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Back Forty Deposit, Menominee Co., Michigan, USAi
Regional Level Types
Back Forty DepositDeposit
Menominee Co.County
MichiganState
USACountry

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Latitude & Longitude (WGS84): 45° 27' 9'' North , 87° 49' 50'' West
Latitude & Longitude (decimal): 45.45250,-87.83056
GeoHash:G#: f01d967sp
Locality type:Deposit
Köppen climate type:Dfb : Warm-summer humid continental climate
Nearest Settlements:
PlacePopulationDistance
Wausaukee568 (2017)13.1km
Amberg180 (2017)13.9km
Daggett254 (2017)17.5km
Stephenson867 (2017)17.9km
Middle Inlet827 (2017)21.9km


The Back Forty Project is an advanced stage exploration program focusing on a newly discovered polymetallic zinc-copper, bimodal felsic type VMS deposit located in Menominee County, Michigan.

Early in 2002, drill testing of a geophysical anomaly resulted in the discovery of the massive sulfide deposit. Subsequent drilling in 2002-03 and 2006-08 totaling over 77,000 meters has defined numerous closely spaced zones of significant zinc-gold-copper-silver mineralization comprising the Back Forty Deposit.



Regions containing this locality

North America PlateTectonic Plate

Select Mineral List Type

Standard Detailed Strunz Dana Chemical Elements

Mineral List


24 valid minerals.

Detailed Mineral List:

Acanthite
Formula: Ag2S
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
'Amphibole Supergroup'
Formula: AX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Arsenopyrite
Formula: FeAsS
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
'Biotite'
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Bornite
Formula: Cu5FeS4
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Cassiterite
Formula: SnO2
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Chalcopyrite
Formula: CuFeS2
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
'Chlorite Group'
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Clausthalite
Formula: PbSe
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Diaphorite
Formula: Ag3Pb2Sb3S8
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
'Electrum'
Formula: (Au, Ag)
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Eugenite
Formula: Ag11Hg2
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Galena
Formula: PbS
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Goethite
Formula: α-Fe3+O(OH)
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Gold
Formula: Au
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Hematite
Formula: Fe2O3
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Luanheite
Formula: Ag3Hg
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Magnetite
Formula: Fe2+Fe3+2O4
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Meneghinite
Formula: Pb13CuSb7S24
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Muscovite
Formula: KAl2(AlSi3O10)(OH)2
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Muscovite var: Sericite
Formula: KAl2(AlSi3O10)(OH)2
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Nickelskutterudite
Formula: (Ni,Co,Fe)As3
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Pyrite
Formula: FeS2
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Pyrrhotite
Formula: Fe7S8
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Quartz
Formula: SiO2
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Ramdohrite
Formula: Pb5.9Fe0.1Mn0.1In0.1Cd0.2Ag2.8Sb10.8S24
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Silver
Formula: Ag
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Skutterudite
Formula: CoAs3
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Sphalerite
Formula: ZnS
Reference: Quigley, Tom, and Mahin, Bob, 2008, Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
'Electrum'1.AA.05(Au, Ag)
Eugenite1.AD.15cAg11Hg2
Gold1.AA.05Au
Luanheite1.AD.15bAg3Hg
Silver1.AA.05Ag
Group 2 - Sulphides and Sulfosalts
Acanthite2.BA.35Ag2S
Arsenopyrite2.EB.20FeAsS
Bornite2.BA.15Cu5FeS4
Chalcopyrite2.CB.10aCuFeS2
Clausthalite2.CD.10PbSe
Diaphorite2.JB.05Ag3Pb2Sb3S8
Galena2.CD.10PbS
Meneghinite2.HB.05bPb13CuSb7S24
Nickelskutterudite2.EC.05(Ni,Co,Fe)As3
Pyrite2.EB.05aFeS2
Pyrrhotite2.CC.10Fe7S8
Ramdohrite2.JB.40aPb5.9Fe0.1Mn0.1In0.1Cd0.2Ag2.8Sb10.8S24
Skutterudite2.EC.05CoAs3
Sphalerite2.CB.05aZnS
Group 4 - Oxides and Hydroxides
Cassiterite4.DB.05SnO2
Goethite4.00.α-Fe3+O(OH)
Hematite4.CB.05Fe2O3
Magnetite4.BB.05Fe2+Fe3+2O4
Quartz4.DA.05SiO2
Group 9 - Silicates
Muscovite9.EC.15KAl2(AlSi3O10)(OH)2
var: Sericite9.EC.15KAl2(AlSi3O10)(OH)2
Unclassified Minerals, Rocks, etc.
'Amphibole Supergroup'-AX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
'Biotite'-
'Chlorite Group'-

List of minerals arranged by Dana 8th Edition classification

Group 1 - NATIVE ELEMENTS AND ALLOYS
Metals, other than the Platinum Group
Eugenite1.1.8.5Ag11Hg2
Gold1.1.1.1Au
Luanheite1.1.8.4Ag3Hg
Silver1.1.1.2Ag
Group 2 - SULFIDES
AmBnXp, with (m+n):p = 2:1
Acanthite2.4.1.1Ag2S
AmBnXp, with (m+n):p = 3:2
Bornite2.5.2.1Cu5FeS4
AmXp, with m:p = 1:1
Clausthalite2.8.1.2PbSe
Galena2.8.1.1PbS
Pyrrhotite2.8.10.1Fe7S8
Sphalerite2.8.2.1ZnS
AmBnXp, with (m+n):p = 1:1
Chalcopyrite2.9.1.1CuFeS2
AmBnXp, with (m+n):p = 1:2
Arsenopyrite2.12.4.1FeAsS
Nickelskutterudite2.12.17.2(Ni,Co,Fe)As3
Pyrite2.12.1.1FeS2
Skutterudite2.12.17.1CoAs3
Group 3 - SULFOSALTS
3 <ø < 4
Meneghinite3.3.5.1Pb13CuSb7S24
ø = 3
Ramdohrite3.4.15.6Pb5.9Fe0.1Mn0.1In0.1Cd0.2Ag2.8Sb10.8S24
2.5 < ø < 3
Diaphorite3.5.4.1Ag3Pb2Sb3S8
Group 4 - SIMPLE OXIDES
A2X3
Hematite4.3.1.2Fe2O3
AX2
Cassiterite4.4.1.5SnO2
Group 6 - HYDROXIDES AND OXIDES CONTAINING HYDROXYL
XO(OH)
Goethite6.1.1.2α-Fe3+O(OH)
Group 7 - MULTIPLE OXIDES
AB2X4
Magnetite7.2.2.3Fe2+Fe3+2O4
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
Unclassified Minerals, Mixtures, etc.
'Amphibole Supergroup'-AX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
'Biotite'-
'Chlorite Group'-
'Electrum'-(Au, Ag)
Muscovite
var: Sericite
-KAl2(AlSi3O10)(OH)2

List of minerals for each chemical element

HHydrogen
H Amphibole SupergroupAX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
H Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
H Goethiteα-Fe3+O(OH)
H MuscoviteKAl2(AlSi3O10)(OH)2
OOxygen
O HematiteFe2O3
O MagnetiteFe2+Fe23+O4
O QuartzSiO2
O Amphibole SupergroupAX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
O Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
O Goethiteα-Fe3+O(OH)
O CassiteriteSnO2
O MuscoviteKAl2(AlSi3O10)(OH)2
FFluorine
F Amphibole SupergroupAX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
AlAluminium
Al Amphibole SupergroupAX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
Al Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
Al MuscoviteKAl2(AlSi3O10)(OH)2
SiSilicon
Si QuartzSiO2
Si Amphibole SupergroupAX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
Si Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
Si MuscoviteKAl2(AlSi3O10)(OH)2
SSulfur
S PyriteFeS2
S SphaleriteZnS
S ChalcopyriteCuFeS2
S GalenaPbS
S ArsenopyriteFeAsS
S PyrrhotiteFe7S8
S BorniteCu5FeS4
S AcanthiteAg2S
S DiaphoriteAg3Pb2Sb3S8
S RamdohritePb5.9Fe0.1Mn0.1In0.1Cd0.2Ag2.8Sb10.8S24
S MeneghinitePb13CuSb7S24
ClChlorine
Cl Amphibole SupergroupAX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
KPotassium
K Muscovite (var: Sericite)KAl2(AlSi3O10)(OH)2
K MuscoviteKAl2(AlSi3O10)(OH)2
TiTitanium
Ti Amphibole SupergroupAX2Z5((Si,Al,Ti)8O22)(OH,F,Cl,O)2
FeIron
Fe Nickelskutterudite(Ni,Co,Fe)As3
Fe PyriteFeS2
Fe ChalcopyriteCuFeS2
Fe HematiteFe2O3
Fe MagnetiteFe2+Fe23+O4
Fe ArsenopyriteFeAsS
Fe PyrrhotiteFe7S8
Fe Goethiteα-Fe3+O(OH)
Fe BorniteCu5FeS4
CoCobalt
Co Nickelskutterudite(Ni,Co,Fe)As3
Co SkutteruditeCoAs3
NiNickel
Ni Nickelskutterudite(Ni,Co,Fe)As3
CuCopper
Cu ChalcopyriteCuFeS2
Cu BorniteCu5FeS4
Cu MeneghinitePb13CuSb7S24
ZnZinc
Zn SphaleriteZnS
AsArsenic
As Nickelskutterudite(Ni,Co,Fe)As3
As ArsenopyriteFeAsS
As SkutteruditeCoAs3
SeSelenium
Se ClausthalitePbSe
AgSilver
Ag SilverAg
Ag Electrum(Au, Ag)
Ag AcanthiteAg2S
Ag DiaphoriteAg3Pb2Sb3S8
Ag RamdohritePb5.9Fe0.1Mn0.1In0.1Cd0.2Ag2.8Sb10.8S24
Ag EugeniteAg11Hg2
Ag LuanheiteAg3Hg
CdCadmium
Cd RamdohritePb5.9Fe0.1Mn0.1In0.1Cd0.2Ag2.8Sb10.8S24
SnTin
Sn CassiteriteSnO2
SbAntimony
Sb DiaphoriteAg3Pb2Sb3S8
Sb RamdohritePb5.9Fe0.1Mn0.1In0.1Cd0.2Ag2.8Sb10.8S24
Sb MeneghinitePb13CuSb7S24
AuGold
Au GoldAu
Au Electrum(Au, Ag)
HgMercury
Hg EugeniteAg11Hg2
Hg LuanheiteAg3Hg
PbLead
Pb GalenaPbS
Pb DiaphoriteAg3Pb2Sb3S8
Pb RamdohritePb5.9Fe0.1Mn0.1In0.1Cd0.2Ag2.8Sb10.8S24
Pb ClausthalitePbSe
Pb MeneghinitePb13CuSb7S24

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

Paleozoic
251.902 - 541 Ma



ID: 3187973
Paleozoic sedimentary rocks

Age: Phanerozoic (251.902 - 541 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]

Orosirian
1800 - 2050 Ma



ID: 2751193
Athelstane Quartz Monzonite

Age: Orosirian (1800 - 2050 Ma)

Stratigraphic Name: Athelstane Quartz Monzonite

Description: Pink, coarse-grained granite to granodiorite containing nearly equal amounts of microcline microperthite, plagioclase, and quartz and 5-10 percent biotite and (or) hornblende. Mafic minerals are interstitial and give a clotty appearance.

Comments: Pembine-Wausau terrane. This unit mostly occurs in Wisconsin but also occurs as a thin sliver in nortwestern Michigan. Original map source: Cannon, W.F., Kress, T.H., Sutphin, D.M., Morey, G.B., Meints, Joyce, and Barber-Delach, Robert, 1997, Digital Geologic Map and mineral deposits of the Lake Superior Region, Minnesota, Wisconsin, Michigan: USGS Open-File Report 97-455 (version 3, Nov. 19

Lithology: Major:{granite,granodiorite}

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)
Dematties, T. A. (2007) An evaluation of the Back Forty volcanogenic massive sulfide (VMS) deposit, Menominee County, Michigan, U.S.A.: Technical report prepared for Aquila Resources Inc., 52p.
Quigley, Tom, and Mahin, Bob. (2008) Back Forty Geology and Mineralization: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 2 - Field Trip Guidebook, 66-85.
Schultz, K.J., Nicholson, S.W., and Van Schmus, W.R. (2008) Penokean massive sulfide deposits: Age, geochemistry, and paleotectonic setting: Proceedings of the Institute on Lake Superior Geology, v. 54, Part 1-Programs and Abstracts, 76-77.
Sims, P.K., Van Schmus, W.R., Schultz, K.J., and Peterman, Z.E. (1989) Tectono-stratigraphic evolution of the early Proterozoic Wisconsin magmatic terranes of the Penokean orogen: Canadian Journal of Earth Sciences, v.26, p.2, 145-2, 158.

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