LIVE REPORT! Munich Show 2026 - last updated 1 hour ago. Click here to watch.
Log InRegister
Search For:
Mineral Name:
Locality Name:
Keyword(s):
 
Home PageAbout MindatThe Mindat ManualHistory of MindatCopyright StatusWho We AreOur ScienceMindat Newsletter [Free Download]Contact Us
Donate to MindatSponsor a PageCorporate SponsorshipSponsored Pages
Learning CenterWhat Is a Mineral?The Most Common Minerals on EarthInformation for EducatorsMindat ArticlesMindat Newsletter [Free Download]The ElementsThe Mineral Quiz
Search FormMinerals by PropertiesMinerals by ChemistryMineral Visual ExplorerAdvanced Locality SearchRandom MineralRandom LocalitySearch by minIDMinerals by CountryAlphabetical Mineral IndexAlphabetical Locality SearchMineral Association SearchList of CountriesLocalities Near MePhoto SearchSearch ArticlesSearch GlossaryThe Rock H. Currier Digital LibraryMore Search Options
The Mindat ManualAdd a New PhotoRate PhotosLocality Edit ReportCoordinate Completion ReportAdd Glossary Item
MineralsPetrologyFossilsMeteoritesGeologic Time
Mining CompaniesStatisticsMineral MuseumsClubs & OrganizationsMineral Shows & EventsDevice SettingsTime Machine
Read DiscussionsIdentification Request
Photo SearchPhoto GalleriesSearch by ColourPhoto Colour ExplorerNew Photos TodayNew Photos YesterdayMembers' Photo GalleriesPast Photo of the Day GalleryPhotography

Cotopaxi Pegmatite area, Cotopaxi, Cotopaxi Mining District, Fremont County, Colorado, USAi
Regional Level Types
Cotopaxi Pegmatite areaArea
CotopaxiResidential Area
Cotopaxi Mining DistrictMining District
Fremont CountyCounty
ColoradoState
USACountry

This page is currently not sponsored. Click here to sponsor this page.
PhotosMapsSearchMineralogy
00803550017272022844933.jpg
Geological Map

Cotopaxi Feldspar Mine, Cotopaxi Pegmatite area, Cotopaxi, Cotopaxi Mining District, Fremont County, Colorado, USA
09842060017272022841939.jpg
Quarry

Cotopaxi Feldspar Mine, Cotopaxi Pegmatite area, Cotopaxi, Cotopaxi Mining District, Fremont County, Colorado, USA
00359970017272022866377.jpg
Trench

Cotopaxi Feldspar Mine, Cotopaxi Pegmatite area, Cotopaxi, Cotopaxi Mining District, Fremont County, Colorado, USA
00803550017272022844933.jpg
Geological Map

Cotopaxi Feldspar Mine, Cotopaxi Pegmatite area, Cotopaxi, Cotopaxi Mining District, Fremont County, Colorado, USA
09842060017272022841939.jpg
Quarry

Cotopaxi Feldspar Mine, Cotopaxi Pegmatite area, Cotopaxi, Cotopaxi Mining District, Fremont County, Colorado, USA
00359970017272022866377.jpg
Trench

Cotopaxi Feldspar Mine, Cotopaxi Pegmatite area, Cotopaxi, Cotopaxi Mining District, Fremont County, Colorado, USA
09214460017272022911910.jpg
Geological Map

Cotopaxi Feldspar Mine, Cotopaxi Pegmatite area, Cotopaxi, Cotopaxi Mining District, Fremont County, Colorado, USA
09842060017272022841939.jpg
Quarry

Cotopaxi Feldspar Mine, Cotopaxi Pegmatite area, Cotopaxi, Cotopaxi Mining District, Fremont County, Colorado, USA
Latitude & Longitude (WGS84):
38° 24' 0'' North , 105° 40' 2'' West
Latitude & Longitude (decimal):
38.40001,-105.66725
GRN:
N26W60
Type:
Area
Köppen climate type:
BSk : Cold semi-arid (steppe) climate
Mindat Locality ID:
293111
Long-form identifier:
mindat:1:2:293111:4
GUID (UUID V4):
0


A area of Nb-Ta-REE-quartz-feldspar-mica pegmatite occurrences located NE-NNE of Cotopaxi, E of Bernard Creek in the Sand Gulch area, N of the Arkansas River. This is a general region of pegmatites, mostly feldspar, quartz, and mica, with some pegmatites having REE, niobium, and tantalum minerals.

Local rocks include granitic rocks of 1700-m.y. age group.

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

17 valid minerals. 1 erroneous literature entry.

Rock Types Recorded


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

Select Rock List Type

Alphabetical List Tree Diagram

Detailed Mineral List:

ⓘ Allanite-(Ce)
Formula: (CaCe)(AlAlFe2+)O[Si2O7][SiO4](OH)
ⓘ 'Allanite Group'
Formula: (A12+REE3+)(M13+M23+M32+)O[Si2O7][SiO4](OH)
ⓘ 'Biotite'
Formula: K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
ⓘ 'Columbite-(Fe)-Columbite-(Mn) Series'
ⓘ Epidote
Formula: (CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)
ⓘ Euxenite-(Y)
Formula: (Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6
ⓘ 'Feldspar Group'
ⓘ Fluorite
Formula: CaF2
ⓘ 'Gadolinite'
ⓘ Gadolinite-(Y)
Formula: Y2Fe2+Be2Si2O10
ⓘ Hematite
Formula: Fe2O3
ⓘ 'Hornblende Root Name Group'
Formula: ◻Ca2(C2+4C3+)(AlSi7O22)W2
ⓘ Kainosite-(Y)
Formula: Ca2Y2(SiO3)4(CO3) · H2O
ⓘ Kaolinite
Formula: Al2(Si2O5)(OH)4
ⓘ 'K Feldspar'
ⓘ Magnetite
Formula: Fe2+Fe3+2O4
ⓘ 'Mica Group'
ⓘ Microcline
Formula: K(AlSi3O8)
ⓘ Monazite-(Ce)
Formula: Ce(PO4)
Description: Reidentified as crytolite
ⓘ Muscovite
Formula: KAl2(AlSi3O10)(OH)2
ⓘ Muscovite var. Sericite
Formula: KAl2(AlSi3O10)(OH)2
Description: An alteration product of plagioclase.
ⓘ 'Plagioclase'
Formula: (Na,Ca)[(Si,Al)AlSi2]O8
ⓘ Quartz
Formula: SiO2
ⓘ Samarskite-(Y)
Formula: YFe3+Nb2O8
ⓘ Synchysite-(Y)
Formula: CaY(CO3)2F
ⓘ Uraninite
Formula: UO2
ⓘ 'Xenotime'
ⓘ Xenotime-(Y)
Formula: Y(PO4)
ⓘ Zircon
Formula: Zr(SiO4)
ⓘ Zircon var. Cyrtolite
Formula: Zr[(SiO4),(OH)4]

List of minerals arranged by Strunz 10th Edition classification

Group 3 - Halides
ⓘFluorite3.AB.25CaF2
Group 4 - Oxides and Hydroxides
ⓘMagnetite4.BB.05Fe2+Fe3+2O4
ⓘHematite4.CB.05Fe2O3
ⓘQuartz4.DA.05SiO2
ⓘSamarskite-(Y)4.DB.25YFe3+Nb2O8
ⓘEuxenite-(Y)4.DG.05(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6
ⓘUraninite4.DL.05UO2
Group 5 - Nitrates and Carbonates
ⓘSynchysite-(Y)5.BD.20cCaY(CO3)2F
Group 8 - Phosphates, Arsenates and Vanadates
ⓘXenotime-(Y)8.AD.35Y(PO4)
ⓘMonazite-(Ce) ?8.AD.50Ce(PO4)
Group 9 - Silicates
ⓘZircon9.AD.30Zr(SiO4)
ⓘvar. Cyrtolite9.AD.30Zr[(SiO4),(OH)4]
ⓘGadolinite-(Y)9.AJ.20Y2Fe2+Be2Si2O10
ⓘEpidote9.BG.05a(CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)
ⓘAllanite-(Ce)9.BG.05b(CaCe)(AlAlFe2+)O[Si2O7][SiO4](OH)
ⓘKainosite-(Y)9.CF.10Ca2Y2(SiO3)4(CO3) · H2O
ⓘMuscovite9.EC.15KAl2(AlSi3O10)(OH)2
ⓘvar. Sericite9.EC.15KAl2(AlSi3O10)(OH)2
ⓘKaolinite9.ED.05Al2(Si2O5)(OH)4
ⓘMicrocline9.FA.30K(AlSi3O8)
Unclassified
ⓘ'Biotite'-K(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
ⓘ'Feldspar Group'-
ⓘ'Xenotime'-
ⓘ'Mica Group'-
ⓘ'Columbite-(Fe)-Columbite-(Mn) Series'-
ⓘ'Hornblende Root Name Group'-◻Ca2(C2+4C3+)(AlSi7O22)W2
ⓘ'Plagioclase'-(Na,Ca)[(Si,Al)AlSi2]O8
ⓘ'K Feldspar'-
ⓘ'Gadolinite'-
ⓘ'Allanite Group'-(A12+REE3+)(M13+M23+M32+)O[Si2O7][SiO4](OH)

List of minerals for each chemical element

HHydrogen
Hⓘ Allanite-(Ce)(CaCe)(AlAlFe2+)O[Si2O7][SiO4](OH)
Hⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Hⓘ Epidote(CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)
Hⓘ Kainosite-(Y)Ca2Y2(SiO3)4(CO3) · H2O
Hⓘ KaoliniteAl2(Si2O5)(OH)4
Hⓘ MuscoviteKAl2(AlSi3O10)(OH)2
Hⓘ Zircon var. CyrtoliteZr[(SiO4),(OH)4]
Hⓘ Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
Hⓘ Allanite Group(A12+REE3+)(M13+M23+M32+)O[Si2O7][SiO4](OH)
BeBeryllium
Beⓘ Gadolinite-(Y)Y2Fe2+Be2Si2O10
CCarbon
Cⓘ Kainosite-(Y)Ca2Y2(SiO3)4(CO3) · H2O
Cⓘ Synchysite-(Y)CaY(CO3)2F
OOxygen
Oⓘ Allanite-(Ce)(CaCe)(AlAlFe2+)O[Si2O7][SiO4](OH)
Oⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Oⓘ Epidote(CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)
Oⓘ Euxenite-(Y)(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6
Oⓘ Gadolinite-(Y)Y2Fe2+Be2Si2O10
Oⓘ HematiteFe2O3
Oⓘ Kainosite-(Y)Ca2Y2(SiO3)4(CO3) · H2O
Oⓘ KaoliniteAl2(Si2O5)(OH)4
Oⓘ MagnetiteFe2+Fe23+O4
Oⓘ MicroclineK(AlSi3O8)
Oⓘ Monazite-(Ce)Ce(PO4)
Oⓘ MuscoviteKAl2(AlSi3O10)(OH)2
Oⓘ QuartzSiO2
Oⓘ Samarskite-(Y)YFe3+Nb2O8
Oⓘ Synchysite-(Y)CaY(CO3)2F
Oⓘ UraniniteUO2
Oⓘ Xenotime-(Y)Y(PO4)
Oⓘ ZirconZr(SiO4)
Oⓘ Zircon var. CyrtoliteZr[(SiO4),(OH)4]
Oⓘ Columbite-(Fe)-Columbite-(Mn) Series
Oⓘ Hornblende Root Name Group◻Ca2(C42+C3+)(AlSi7O22)W2
Oⓘ Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
Oⓘ Plagioclase(Na,Ca)[(Si,Al)AlSi2]O8
Oⓘ Allanite Group(A12+REE3+)(M13+M23+M32+)O[Si2O7][SiO4](OH)
FFluorine
Fⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Fⓘ FluoriteCaF2
Fⓘ Synchysite-(Y)CaY(CO3)2F
NaSodium
Naⓘ Plagioclase(Na,Ca)[(Si,Al)AlSi2]O8
MgMagnesium
Mgⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
AlAluminium
Alⓘ Allanite-(Ce)(CaCe)(AlAlFe2+)O[Si2O7][SiO4](OH)
Alⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Alⓘ Epidote(CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)
Alⓘ KaoliniteAl2(Si2O5)(OH)4
Alⓘ MicroclineK(AlSi3O8)
Alⓘ MuscoviteKAl2(AlSi3O10)(OH)2
Alⓘ Hornblende Root Name Group◻Ca2(C42+C3+)(AlSi7O22)W2
Alⓘ Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
Alⓘ Plagioclase(Na,Ca)[(Si,Al)AlSi2]O8
SiSilicon
Siⓘ Allanite-(Ce)(CaCe)(AlAlFe2+)O[Si2O7][SiO4](OH)
Siⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Siⓘ Epidote(CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)
Siⓘ Gadolinite-(Y)Y2Fe2+Be2Si2O10
Siⓘ Kainosite-(Y)Ca2Y2(SiO3)4(CO3) · H2O
Siⓘ KaoliniteAl2(Si2O5)(OH)4
Siⓘ MicroclineK(AlSi3O8)
Siⓘ MuscoviteKAl2(AlSi3O10)(OH)2
Siⓘ QuartzSiO2
Siⓘ ZirconZr(SiO4)
Siⓘ Zircon var. CyrtoliteZr[(SiO4),(OH)4]
Siⓘ Hornblende Root Name Group◻Ca2(C42+C3+)(AlSi7O22)W2
Siⓘ Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
Siⓘ Plagioclase(Na,Ca)[(Si,Al)AlSi2]O8
Siⓘ Allanite Group(A12+REE3+)(M13+M23+M32+)O[Si2O7][SiO4](OH)
PPhosphorus
Pⓘ Monazite-(Ce)Ce(PO4)
Pⓘ Xenotime-(Y)Y(PO4)
KPotassium
Kⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Kⓘ MicroclineK(AlSi3O8)
Kⓘ MuscoviteKAl2(AlSi3O10)(OH)2
Kⓘ Muscovite var. SericiteKAl2(AlSi3O10)(OH)2
CaCalcium
Caⓘ Allanite-(Ce)(CaCe)(AlAlFe2+)O[Si2O7][SiO4](OH)
Caⓘ Epidote(CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)
Caⓘ Euxenite-(Y)(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6
Caⓘ FluoriteCaF2
Caⓘ Kainosite-(Y)Ca2Y2(SiO3)4(CO3) · H2O
Caⓘ Synchysite-(Y)CaY(CO3)2F
Caⓘ Hornblende Root Name Group◻Ca2(C42+C3+)(AlSi7O22)W2
Caⓘ Plagioclase(Na,Ca)[(Si,Al)AlSi2]O8
TiTitanium
Tiⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Tiⓘ Euxenite-(Y)(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6
MnManganese
Mnⓘ Columbite-(Fe)-Columbite-(Mn) Series
FeIron
Feⓘ Allanite-(Ce)(CaCe)(AlAlFe2+)O[Si2O7][SiO4](OH)
Feⓘ BiotiteK(Fe2+/Mg)2(Al/Fe3+/Mg/Ti)([Si/Al/Fe]2Si2O10)(OH/F)2
Feⓘ Epidote(CaCa)(AlAlFe3+)O[Si2O7][SiO4](OH)
Feⓘ Gadolinite-(Y)Y2Fe2+Be2Si2O10
Feⓘ HematiteFe2O3
Feⓘ MagnetiteFe2+Fe23+O4
Feⓘ Samarskite-(Y)YFe3+Nb2O8
Feⓘ Columbite-(Fe)-Columbite-(Mn) Series
YYttrium
Yⓘ Euxenite-(Y)(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6
Yⓘ Gadolinite-(Y)Y2Fe2+Be2Si2O10
Yⓘ Kainosite-(Y)Ca2Y2(SiO3)4(CO3) · H2O
Yⓘ Samarskite-(Y)YFe3+Nb2O8
Yⓘ Synchysite-(Y)CaY(CO3)2F
Yⓘ Xenotime-(Y)Y(PO4)
ZrZirconium
Zrⓘ ZirconZr(SiO4)
Zrⓘ Zircon var. CyrtoliteZr[(SiO4),(OH)4]
NbNiobium
Nbⓘ Euxenite-(Y)(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6
Nbⓘ Samarskite-(Y)YFe3+Nb2O8
Nbⓘ Columbite-(Fe)-Columbite-(Mn) Series
CeCerium
Ceⓘ Allanite-(Ce)(CaCe)(AlAlFe2+)O[Si2O7][SiO4](OH)
Ceⓘ Euxenite-(Y)(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6
Ceⓘ Monazite-(Ce)Ce(PO4)
TaTantalum
Taⓘ Euxenite-(Y)(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6
ThThorium
Thⓘ Euxenite-(Y)(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6
UUranium
Uⓘ Euxenite-(Y)(Y,Ca,Ce,U,Th)(Nb,Ta,Ti)2O6
Uⓘ UraniniteUO2

Other Databases

Link to USGS MRDS:10009125

Localities in this Region

USA

Other Regions, Features and Areas containing this locality

North AmericaContinent
North America PlateTectonic Plate
USA

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

Hanley, J.B., Heinrich, E.W., Page, L.R. (1950) Pegmatite investigations in Colorado, Wyoming, and Utah, 1942-1944. Professional Paper 227. US Geological Survey doi:10.3133/pp227
(2005) Mineral Resources Data System (MRDS), US Geological Survey.
Quick NavTopCommoditiesMineral ListRock TypesOther DatabasesLocalities in RegionOther RegionsReferences
 
and/or  
Mindat.org® is an outreach project of the Hudson Institute of Mineralogy, a 501(c)(3) not-for-profit organization. Mindat® and mindat.org® are registered trademarks of the Hudson Institute of Mineralogy.
Copyright © mindat.org and the Hudson Institute of Mineralogy 1993-2026, except where stated. Most political location boundaries are © OpenStreetMap contributors. Mindat.org relies on the contributions of thousands of members and supporters. Founded in 2000 by Jolyon Ralph and Ida Chau.
Content on this site may not be used to train, fine-tune, or otherwise develop artificial intelligence or machine learning models without prior written permission - see our Terms & Conditions.
To cite: Ralph, J., Von Bargen, D., Martynov, P., Zhang, J., Que, X., Prabhu, A., Morrison, S. M., Li, W., Chen, W., & Ma, X. (2025). Mindat.org: The open access mineralogy database to accelerate data-intensive geoscience research. American Mineralogist, 110(6), 833–844. doi:10.2138/am-2024-9486.
Privacy Policy - Terms & Conditions - Contact Us / DMCA issues - Report a bug/vulnerability Current server date and time: October 22, 2026 12:42:28 Page updated: July 24, 2026 11:06:03
Go to top of page