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Fort Knox Gold Mine, Fairbanks North Star Borough, Alaska, USAi
Regional Level Types
Fort Knox Gold MineMine
Fairbanks North Star BoroughBorough
AlaskaState
USACountry

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Latitude & Longitude (WGS84): 64° 59' 57'' North , 147° 20' 11'' West
Latitude & Longitude (decimal): 64.99923,-147.33629
GeoHash:G#: bex1z28zz
Locality type:Mine
Köppen climate type:Dfc : Subarctic climate
Nearest Settlements:
PlacePopulationDistance
Fox417 (2011)14.0km
Farmers Loop4,853 (2017)19.8km
Two Rivers719 (2011)19.9km
Badger19,482 (2011)24.0km
Fairbanks32,325 (2017)25.4km


Located NE of Fairbanks on the north flank of Gilmore Dome, between Monte Cristo and Melba Creeks.

The Fort Knox gold deposit occurs in a granite body now commonly refered to as the Fort Knox Pluton. Gold occurs along margins of stockwork quartz veins and veinlets, on quartz-filled shear zones, and along fractures within the granite.

Discovered by a geologist walking behind a bulldozer on the Fort Knox claims, who picked up a piece of granite containing visible gold.

First gold bars were poured on Dec. 20, 1996. Total gold recovered as of Jan. 31, 2000 is 1,113,137 ounces. As of 2000, largest gold mine in Alaska, producing 1,000 ounces of gold from 36,000 to 44,000 tons of ore per day. Reserves are estimated at 186 million tons grading 0.027 ozs./ton, or 5.04 million ozs. The gold varies from 948 to 990 fine. Size of the open pit in 2000 was 3,000 feet by 5,000 feet.

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


17 valid minerals.

Detailed Mineral List:

Albite
Formula: Na(AlSi3O8)
Reference: Thompson, J.F.H., Sillitoe, R.H., Baker, T., Lang, J.R., and Mortensen, J.K. (1999): Mineralium Deposita 34, 323-334.
Arsenopyrite
Formula: FeAsS
Reference: USGS OFR 98-287(Freeman,1998); Thompson, J.F.H., Sillitoe, R.H., Baker, T., Lang, J.R., and Mortensen, J.K. (1999): Mineralium Deposita 34, 323-334.
'Biotite'
Reference: Econ Geol (1991) 86:402-405
Bismuth
Formula: Bi
Reference: USGS OFR 98-287(Freeman,1998); Econ Geol (1991) 86:402-405
Bismuthinite
Formula: Bi2S3
Reference: USGS OFR 98-287(Freeman,1998); Thompson, J.F.H., Sillitoe, R.H., Baker, T., Lang, J.R., and Mortensen, J.K. (1999): Mineralium Deposita 34, 323-334.; Econ Geol (1991) 86:402-405
Calcite
Formula: CaCO3
Reference: USGS OFR 98-287(Freeman,1998)
Cassiterite
Formula: SnO2
Reference: Econ Geol (1991) 86:402-405
'Garnet Group'
Formula: X3Z2(SiO4)3
Reference: USGS OFR 98-287(Freeman,1998)
Gold
Formula: Au
Reference: USGS OFR 98-287(Freeman,1998); Econ Geol (1991) 86:402-405
'K Feldspar'
Reference: Thompson, J.F.H., Sillitoe, R.H., Baker, T., Lang, J.R., and Mortensen, J.K. (1999): Mineralium Deposita 34, 323-334.
Marcasite
Formula: FeS2
Reference: Thompson, J.F.H., Sillitoe, R.H., Baker, T., Lang, J.R., and Mortensen, J.K. (1999): Mineralium Deposita 34, 323-334.
Microcline
Formula: K(AlSi3O8)
Reference: Econ Geol (1991) 86:402-405
Molybdenite
Formula: MoS2
Reference: Thompson, J.F.H., Sillitoe, R.H., Baker, T., Lang, J.R., and Mortensen, J.K. (1999): Mineralium Deposita 34, 323-334.; Econ Geol (1991) 86:402-405
Muscovite
Formula: KAl2(AlSi3O10)(OH)2
Reference: Thompson, J.F.H., Sillitoe, R.H., Baker, T., Lang, J.R., and Mortensen, J.K. (1999): Mineralium Deposita 34, 323-334.
Orthoclase
Formula: K(AlSi3O8)
Reference: Econ Geol (1991) 86:402-405
Pyrite
Formula: FeS2
Reference: Thompson, J.F.H., Sillitoe, R.H., Baker, T., Lang, J.R., and Mortensen, J.K. (1999): Mineralium Deposita 34, 323-334.; Econ Geol (1991) 86:402-405
Pyrrhotite
Formula: Fe7S8
Reference: Thompson, J.F.H., Sillitoe, R.H., Baker, T., Lang, J.R., and Mortensen, J.K. (1999): Mineralium Deposita 34, 323-334.
Quartz
Formula: SiO2
Reference: USGS OFR 98-287(Freeman,1998); Thompson, J.F.H., Sillitoe, R.H., Baker, T., Lang, J.R., and Mortensen, J.K. (1999): Mineralium Deposita 34, 323-334.; Econ Geol (1991) 86:402-405
Quartz var: Chalcedony
Formula: SiO2
Reference: USGS OFR 98-287(Freeman,1998)
Scheelite
Formula: Ca(WO4)
Reference: USGS OFR 98-287(Freeman,1998); Econ Geol (1991) 86:402-405
'Stilbite subgroup'
Reference: USGS OFR 98-287(Freeman,1998)
Tetradymite
Formula: Bi2Te2S
Reference: Econ Geol (1991) 86:402-405
'Wolframite'
Formula: (Fe2+)WO4 to (Mn2+)WO4
Reference: Econ Geol (1991) 86:402-405

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
Bismuth1.CA.05Bi
Gold1.AA.05Au
Group 2 - Sulphides and Sulfosalts
Arsenopyrite2.EB.20FeAsS
Bismuthinite2.DB.05Bi2S3
Marcasite2.EB.10aFeS2
Molybdenite2.EA.30MoS2
Pyrite2.EB.05aFeS2
Pyrrhotite2.CC.10Fe7S8
Tetradymite2.DC.05Bi2Te2S
Group 4 - Oxides and Hydroxides
Cassiterite4.DB.05SnO2
Quartz4.DA.05SiO2
var: Chalcedony4.DA.05SiO2
Group 5 - Nitrates and Carbonates
Calcite5.AB.05CaCO3
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
Scheelite7.GA.05Ca(WO4)
Group 9 - Silicates
Albite9.FA.35Na(AlSi3O8)
Microcline9.FA.30K(AlSi3O8)
Muscovite9.EC.15KAl2(AlSi3O10)(OH)2
Orthoclase9.FA.30K(AlSi3O8)
Unclassified Minerals, Rocks, etc.
'Biotite'-
'Garnet Group'-X3Z2(SiO4)3
'K Feldspar'-
'Stilbite subgroup'-
'Wolframite'-(Fe2+)WO4 to (Mn2+)WO4

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
Semi-metals and non-metals
Bismuth1.3.1.4Bi
Group 2 - SULFIDES
AmXp, with m:p = 1:1
Pyrrhotite2.8.10.1Fe7S8
AmBnXp, with (m+n):p = 2:3
Bismuthinite2.11.2.3Bi2S3
Tetradymite2.11.7.1Bi2Te2S
AmBnXp, with (m+n):p = 1:2
Arsenopyrite2.12.4.1FeAsS
Marcasite2.12.2.1FeS2
Molybdenite2.12.10.1MoS2
Pyrite2.12.1.1FeS2
Group 4 - SIMPLE OXIDES
AX2
Cassiterite4.4.1.5SnO2
Group 14 - ANHYDROUS NORMAL CARBONATES
A(XO3)
Calcite14.1.1.1CaCO3
Group 48 - ANHYDROUS MOLYBDATES AND TUNGSTATES
AXO4
Scheelite48.1.2.1Ca(WO4)
Group 71 - PHYLLOSILICATES Sheets of Six-Membered Rings
Sheets of 6-membered rings with 2:1 layers
Muscovite71.2.2a.1KAl2(AlSi3O10)(OH)2
Group 75 - TECTOSILICATES Si Tetrahedral Frameworks
Si Tetrahedral Frameworks - SiO2 with [4] coordinated Si
Quartz75.1.3.1SiO2
Group 76 - TECTOSILICATES Al-Si Framework
Al-Si Framework with Al-Si frameworks
Albite76.1.3.1Na(AlSi3O8)
Microcline76.1.1.5K(AlSi3O8)
Orthoclase76.1.1.1K(AlSi3O8)
Unclassified Minerals, Mixtures, etc.
'Biotite'-
'Garnet Group'-X3Z2(SiO4)3
'K Feldspar'-
Quartz
var: Chalcedony
-SiO2
'Stilbite subgroup'-
'Wolframite'-(Fe2+)WO4 to (Mn2+)WO4

List of minerals for each chemical element

HHydrogen
H MuscoviteKAl2(AlSi3O10)(OH)2
CCarbon
C CalciteCaCO3
OOxygen
O QuartzSiO2
O CalciteCaCO3
O Quartz (var: Chalcedony)SiO2
O ScheeliteCa(WO4)
O Garnet GroupX3Z2(SiO4)3
O AlbiteNa(AlSi3O8)
O MuscoviteKAl2(AlSi3O10)(OH)2
O OrthoclaseK(AlSi3O8)
O MicroclineK(AlSi3O8)
O Wolframite(Fe2+)WO4 to (Mn2+)WO4
O CassiteriteSnO2
NaSodium
Na AlbiteNa(AlSi3O8)
AlAluminium
Al AlbiteNa(AlSi3O8)
Al MuscoviteKAl2(AlSi3O10)(OH)2
Al OrthoclaseK(AlSi3O8)
Al MicroclineK(AlSi3O8)
SiSilicon
Si QuartzSiO2
Si Quartz (var: Chalcedony)SiO2
Si Garnet GroupX3Z2(SiO4)3
Si AlbiteNa(AlSi3O8)
Si MuscoviteKAl2(AlSi3O10)(OH)2
Si OrthoclaseK(AlSi3O8)
Si MicroclineK(AlSi3O8)
SSulfur
S ArsenopyriteFeAsS
S BismuthiniteBi2S3
S PyriteFeS2
S MarcasiteFeS2
S PyrrhotiteFe7S8
S MolybdeniteMoS2
S TetradymiteBi2Te2S
KPotassium
K MuscoviteKAl2(AlSi3O10)(OH)2
K OrthoclaseK(AlSi3O8)
K MicroclineK(AlSi3O8)
CaCalcium
Ca CalciteCaCO3
Ca ScheeliteCa(WO4)
MnManganese
Mn Wolframite(Fe2+)WO4 to (Mn2+)WO4
FeIron
Fe ArsenopyriteFeAsS
Fe PyriteFeS2
Fe MarcasiteFeS2
Fe PyrrhotiteFe7S8
Fe Wolframite(Fe2+)WO4 to (Mn2+)WO4
AsArsenic
As ArsenopyriteFeAsS
MoMolybdenum
Mo MolybdeniteMoS2
SnTin
Sn CassiteriteSnO2
TeTellurium
Te TetradymiteBi2Te2S
WTungsten
W ScheeliteCa(WO4)
W Wolframite(Fe2+)WO4 to (Mn2+)WO4
AuGold
Au GoldAu
BiBismuth
Bi BismuthiniteBi2S3
Bi BismuthBi
Bi TetradymiteBi2Te2S

Geochronology

Mineralization age: Late Cretaceous : 93.4 Ma to 91.5 Ma

Important note: This table is based only on rock and mineral ages recorded below and is not necessarily a complete representation of the geochronology, but does give an indication of possible mineralization events relevant to this locality. As more age information is added this table may expand in the future. A break in the table simply indicates a lack of data entered here, not necessarily a break in the geologic sequence. Grey background entries are from different, related, localities.

Geologic TimeRocks, Minerals and Events
Phanerozoic
 Mesozoic
  Cretaceous
   Late Cretaceous
ⓘ Molybdenite (youngest age)91.5 Ma
ⓘ Molybdenite (oldest age)93.4 Ma

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
0 - 2.588 Ma



ID: 1594494
Unconsolidated surficial deposits, undivided

Age: Pleistocene (0 - 2.588 Ma)

Description: Massive, homogeneous unconsolidated, well-sorted silt of eolian origin containing less than 10% clay, locally rich in organic silt and larger organic fragments. Inorganic components are angular grains of quartz, feldspar, and mica, locally cemented by iron oxides. It is buff to brown or gray, locally mottled. Organic silt is brown to grayish black

Lithology: Unconsolidated

Reference: Wilson, F.H., Hults, C.P., Mull, C.G, and Karl, S.M. (compilers). Geologic map of Alaska. doi: 10.3133/sim3340. U.S. Geological Survey Scientific Investigations Map 3340, pamphlet 196. [21]

Paleozoic - Precambrian
251.902 - 4000 Ma



ID: 3189253
Precambrian-Phanerozoic crystalline metamorphic rocks

Age: Eoarchean to Triassic (251.902 - 4000 Ma)

Lithology: Crystalline metamorphic 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]

Devonian - Cambrian
358.9 - 541 Ma



ID: 654029
Sedimentary; Sedimentary: undivided

Age: Paleozoic (358.9 - 541 Ma)

Description: Eastern Alaska, Yukon, Mackenzie region, Yukon-Tanana upland

Comments: Orogen, magmatic arc/suite; Wilson & Hults, unpublished compilation, 2007-08

Lithology: Sandstone, siltstone, shale, limestone or metamorphosed equivalent

Reference: J.C. Harrison, M.R. St-Onge, O.V. Petrov, S.I. Strelnikov, B.G. Lopatin, F.H. Wilson, S. Tella, D. Paul, T. Lynds, S.P. Shokalsky, C.K. Hults, S. Bergman, H.F. Jepsen, and A. Solli. Geological map of the Arctic. doi:10.4095/287868. Geological Survey of Canada Map 2159A. [2]

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)
- USGS Open File Report 98-287 (Freeman,1998).
- Thompson, J.F.H., Sillitoe, R.H., Baker, T., Lang, J.R., and Mortensen, J.K. (1999): Intrusion-related gold deposits associated with tungsten-tin provinces. Mineralium Deposita 34, 323-334.


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