a total production between 1986 and 2004 of 3,524,872 ounces of gold and 115,052,184 ounces of silver.



    Reserves/resources

    proven and probable reserves

    1981: 2.5 million tons, 0.08 opt Au, 1 opt Ag (McCoy)

    1987: 14 million tons, 0.05 opt Au (McCoy); 4 million ounces of gold, 250 million ounces of silver (Cove)

    1989: 2.9 million ounces of gold, 128 million ounces of silver plus a

    geologic resource of 3.5 million ounces of gold, 1.50 million ounces of silver



    1999: proven and probable reserves of 11.8 million tons, 0.043 opt Au, 2.387 opt Ag plus 100,000 tons, 0.350 opt Au, 2.0 opt other mineralization



    2000: proven and probable reserves of 4.7 million tons, 0.034 opt Au, 2.309 opt Ag

    2001: 430,000 tons, 0.031 opt Au, 2.624 opt Ag



    Newmont Mining Corp. was still reporting production from its McCoy/Cove Mine in 2004.

Comments on development

  • In January, 1986, Tenneco Minerals Corp. began a McCoy district exploration program, the purpose of which was to evaluate the Triassic rocks which host the McCoy gold skarn deposit. Work consisted of stream sediment sampling, soil sampling, rock sampling, and geologic mapping. By early 1986, 500 stream sediment samples had been collected from the 8 square miles which surround the McCoy mine. Au values for all samples ranged from <1 ppb to 34 ppm; for samples in the vicinity of the Cove deposit, au values ranged up to 72 ppb with anomalous Ag, Hg, As, Sb, Tl. Follow-up outcrop sampling in the cove area identified a zone of over 1000 ft. of strike length with gold values ranging from 0.1 - 1.9 ppm. In September and October, 1986, soil sampling was conducted in the Cove area. 147 soil samples were collected of the B and C soil horizons on a 100 ft. by 200 ft. grid spacing. A geochemical anomaly approx. 2800 ft. long and 100-1000 ft. wide with gold values up to 2600 ppb and As values up to 1000 ppm was identified. The eastern portion of this gold-arsenic anomaly was also anomalous in silver (up to 210 ppm, or 6 opt!). In late 1986, dozer trenching indicated ore -grade mineralization over the strike length of the soil geochemical anomaly. In January, 1987, a 25-hole reverse circulation drilling program of 5000 ft. was started. The first hole intersected 110 ft./0.024 opt gold, 0.92 opt silver and subsequent drill holes encountered equally good ore grade mineralization. Discovery was announced March 31, 1987. Initial development drilling began in March, 1987 with 2 drills operating 1 shift/day. By May, these 2 drills were operating 2 shifts/day. By December, 5 drills were operating 24 hrs./day. By the end of 1988, more than 400,000 ft. of reverse circulation drilling in 475 holes and 38,000 ft. of diamond drilling in 25 holes had been completed. Haul road construction began December, 1987, and limited mining operations began January, 1988, one year after discovery. Full scale mining began March, 1988. Initial mining rate was 75,000 tpd of ore and waste. Mill construction began in 1988, scheduled for mid-1989 completion. In early 1989, additional development angle diamond drill holes were being drilled underneath the Cove open pit. Projected production rate was 225,000 ounces of gold and 2,500,000 ounces of silver annually.
  • McCoy mine only: the discovery of gold-bearing ore was made in 1914 by J.H. McCoy who located nine claims. McCoy Consolidated Mines (1929). Summa Corp drilled over 200 holes in what is now the McCoy deposit, in 1969; Houston Oil bought out Summa's holdings in 1977 and drilled another 120 holes in the deposit and in 1981 announced sub-economic reserves. Property was leased to Consoidated Goldfields PLC who in 1984 decided that the property was still subeconomic and turned it back to Tenneco (successor of Himco). Tenneco reappraised the property and decided to put it into production as an open-pit, heap leach operation in 1985. Development began in Sept. 1985 with first gold poured April, 1986. Tenneco explored adjacent ground and more than doubled the mineable reserve to 615, 000 ounces of gold. Echo Bay acquired Tenneco's precious metals properties in Nov. 1986, and Newmont subsequently acquired Echo Bay's properties.

Reference information

Bibliographic references

  • Deposit

    Emmons, D.L, 1989, The Cove Gold-Silver Discovery, Lander County, Nevada, Oral Presentation At 118th Annual Meeting of AIME, Las Vegas, March 2.

  • Deposit

    Emmons, D.L., and Coyle, R.D., 1988, Echo Bay Details Exploration Activities at its Cove Deposit in Nevada; Mining Engineering,, August, 1988, p. 791-794.

  • Deposit

    NBMG Mining District File 157, item 12, unpublished report by Echo Bay Mines, and numerous press Clippings.

  • Deposit

    Bonham, H.F., 1988, NBMG MI-1987.

  • Deposit

    Engineering and Mining Journal, June, 1988, p. 43.

  • Deposit

    NBMG, 1994, MI-1993

  • Deposit

    Long, K.R., DeYoung, J.H., Jr., and Ludington, S.D., 1998, Database of significant deposits of gold, silver, copper, lead, and zinc in the United States; Part A, Database description and analysis; part B, Digital database: U.S. Geological Survey Open-File Report 98-206, 33 p., one 3.5 inch diskette.

  • Deposit

    Felix E. Mutschler, Steve Ludington, and Arthur A. Bookstrom, 1999, Giant Porphyry-Related Metal Camps of the World-A Database; USGS Open-File Report 99-556.

  • Deposit

    Marcus K. Johnston, 1999, Structural and stratigraphic controls on hypogene alteration and precious metals distributions at the Cove gold-silver mine, Nevada; GSN Newsletter, May, 1999.

  • Deposit

    Stager, H.K. (1977) Geology and Mineral Resources of Lander Co., N.B.M. Bull 88

  • Deposit

    Burgess J.A. (1914) Report on Camp McCoy, Lander Co. Nev., N.B.M. District file 157, item 1

  • Deposit

    Lane, M.F., 1987, Geology and Mineralization of The McCoy Skarn, Lander Co., Nevada; Unpub. paper presented at 93rd NW Mining Assoc. Convention, 1987.

  • Deposit

    Unpub. report by Echo Bay Mines, on file at NBMG, mining district file 157.

  • Deposit

    Kuyper, B.A., 1986, Geology of the McCoy Gold Deposit, GSN Precious Metals Symposium Paper.

  • Deposit

    Shrader, F.C., 1934, USGS IC. #10.

  • Deposit

    Bonham, H.F., 1986, NBMG Map 91.

  • Deposit

    Smith, P. and Bentz, J., Nov, 1981, NBMG Field Examination Report.

General comments

Subject category Comment text
Deposit The McCoy-Cove mine is listed as one of the USGS world-class ?Giant? porphyry - related gold systems of the world.

The Cove Deposit consists of two main ore zones that are stacked. The upper zone is hosted by lower Augusta Mountain Formation, the lower zone by the Panther Canyon Formation.

The deposit consists of an oxide orebody and two refractory orebodies. Ore minerals comprise disseminated, crustiform, and vein sulfides, sulfosalts, oxides, and native metals hosted by the middle to early-late Triassic Augusta Mountain Formation, a post-Sonoma orogeny overlap passive margin sequence. Three host units have been exposed by open-pit mining: 1) the early Ladinian (Mid-Triassic) Home Station Member, consisting of massively bedded silty to sandy diagenetic dolostone; 2) the late Ladinian (Mid-Triassic) Panther Canyon Member, consisting of a lower primary dolostone submember and an upper transitional submember, grading from basal microcrystalline limestone through middle silty limestone and calcite-cemented sandstone to upper conglomerate; and 3) the late Ladinian to early Karnian (LateTriassic) Smelser Pass Member, consisting of medium to thickly bedded limestone with lesser carbonate shale interbeds. The host package is overlain by the unmineralized Oligocene Caetano Tuff.

The deposit is centered on the N40?W-striking, 19.5? SE-plunging asymmetrical Cove anticline, which is segmented by extensional faulting. The hypogene orebody controls consist of reactive limestone and dolostone strata, reactive and permeable carbonate-cemented clastic strata, semi-permeable intrusive barriers, and structural highs produced through combinations of folding and faulting.

In the upper ore zone, gold and silver mineralization are associated with argillization and with penetrative manganese replacement. In the lower ore zone, gold and silver mineralization are associated with disseminated sulfides, sulfide veinlets, and high lead and zinc contents.

The strongest ore intervals are stratabound within the 500 ft thick Panther Canyon transitional submember, in a horst block between two N- and NE-striking faults. This structural high apparently localized ascending pregnant hydrothermal solutions. A large sill in the upper clastic part of the transitional unit trapped a significant volume of the mineralizing fluids, producing in its footwall the largest high-grade ore zone in the deposit. The Smelser Pass limestone formed a physiochemical barrier that also focused fluids and Au-Ag deposition in the underlying transitional unit. Other ore zones occur in the carbonate units above and below the transitional unit, also associated with the horst. Although high-grade hypogene Au and Ag ores typically coincide in space associated with favorable stratigraphic and structural settings, lower-grade ores commonly consist of structurally and stratigraphically localized Ag grading into distal Au. Reverse Ag-Au zonations are not uncommon.



Reported K-Ar age dates for fresh and altered intrusive rocks at Cove and the adjacent McCoy gold-copper skarn range between 43 and 37 Ma, indicating that hydrothermal alteration and mineralization closely followed and were related to the emplacement of the igneous bodies. Ten hypogene alteration assemblages indicative of an evolving hydrothermal system occur in the Cove intrusive porphyries. In general terms, these assemblages can be grouped into early weak biotitization, middle propylitization and quartz-sericite-pyrite (QSP) alteration, later argillization characterized by smectite-group clays, and latest barren calcite veining. Analogous alteration styles occur in the sedimentary host units, with the exceptions of the biotite and propylitic assemblages that may be expressed by an early decarbonatization event. The main ore stage is associated with the QSP and argillic alteration stages, and consists primarily of base-metal sulfide veins/veinlets with wide halos of disseminated ore minerals.
Deposit McCoy mine only: Gold occurs with quartz, opalite, jasper, iron oxides, and calcite in highly altered diorite or shear zones in the diorite.

Lode consists of quartz and clay stringers 15-30 feet wide, with up to 80% quartz.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-NOV-2006 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. Blended in and deleted McCoy Gold Mine 10310312.

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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