Lost Creek In-Situ Recovery Project

Site Name

Primary: Lost Creek In-Situ Recovery Project
Secondary: DAR claims
Secondary: SAGE claims
Secondary: TONY claims
Secondary: Lost Creek ISR

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Commodity

Primary: Uranium

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Location

State: Wyoming
County: Sweetwater
District: Wyoming West Uranium Milling Region (GEIS, NRC 2009)

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Land Status

Land ownership: State
Note: the land ownership field only identifies whether the area the mine is in is generally on public lands like Forest Service or BLM land, or if it is in an area that is generally private property. It does not definitively identify property status, nor does it indicate claim status or whether an area is open to prospecting. Always respect private property.
Administrative Organization: (15%)

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Holdings

Not available

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Workings

Type: Underground

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Ownership

Owner Name: Ur-Energy
Home Office: Ur-Energy USA Inc 10758 W. Centennial Rd, Ste 200 Littleton, CO 80127 303-269-7755 or 866-981-4588 x 223
Info Year: 2011
Years: 2005 -

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Production

Not available

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Deposit

Record Type: Site
Operation Category: Prospect
Operation Type: Well
Mining Method: In Situ Leach
Years of Production:
Organization:
Significant: Y

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Physiography

Not available

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Mineral Deposit Model

Not available

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Orebody

Not available

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Structure

Not available

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Alterations

Not available

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Rocks

Not available

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Analytical Data

Not available

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Materials

Not available

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Comments

Comment (General): Dawn Schippe, our contact at Ur-Energy, has an invalid email address as of January, 2011. Last coresponded by email in Dec. 2009. Email was [email protected]

Comment (Location): Location supplied by Dawn Schippe, Ur-Energy USA, by email to A.B. Wilson, December 2009. NAD83, State Plane, West Central Zone. Northing 598055. Easting 2209622. These coordinates appear to be erroneous as they compute to 5.22 deg. north Lat, -89.75 W long.

Comment (Development): As of 2006, the property was "undeveloped but is covered by various drilling access roads" (Wallis, 2006, NI-43-101, p. 5, Section 2.0)

Comment (Location): (Wallis, 2006, NI-43-101, p. 6, Sec. 4.0.a): 201 unpatented lode claims and one state section lease totalling 4,220 acres. T25N R92 and T25N 93W. 42o 8' N and 107o 51' W

Comment (Deposit): From USNRC, 2009, p. 3-10 (p. 101 of 350): The age of mineralization in the Battle Spring Formation is considered to be between 35 and 26 million years before present. Uranium mineralization in the Basin generally occurs either as tabular or C-shaped roll-front deposits. Oxygen-rich ground water, carrying dissolved uranium, entered various sandstones in the Basin. The water percolated down dip, oxidizing the sandstones on its way down dip. Upon reaching sites rich in organic matter, the water lost its oxidizing potential and deposited the uranium, forming the two types of mineralization mentioned above. The presence of pyrite and carbonaceous material appear to be the major controlling factors for the precipitation of uranium mineralization. Thinning of sandstones and diminishing grain size probably slowed the advance of the uranium-bearing solutions and further enhanced the chances of precipitation in the location of the pumping tests. The applicant has stated that known mineralized intervals are found at depths ranging from near surface down to 350.5 m (1,150 ft) below the surface in the project area. It is possible that deeper mineralization may exist as well. The main mineralization horizons trend in an east14 northeast direction for at least 4.8 km (3 mi), and are up to 609.6 m (2,000 ft) wide. The thickness of individual mineralized beds at the project area ranges from five to 8.5 m (28 ft) and averages about 4.9 m (16 ft). The mineralization grade ranges from 0.03 percent to more than 0.20 percent equivalent uranium oxide (U3O8). Four main mineralized horizons, from depths of 106.6 to 182.8 m (350 to 600 ft), have been identified. The richest mineralized zone occurs in the middle part of the HJ Horizon (MHJ Sand) and it is about 9 m (30 ft) thick, 122 to 137 m (400 to 450 ft) deep, and is believed to contain more than 50 percent of the total resource under the project area.

Comment (Geology): From USNRC, 2009, p. 3-11 (p. 102 of 350): The geologic structure in the project area is rather simple. The Battle Spring Formation dips gently to the west at three degrees and only one fault (e.g., the Fault) was identified in the study area. The Fault has previously been identified as a ?scissor fault? that extends the length of the project area from the west-southwest to the east-northeast. A scissor fault is a fault in which the offset or displacement of the formations on either side of the fault increases in one direction from an initial point along and decreases in the other direction. However, the applicant (LCI) has recently indicated that the Fault may not actually be a scissors fault and that it may be eventually be reclassified. The Fault was initially interpreted to be a scissor fault, with a reversal of displacement direction occurring in the western third of the Permit Area. Recent interpretation has revealed that it is, instead, a sequence of sub-parallel faults with opposite displacement occurring in an en echelon configuration. The fault runs through the mineralized area that is intended for mining, and solution mining is planned on both sides of the fault. As a result, the sandstones and alternating confining layers in the mining zone are off-set and not continuous through the mining area. The maximum displacement at the west end of the project area is around 13.7 m (45 ft), dropping down to the north; whereas the displacement on the east side of the project area is about 24 m (80 ft) the down-dropped side to the south, creating the scissor fault.

Comment (Geology): From USNRC, 2009, p. 3-8 (p. 99 of 350): The Crooks Gap Uranium District is located in the Great Divide Basin, an oval-shaped structural depression, encompassing some 8,960 km2 (3,500 mi2) in south-central Wyoming (GEIS, NRC 2009). The project area is located near the north-central part of the basin. The Basin is bounded on the north by the Green and Granite Mountains, on the east by the Rawlins Uplift, on the south by the Wamsutter Arch and on the west by the Rock Springs Uplift. The dominant source of sediment in the Great Divide Basin was Precambrian (greater than 540-million-year-old) granitic rock of the Sweetwater Arch. Uplift of the Sweetwater Arch began to affect sedimentation in the adjacent Great Divide Basin in the Late Cretaceous tine (65 to 99 million years ago). Rapidly subsiding portions of the Basins received thick clastic wedges of predominant arkosic sediments, while more slowly subsiding portions of the basin received a greater portion of paludal (marsh) and lacustrine (lake) sediments. Sediment transported southward into the Great Divide Basin was deposited on an apron of alluvial fans. One of the major fans is centered near the Crooks Gap Uranium District. Deposition within the basins probably continued through the Miocene (5.3 to 23.8 million-year-old), but post-Miocene erosion has completely removed the Oligocene and Miocene units. The formation hosting the major sandstone-type uranium deposits in the Great Divide Basin is the Battle Spring Formation. The Battle Spring Formation outcrops (surfaces) occur throughout the study area. Thus, the Battle Spring Formation lies at the surface of most of the project area, although thin deposits of Quaternary (as old as 2.6 million years) sediments are present within surface drainages in the project area. Generally, in the Great Divide Basin, Battle Spring and Wasatch Formations, which were deposited at equivalent times, inter-finger with one another. In the project area, the upper half of the lithologic units (rock units grouped according to similarity in characteristics such as color, mineralogic composition, and grain size) consists of Battle Spring Formation and the lower half is made up of Wasatch Formation. The applicant indicates that the total thickness of the Battle Spring and Wasatch Formations under the project area is about 1,890 m (6,200 ft). The Fort Union Formation is 1,417 m (4,650 ft) thick beneath the project area and unconformably underlies the Battle Spring/Wasatch Formations. Deeper in the Basin and lying unconformably are various Cretaceous, Jurassic, Triassic, Paleozoic, and Precambrian basement lithologic units (LCI, 2008b). A schematic geologic cross section across the project area is shown in Figure 3-4 depicting the entire lithologic units that are present under the project area (LCI, 2008b). As indicated by the applicant, the Battle Spring Formation in the project area is part of a major alluvial system, consisting of thick beds of very fine- to coarse-grained arkosic sandstones separated by various layers of mudstones and siltstones. Conglomerate beds may exist locally. The uranium mineralization is associated with finer-grained sandstones and siltstones, which may contain minor organic matter in a few areas. The upper portion of the Battle Spring Formation is host to the uranium mineralization in the project area.

Comment (Deposit): From USNRC, 2009, p. 3-10 to 3-11 (p. 101-102 of 350): In the project area, the top 213 m (700 ft) of the Battle Spring Formation is divided by the applicant into at least five horizons marked from top to bottom as BC, DE, FG, HJ, and KM (see Figure 3-4). These horizons are sandstone layers separated from one another by various thicknesses of shale, mudstone and siltstone. Each of these sandstones may themselves contain some shale, mudstone, and/or siltstone lenses. The two horizons with most mineralization, the HJ and the KM, have been divided into upper, middle and lower sub-units of these sandstones (UHJ Sand, MHJ Sand, and LHJ Sand; and UKM Sand, MKM Sand, and LKM Sand). The primary uranium production zone is identified as the HJ horizon, although the KM horizon may be considered for mining at a later date. The HJ horizon is bounded above and below by extensive confining units identified as the Lost Creek Shale and the Sage Brush Shale, respectively. While these shales are aerially extensive, large sections of the Sage Brush Shale are less than 3.4 m (10 ft) thick in the proposed mine area, and several areas of the Lost Creek Shale are less than 3.4 m (10 ft) thick in the proposed project area. The FG sand directly overlies the Lost Creek Shale and the KM Sand directly underlies the Sage Brush Shale. The FG and DM sands are also composed of multiple sand units that are separated by discontinuous shales, mudstones, or siltstones. In a manner similar to HJ Horizon, the FG and KM Sands have been divided by the applicant into upper, middle, and lower subunits (UFG, MFG, LFG, UKM, MKM, and LKM). Geological cross sections through the mineralized zones in the project area are presented in Plates 2.6-1a, b, c, d, and e of the ER (LCI, 2008a). Thickness (isopach) maps of the HJ Horizon and UKM Sand, as well as the shales above HJ (Lost Creek Shale) and below HJ (Sage Brush Shale), are presented in Plates 2.6-2a, b, c, and d of the ER (LCI, 2008a). The top of the HJ Horizon ranges from approximately 116 to 153 m (340 to 450 ft) below ground surface (bgs). The HJ Horizon is 37 to 44.3 m (110 to 130 ft) thick, averaging about 41 m (120 ft). The thinner part of HJ is generally south of the Fault (see below). A thicker part of the HJ Horizon runs parallel to the Fault. The mineralization is mostly concentrated in the middle part of the HJ Horizon and occurs as both roll front and tabular deposits. The subdivided sand units within the HJ horizon are separated by discontinuous shale, siltstone, and mudstone. The total thickness of the overlying FG Horizon is approximately 30 m (100 ft). The top of the FG Horizon occurs at depths approximately 61 m to 76 ft (200 to 250 ft) on the north side of the Fault and 91 to 107 m (300 to 350 ft) bgs on the south side of the fault within the project area. Directly underlying the Sage Brush Shale, the UKM Sand is typically 9 m to 18 m (30 to 60 ft) thick but can reach over 23 m (75 ft) in thickness. The top of the UKM Sand is usually between 137 and 183 m (450 and 600 ft) bgs within the project area.

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References

Reference (Deposit): http://www.ur-energy.com/lost-creek/
URL: http://www.ur-energy.com/lost-creek/

Reference (Deposit): U.S. Nuclear Regulatory Commission, 2009, Environmental impact statement for the Lost Creek ISR Project in Sweetwater County, Wyoming--Supplement to the generic environmental impact statement for in-situ leach uranium milling facilities: U.S. Nuclear Regulatory Commission NUREG-1910, Supplement 3, 350 p. available at http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1910/s3/
URL: http://www.nrc.gov/reading-rm/doc-collections/nuregs/staff/sr1910/s3/

Reference (Deposit): Gregory, R.W., Jones, R.W., Cottingham, K.D., 2010, Uranium map of Wyoming: Wyoming State Geological Survey Map Series 94, scale 1:500,000.

Reference (Deposit): Wallis, C.S., 2006, Technical report on the Lost Creek Project, Wyoming: Prepared for Ur-Energy by Roscoe Postle Associates Inc., June 15, 2006. [Filed with www.Sedar.com July 14, 2006.]

Reference (Deposit): Kyle, J.I., and Maxwell, D.K., 2008, NI-43-101 preliminary assessment for the Lost Creek Project, Sweetwater County, Wyoming: Prepared for Ur-Energy by Lyntek Inc., April 2, 2008. [Filed with www.Sedar.com April 7, 2008.] http://www.sedar.com/GetFile.do?lang=EN&docClass=24&issuerNo=00021840&fileName=/csfsprod/data88/filings/01245570/00000001/C%3A%5CMyFiles%5CUr-Energy%5CFinal-Report.pdf
URL: http://www.sedar.com/GetFile.do?lang=EN&docClass=24&issuerNo=00021840&fileName=/csfsprod/data88/filings/01245570/00000001/C%3A%5CMyFiles%5CUr-Energy%5CFinal-Report.pdf

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