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Cortez mine (Cortez Hills deposit; Cortez Hills underground mine; Garrison mine), Cortez District, Eureka Co., Nevada, USAi
Regional Level Types
Cortez mine (Cortez Hills deposit; Cortez Hills underground mine; Garrison mine)Mine
Cortez DistrictMining District
Eureka Co.County
NevadaState
USACountry

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Key
Lock Map
Latitude & Longitude (WGS84):
40° 9' 19'' North , 116° 36' 49'' West
Latitude & Longitude (decimal):
Owned/operated by:
Locality type:
Nearest Settlements:
PlacePopulationDistance
Crescent Valley392 (2011)29.2km


Now a large opencast gold operation and underground mine using underhand cut-and-fill method. Extends into Lander county.

Historically included the Cage shaft, Artic level, Fitzgerald drift.
Structure: The deposit lies within the Cortez Window of the Roberts Mountain Thrust (Cortez Range). The deposit occurs within the Cortez Window in the Roberts Mountain Thrust.

Alteration: Host rocks have been decalcified, silicified, leached, bleached, argillized, and oxidized. This phase of low grade hydrothermal alteration occurred after intrusion of the porphyry sill, and removed most of the carbon. A decalcification halo extends into the host rock surrounding the mineralized area. Mineralization is associated with silicification. Pervasive oxidation and marble development are key alteration types associated with gold deposition

Tectonics: The upper portion of the Devonian carbonate sequence beneath the Roberts Mountains thrust hosts the Cortez Hills deposit.

Commodity: Commodity Info: Gold is submicroscopic (micron to submicron-sized particles of native gold), occurring in minute specks of arsenian pyrite. Ore Materials: native gold, pyrite Gangue Materials: hematite, goethite; gangue: quartz, carbonate, clays

Deposit: The recent Cortez Hills discovery is the result of focused exploration efforts along an extensive high-angle fault corridor that localizes the distribution of gold in the Cortez area. Projection of this structural corridor under cover, coupled with gravity data, were the key exploration techniques that led to the discovery of Cortez Hills. Gold is localized where limestone was faulted, brecciated and folded along margin of Tertiary intrusive, gold is micron-to sub-micron-size. The upper portion of the Devonian carbonate sequence beneath the Roberts Mountains thrust hosts the Cortez Hills deposit. Pervasive oxidation and marble development are key alteration types associated with gold deposit. The Cortez Hills deposit is hosted in the upper portion of the Devonian carbonate sequence. It has a strike length of more than 300 m and is approximately 200 m wide. The mineralized zone starts approximately 120 m below surface and continues up to 460 m. The deposit remains open with expansion potential evident to the west and at depth.

Deposit type: Sediment-hosted Au

Development: Placer Dome is the operator and owner of a 60% joint venture interest in the Cortez Joint Venture (CJV). The remaining 40% is held by Kennecott Explorations (Australia) Ltd. The recent Cortez Hills discovery is the result of focused exploration efforts by CJV staff along an extensive high-angle fault corridor that localizes the distribution of gold in the Cortez area. Projection of this structural corridor under cover, coupled with gravity data, were the key exploration techniques that led to the discovery of Cortez Hills. June 2004, Placer announced that they had drilled a hole in the area between the Cortez Hills and the Pediment deposits that had returned 1.5 ounces per ton over more than 400 feet.

Geology: The deposit is also associated with the Horse Canyon volcanics (andesite flows, rhyolite plug) and the Roberts Mountain Limestone (silty, argillaceous, carbonaceous, pyrite-bearing limestone).

Ore(s): Gold is localized where limestone was faulted, brecciated and folded along the margin of a Tertiary intrusive.

Regions containing this locality

North America PlateTectonic Plate

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded at this locality.


Mineral List


22 valid minerals.

Rock Types Recorded

Note: this is a very new system on mindat.org and data is currently VERY limited. Please bear with us while we work towards adding this information!

Select Rock List Type

Alphabetical List Tree Diagram

Detailed Mineral List:

Acanthite
Formula: Ag2S
Reference: Rocks & Minerals, Nov. 1999
Aurichalcite
Formula: (Zn,Cu)5(CO3)2(OH)6
Reference: Rocks & Minerals, Nov. 1999
Boulangerite
Formula: Pb5Sb4S11
Reference: NBMG Spec. Pub. 31 Minerals of Nevada
Calcite
Formula: CaCO3
Reference: NBMG Bull 64 Geology and Mineral Resources of Eureka County, Nevada
Chalcophyllite
Formula: Cu18Al2(AsO4)4(SO4)3(OH)24 · 36H2O
Reference: Rocks & Minerals, Nov. 1999
Chlorargyrite
Formula: AgCl
Reference: NBMG Bull 64 Geology and Mineral Resources of Eureka County, Nevada
'Copper Stain'
Reference: NBMG Bull 64 Geology and Mineral Resources of Eureka County, Nevada
Freibergite
Formula: Ag6[Cu4Fe2]Sb4S13-x
Reference: Rocks & Minerals, Nov. 1999
Galena
Formula: PbS
Reference: NBMG Bull 64 Geology and Mineral Resources of Eureka County, Nevada
Goethite
Formula: α-Fe3+O(OH)
Reference: NBMG Spec. Pub. 31 Minerals of Nevada; U.S. Geological Survey (2005) Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
Gold
Formula: Au
Reference: http://www.barrick.com/operations/barrick-nevada/default.aspx; U.S. Geological Survey (2005) Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
Hematite
Formula: Fe2O3
Reference: U.S. Geological Survey (2005) Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
Hemimorphite
Formula: Zn4Si2O7(OH)2 · H2O
Reference: Rocks & Minerals, Nov. 1999
'Limonite'
Formula: (Fe,O,OH,H2O)
Reference: NBMG Bull 64 Geology and Mineral Resources of Eureka County, Nevada
Polybasite
Formula: [(Ag,Cu)6(Sb,As)2S7][Ag9CuS4]
Reference: Rocks & Minerals, Nov. 1999
Pyrite
Formula: FeS2
Reference: NBMG Bull 64 Geology and Mineral Resources of Eureka County, Nevada; U.S. Geological Survey (2005) Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
Quartz
Formula: SiO2
Reference: NBMG Bull 64 Geology and Mineral Resources of Eureka County, Nevada; U.S. Geological Survey (2005) Mineral Resources Data System: U.S. Geological Survey, Reston, Virginia.
Rosasite
Formula: (Cu,Zn)2(CO3)(OH)2
Reference: Rocks & Minerals, Nov. 1999
Sphalerite
Formula: ZnS
Reference: NBMG Bull 64 Geology and Mineral Resources of Eureka County, Nevada
Stephanite
Formula: Ag5SbS4
Reference: NBMG Spec. Pub. 31 Minerals of Nevada
Stibnite
Formula: Sb2S3
Reference: NBMG Bull 64 Geology and Mineral Resources of Eureka County, Nevada
Stromeyerite
Formula: AgCuS
Reference: NBMG Bull 64 Geology and Mineral Resources of Eureka County, Nevada
Tetrahedrite
Formula: Cu6[Cu4(Fe,Zn)2]Sb4S13
Reference: Rocks & Minerals, Nov. 1999
Tyrolite
Formula: Ca2Cu9(AsO4)4(CO3)(OH)8 · 11H2O
Reference: Rocks & Minerals, Nov. 1999
'Wad'
Reference: NBMG Bull 64 Geology and Mineral Resources of Eureka County, Nevada

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
Gold1.AA.05Au
Group 2 - Sulphides and Sulfosalts
Acanthite2.BA.35Ag2S
Boulangerite2.HC.15Pb5Sb4S11
Freibergite2.GB.05Ag6[Cu4Fe2]Sb4S13-x
Galena2.CD.10PbS
Polybasite2.GB.15[(Ag,Cu)6(Sb,As)2S7][Ag9CuS4]
Pyrite2.EB.05aFeS2
Sphalerite2.CB.05aZnS
Stephanite2.GB.10Ag5SbS4
Stibnite2.DB.05Sb2S3
Stromeyerite2.BA.40AgCuS
Tetrahedrite2.GB.05Cu6[Cu4(Fe,Zn)2]Sb4S13
Group 3 - Halides
Chlorargyrite3.AA.15AgCl
Group 4 - Oxides and Hydroxides
Goethite4.00.α-Fe3+O(OH)
Hematite4.CB.05Fe2O3
Quartz4.DA.05SiO2
Group 5 - Nitrates and Carbonates
Aurichalcite5.BA.15(Zn,Cu)5(CO3)2(OH)6
Calcite5.AB.05CaCO3
Rosasite5.BA.10(Cu,Zn)2(CO3)(OH)2
Group 8 - Phosphates, Arsenates and Vanadates
Chalcophyllite8.DF.30Cu18Al2(AsO4)4(SO4)3(OH)24 · 36H2O
Tyrolite8.DM.10Ca2Cu9(AsO4)4(CO3)(OH)8 · 11H2O
Group 9 - Silicates
Hemimorphite9.BD.10Zn4Si2O7(OH)2 · H2O
Unclassified Minerals, Rocks, etc.
'Copper Stain'-
'Limonite'-(Fe,O,OH,H2O)
'Wad'-

List of minerals arranged by Dana 8th Edition classification

Group 1 - NATIVE ELEMENTS AND ALLOYS
Metals, other than the Platinum Group
Gold1.1.1.1Au
Group 2 - SULFIDES
AmBnXp, with (m+n):p = 2:1
Acanthite2.4.1.1Ag2S
Stromeyerite2.4.6.1AgCuS
AmXp, with m:p = 1:1
Galena2.8.1.1PbS
Sphalerite2.8.2.1ZnS
AmBnXp, with (m+n):p = 2:3
Stibnite2.11.2.1Sb2S3
AmBnXp, with (m+n):p = 1:2
Pyrite2.12.1.1FeS2
Group 3 - SULFOSALTS
ø > 4
Polybasite3.1.7.2[(Ag,Cu)6(Sb,As)2S7][Ag9CuS4]
ø = 4
Stephanite3.2.4.1Ag5SbS4
3 <ø < 4
Freibergite3.3.6.3Ag6[Cu4Fe2]Sb4S13-x
Tetrahedrite3.3.6.1Cu6[Cu4(Fe,Zn)2]Sb4S13
2.5 < ø < 3
Boulangerite3.5.2.1Pb5Sb4S11
Group 4 - SIMPLE OXIDES
A2X3
Hematite4.3.1.2Fe2O3
Group 6 - HYDROXIDES AND OXIDES CONTAINING HYDROXYL
XO(OH)
Goethite6.1.1.2α-Fe3+O(OH)
Group 9 - NORMAL HALIDES
AX
Chlorargyrite9.1.4.1AgCl
Group 14 - ANHYDROUS NORMAL CARBONATES
A(XO3)
Calcite14.1.1.1CaCO3
Group 16a - ANHYDROUS CARBONATES CONTAINING HYDROXYL OR HALOGEN
Rosasite16a.3.1.2(Cu,Zn)2(CO3)(OH)2
Aurichalcite16a.4.2.1(Zn,Cu)5(CO3)2(OH)6
Group 42 - HYDRATED PHOSPHATES, ETC.CONTAINING HYDROXYL OR HALOGEN
(AB)5(XO4)2Zq·xH2O
Tyrolite42.4.3.1Ca2Cu9(AsO4)4(CO3)(OH)8 · 11H2O
Group 43 - COMPOUND PHOSPHATES, ETC.
Hydrated Compound Phosphates, etc·, Containing Hydroxyl or Halogen
Chalcophyllite43.5.14.1Cu18Al2(AsO4)4(SO4)3(OH)24 · 36H2O
Group 56 - SOROSILICATES Si2O7 Groups, With Additional O, OH, F and H2O
Si2O7 Groups and O, OH, F, and H2O with cations in [4] coordination
Hemimorphite56.1.2.1Zn4Si2O7(OH)2 · H2O
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2
Unclassified Minerals, Mixtures, etc.
'Copper Stain'-
'Limonite'-(Fe,O,OH,H2O)
'Wad'-

List of minerals for each chemical element

HHydrogen
H Aurichalcite(Zn,Cu)5(CO3)2(OH)6
H ChalcophylliteCu18Al2(AsO4)4(SO4)3(OH)24 · 36H2O
H HemimorphiteZn4Si2O7(OH)2 · H2O
H Rosasite(Cu,Zn)2(CO3)(OH)2
H TyroliteCa2Cu9(AsO4)4(CO3)(OH)8 · 11H2O
H Limonite(Fe,O,OH,H2O)
H Goethiteα-Fe3+O(OH)
CCarbon
C Aurichalcite(Zn,Cu)5(CO3)2(OH)6
C Rosasite(Cu,Zn)2(CO3)(OH)2
C TyroliteCa2Cu9(AsO4)4(CO3)(OH)8 · 11H2O
C CalciteCaCO3
OOxygen
O Aurichalcite(Zn,Cu)5(CO3)2(OH)6
O ChalcophylliteCu18Al2(AsO4)4(SO4)3(OH)24 · 36H2O
O HemimorphiteZn4Si2O7(OH)2 · H2O
O Rosasite(Cu,Zn)2(CO3)(OH)2
O TyroliteCa2Cu9(AsO4)4(CO3)(OH)8 · 11H2O
O Limonite(Fe,O,OH,H2O)
O QuartzSiO2
O CalciteCaCO3
O Goethiteα-Fe3+O(OH)
O HematiteFe2O3
AlAluminium
Al ChalcophylliteCu18Al2(AsO4)4(SO4)3(OH)24 · 36H2O
SiSilicon
Si HemimorphiteZn4Si2O7(OH)2 · H2O
Si QuartzSiO2
SSulfur
S AcanthiteAg2S
S ChalcophylliteCu18Al2(AsO4)4(SO4)3(OH)24 · 36H2O
S FreibergiteAg6[Cu4Fe2]Sb4S13-x
S Polybasite[(Ag,Cu)6(Sb,As)2S7][Ag9CuS4]
S TetrahedriteCu6[Cu4(Fe,Zn)2]Sb4S13
S GalenaPbS
S StibniteSb2S3
S PyriteFeS2
S SphaleriteZnS
S StromeyeriteAgCuS
S BoulangeritePb5Sb4S11
S StephaniteAg5SbS4
ClChlorine
Cl ChlorargyriteAgCl
CaCalcium
Ca TyroliteCa2Cu9(AsO4)4(CO3)(OH)8 · 11H2O
Ca CalciteCaCO3
FeIron
Fe FreibergiteAg6[Cu4Fe2]Sb4S13-x
Fe TetrahedriteCu6[Cu4(Fe,Zn)2]Sb4S13
Fe PyriteFeS2
Fe Limonite(Fe,O,OH,H2O)
Fe Goethiteα-Fe3+O(OH)
Fe HematiteFe2O3
CuCopper
Cu Aurichalcite(Zn,Cu)5(CO3)2(OH)6
Cu ChalcophylliteCu18Al2(AsO4)4(SO4)3(OH)24 · 36H2O
Cu FreibergiteAg6[Cu4Fe2]Sb4S13-x
Cu Polybasite[(Ag,Cu)6(Sb,As)2S7][Ag9CuS4]
Cu Rosasite(Cu,Zn)2(CO3)(OH)2
Cu TetrahedriteCu6[Cu4(Fe,Zn)2]Sb4S13
Cu TyroliteCa2Cu9(AsO4)4(CO3)(OH)8 · 11H2O
Cu StromeyeriteAgCuS
ZnZinc
Zn Aurichalcite(Zn,Cu)5(CO3)2(OH)6
Zn HemimorphiteZn4Si2O7(OH)2 · H2O
Zn Rosasite(Cu,Zn)2(CO3)(OH)2
Zn TetrahedriteCu6[Cu4(Fe,Zn)2]Sb4S13
Zn SphaleriteZnS
AsArsenic
As ChalcophylliteCu18Al2(AsO4)4(SO4)3(OH)24 · 36H2O
As Polybasite[(Ag,Cu)6(Sb,As)2S7][Ag9CuS4]
As TyroliteCa2Cu9(AsO4)4(CO3)(OH)8 · 11H2O
AgSilver
Ag AcanthiteAg2S
Ag FreibergiteAg6[Cu4Fe2]Sb4S13-x
Ag Polybasite[(Ag,Cu)6(Sb,As)2S7][Ag9CuS4]
Ag StromeyeriteAgCuS
Ag ChlorargyriteAgCl
Ag StephaniteAg5SbS4
SbAntimony
Sb FreibergiteAg6[Cu4Fe2]Sb4S13-x
Sb Polybasite[(Ag,Cu)6(Sb,As)2S7][Ag9CuS4]
Sb TetrahedriteCu6[Cu4(Fe,Zn)2]Sb4S13
Sb StibniteSb2S3
Sb BoulangeritePb5Sb4S11
Sb StephaniteAg5SbS4
AuGold
Au GoldAu
PbLead
Pb GalenaPbS
Pb BoulangeritePb5Sb4S11

Regional Geology

This geological map and associated information on rock units at or nearby to the coordinates given for this locality is based on relatively small scale geological maps provided by various national Geological Surveys. This does not necessarily represent the complete geology at this locality but it gives a background for the region in which it is found.

Click on geological units on the map for more information. Click here to view full-screen map on Macrostrat.org

Quaternary - Miocene
0 - 23.03 Ma



ID: 3185380
Cenozoic sedimentary rocks

Age: Cenozoic (0 - 23.03 Ma)

Lithology: Sedimentary rocks

Reference: Chorlton, L.B. Generalized geology of the world: bedrock domains and major faults in GIS format: a small-scale world geology map with an extended geological attribute database. doi: 10.4095/223767. Geological Survey of Canada, Open File 5529. [154]

Pleistocene - Pliocene
0.0117 - 5.333 Ma



ID: 3006346
Older alluvium and alluvial fan deposits

Age: Cenozoic (0.0117 - 5.333 Ma)

Description: Unit consists mostly of older alluvium and alluvial fans. It also includes various stream deposits, gravel, fanglomerates, and older gravels. It is not very consistent in description from county to county. This is used in all counties except Clark.

Comments: Original map source: Crafford, A.E.J., 2007, Geologic Map of Nevada: U.S. Geological Survey Data Series 249, 1 CD-ROM, 46 p., 1 plate; Scale 1:250,000.

Lithology: Major:{coarse alluvium,fine alluvium}

Reference: Horton, J.D., C.A. San Juan, and D.B. Stoeser. The State Geologic Map Compilation (SGMC) geodatabase of the conterminous United States. doi: 10.3133/ds1052. U.S. Geological Survey Data Series 1052. [133]

Data and map coding provided by Macrostrat.org, used under Creative Commons Attribution 4.0 License

References

Sort by

Year (asc) Year (desc) Author (A-Z) Author (Z-A)
Division of Mine Inspection, Dec. (1983), Directory of Nevada Mine Operations Active in Calendar Year 1983.
NBMG, (1983), Map 84, Active Mines and Oil Fields.
NBMG, (1983), Active Mines and Oil Fields, Map 84.
Bentz, J. and Smith, P., (1982), Field Examination Report, July 12, 1982.
Metal Market Consultants, Inc., (1987), Gold Situation Map
Nevada Dept. of Minerals, (1993).95-2
.Geological Society of Nevada (1997) Spring Field Trip: Geology and Ore Deposits of Northeastern Nevada, Special Publication No. 25
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.
Geology and Ore Deposits of the American Cordillera, Field Trip Guidebook Compendium of the April (1995) Geological Society of NevadaSymposium; 501 p
Robert C. Hays, Jr., (2003), The Cortez Hills Deposit, a recent discovery in an historic mining district, Lander County, Nevada, abstract for Geological Society of Nevada talk given in spring 2004.

USGS MRDS Record:10310435
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