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:
Crooks Gap-Green Mountain District, Fremont Co., Wyoming, USA

Oldest recorded age at locality: 35.4
Youngest recorded age at locality: 27.6

mindat Locality ID: 7194
mindat URL: http://www.mindat.org/loc-7194.html

Tectonic Settings:

Total number of sublocalities beneath "Crooks Gap-Green Mountain District, Fremont Co., Wyoming, USA": 0
Total number of bottom-level sublocalities: 0

Latitude: 0°0'0"N
Longitude: 0°0'0"E
Decimal Degree (lat, lon): 0,0

A	This mineral is Anthropogenic.
G	This mineral is directly dated.
B	This mineral is reported as having this age.
Y	This mineral is using an age reported as an element mineralization period.
O	This mineral is using an age calculated from all data at the locality.
R	The age displayed for this mineral originates from a different, non-child locality.
P	The 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.

Autunite	Fluorite	Fritzscheite	None	Phosphuranylite	Zircon

Autunite ()*	Becquerelite ()*	Carnotite ()*	Coffinite ()*	Liebigite ()*
Metatyuyamunite ()*	Phosphuranylite ()*	Schröckingerite ()*	Tyuyamunite ()*	Uraninite ()*
Uranophane-α ()*

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: C Ca F H K Na O P S Si U V

Elements from minerals reported directly at this locality: C Ca F H K Na O P S Si U V

Structural Groups for minerals in this locality:
Autunite Fluorite Fritzscheite None Phosphuranylite Zircon

11 IMA Minerals at location:

Mineral name	Structural Groups	IMA Formula	Max Age (Ma)	Min Age (Ma)	# of localities containing mineral
Autunite ()*	Autunite	Ca(UO₂)₂(PO₄)₂·10-12H₂O	35.4	27.6	1272
Becquerelite ()*	None	Ca(UO₂)₆O₄(OH)₆·8H₂O	35.4	27.6	92
Carnotite ()*	None	K₂(UO₂)₂(VO₄)₂·3H₂O	35.4	27.6	1184
Coffinite ()*	Zircon	U(SiO₄)·nH₂O	35.4	27.6	566
Liebigite ()*	None	Ca₂(UO₂)(CO₃)₃·11H₂O	35.4	27.6	78
Metatyuyamunite ()*	Fritzscheite	Ca(UO₂)₂(VO₄)₂·3H₂O	35.4	27.6	129
Phosphuranylite ()*	Phosphuranylite	KCa(H₃O)₃(UO₂)₇(PO₄)₄O₄·8H₂O	35.4	27.6	182
Schröckingerite ()*	None	NaCa₃(UO₂)(SO₄)(CO₃)₃F·10H₂O	35.4	27.6	128
Tyuyamunite ()*	None	Ca(UO₂)₂(VO₄)₂·5-8H₂O	35.4	27.6	628
Uraninite ()*	Fluorite	UO₂	35.4	27.6	2718
Uranophane-α ()*	None	Ca(UO₂)₂(SiO₃OH)₂·5H₂O	35.4	27.6	890

Locality Notes from all Ages at Locality:

Age ID	Locality Notes
Giersdorf_00000871	Immature arkosic sandstones and conglomerates of the early Eocene Wind River Formation (in the Gas Hills) and Battle Spring Formation occurred in the early Eocene and between post-Miocene and Pleistocene time. The Crooks Gap district is structurally somewhat more complex. There the Battle Spring Formation is more folded and faulted, and dips from 10 to 20 degrees to the southeast. Thrust faults of Eocene age and normal faults of post-middle Eocene to Pliocene age occur within a few miles of the uranium deposits. Some pertinent aspects of the geologic history of the Gas Hills and Crooks Gap districts are: (1) Accumulation of the Wind River and Battle Spring Formation arkoses, conglomerates, and mudstones in early Eocene time. Volcanic ash from the Absaroka-Yellowstone province to the east was added to the western part of the Wind River basin. Climate at this time was tropical to subtropical. (2) Renewed uplift of the Granite Mountains in the late early Eocene, followed by stability in the middle Eocene. Volcanic centers in the nearby Rattlesnake Hills developed in the middle Eocene, with activity continuing through the late Eocene. (3) A major change in climate in the late Eocene early Oligocene from tropical-subtropical to more temperate. Uplift in the southern Wind River Range caused extensive erosion of middle Eocene rocks. (4) Accumulation of sediments rich in felsic ash (White River Formation) began in the early Oligocene, on an irregular surface of Eocene and older rocks. This accumulation continued until at least mid-Oligocene. (5) After an erosional interval, deposition of large volumes of tuffaceous sandstone occurred (Split Rock Formation of Miocene age). (6) Renewed crustal activity began in the early Pliocene, and a thick section of tuffaceous sandstone (Moonstone Formation) accumulated. Regional uplift beginning in the late Pliocene-early Pleistocene began the present cycle of erosion. In both districts the major uranium occurrences are in "roll-type" deposits where the uranium is concentrated in arcuate zones between relatively oxidized ("altered") and relatively reduced ("unaltered") sandstone. The uranium in such deposits is generally thought to have been transported as U6+ by oxygenated ground water traveling downdip in the host sandstone, and to have precipitated as insoluble U4+ minerals (uraninite and coffinite) along the slowly moving interface between oxidized and reduced ground. Typical gangue minerals are pyrite, marcasite, and calcite, with less common selenides and Mo-sulfides. The source of the uranium is a matter of dispute. The granitic rocks of the nearby Granite Mountains are known to have lost large amounts of uranium within the last few hundred million years, evidently in response to uplift and weathering and thus are a reasonable source material for the uranium. Also, most of the host sandstones of the uranium deposits are made up of detritus from such rocks, so that the host rocks themselves have been suggested as source rocks Alternatively, leaching of uranium from relatively U rich felsic ashes has been suggested as the most reasonable source of uranium. Tuffaceous materials in the Pliocene Split Rock Formation, the Miocene Moonstone Formation, and the Oligocene White River Formation and Wagon Bed Formation all have been suggested as possible uranium sources.
Giersdorf_00000872	Immature arkosic sandstones and conglomerates of the early Eocene Wind River Formation (in the Gas Hills) and Battle Spring Formation occurred in the early Eocene and between post-Miocene and Pleistocene time. The Crooks Gap district is structurally somewhat more complex. There the Battle Spring Formation is more folded and faulted, and dips from 10 to 20 degrees to the southeast. Thrust faults of Eocene age and normal faults of post-middle Eocene to Pliocene age occur within a few miles of the uranium deposits. Some pertinent aspects of the geologic history of the Gas Hills and Crooks Gap districts are: (1) Accumulation of the Wind River and Battle Spring Formation arkoses, conglomerates, and mudstones in early Eocene time. Volcanic ash from the Absaroka-Yellowstone province to the east was added to the western part of the Wind River basin. Climate at this time was tropical to subtropical. (2) Renewed uplift of the Granite Mountains in the late early Eocene, followed by stability in the middle Eocene. Volcanic centers in the nearby Rattlesnake Hills developed in the middle Eocene, with activity continuing through the late Eocene. (3) A major change in climate in the late Eocene early Oligocene from tropical-subtropical to more temperate. Uplift in the southern Wind River Range caused extensive erosion of middle Eocene rocks. (4) Accumulation of sediments rich in felsic ash (White River Formation) began in the early Oligocene, on an irregular surface of Eocene and older rocks. This accumulation continued until at least mid-Oligocene. (5) After an erosional interval, deposition of large volumes of tuffaceous sandstone occurred (Split Rock Formation of Miocene age). (6) Renewed crustal activity began in the early Pliocene, and a thick section of tuffaceous sandstone (Moonstone Formation) accumulated. Regional uplift beginning in the late Pliocene-early Pleistocene began the present cycle of erosion. In both districts the major uranium occurrences are in "roll-type" deposits where the uranium is concentrated in arcuate zones between relatively oxidized ("altered") and relatively reduced ("unaltered") sandstone. The uranium in such deposits is generally thought to have been transported as U6+ by oxygenated ground water traveling downdip in the host sandstone, and to have precipitated as insoluble U4+ minerals (uraninite and coffinite) along the slowly moving interface between oxidized and reduced ground. Typical gangue minerals are pyrite, marcasite, and calcite, with less common selenides and Mo-sulfides. The source of the uranium is a matter of dispute. The granitic rocks of the nearby Granite Mountains are known to have lost large amounts of uranium within the last few hundred million years, evidently in response to uplift and weathering and thus are a reasonable source material for the uranium. Also, most of the host sandstones of the uranium deposits are made up of detritus from such rocks, so that the host rocks themselves have been suggested as source rocks Alternatively, leaching of uranium from relatively U rich felsic ashes has been suggested as the most reasonable source of uranium. Tuffaceous materials in the Pliocene Split Rock Formation, the Miocene Moonstone Formation, and the Oligocene White River Formation and Wagon Bed Formation all have been suggested as possible uranium sources.

Age ID

Locality Notes

Giersdorf_00000871

Immature arkosic sandstones and conglomerates of the early Eocene Wind River Formation (in the Gas Hills) and Battle Spring Formation occurred in the early Eocene and between post-Miocene and Pleistocene time. The Crooks Gap district is structurally somewhat more complex. There the Battle Spring Formation is more folded and faulted, and dips from 10 to 20 degrees to the southeast. Thrust faults of Eocene age and normal faults of post-middle Eocene to Pliocene age occur within a few miles of the uranium deposits. Some pertinent aspects of the geologic history of the Gas Hills and Crooks Gap districts are: (1) Accumulation of the Wind River and Battle Spring Formation arkoses, conglomerates, and mudstones in early Eocene time. Volcanic ash from the Absaroka-Yellowstone province to the east was added to the western part of the Wind River basin. Climate at this time was tropical to subtropical. (2) Renewed uplift of the Granite Mountains in the late early Eocene, followed by stability in the middle Eocene. Volcanic centers in the nearby Rattlesnake Hills developed in the middle Eocene, with activity continuing through the late Eocene. (3) A major change in climate in the late Eocene early Oligocene from tropical-subtropical to more temperate. Uplift in the southern Wind River Range caused extensive erosion of middle Eocene rocks. (4) Accumulation of sediments rich in felsic ash (White River Formation) began in the early Oligocene, on an irregular surface of Eocene and older rocks. This accumulation continued until at least mid-Oligocene. (5) After an erosional interval, deposition of large volumes of tuffaceous sandstone occurred (Split Rock Formation of Miocene age). (6) Renewed crustal activity began in the early Pliocene, and a thick section of tuffaceous sandstone (Moonstone Formation) accumulated. Regional uplift beginning in the late Pliocene-early Pleistocene began the present cycle of erosion. In both districts the major uranium occurrences are in "roll-type" deposits where the uranium is concentrated in arcuate zones between relatively oxidized ("altered") and relatively reduced ("unaltered") sandstone. The uranium in such deposits is generally thought to have been transported as U6+ by oxygenated ground water traveling downdip in the host sandstone, and to have precipitated as insoluble U4+ minerals (uraninite and coffinite) along the slowly moving interface between oxidized and reduced ground. Typical gangue minerals are pyrite, marcasite, and calcite, with less common selenides and Mo-sulfides. The source of the uranium is a matter of dispute. The granitic rocks of the nearby Granite Mountains are known to have lost large amounts of uranium within the last few hundred million years, evidently in response to uplift and weathering and thus are a reasonable source material for the uranium. Also, most of the host sandstones of the uranium deposits are made up of detritus from such rocks, so that the host rocks themselves have been suggested as source rocks Alternatively, leaching of uranium from relatively U rich felsic ashes has been suggested as the most reasonable source of uranium. Tuffaceous materials in the Pliocene Split Rock Formation, the Miocene Moonstone Formation, and the Oligocene White River Formation and Wagon Bed Formation all have been suggested as possible uranium sources.

Giersdorf_00000872

2 Ages assigned to this locality:

	Excel ID	Max Age (Ma)	Min Age (Ma)	Age as listed in reference	Dating Method	Age Interpret	Prioritized?	Sample Source	Sample Num	Run Num	Age from other Locality	Dated Mineral	Minerals explicitely stated as having this age	Age applies to these Elements	MinDat Locality ID	Dated Locality (Max Age)	Location as listed in reference	Reference	Reference DOI	Reference ID	Age Notes
	Giersdorf_00000871	28	27.6	28-27.6				uraninite, coffinite, pyrite	CG-A5				Coffinite, Pyrite, Uraninite	U, Pb	7194	Crooks Gap-Green Mountain District, Fremont Co., Wyoming, USA	Crooks Gap	Ludwig (1979)	10.2113/gsecongeo.74.7.1654	EG74_1654	Ages are selected by the author of the paper as being one of the highest quality samples and most accurate ages. The Minimum ages are acquired from U235-Pb207, and the maximum ages are derived from a pyrite choncordia analysis
	Giersdorf_00000872	35.4	35.4	35.4				uraninite, coffinite, pyrite	CG-A8				Coffinite, Pyrite, Uraninite	U, Pb	7194	Crooks Gap-Green Mountain District, Fremont Co., Wyoming, USA	Crooks Gap	Ludwig (1979)	10.2113/gsecongeo.74.7.1654	EG74_1654	The age given for this sample is described as having a minimum age of 35.4 My and a maximum age of >35.4. Ages are selected by the author of the paper as being one of the highest quality samples and most accurate ages. The Minimum ages are acquired from U235-Pb207, and the maximum ages are derived from a pyrite choncordia analysis

Sample	Source Locality	Reference URL

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