This data release includes elemental analysis of soil samples collected at breccia-pipe uranium mines, at one undeveloped breccia-pipe uranium deposit, and at a reference site in northern Arizona. Samples were collected near the Arizona 1, Canyon, Kanab North, and Pinenut uranium mines, over the EZ2 breccia-pipe uranium deposit, and at the Little Robinson Tank reference site. Samples were collected around the Arizona 1 mine after active mining had ceased during July 2015; around and within the mine yard at the Canyon mine during mine-development activity and before active mining occurred in June 2013; around and within the mine yard at the Kanab North mine during reclamation and before reclamation was completed in June 2016; around the Pinenut mine during active mining in October 2014; directly over the EZ2 deposit before any development activity occurred during November 2015; and at the Little Robinson Tank reference site during November 2015. This data release includes data for four different types of soil samples: (type 1) incremental soil samples where more than 30 equally-spaced subsamples were collected and composited over a limited areal extent termed a decision unit and depicted generally as a trapezoidal-shaped polygon mapped within a mine yard, or surrounding a mine site; (type 2) incremental soil samples where more than 30 subsamples were collected and composited over a roughly two dimensional linear or sinuous mapped pattern following roads also termed a decision unit; (type 3) discrete integrated soil samples (Bern and others, 2019 use the term “point” for these samples) where more than 30 subsamples were collected within fenced exclosures (generally about 3 meters square) containing Big Springs Number Eight dust sampling equipment; and (type 4) integrated soil samples comprised of at least 10 subsamples collected from underneath plywood cover boards used to collect herpetofauna. Incremental samples (types 1 and 2) were collected in triplicate from the soil surface from 0-5 centimeters (cm) depth using a Multi-Incremental Sampling Tool (MIST) collecting approximately the same volume for each subsample subject to slight variation due to variable soil conditions. The volume of soil represented by each type 1 and 2 sample is termed a decision unit (DU), the areal extent of which is defined by a mapped polygonal or sinuous or linear area, and the depth of which is the 5 cm that is sampled by the MIST. Each subsample of each triplicate incremental sample was passed through a 2-millimeter sieve and composited into a clean 19-liter bucket, with each completed triplicate sample transferred to double zip-top bags for transfer to the laboratory. Integrated samples (types 3 and 4) were collected using a plastic soil scoop to collect soil from 0-5 cm depth and were composited into double zip-top plastic bags for transfer to the laboratory. Data are divided into two different data tables based upon type: types 1 and 2 are in T1_DUSamples.csv; types 3 and 4 are in T2_BSNESamples.csv. The file DataDictionary_v1.csv defines all table headings and abbreviations. Sample preparation and analytical techniques are described in the metadata file. This data release also includes location information for the approximate center points of the incremental sample polygons and linear features (decision units) and for the discrete integrated samples. Note, locations for incremental samples for decision units (sample types 1 and 2) are the approximate center of the geographical area (polygon, linear, or sinuous feature) over which the sample was collected. As such, the elemental values represent average concentrations for the sample volume collected over the entire geographic area and depth of 0-5 centimeters of each decision unit, and do not represent concentrations that would be measured in a discrete sample collected at that central location.

This data release includes elemental analysis of soil samples collected at breccia-pipe uranium mines, at one undeveloped breccia-pipe uranium deposit, and at a reference site in northern Arizona. Samples were collected near the Arizona 1, Canyon, Kanab North, and Pinenut uranium mines, over the EZ2 breccia-pipe uranium deposit, and at the Little Robinson Tank reference site. Samples were collected around the Arizona 1 mine after active mining had ceased during July 2015; around and within the mine yard at the Canyon mine during mine-development activity and before active mining occurred in June 2013; around and within the mine yard at the Kanab North mine during reclamation and before reclamation was completed in June 2016; around the Pinenut mine during active mining in October 2014; directly over the EZ2 deposit before any development activity occurred during November 2015; and at the Little Robinson Tank reference site during November 2015. This data release includes data for four different types of soil samples: (type 1) incremental soil samples where more than 30 equally-spaced subsamples were collected and composited over a limited areal extent termed a decision unit and depicted generally as a trapezoidal-shaped polygon mapped within a mine yard, or surrounding a mine site; (type 2) incremental soil samples where more than 30 subsamples were collected and composited over a roughly two dimensional linear or sinuous mapped pattern following roads also termed a decision unit; (type 3) discrete integrated soil samples (Bern and others, 2019 use the term “point” for these samples) where more than 30 subsamples were collected within fenced exclosures (generally about 3 meters square) containing Big Springs Number Eight dust sampling equipment; and (type 4) integrated soil samples comprised of at least 10 subsamples collected from underneath plywood cover boards used to collect herpetofauna. Incremental samples (types 1 and 2) were collected in triplicate from the soil surface from 0-5 centimeters (cm) depth using a Multi-Incremental Sampling Tool (MIST) collecting approximately the same volume for each subsample subject to slight variation due to variable soil conditions. The volume of soil represented by each type 1 and 2 sample is termed a decision unit (DU), the areal extent of which is defined by a mapped polygonal or sinuous or linear area, and the depth of which is the 5 cm that is sampled by the MIST. Each subsample of each triplicate incremental sample was passed through a 2-millimeter sieve and composited into a clean 19-liter bucket, with each completed triplicate sample transferred to double zip-top bags for transfer to the laboratory. Integrated samples (types 3 and 4) were collected using a plastic soil scoop to collect soil from 0-5 cm depth and were composited into double zip-top plastic bags for transfer to the laboratory. Data are divided into two different data tables based upon type: types 1 and 2 are in T1_DUSamples.csv; types 3 and 4 are in T2_BSNESamples.csv. The file DataDictionary_v1.csv defines all table headings and abbreviations. Sample preparation and analytical techniques are described in the metadata file. This data release also includes location information for the approximate center points of the incremental sample polygons and linear features (decision units) and for the discrete integrated samples. Note, locations for incremental samples for decision units (sample types 1 and 2) are the approximate center of the geographical area (polygon, linear, or sinuous feature) over which the sample was collected. As such, the elemental values represent average concentrations for the sample volume collected over the entire geographic area and depth of 0-5 centimeters of each decision unit, and do not represent concentrations that would be measured in a discrete sample collected at that central location.

Apatite [Ca5(PO4)3F], titanite [CaTiSiO5], and rutile [TiO2] samples were collected by the U.S. Geological Survey (USGS) from the Coles Hill uranium deposit, Virginia. The samples (in the form of polished thin sections) were prepared and analyzed for direct age dating on a laser ablation inductively coupled plasma mass spectrometer (LA–ICPMS) system at the USGS in Denver, Colorado from August 2017 to March 2019.

This data release includes solid and aqueous chemical data related to a set of sequential laboratory batch experiments conducted to test and simulate the mobility of trace elements as natural waters contact ore from breccia pipe uranium (BPU) deposits located in northern Arizona. The experiments made use of aquifer-related, sedimentary rocks collected specifically for this study and archival ore material (https://doi.org/10.5066/P9VM6GKF). Data provided on solid phase materials include elemental chemistry (file “Aquifer_related_rock_elemental_chemistry_final.csv ”) and quantitative mineralogy of the sedimentary rocks (file “Aquifer_related_rock_quantitative_mineralogy_final.csv”) used in the laboratory experiments. The sedimentary rock samples were collected from surface exposures in Grand Canyon National Park. Latitude, longitude, and geologic formation information are provided for each rock sample. Aqueous data were generated from laboratory leaching experiments conducted in U.S. Geological Survey laboratories in Boulder, Colorado (file “Aqueous_samples_final.csv”). The experiments consisted of five steps that involved reacting synthetic groundwater with a subset of the sedimentary rocks and different gas mixtures to simulate natural conditions and processes. Step 1 created artificial shallow groundwater in the Grand Canyon region. Step 2 created 2 different artificial mine waters. Step 3 mimicked mine water entering a downgradient anoxic environment and encountering aquifer-related rocks. Step 4 mimicked those waters entering an oxic environment. Step 5 mimicked additional oxidation of the water in the subsurface and additional contact with aquifer-related rocks. Sample preparation, analytical techniques, and quality controls are described in the metadata file. All table attributes and abbreviations are defined in the file “Data_Dictionary_final.csv” file.

This data release includes solid and aqueous chemical data related to a set of sequential laboratory batch experiments conducted to test and simulate the mobility of trace elements as natural waters contact ore from breccia pipe uranium (BPU) deposits located in northern Arizona. The experiments made use of aquifer-related, sedimentary rocks collected specifically for this study and archival ore material (https://doi.org/10.5066/P9VM6GKF). Data provided on solid phase materials include elemental chemistry (file “Aquifer_related_rock_elemental_chemistry_final.csv ”) and quantitative mineralogy of the sedimentary rocks (file “Aquifer_related_rock_quantitative_mineralogy_final.csv”) used in the laboratory experiments. The sedimentary rock samples were collected from surface exposures in Grand Canyon National Park. Latitude, longitude, and geologic formation information are provided for each rock sample. Aqueous data were generated from laboratory leaching experiments conducted in U.S. Geological Survey laboratories in Boulder, Colorado (file “Aqueous_samples_final.csv”). The experiments consisted of five steps that involved reacting synthetic groundwater with a subset of the sedimentary rocks and different gas mixtures to simulate natural conditions and processes. Step 1 created artificial shallow groundwater in the Grand Canyon region. Step 2 created 2 different artificial mine waters. Step 3 mimicked mine water entering a downgradient anoxic environment and encountering aquifer-related rocks. Step 4 mimicked those waters entering an oxic environment. Step 5 mimicked additional oxidation of the water in the subsurface and additional contact with aquifer-related rocks. Sample preparation, analytical techniques, and quality controls are described in the metadata file. All table attributes and abbreviations are defined in the file “Data_Dictionary_final.csv” file.

The risks to wildlife and humans from uranium (U) mining to the Grand Canyon watershed are largely unknown. In addition to U, other co-occurring ore constituents contribute to risks to biological receptors depending on their toxicological profiles. This data was collected to characterize the pre-mining concentrations of total arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), mercury (Hg), nickel (Ni), selenium (Se), thallium (Tl), U, and zinc (Zn); radiation levels; and histopathologies in biota (vegetation, invertebrates, amphibians, birds, and mammals) at the Canyon Mine.

The risks to wildlife and humans from uranium (U) mining to the Grand Canyon watershed are largely unknown. In addition to U, other co-occurring ore constituents contribute to risks to biological receptors depending on their toxicological profiles. This data was collected to characterize the pre-mining concentrations of total arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), mercury (Hg), nickel (Ni), selenium (Se), thallium (Tl), U, and zinc (Zn); radiation levels; and histopathologies in biota (vegetation, invertebrates, amphibians, birds, and mammals) at the Canyon Mine.

This data release compiles the electron microprobe spot analyses of U, Th, and Pb concentrations in uraninite (U oxide) particles, and corresponding calculated age determinations, measured in samples of ore from two uranium-copper breccia pipe ore bodies, the Canyon (Pinyon Plain) and Hack II deposits. The U-rich samples that were analyzed typify the deposits hosted by solution-collapse breccia pipes in the Grand Canyon region of northwestern Arizona. Applying procedures outlined by Bowles (1990), the U, Pb, and Th measurements from each spot analysis were used to calculate a model age for the formation of each uraninite particle. The U, Pb, and Th analyses and calculated age determinations are provided as additional information on the timing and origin of the uranium deposition within the unusual breccia pipe deposits of northwestern Arizona. One of the analyzed samples (CMCH-053-21A) was selected from drill core of a U-Cu ore body of the Canyon deposit, hosted in a solution-collapse breccia pipe. This deposit lies about 750 to 2,000 ft (230 to 610 m) below the surface about 6.1 miles (10 km) south-southeast of Tusayan, Arizona, at latitude 35.88333 North, longitude -112.09583 West (datum WGS 1984). Energy Fuels Inc., owner and operator of the property, conducted extensive drilling into the Canyon deposit, delineating the extent and uranium and copper content of the ore bodies (Mathisen and others, 2017). Mining facilities, including a shaft, have been developed by Energy Fuels at the deposit. The company renamed the Canyon mine as the “Pinyon Plain mine” in 2021. As of October 2021, they await favorable economic conditions to resume mining operations and recover the ore. An earlier-published data release (Van Gosen and others, 2020a) provides the geochemical analyses of 63 elements for 35 drill core samples of the Canyon deposit that were collected by the USGS. X-ray diffraction (XRD) analyses were performed on 28 of these samples to examine their mineralogy; the raw XRD data are provided in Van Gosen and others (2020a). In addition to the XRD analyses, ore mineralogy was also determined by examinations of thin sections of 21 of the ore samples using a scanning electron microscope equipped with an energy dispersive spectrometer (SEM-EDS). The mineralogical analyses are published in Van Gosen and others (2020c). The bulk geochemistry and mineralogy of Canyon deposit sample CHCH-053-21A, analyzed in this study, is provided in Van Gosen and others (2020a, 2020b). The geochemical and mineralogical analysis of ore samples collected from the Hack II deposit, also hosted by a solution-collapse breccia pipe, are published in another data release (Van Gosen and others, 2020b). That data release includes the bulk geochemistry and mineralogy of samples 84-HJW-12 and 84-HJW-3A, which were examined by this study. The Hack II deposit is one of four breccia pipes mined in Hack Canyon near its intersection with Robinson Canyon, approximately 30 miles (48 km) southwest of Fredonia and 9 miles (14.5 km) north-northwest of Kanab Creek, at latitude 36.58219 north, longitude -112.81059 west (datum of WGS84). Mining began at Hack II in 1981 and ended in May 1987. The USGS collected the samples from the Hack II mine in 1984 from underground exposures during active mining. The Canyon and Hack II deposits are representative of numerous other uranium deposits hosted by solution-collapse breccia pipes in the Grand Canyon region of northwest Arizona. These U-Cu deposits occur within matrix-supported, vertical columns of breccia (a "breccia pipe") that formed by solution and collapse of sedimentary strata (Wenrich, 1985; Alpine, 2010). The breccia pipes average about 300 ft (90 m) in diameter and can extend vertically for as much as 3,000 ft (900 m), from their base in the Mississippian Redwall Limestone to as stratigraphically high as the Triassic Chinle Formation. The regions north, south, and east of the Grand Canyon host hundreds of

The risks to wildlife and humans from uranium (U) mining to the Grand Canyon watershed are largely unknown. In addition to U, other co-occurring ore constituents contribute to risks to biological receptors depending on their toxicological profiles. This data was collected to characterize the pre-mining concentrations of total arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), mercury (Hg), nickel (Ni), selenium (Se), thallium (Tl), U, and zinc (Zn); radiation levels; and histopathologies in biota (vegetation, invertebrates, amphibians, birds, and mammals) at the Canyon Mine.

The risks to wildlife and humans from uranium (U) mining to the Grand Canyon watershed are largely unknown. In addition to U, other co-occurring ore constituents contribute to risks to biological receptors depending on their toxicological profiles. This data was collected to characterize the pre-mining concentrations of total arsenic (As), cadmium (Cd), copper (Cu), lead (Pb), mercury (Hg), nickel (Ni), selenium (Se), thallium (Tl), U, and zinc (Zn); radiation levels; and histopathologies in biota (vegetation, invertebrates, amphibians, birds, and mammals) at the Canyon Mine.