Mineral Evolution Database
Created and maintained by the Mineral Evolution Project in partnership with RRUFF and mindat.
Mineral locality data provided by mindat.org



The Mineral Evolution database is currently under development.

The goal of this page is to present localities at which the mineral is found, and estimates of the oldest possible geologic age of the minerals at these localities.


Locality Name:
Lookout No. 22 Claim, Marshall Pass District, Saguache Co., Colorado, USA

Oldest recorded age at locality: 203
Youngest recorded age at locality: 94

mindat Locality ID: 30136
mindat URL: http://www.mindat.org/loc-30136.html

Tectonic Settings:

Total number of sublocalities beneath "Lookout No. 22 Claim, Marshall Pass District, Saguache Co., Colorado, USA": 0
Total number of bottom-level sublocalities: 0

Latitude: 38°23'40"N
Longitude: 106°17'3"W
Decimal Degree (lat, lon): 38.394444444444,-106.28416666667

AThis mineral is Anthropogenic.
GThis mineral is directly dated.
BThis mineral is reported as having this age.
YThis mineral is using an age reported as an element mineralization period.
OThis mineral is using an age calculated from all data at the locality.
RThe age displayed for this mineral originates from a different, non-child locality.
PThe age displayed for this mineral is the range of ages for this mineral at all of this locality's children.
This mineral's age has not yet been recorded.

This Mineral list contains entries from this locality, including sub-localities. Minerals in bold are reported by mindat.org as occurring directly at this locality, and do not occur at any children (sublocalities) of this locality.

Elements at this locality, including sub-localities: As Ca Cu Fe H K Na O P Pb S Sb Si U Zn 

Elements from minerals reported directly at this locality: As Ca Cu Fe H K Na O P Pb S Sb Si U Zn 

Structural Groups for minerals in this locality: 
AutuniteChalcopyriteCorundumCovelliteFluoriteMarcasiteMeta-autuniteNonePyriteRocksalt
SchoepiteSphaleriteTetrahedrite

22 IMA Minerals at location:
Autunite  (*)Becquerelite  (*)Boltwoodite  (*)Chalcocite  (*)Chalcopyrite  (*)
Covellite  (*)Fourmarierite  (*)Galena  (*)Hematite  (*)Ianthinite  (*)
Kasolite  (*)Marcasite  (*)Meta-autunite  (*)Metazeunerite  (*)Pyrite  (*)
Schoepite  (*)Soddyite  (*)Sphalerite  (*)Tetrahedrite-(Zn)  (*)Uraninite  (*)
Uranophane-α  (*)Zeunerite  (*)
Mineral nameStructural GroupsIMA FormulaMax Age (Ma)Min Age (Ma)# of Sublocalities containing mineralLOCALITY IDs, not mindat ids# of localities containing mineral
Autunite  (*)AutuniteCa(UO2)2(PO4)2·10-12H2O2039401272
Becquerelite  (*)NoneCa(UO2)6O4(OH)6·8H2O20394092
Boltwoodite  (*)None(K,Na)(UO2)(SiO3OH)·1.5H2O20394067
Chalcocite  (*)NoneCu2S2039405707
Chalcopyrite  (*)ChalcopyriteCuFeS220394027198
Covellite  (*)CovelliteCuS2039404165
Fourmarierite  (*)SchoepitePb1-xO3-2x(UO2)4(OH)4+2x·4H2O20394061
Galena  (*)RocksaltPbS20394024243
Hematite  (*)CorundumFe2O320394014640
Ianthinite  (*)NoneU4+2(UO2)4O6(OH)4·9H2O20394031
Kasolite  (*)NonePb(UO2)(SiO4)·H2O203940198
Marcasite  (*)MarcasiteFeS22039405674
Meta-autunite  (*)Meta-autuniteCa(UO2)2(PO4)2·6H2O203940388
Metazeunerite  (*)NoneCu(UO2)2(AsO4)2·8H2O203940182
Pyrite  (*)PyriteFeS220394039462
Schoepite  (*)Schoepite(UO2)4O(OH)6(H2O)620394094
Soddyite  (*)None(UO2)2(SiO4)(H2O)220394044
Sphalerite  (*)SphaleriteZnS20394021482
Tetrahedrite-(Zn)  (*)TetrahedriteCu6(Cu4Zn2)Sb4S132039405317
Uraninite  (*)FluoriteUO22039402718
Uranophane-α  (*)NoneCa(UO2)2(SiO3OH)2·5H2O203940890
Zeunerite  (*)AutuniteCu(UO2)2(AsO4)2·12H2O203940185



Locality Notes from all Ages at Locality:
Age IDLocality Notes
Giersdorf_00000794The Lookout claims are a set of 34 claims in Saguache Co., Colorado, in the Marshall Pass uranium district. The district is located about 12 miles southeast of Sargents and spans the Saguache and Gunnison counties. Two of the major ore bodies, including the Lookout 22 body in particular, were found in alluvium at an elevation of approximately 10,000 feet.
Giersdorf_00000795The Lookout claims are a set of 34 claims in Saguache Co., Colorado, in the Marshall Pass uranium district. The district is located about 12 miles southeast of Sargents and spans the Saguache and Gunnison counties. Two of the major ore bodies, including the Lookout 22 body in particular, were found in alluvium at an elevation of approximately 10,000 feet.
Giersdorf_00000796The Lookout claims are a set of 34 claims in Saguache Co., Colorado, in the Marshall Pass uranium district. The district is located about 12 miles southeast of Sargents and spans the Saguache and Gunnison counties. Two of the major ore bodies, including the Lookout 22 body in particular, were found in alluvium at an elevation of approximately 10,000 feet.


3 Ages assigned to this locality:

Excel IDMax Age (Ma)Min Age (Ma)Age as listed in referenceDating MethodAge InterpretPrioritized?Sample SourceSample NumRun NumAge from other LocalityDated MineralMinerals explicitely stated as having this ageAge applies to these ElementsMinDat Locality IDDated Locality (Max Age)Location as listed in referenceReferenceReference DOIReference IDAge Notes
Giersdorf_00000794949494202Pb-238UThe ages given are noted by the author to be insufficiently sourced as they are only derived from a single sample. The author expresses that more Marshall Pass uranium minerals should be dated to collect an average age for the set of deposits.uraninite   UraniniteAutunite, Boltwoodite, Chalcocite, Chalcopyrite, Covellite, Galena, Ianthinite, Marcasite, Metazeunerite, Pyrite, Schoepite, Soddyite, Sphalerite, Uraninite, ZeuneriteU30136Lookout No. 22 Claim, Marshall Pass District, Saguache Co., Colorado, USALookout No. 22 ClaimGross (1965) AM50_909Pb202-U238 age for a uraninite sample
Giersdorf_00000795999999207Pb-235UThe ages given are noted by the author to be insufficiently sourced as they are only derived from a single sample. The author expresses that more Marshall Pass uranium minerals should be dated to collect an average age for the set of deposits.uraninite   UraniniteAutunite, Boltwoodite, Chalcocite, Chalcopyrite, Covellite, Galena, Ianthinite, Marcasite, Metazeunerite, Pyrite, Schoepite, Soddyite, Sphalerite, Uraninite, ZeuneriteU30136Lookout No. 22 Claim, Marshall Pass District, Saguache Co., Colorado, USALookout No. 22 ClaimGross (1965) AM50_909Pb207-U235 age for a uraninite sample
Giersdorf_00000796203203203207Pb-206PbThe ages given are noted by the author to be insufficiently sourced as they are only derived from a single sample. The author expresses that more Marshall Pass uranium minerals should be dated to collect an average age for the set of deposits.uraninite   UraniniteAutunite, Boltwoodite, Chalcocite, Chalcopyrite, Covellite, Galena, Ianthinite, Marcasite, Metazeunerite, Pyrite, Schoepite, Soddyite, Sphalerite, Uraninite, ZeuneriteU30136Lookout No. 22 Claim, Marshall Pass District, Saguache Co., Colorado, USALookout No. 22 ClaimGross (1965) AM50_909Pb207-Pb206 age for a uraninite sample


SampleSource LocalityReference URL


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