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Kofa Mining District, Yuma County, Arizona, USAi
Regional Level Types
Kofa Mining DistrictMining District
Yuma CountyCounty
ArizonaState
USACountry

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Latitude & Longitude (WGS84):
32° North , 113° West (est.)
Estimate based on other nearby localities or region boundaries.
Margin of Error:
~98km
KΓΆppen climate type:
Mindat Locality ID:
33516
Long-form identifier:
mindat:1:2:33516:7
GUID (UUID V4):
8282773d-9ca8-465e-be6b-f6b905c2a76b


A Au-Ag-Mn-W-Cu-Pb-F mining district located in T1-2S, R15-17W, G&SRM, in the southern/SW margin of the Kofa (S.H.) Mountains.

Mineralization within the district varies: (1) Spotty, but often high-grade, fine-grained, gold and silver mineralization in lensing quartz-calcite, brecciated rock, fissure veins cutting Cretaceous or Tertiary andesite and Mesozoic schist or slate. Minor copper and lead, and often considerable manganese and local fluorite. Wall rocks are strongly silicified; (2) Erratic and irregular manganese oxides in fracture zones in fragmented Cretaceous or Tertiary andesitic volcanics; and, (3) Spotty stringers, pods, and disseminated grains of scheelite, associated with quartz and iron oxides, in fracture zones in fragmented volcanics and schist.

Workings include 2 major mines and numerous prospects and small mines operated mainly in the late 1800's and early 1900's, with small, intermittent operations until 1954. Total estimated and recorded production of precious and base metals through 1974 would be some 779,500 tons of ore containing about 227,500 ounces Au, 103,700 ounces Ag, 3 tons of lead and one ton of copper. Over 1,000 ounces of placer gold were recovered. Manganese production was about 230 long tons of 27% Mn and about 94 short ton units of WO3. Total production s set at some $5,000,000 (period values).

Select Mineral List Type

Standard Detailed Gallery Strunz Chemical Elements

Commodity List

This is a list of exploitable or exploited mineral commodities recorded from this region.


Mineral List

Mineral list contains entries from the region specified including sub-localities

25 valid minerals.

Rock Types Recorded

Note: data is currently VERY limited. Please bear with us while we work towards adding this information!

Rock list contains entries from the region specified including sub-localities

Select Rock List Type

Alphabetical List Tree Diagram

Detailed Mineral List:

β“˜ Aurorite
Formula: Mn2+Mn4+3O7 · 3H2O
β“˜ Baryte
Formula: BaSO4
β“˜ 'Biotite'
Formula: K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
β“˜ Bixbyite-(Mn)
Formula: Mn3+2O3
β“˜ Boulangerite
Formula: Pb5Sb4S11
Description: Occurs in veinlets.
β“˜ Calcite
Formula: CaCO3
β“˜ Calcite var. Manganese-bearing Calcite
Formula: (Ca,Mn)CO3
Colour: Black to brown
Description: Highly manganoan.
β“˜ Chalcophanite
Formula: ZnMn4+3O7 · 3H2O
β“˜ 'Chlorite Group'
β“˜ Epidote
Formula: (CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)
β“˜ Fluorite
Formula: CaF2
Localities: Reported from at least 7 localities in this region.
β“˜ Galena
Formula: PbS
Description: Disseminated in gangue of fluorite & calcite.
β“˜ Gold
Formula: Au
Localities: Reported from at least 9 localities in this region.
Description: As fine-grained free gold. with silver.
β“˜ Groutite
Formula: Mn3+O(OH)
β“˜ 'K Feldspar'
Description: Microscopic mixture with quartz.
β“˜ 'K Feldspar var. Adularia'
Formula: KAlSi3O8
Description: Microscopic mixture with quartz.
β“˜ Manganite
Formula: Mn3+O(OH)
β“˜ Muscovite
Formula: KAl2(AlSi3O10)(OH)2
β“˜ Nsutite
Formula: (Mn4+,Mn2+)(O,OH)2
β“˜ Opal
Formula: SiO2 · nH2O
Habit: botryoidal
Colour: colorless
Fluorescence: green
Description: Botryoidal formations partly covered by white calcite and quartz.
β“˜ Opal var. Opal-AN
Formula: SiO2 · nH2O
Habit: botryoidal
Colour: colorless
Fluorescence: green
Description: Botryoidal formations partly covered by white calcite and quartz.
β“˜ 'Plagioclase'
Formula: (Na,Ca)[(Si,Al)AlSi2]O8
β“˜ Polybasite
Formula: [Ag6Sb2S7][Ag9CuS4]
β“˜ 'Psilomelane'
β“˜ Pyrite
Formula: FeS2
Description: Finely disseminated in calcareous shale footwall rock.
β“˜ Pyrolusite
Formula: Mn4+O2
β“˜ Quartz
Formula: SiO2
Description: Crystals in small veinlets.
β“˜ Quartz var. Chalcedony
Formula: SiO2
Description: Banded; a breccia cement.
β“˜ Rhodochrosite
Formula: MnCO3
β“˜ Rhodonite
Formula: CaMn3Mn[Si5O15]
Description: Occurs in veins in the Eichelberger exotic breccia.
β“˜ Scheelite
Formula: Ca(WO4)
Description: Sparse.
β“˜ Silver
Formula: Ag
Description: With gold.
β“˜ Todorokite
Formula: (Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
β“˜ Willemite
Formula: Zn2SiO4

List of minerals arranged by Strunz 10th Edition classification

Group 1 - Elements
β“˜Silver1.AA.05Ag
β“˜Gold1.AA.05Au
Group 2 - Sulphides and Sulfosalts
β“˜Galena2.CD.10PbS
β“˜Pyrite2.EB.05aFeS2
β“˜Polybasite2.GB.15[Ag6Sb2S7][Ag9CuS4]
β“˜Boulangerite2.HC.15Pb5Sb4S11
Group 3 - Halides
β“˜Fluorite3.AB.25CaF2
Group 4 - Oxides and Hydroxides
β“˜Bixbyite-(Mn)4.CB.10Mn3+2O3
β“˜Quartz4.DA.05SiO2
β“˜var. Chalcedony4.DA.05SiO2
β“˜Opal
var. Opal-AN
4.DA.10SiO2 Β· nH2O
β“˜4.DA.10SiO2 Β· nH2O
β“˜Pyrolusite4.DB.05Mn4+O2
β“˜Nsutite4.DB.15c(Mn4+,Mn2+)(O,OH)2
β“˜Todorokite4.DK.10(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 Β· 3-4H2O
β“˜Groutite4.FD.10Mn3+O(OH)
β“˜Manganite4.FD.15Mn3+O(OH)
β“˜Chalcophanite4.FL.20ZnMn4+3O7 Β· 3H2O
β“˜Aurorite4.FL.20Mn2+Mn4+3O7 Β· 3H2O
Group 5 - Nitrates and Carbonates
β“˜Rhodochrosite5.AB.05MnCO3
β“˜Calcite
var. Manganese-bearing Calcite
5.AB.05(Ca,Mn)CO3
β“˜5.AB.05CaCO3
Group 7 - Sulphates, Chromates, Molybdates and Tungstates
β“˜Baryte7.AD.35BaSO4
β“˜Scheelite7.GA.05Ca(WO4)
Group 9 - Silicates
β“˜Willemite9.AA.05Zn2SiO4
β“˜Epidote9.BG.05a(CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)
β“˜Rhodonite9.DK.05CaMn3Mn[Si5O15]
β“˜Muscovite9.EC.15KAl2(AlSi3O10)(OH)2
Unclassified
β“˜'Plagioclase'-(Na,Ca)[(Si,Al)AlSi2]O8
β“˜'K Feldspar
var. Adularia'
-KAlSi3O8
β“˜'Psilomelane'-
β“˜'Chlorite Group'-
β“˜'Biotite'-K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
β“˜'K Feldspar'-

List of minerals for each chemical element

HHydrogen
Hβ“˜ AuroriteMn2+Mn34+O7 · 3H2O
Hβ“˜ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Hβ“˜ ChalcophaniteZnMn34+O7 · 3H2O
Hβ“˜ Epidote(CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)
Hβ“˜ GroutiteMn3+O(OH)
Hβ“˜ Opal var. Opal-ANSiO2 · nH2O
Hβ“˜ ManganiteMn3+O(OH)
Hβ“˜ MuscoviteKAl2(AlSi3O10)(OH)2
Hβ“˜ Nsutite(Mn4+,Mn2+)(O,OH)2
Hβ“˜ OpalSiO2 · nH2O
Hβ“˜ Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
CCarbon
Cβ“˜ CalciteCaCO3
Cβ“˜ Calcite var. Manganese-bearing Calcite(Ca,Mn)CO3
Cβ“˜ RhodochrositeMnCO3
OOxygen
Oβ“˜ K Feldspar var. AdulariaKAlSi3O8
Oβ“˜ AuroriteMn2+Mn34+O7 · 3H2O
Oβ“˜ BaryteBaSO4
Oβ“˜ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Oβ“˜ Bixbyite-(Mn)Mn23+O3
Oβ“˜ CalciteCaCO3
Oβ“˜ ChalcophaniteZnMn34+O7 · 3H2O
Oβ“˜ Quartz var. ChalcedonySiO2
Oβ“˜ Epidote(CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)
Oβ“˜ GroutiteMn3+O(OH)
Oβ“˜ Opal var. Opal-ANSiO2 · nH2O
Oβ“˜ ManganiteMn3+O(OH)
Oβ“˜ Calcite var. Manganese-bearing Calcite(Ca,Mn)CO3
Oβ“˜ MuscoviteKAl2(AlSi3O10)(OH)2
Oβ“˜ Nsutite(Mn4+,Mn2+)(O,OH)2
Oβ“˜ OpalSiO2 · nH2O
Oβ“˜ PyrolusiteMn4+O2
Oβ“˜ QuartzSiO2
Oβ“˜ RhodochrositeMnCO3
Oβ“˜ RhodoniteCaMn3Mn[Si5O15]
Oβ“˜ ScheeliteCa(WO4)
Oβ“˜ Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
Oβ“˜ WillemiteZn2SiO4
Oβ“˜ Plagioclase(Na,Ca)[(Si,Al)AlSi2]O8
FFluorine
Fβ“˜ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Fβ“˜ FluoriteCaF2
NaSodium
Naβ“˜ Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
Naβ“˜ Plagioclase(Na,Ca)[(Si,Al)AlSi2]O8
MgMagnesium
Mgβ“˜ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Mgβ“˜ Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
AlAluminium
Alβ“˜ K Feldspar var. AdulariaKAlSi3O8
Alβ“˜ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Alβ“˜ Epidote(CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)
Alβ“˜ MuscoviteKAl2(AlSi3O10)(OH)2
Alβ“˜ Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
Alβ“˜ Plagioclase(Na,Ca)[(Si,Al)AlSi2]O8
SiSilicon
Siβ“˜ K Feldspar var. AdulariaKAlSi3O8
Siβ“˜ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Siβ“˜ Quartz var. ChalcedonySiO2
Siβ“˜ Epidote(CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)
Siβ“˜ Opal var. Opal-ANSiO2 · nH2O
Siβ“˜ MuscoviteKAl2(AlSi3O10)(OH)2
Siβ“˜ OpalSiO2 · nH2O
Siβ“˜ QuartzSiO2
Siβ“˜ RhodoniteCaMn3Mn[Si5O15]
Siβ“˜ WillemiteZn2SiO4
Siβ“˜ Plagioclase(Na,Ca)[(Si,Al)AlSi2]O8
SSulfur
Sβ“˜ BaryteBaSO4
Sβ“˜ BoulangeritePb5Sb4S11
Sβ“˜ GalenaPbS
Sβ“˜ Polybasite[Ag6Sb2S7][Ag9CuS4]
Sβ“˜ PyriteFeS2
KPotassium
Kβ“˜ K Feldspar var. AdulariaKAlSi3O8
Kβ“˜ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Kβ“˜ MuscoviteKAl2(AlSi3O10)(OH)2
Kβ“˜ Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
CaCalcium
Caβ“˜ CalciteCaCO3
Caβ“˜ Epidote(CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)
Caβ“˜ FluoriteCaF2
Caβ“˜ Calcite var. Manganese-bearing Calcite(Ca,Mn)CO3
Caβ“˜ RhodoniteCaMn3Mn[Si5O15]
Caβ“˜ ScheeliteCa(WO4)
Caβ“˜ Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
Caβ“˜ Plagioclase(Na,Ca)[(Si,Al)AlSi2]O8
TiTitanium
Tiβ“˜ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
MnManganese
Mnβ“˜ AuroriteMn2+Mn34+O7 · 3H2O
Mnβ“˜ Bixbyite-(Mn)Mn23+O3
Mnβ“˜ ChalcophaniteZnMn34+O7 · 3H2O
Mnβ“˜ GroutiteMn3+O(OH)
Mnβ“˜ ManganiteMn3+O(OH)
Mnβ“˜ Calcite var. Manganese-bearing Calcite(Ca,Mn)CO3
Mnβ“˜ Nsutite(Mn4+,Mn2+)(O,OH)2
Mnβ“˜ PyrolusiteMn4+O2
Mnβ“˜ RhodochrositeMnCO3
Mnβ“˜ RhodoniteCaMn3Mn[Si5O15]
Mnβ“˜ Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
FeIron
Feβ“˜ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Feβ“˜ Epidote(CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)
Feβ“˜ PyriteFeS2
CuCopper
Cuβ“˜ Polybasite[Ag6Sb2S7][Ag9CuS4]
ZnZinc
Znβ“˜ ChalcophaniteZnMn34+O7 · 3H2O
Znβ“˜ WillemiteZn2SiO4
SrStrontium
Srβ“˜ Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
AgSilver
Agβ“˜ Polybasite[Ag6Sb2S7][Ag9CuS4]
Agβ“˜ SilverAg
SbAntimony
Sbβ“˜ BoulangeritePb5Sb4S11
Sbβ“˜ Polybasite[Ag6Sb2S7][Ag9CuS4]
BaBarium
Baβ“˜ BaryteBaSO4
Baβ“˜ Todorokite(Na,Ca,K,Ba,Sr)1-x(Mn,Mg,Al)6O12 · 3-4H2O
WTungsten
Wβ“˜ ScheeliteCa(WO4)
AuGold
Auβ“˜ GoldAu
PbLead
Pbβ“˜ BoulangeritePb5Sb4S11
Pbβ“˜ GalenaPbS

Localities in this Region

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This page contains all mineral locality references listed on mindat.org. This does not claim to be a complete list. If you know of more minerals from this site, please register so you can add to our database. This locality information is for reference purposes only. You should never attempt to visit any sites listed in mindat.org without first ensuring that you have the permission of the land and/or mineral rights holders for access and that you are aware of all safety precautions necessary.

References

 
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