Fortitude Mine

Past Producer in Lander county in Nevada, United States with commodities Gold, Silver, Copper, Lead, Zinc, Arsenic, Bismuth, Tellurium, Antimony, Cobalt, Nickel, Chromium, Manganese, Mercury, Molybdenum

Geologic information

Identification information

Deposit ID 10310329
MRDS ID W700375
Record type Site
Current site name Fortitude Mine
Related records 10149516

Comments on the site identification

  • The current record incorporates material from previous MRDS records # W700375 and #W700601 for the Fortitude Mine as well as additional new information.

Geographic coordinates

Point of reference Geographic coordinates: Elevation UTM Precision Relative position Point location
Pit -117.13244, 40.5483 (WGS84) 1890 The Fortitude Mine is located about 14 miles southwest of Battle Mountain, Nevada
(click for info)
Plant -117.12997, 40.53685 (WGS84) 100 Copper Canyon mill

Geographic areas

Country State County
United States Nevada Lander

Public Land Survey System information

Meridian Township Range Section Fraction State
Mount Diablo 031N 043E 21 AND 22 NE Nevada

Comments on the location information

  • The Fortitude Mine is located in Copper Canyon, in the Battle Mountain Range.

Commodities

Commodity Importance
Gold Primary
Silver Primary
Copper Secondary
Lead Secondary
Zinc Secondary
Arsenic Tertiary
Bismuth Tertiary
Tellurium Tertiary
Antimony Tertiary
Cobalt Tertiary
Nickel Tertiary
Chromium Tertiary
Manganese Tertiary
Mercury Tertiary
Molybdenum Tertiary

Comments on the commodity information

  • Ore Materials: native gold, electrum, pyrrhotite, pyrite, chalcopyrite, arsenopyrite, marcasite, galena, sphalerite, native bismuth, hedleyite, joesite, volnyskite
  • Gangue Materials: hedenbergite, andradite garnet (with grossularlite rims), diopside, actinolite, chlorite, epidote, prehnite, calcite, quartz

Materials information

Materials Type of material
Gold Ore
Electrum Ore
Pyrrhotite Ore
Pyrite Ore
Chalcopyrite Ore
Arsenopyrite Ore
Marcasite Ore
Galena Ore
Sphalerite Ore
Bismuth Ore
Hedleyite Ore
Jonesite Ore
Volynskite Ore
Hedenbergite Gangue
Andradite Gangue
Diopside Gangue
Actinolite Gangue
Chlorite Gangue
Epidote Gangue
Prehnite Gangue
Calcite Gangue
Quartz Gangue
Garnet Gangue
Grossularite Gangue

Alteration

  • (Local) Skarn formation began with the alteration of clastic rich sedimentary rocks to biotite/skarn hornfels. Introduction of metasomatic fluids further extended the biotite halo, flooding the system with k and fe, and adding orthoclase to the biotite hornfels assemblage. This assemblage replaced much of the protolith regardless of original composition. Continued metasomatism at high temperature (300C - 550C) formed garnet and pyroxene in calcareous rocks and overprinted the biotite-orthoclase hornfels. Sulfide minerals, dominated by pyrrhotite, began to precipitate with the garnet-pyroxene skarn and continued as temperatures declined. Gold mineralization began at 300C-400C and continued to lower temperatures along with minor arsenopyrite, pyrite, marcasite, sphalerite, galena, bismuth, and tellurides. During cooling of the hydrothermal system, the garnet-pyroxene skarn was altered to actinolite, prehnite, and chlorite.

Analytical data

Result REPRESENTATIVE GEOCHEMISTRY VALUES FROM THE 6075 LEVEL OF THE FORTITUDE DEPOSIT ARE:AU-0.15 OPT, CU< 0.1%, AG-30 PPM, AS-1426 PPM, BI-68 PPM, CD-25 PPM, CO-17 PPM, CR-48 PPM, HG-657 PPB, MN-2784 PPM, MO-8 PPM, NI-28 PPM, PB-2316 PPM, SB-74 PPM, W-5 PPM, ZN-2523 PPM. METALS ARE ZONED RELATIVE TO THE GRANODIORITE PORPHYRY STOCK WITH CU, MO, CO, CR, AND NI OCCURRING PROXIMAL TO THE STOCK (E.G. THE WEST OREBODY) AND AU, AS, TE, BI, SB, CD, MN, AND HG OCCURRING IN THE MAIN FORTITUDE ORE ZONE.

Mineral occurrence model information

Model code 59
USGS model code 18b
Deposit model name Skarn Cu
Mark3 model number 8

Host and associated rocks

  • Host or associated Host
    Rock type Sedimentary Rock > Carbonate > Limestone
    Rock type qualifier silty
    Rock unit name Antler Peak Limestone
    Stratigraphic age (youngest) Early Permian
    Stratigraphic age (oldest) Late Pennsylvanian
  • Host or associated Host
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Conglomerate
    Rock unit name Antler Sequence
    Stratigraphic age (youngest) Early Permian
    Stratigraphic age (oldest) Middle Pennsylvanian
  • Host or associated Host
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Conglomerate
    Rock unit name Battle Formation
    Stratigraphic age (youngest) Middle Pennsylvanian
  • Host or associated Host
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Siltstone
    Rock type qualifier calcareous
    Rock unit name Battle Formation
    Stratigraphic age (youngest) Middle Pennsylvanian
  • Host or associated Associated
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Conglomerate
    Rock unit name Battle Formation
    Stratigraphic age (youngest) Middle Pennsylvanian
  • Host or associated Associated
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Shale
    Rock type qualifier calcareous
    Rock unit name Battle Formation
    Stratigraphic age (youngest) Middle Pennsylvanian
  • Host or associated Associated
    Rock type Metamorphic Rock > Metasedimentary Rock > Quartzite
    Rock unit name Battle Formation
    Stratigraphic age (youngest) Middle Pennsylvanian
  • Host or associated Associated
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Sandstone
    Rock type qualifier calcareous
    Rock unit name Edna Mountain Formation
    Stratigraphic age (youngest) Late Permian
  • Host or associated Associated
    Rock type Sedimentary Rock > Carbonate > Limestone
    Rock unit name Edna Mountain Formation
    Stratigraphic age (youngest) Late Permian
  • Host or associated Associated
    Rock type Sedimentary Rock > Clastic Sedimentary Rock > Conglomerate
    Rock unit name Edna Mountain Formation
    Stratigraphic age (youngest) Late Permian
  • Host or associated Associated
    Rock type Plutonic Rock > Granitoid > Granodiorite
    Rock unit name Copper Canyon Granodiorite
    Chronological age 38
    Dating method K-Ar
    Stratigraphic age (youngest) Middle Eocene
    Chronological age 38.5
    Dating method K-Ar
    Stratigraphic age (youngest) Middle Eocene

Nearby scientific data

Pit (1) -117.13244, 40.5483
Plant (2) -117.12997, 40.53685

Geologic structures

Type Description Terms
Local Virgin Fault
Regional Golconda Thrust

Ore body information

  • General form tabular
    Strike ALONG LINEAR STRUCTURALLY CONTROLLED TRENDS
    Dip GENTLY TO WEST
    Thickness 30M
    Width 300M
    Length 400M

Comments on the geologic information

  • Skarn minerals are zoned in abundance and composition relative to the granodiorite porphyry stock. Proximal skarn near the pluton contact is garnet and copper rich, relatively oxidized, and formed at high temperatures. Distal skarn, up to 1.5 km from the pluton contact, is pyroxene and gold-rich, relatively reduced, and formed at lower temperatures. Average garnet-pyroxene ratios and pyroxene iron-manganese contents are useful guides to position within the skarn system and to gold and copper grades. The reduced nature of the Copper Canyon porphyry, indicated by very low ferric/ferrous iron ratio (Fe +3/Fe +2 < 0.5), is an important characteristic of this gold-enriched system and distinguishes it from other gold-poor igneous/hydrothermal systems. Doebrich notes that contouring of blast hole assay maps shows strong N-S and NNE- linear trends in gold concentration. These higher grade gold zones correspond to garnetiferous skarn within an overall pyroxene skarn zone. Conglomerate hosts ore in the upper zone.

Economic information

Economic information about the deposit and operations

Operation type Surface
Development status Past Producer
Commodity type Metallic
Deposit size Medium
Significant Yes
Year of first production 1984
Year of last production 1993
Production years 1984-1993

Mining district

District name Battle Mountain District

Land status

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

Ownership information

  • Type Owner-Operator
    Owner Newmont Mining Corp.
    Year 2004

Production statistics

  • Year 1985
    Material ORE
    Ore mined 1,079,000mt
    Accuracy Accurate
    Description Ap_Grade: ^0.21 Opt Au, 1.19 Opt Ag
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary Ore Silver Silver 41g/mt
    Primary Ore Gold Gold 7g/mt 92
  • Year 1986
    Material ore
    Ore mined 1,020,000mt
    Accuracy Accurate
    Description Ap_Grade: ^0.24 Opt Au, 1.50 Opt Ag
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary Gold Gold 8g/mt 96
    Primary Silver Silver 51g/mt
  • Year 1987
    Material ore
    Ore mined 1,008,000mt
    Accuracy Accurate
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary Gold Gold 8g/mt 96
  • Year 1993
    Period 1985-93
    Material AU ORE
    Ore mined 10,860,000mt
    Accuracy Accurate
    Description Cp_Grade: ^0.194 Opt Au., Approx. 2.3 Million Oz. Au; Cp_Grade: ^0.9 Opt Ag., Approx. 10.8 Million Oz.
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary Ore Gold Gold 7g/mt
    Primary Silver Silver 31g/mt
  • Year 1994
    Period to 1993
    Accuracy Accurate
    Importance Item Commodity Group Amount recovered Grade Recovery percentage
    Primary Gold Gold 65mt 100wt-pct
    Primary Silver Silver 110mt 100wt-pct

Comments on the production information

  • 1985-1987 ANNUAL PRODUCTION: BATTLE MOUNTAIN GOLD CO., 1988, ANNUAL REPORT FOR 1987. CUMULATIVE PRODUCTION FIGURES FROM DOEBRICH, WRITTEN COMMUNICATION, JUNE 1993, FROM COMPANY SOURCES. NBMG MI-1993

Reserves and resources

  • Type In-situ
    Estimate year 1985
    Total resources 7,040,000mt ore
    Commodity Subtype Grade units Group Importance Year
    Gold Au 7.82 g/mt Gold Major 1985
    Silver Ag 20.7 g/mt Silver Major 1985
  • Type In-situ
    Estimate year 1986
    Total resources 6,536,000mt ore
    Commodity Subtype Grade units Group Importance Year
    Gold Au 7.71 g/mt Gold Major 1986
    Silver Ag 19.75 g/mt Silver Major 1986
  • Type In-situ
    Estimate year 1987
    Total resources 5,497,000mt ore
    Commodity Subtype Grade units Group Importance Year
    Gold Au 7.51 g/mt Gold Major 1987
    Silver Ag 15.8 g/mt Silver Major 1987
  • Type In-situ
    Estimate year 1993
    Measured 5mt commodity
    Commodity Subtype Grade units Group Importance Year
    Gold Au metal 100 wt-pct Gold Primary 1993
  • Type In-situ
    Estimate year 1993
    Measured 39mt commodity
    Commodity Subtype Grade units Group Importance Year
    Silver Ag metal 100 wt-pct Silver Primary 1993

Comments on the workings information

  • Ore is extracted from the Fortitude and Upper Fortitude open pits.

Comments on other economic factors

  • The Fortitude deposit produced 10.86 million metric tons of ore averaging 6 grams per tonne gold and 28 grams per tonne silver.

Comments on development

  • The Fortitude Deposit was discovered in late 1980 north of the West orebody at Battle Mountain Gold?s operations. After three years of pre-production striping and miing of the upper Fortitude ore zone, the larger, higher-grade lower Fortitude ore zone began production in late 1984. Mining ceased in 1993 after the reserves were depleted. In November, 1988 Dighem flew a test line over the exposed sulfide body at Fortitude at a bird height of 30-50 m. The magnetic anomaly over ore in the pit was 500 nt. The massive sulfide ore also gave a strong inphase em response with a high inphase-to-quadrature ratio. The apparent resistivity of ore measured 0.1 ohm-m in contrast to 10-100 ohm-m for limestone host rock. ; econ.com: production costs per equivalent ounce of gold after byproduct credits and including depreciation were $206 in 1985, $172 in 1986, and $156 in 1987. Battle Mountain Gold Co. pays no royalties on production from the Fortitude deposit.

Reference information

Links to other databases

Agency Database name Acronym Record ID Notes
USGS Mineral Resources Data System MRDS W700375 MRDS dep_id 10084951 merged into this record.

Bibliographic references

  • Deposit

    MYERS, G. L. AND MEINERT, L.D., 1991, ALTERATION, MINERALIZATION, AND GOLD DISTRIBUTION IN THE FORTITUDE GOLD SKARN, IN RAINES, G.L., ET AL, EDS., GEOLOGY AND ORE DEPOSITS OF THE GREAT BASIN, THE GEOLOGICAL SOCIETY OF NEVADA, RENO, P. 407-417.

  • Production

    1985-1987 ANNUAL PRODUCTION: BATTLE MOUNTAIN GOLD CO., 1988, ANNUAL REPORT FOR 1987. CUMULATIVE PRODUCTION FIGURES FROM DOEBRICH, WRITTEN COMMUNICATION, JUNE 1993, FROM COMPANY SOURCES. NBMG MI-1993

  • Reserve-Resource

    1985 -1987 RESERVE FIGURES: BATTLE MOUNTAIN GOLD CO., 1988, ANNUAL REPORT FOR 1987. NBMG MI-1993

  • Deposit

    MYERS, G.L., 1990, ALTERATION ZONATION OF THE FORTITUDE GOLD SKARN DEPOSIT, LANDER COUNTY, NEVADA, MINING ENGINEERING, VOL. 42, NO. 4, P. 360-368.

  • Deposit

    TAYLOR, R. S., 1990 AIRBORNE EM RESISTIVITY APPLIED TO EXPLORATION FOR DISSEMINATED PRECIOUS METAL DEPOSITS, GEOPHYSICS; THE LEADING EDGE OF EXPLORATION, VOL. 9, NO. 2, P. 34-41.

  • Deposit

    ROCKY MOUNTAIN PAY DIRT, MAY, 1988, P. 6A-8A.

  • Deposit

    METAL MARKET CONSULTANTS, INC., 1987, GOLD SITUATION MAP.

  • Deposit

    MINING MAGAZINE, JANUARY, 1989, P. 44.

  • Deposit

    BATTLE MOUNTAIN GOLD CO., 1988, ANNUAL REPORT FOR 1987.

  • Deposit

    WOTRUBA, P.R., BENSON, R.G., AND SCHMIDT, K.W., 1988, GEOLOGY OF THE FORTITUDE GOLD-SILVER SKARN DEPOSIT, COPPER CANYON, LANDER COUNTY, NEVADA IN SCHAFER, R.W., COOPER, J.J., AND VIKRE, P.G., EDS., BULK MINEABLE PRECIOUS METAL DEPOSITS OF THE WESTERN UNITED STATES SYMPOSIUM PROCEEDINGS, GEOLOGICAL SOCIETY OF NEVADA, RENO, NEVADA, APRIL 6-8, 1987, P.150-171.

  • Deposit

    WOTRUBA, P.R., BENSON, R.G., AND SCHMIDT, K.W., 1986, BATTLE MOUNTAIN DESCRIBES THE GEOLOGY OF THE FORTITUDE GOLD-SILVER DEPOSIT AT COPPER CANYON: MINING ENGINEERING, V. 38, N. 7 (JULY), P495-499

  • Deposit

    DOEBRICH, JEFF, 1993, ORAL AND WRITTEN COMMUNICATIONS CONCERNING THIS RECORD, BASED ON HIS FIELD WORK AND PROFESSIONAL CONTACTS, MAY AND JUNE 1993

  • Deposit

    NBMG, 1994, MI-1993

  • Deposit

    NEVADA DIVISION OF MINERALS, 1994

  • 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

    Doebrich, Jeff, 1995, Geology and Mineral Deposits of the Antler Peak n7.5-minute quadrangle, Lander County, Nevada, NBMG Bull 109, 44 p.

  • Deposit

    Geological Society of Nevada, 1999, Geology and Gold Mineralization of the Buffalo Valley Area, Northwestern Battle Mountain Trend; GSN Special Publication No. 31, 1999 Fall field trip Guidebook.

  • Deposit

    Wendt, Clancy, 2004, Technical Report on the ICBM/COPPER BASIN Property, Lander and Humboldt Counties, Nevada, Staccato Gold website, : http://www.staccatogold.com/i/pdf/icbm-43-101.pdf

General comments

Subject category Comment text
Deposit The Fortitude Deposit is a world-class gold-silver skarn deposit in the main Battle Mountain District. The deposit was comprised of an upper and a lower ore zone, formed in place, but separated by the N-striking, W-dipping Virgin Fault and by a granodiorite porphyry dike intruded along the fault. The upper ore zone in and east of the footwall of the fault formed in host rocks calcareous siltstone and conglomerate of the Battle Formation. The larger lower ore zone that formed the major portion of the deposit formed in host Antler Peak Limestone west of and in the hanging wall of the Virgin Fault. Discontinuous upper zone ore consisted of selective sulfide replacement of thin calc-silicate pods and lenses concentrated along faults or at fault interesections. Lower zone ore was a more continuous stratiform and stratabound orebody elongated northeast, up to 600 meters long, averaging 150 meters wide and 25-30 meters thick. Native gold is common and is most frequently associated with arsenopyrite, native bismuth, and tellurides. The highest gold concentrations occur in the pyrrhotite-dominant sulfide zones which contain only minor chalcopyrite.

Reporter information

Type Date Name Affiliation Comment
Reporter 01-AUG-88 Paidakovich, Matthew E. U.S. Geological Survey
Updater 01-SEP-88 Schruben, Paul G. U.S. Geological Survey
Updater 01-SEP-88 Beougher, Dee (Spanski, Gregory T.) U.S. Geological Survey
Updater 01-AUG-89 Beougher, Dee (Spanski, Gregory T.) U.S. Geological Survey
Updater 01-NOV-90 Skurski, M. (Marcus, Sue) U.S. Geological Survey
Updater 01-OCT-92 Phinisey, J. D. (Marcus, S.) U.S. Geological Survey
Updater 01-JUN-93 Marcus, S. U.S. Geological Survey
Updater 01-SEP-94 Li, Zhiping (Moyer, Lorre A.) U.S. Geological Survey
Reporter 01-FEB-05 LaPointe., D.D. Nevada Bureau of Mines and Geology
Editor 01-SEP-07 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.