This data release includes new major and trace element geochemical data acquired by the U.S. Geological Survey (USGS) for igneous rocks in the Cripple Creek district in Colorado. Cripple Creek is among the largest epithermal districts in the world, with more than 800 metric tons (t) Au (>26.4 Moz). The ores are associated spatially, temporally, and genetically with ~34 to 28 Ma alkaline igneous rocks that were emplaced into an 18 km2- diatreme complex and surrounding Proterozoic rocks (Kelley and others, 2020). Igneous rocks associated with Cripple Creek are part of a regionally extensive episode of Oligocene alkaline magmatism that extended southward along the axis of the Rio Grande rift through New Mexico and into the Trans Pecos region of Texas and northern Mexico (McLemore, 1996; Kelley and Ludington, 2002). The deposits at Cripple Creek are known as alkalic-type gold deposits, but they have been referred to as alkalic-related and Great Plains margin deposits in previous literature (McLemore, 1996). Many of the deposits in this class are enriched in critical elements, the most common of which is tellurium (Kelley and Spry, 2016). However, not all deposits are characterized by enriched tellurium concentrations. Cripple Creek is highly enriched, whereas other deposits in New Mexico are less enriched. The objective of the USGS study was to characterize the tellurium contents (and other trace elements) of predominantly unaltered alkaline igneous rocks that are genetically associated with mineralization in order to better understand possible source(s) and mechanism of enrichment of tellurium in these systems. This data release provides the analytical results of 25 rock hand samples collected by USGS geologists in collaboration with the New Mexico Bureau of Geology and Mineral Resources (NMBGMR) during site visits to Cripple Creek in 1989, 2015, and 2016. In addition, 50 samples collected in 2013 by Anne Rahfeld (Rahfeld, 2013) were submitted and analyzed by the USGS. The mapped rock units from which the samples were collected are described in Wobus and others (1976) and brief descriptions of rock types are given in Kelley and others (1998). Several analytical methods were used and include 55 major and trace elements using inductively coupled plasma-atomic emission spectrometry (ICP-AES) and 42 elements using inductively coupled plasma-atomic emission spectrometry (ICP-AES). Some samples were also analyzed for major elements using wavelength dispersive x-ray fluorescence spectrometry (WDXRF), for Au by fire assay ICP-MS and Au and PGE by fire assay.

This data release contains the whole-rock major and trace element analyses of 51 samples of intrusive igneous rocks from the Wet Mountains area of Custer and Fremont counties of south-central Colorado, collected by U.S. Geological Survey (USGS) geologists. The samples were collected from breccias, veins and thin dikes, and a variety of carbonatite, felsic, mafic, and ultramafic intrusions across the area. The first 41 samples listed in this data release were collected in July 2007, originally as part of a reconnaissance study of the thorium deposits of the area (Van Gosen and others, 2009). The samples are grab samples from outcrops, shallow open-pit excavations, and mineral prospect trenches. The last 10 samples listed in this data release were originally collected and geochemically analyzed in 1976 as part of a USGS study of carbonatites in this area (Armbrustmacher, 1976, 1979; Armbrustmacher and Brownfield, 1978). These 10 carbonatite samples were reanalyzed by modern analytical methods in 2007, and the new data are included in this data release. The Wet Mountains area hosts a variety of alkaline intrusions (Armbrustmacher, 1984), which includes three Cambrian-age alkaline complexes (Olson and others, 1977) that intruded the surrounding Precambrian terrane. These are (1) the McClure Mountain Complex (Shawe and Parker, 1967; Armbrustmacher, 1984), (2) the Gem Park Complex (Parker and Sharp, 1970), and (3) the complex at Democrat Creek (Armbrustmacher, 1984). In the Wet Mountains area, elevated concentrations of thorium and rare earth elements (REEs) occur in veins, syenite dikes, fracture zones, breccias, and carbonatite dikes (Armbrustmacher, 1988). These thorium-REE deposits are distal to the alkaline complexes but are thought to be genetically associated. Characteristics of the thorium and REE deposits in the area, as well as typical concentrations and resource estimates, are detailed in the publications listed in the supplementary file “Wet Mountains area publications.pdf”. Armbrustmacher (1988) determined that vein and fracture zone deposits contain most of the thorium and REE resources in the area. These are linear features, typically 1–2 meters thick, but a few are as much as 15 meters thick. Some individual thorium veins can be traced in outcrop for 1,500 m and some radioactive fracture zones for as much as 13 kilometers. Most of these vein- and fracture-zone deposits occur within a 57 square kilometers tract of Precambrian gneiss and migmatite (Scott and others, 1976) located south and southeast of the quartz syenite complex at Democrat Creek; in this area Christman and others (1953, 1959) mapped nearly 400 veins. Most of the samples in this data release are examples of unaltered alkaline igneous rocks of the intrusive complexes rather than the mineral deposits. These samples were selected in the field to study possible relationships between the magmatic complexes and the thorium-REE deposits. All samples included in this data release were analyzed by laboratories contracted by the USGS. Major and trace element concentrations were determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES) and inductively coupled plasma-mass spectrometry (ICP-MS). An acceptable criteria for the data has been identified based on (1) if recovery of each element is within a designated percentage at five times the lower limit of determination, and (2) the calculated relative standard deviation of duplicate samples is no greater than that percentage. The reported laboratory percentages for the acceptance criteria are +/- 15 percent for ICP-AES and ICP-MS. Ten carbonatite samples were additionally analyzed by wavelength dispersive X-ray fluorescence (WDXRF) to determine the concentrations of major elements as oxides. The reported laboratory percentages for the acceptance criteria are +/- 5 percent for WDXRF. Data are reported in a comma-separated values (CSV) file that lists the samples that were analyzed,

This data release contains the whole-rock major and trace element analyses of 51 samples of intrusive igneous rocks from the Wet Mountains area of Custer and Fremont counties of south-central Colorado, collected by U.S. Geological Survey (USGS) geologists. The samples were collected from breccias, veins and thin dikes, and a variety of carbonatite, felsic, mafic, and ultramafic intrusions across the area. The first 41 samples listed in this data release were collected in July 2007, originally as part of a reconnaissance study of the thorium deposits of the area (Van Gosen and others, 2009). The samples are grab samples from outcrops, shallow open-pit excavations, and mineral prospect trenches. The last 10 samples listed in this data release were originally collected and geochemically analyzed in 1976 as part of a USGS study of carbonatites in this area (Armbrustmacher, 1976, 1979; Armbrustmacher and Brownfield, 1978). These 10 carbonatite samples were reanalyzed by modern analytical methods in 2007, and the new data are included in this data release. The Wet Mountains area hosts a variety of alkaline intrusions (Armbrustmacher, 1984), which includes three Cambrian-age alkaline complexes (Olson and others, 1977) that intruded the surrounding Precambrian terrane. These are (1) the McClure Mountain Complex (Shawe and Parker, 1967; Armbrustmacher, 1984), (2) the Gem Park Complex (Parker and Sharp, 1970), and (3) the complex at Democrat Creek (Armbrustmacher, 1984). In the Wet Mountains area, elevated concentrations of thorium and rare earth elements (REEs) occur in veins, syenite dikes, fracture zones, breccias, and carbonatite dikes (Armbrustmacher, 1988). These thorium-REE deposits are distal to the alkaline complexes but are thought to be genetically associated. Characteristics of the thorium and REE deposits in the area, as well as typical concentrations and resource estimates, are detailed in the publications listed in the supplementary file “Wet Mountains area publications.pdf”. Armbrustmacher (1988) determined that vein and fracture zone deposits contain most of the thorium and REE resources in the area. These are linear features, typically 1–2 meters thick, but a few are as much as 15 meters thick. Some individual thorium veins can be traced in outcrop for 1,500 m and some radioactive fracture zones for as much as 13 kilometers. Most of these vein- and fracture-zone deposits occur within a 57 square kilometers tract of Precambrian gneiss and migmatite (Scott and others, 1976) located south and southeast of the quartz syenite complex at Democrat Creek; in this area Christman and others (1953, 1959) mapped nearly 400 veins. Most of the samples in this data release are examples of unaltered alkaline igneous rocks of the intrusive complexes rather than the mineral deposits. These samples were selected in the field to study possible relationships between the magmatic complexes and the thorium-REE deposits. All samples included in this data release were analyzed by laboratories contracted by the USGS. Major and trace element concentrations were determined by inductively coupled plasma-atomic emission spectrometry (ICP-AES) and inductively coupled plasma-mass spectrometry (ICP-MS). An acceptable criteria for the data has been identified based on (1) if recovery of each element is within a designated percentage at five times the lower limit of determination, and (2) the calculated relative standard deviation of duplicate samples is no greater than that percentage. The reported laboratory percentages for the acceptance criteria are +/- 15 percent for ICP-AES and ICP-MS. Ten carbonatite samples were additionally analyzed by wavelength dispersive X-ray fluorescence (WDXRF) to determine the concentrations of major elements as oxides. The reported laboratory percentages for the acceptance criteria are +/- 5 percent for WDXRF. Data are reported in a comma-separated values (CSV) file that lists the samples that were analyzed,

This data release contains analytical data and images for a suite of drill core samples from the Mineral Hill alkaline complex (MHAC), northeastern Wyoming. Geochemistry data include major and trace element analytical results for 103 alkaline igneous rock samples. Images include hand sample photographs of halved core and full thin section images captured in transmitted, plane-polarized and cross-polarized light. Samples are from two core holes drilled by Humble Oil Company in 1970, and subsequently acquired and stored by Felix Mutschler at Eastern Washington University. The two skeletonized (incomplete) drill cores were acquired by the U.S. Geological Survey Geology, Minerals, Energy, and Geophysics Spokane office in 2019, through a co-operative agreement with Eastern Washington University. The collection contains full-core pieces from select intervals representative of the different lithologies and textures in the complex. Mineral Hill is a Paleogene-age, ring-shaped, multi-phase alkaline (miaskitic) igneous complex that intrudes Precambrian schists and lower Paleozoic units of the Tinton uplift on the northwest flank of the broader Black Hills uplift (Welch, 1974; Ray, 1979). The outer ring of the complex is composed of foid syenite and compositionally similar rocks, whereas clinopyroxenite (jacupirangite) and other foid-bearing mafic rocks (ijolite and melteigite) form an irregular inner ring. The center of the complex is composed of a central feldspathic diatreme breccia pipe that exhibits pervasive potassic and sulfidic alteration (DeWitt and others, 1986). Alkali feldspar trachyte/latite porphyry is exposed as large masses in a steep-walled, columnar-jointed zone peripheral to foid syenite of the Mineral Hill dome and as high-angle sills within the central area (Ray, 1979). Alkalic lamprophyres throughout the complex are thought to be related to clinopyroxenite and may have formed from a volatile-rich fraction of the pyroxenite magma (Ray 1979). Pseudoleucite porphyry and melteigite/feldspathic ijolite may be variations of foid syenite and foid clinopyroxenite, respectively. Historic mineral production in the area occurred between the 1870s and 1930s: principally alluvial gold, gold and silver at the Treadwell Mine, and gold and copper at the Interocean Mine. Exploration since 2000 has shown that gold and silver at the Treadwell Mine is related to epithermal-style mineralization and adularia-bearing potassic alteration (Eurasian Minerals Inc., 2016). Higher temperature, porphyry-style potassic alteration associated with gold and copper was identified near the Interocean Mine. Investigations of critical mineral potential in the area have focused on Precambrian pegmatites in the Tinton district which produced some cassiterite (Sn) and tantalite-columbite (Ta) ore, and the Spotted Tail and Sand Creek gold placers which produced some cassiterite (Sn) (Smith and Page, 1941; Hausel, 1990). The critical mineral potential of Paleogene intrusive rocks of the Mineral Hill complex has received comparatively little attention. All samples were analyzed by the U.S. Geological Survey contract laboratory, AGAT Laboratories. Major and trace element concentrations were determined by wavelength dispersive X-ray fluorescence, inductively coupled plasma-optical emission spectrometry or inductively coupled plasma-mass spectrometry (ICP-MS). Additional analytical methods included determination of carbonate carbon by combustion and infrared detection (IR); gold, platinum and palladium by lead fusion fire assay and ICP-MS; fluoride by ion-selective electrode; ferrous iron by titration; non-essential and essential water by gravimetric methods; total sulfur by IR; and gold and platinum group elements by nickel sulfide fire-assay followed by instrumental neutron activation analysis. For each method outlined above, an acceptable criteria for the data has been identified based on 1) if recovery of each element is within a designated percentage at

This data release contains analytical data and images for a suite of drill core samples from the Mineral Hill alkaline complex (MHAC), northeastern Wyoming. Geochemistry data include major and trace element analytical results for 103 alkaline igneous rock samples. Images include hand sample photographs of halved core and full thin section images captured in transmitted, plane-polarized and cross-polarized light. Samples are from two core holes drilled by Humble Oil Company in 1970, and subsequently acquired and stored by Felix Mutschler at Eastern Washington University. The two skeletonized (incomplete) drill cores were acquired by the U.S. Geological Survey Geology, Minerals, Energy, and Geophysics Spokane office in 2019, through a co-operative agreement with Eastern Washington University. The collection contains full-core pieces from select intervals representative of the different lithologies and textures in the complex. Mineral Hill is a Paleogene-age, ring-shaped, multi-phase alkaline (miaskitic) igneous complex that intrudes Precambrian schists and lower Paleozoic units of the Tinton uplift on the northwest flank of the broader Black Hills uplift (Welch, 1974; Ray, 1979). The outer ring of the complex is composed of foid syenite and compositionally similar rocks, whereas clinopyroxenite (jacupirangite) and other foid-bearing mafic rocks (ijolite and melteigite) form an irregular inner ring. The center of the complex is composed of a central feldspathic diatreme breccia pipe that exhibits pervasive potassic and sulfidic alteration (DeWitt and others, 1986). Alkali feldspar trachyte/latite porphyry is exposed as large masses in a steep-walled, columnar-jointed zone peripheral to foid syenite of the Mineral Hill dome and as high-angle sills within the central area (Ray, 1979). Alkalic lamprophyres throughout the complex are thought to be related to clinopyroxenite and may have formed from a volatile-rich fraction of the pyroxenite magma (Ray 1979). Pseudoleucite porphyry and melteigite/feldspathic ijolite may be variations of foid syenite and foid clinopyroxenite, respectively. Historic mineral production in the area occurred between the 1870s and 1930s: principally alluvial gold, gold and silver at the Treadwell Mine, and gold and copper at the Interocean Mine. Exploration since 2000 has shown that gold and silver at the Treadwell Mine is related to epithermal-style mineralization and adularia-bearing potassic alteration (Eurasian Minerals Inc., 2016). Higher temperature, porphyry-style potassic alteration associated with gold and copper was identified near the Interocean Mine. Investigations of critical mineral potential in the area have focused on Precambrian pegmatites in the Tinton district which produced some cassiterite (Sn) and tantalite-columbite (Ta) ore, and the Spotted Tail and Sand Creek gold placers which produced some cassiterite (Sn) (Smith and Page, 1941; Hausel, 1990). The critical mineral potential of Paleogene intrusive rocks of the Mineral Hill complex has received comparatively little attention. All samples were analyzed by the U.S. Geological Survey contract laboratory, AGAT Laboratories. Major and trace element concentrations were determined by wavelength dispersive X-ray fluorescence, inductively coupled plasma-optical emission spectrometry or inductively coupled plasma-mass spectrometry (ICP-MS). Additional analytical methods included determination of carbonate carbon by combustion and infrared detection (IR); gold, platinum and palladium by lead fusion fire assay and ICP-MS; fluoride by ion-selective electrode; ferrous iron by titration; non-essential and essential water by gravimetric methods; total sulfur by IR; and gold and platinum group elements by nickel sulfide fire-assay followed by instrumental neutron activation analysis. For each method outlined above, an acceptable criteria for the data has been identified based on 1) if recovery of each element is within a designated percentage at

This U.S. Geological Survey (USGS) data release contains data from stream water, groundwater, and soil samples collected in 2019 and 2020 in the North Quartz Creek watershed in central Colorado. Fourteen streambank wells were installed in pairs at seven locations in August 2020 to capture the emerging groundwater from the left bank and right banks (relative to downstream-facing direction) and a synoptic sampling campaign was conducted to quantify metal contributions to the stream. A continuous, instream injection of sodium bromide (NaBr) was initiated at the head of the 5 km study reach several days prior to the synoptic sampling campaign and maintained throughout the duration of the study. Bromide concentrations were subsequently used to determine streamflow in the primary study reach (upper 1.3 km) using the tracer-dilution method, and as an indicator of hydrologic connections between North Quartz Creek and subsurface water. Streamflow was quantified in a secondary study reach (lower 3.7 km) using data from a series of sodium chloride slug additions wherein specific conductivity readings were used as a surrogate for the tracer concentration. Surface water samples were collected along North Quartz Creek including inflows from the left (LBI) and right (RBI) banks. Soil and sediment samples were collected along the transport path from source material (natural weathering and mine tailings/mine drainage) to the stream.

This U.S. Geological Survey (USGS) data release contains data from stream water, groundwater, and soil samples collected in 2019 and 2020 in the North Quartz Creek watershed in central Colorado. Fourteen streambank wells were installed in pairs at seven locations in August 2020 to capture the emerging groundwater from the left bank and right banks (relative to downstream-facing direction) and a synoptic sampling campaign was conducted to quantify metal contributions to the stream. A continuous, instream injection of sodium bromide (NaBr) was initiated at the head of the 5 km study reach several days prior to the synoptic sampling campaign and maintained throughout the duration of the study. Bromide concentrations were subsequently used to determine streamflow in the primary study reach (upper 1.3 km) using the tracer-dilution method, and as an indicator of hydrologic connections between North Quartz Creek and subsurface water. Streamflow was quantified in a secondary study reach (lower 3.7 km) using data from a series of sodium chloride slug additions wherein specific conductivity readings were used as a surrogate for the tracer concentration. Surface water samples were collected along North Quartz Creek including inflows from the left (LBI) and right (RBI) banks. Soil and sediment samples were collected along the transport path from source material (natural weathering and mine tailings/mine drainage) to the stream.

This U.S. Geological Survey (USGS) data release contains analytical data from a suite of rock and mineral samples collected from drill core within the Elk Creek alkaline complex, southeast Nebraska. This complex hosts the Elk Creek carbonatite, a multilithologic carbonatite enriched in niobium, rare earth elements (REEs), scandium, and titanium. Mineralized carbonatites are the world’s primary source of rare earth elements (REEs) and niobium, but only a few deposits are responsible for meeting the current demand of these critical elements such that there is increasing interest in other carbonatites that have the potential to help meet future demands. This study focuses on the Elk Creek carbonatite, the largest Nb resource in the United States and a REE exploration target. The Elk Creek carbonatite is comprised of three carbonatitic lithologies; apatite dolomite carbonatite, magnetite dolomite carbonatite, and barite dolomite carbonatite as well as multiple breccias. Samples were collected from drill core from mineral exploration holes drilled by the Molybdenum Corporation of America between 1973 and 1986. The drill cores are housed at the Nebraska Geological Survey storage facility near Lincoln, Nebraska. Geochemistry data include major and trace element analytical results for 105 samples including alkaline igneous rocks, carbonatites, and paleosol samples. Dolomite and apatite geochemical data were collected using electron microprobe and laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses. A set of dolomite samples were analyzed for their carbon and oxygen isotopic compositions. Data are reported in comma-separated values (CSV) files. All column headings, abbreviations, and limits of the data values are explained in the Entity and Attribute Information section of these metadata.

This U.S. Geological Survey (USGS) data release contains analytical data from a suite of rock and mineral samples collected from drill core within the Elk Creek alkaline complex, southeast Nebraska. This complex hosts the Elk Creek carbonatite, a multilithologic carbonatite enriched in niobium, rare earth elements (REEs), scandium, and titanium. Mineralized carbonatites are the world’s primary source of rare earth elements (REEs) and niobium, but only a few deposits are responsible for meeting the current demand of these critical elements such that there is increasing interest in other carbonatites that have the potential to help meet future demands. This study focuses on the Elk Creek carbonatite, the largest Nb resource in the United States and a REE exploration target. The Elk Creek carbonatite is comprised of three carbonatitic lithologies; apatite dolomite carbonatite, magnetite dolomite carbonatite, and barite dolomite carbonatite as well as multiple breccias. Samples were collected from drill core from mineral exploration holes drilled by the Molybdenum Corporation of America between 1973 and 1986. The drill cores are housed at the Nebraska Geological Survey storage facility near Lincoln, Nebraska. Geochemistry data include major and trace element analytical results for 105 samples including alkaline igneous rocks, carbonatites, and paleosol samples. Dolomite and apatite geochemical data were collected using electron microprobe and laser ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS) analyses. A set of dolomite samples were analyzed for their carbon and oxygen isotopic compositions. Data are reported in comma-separated values (CSV) files. All column headings, abbreviations, and limits of the data values are explained in the Entity and Attribute Information section of these metadata.

This set of data files contains analyses of samples representing Triassic units (Shublik and Ivishak Formations and Karen Creek Sandstone) in Alaska. The samples were collected from 20 outcrop localities in northeastern Alaska. The data set includes total organic carbon (TOC) and geochemical data from inductively coupled plasma-optical emission spectroscopy-mass spectroscopy (ICP-OES-MS) and portable X-ray fluorescence (p-XRF). The data presented here are described and interpreted in a paper titled "Facies Variation within Outcrops of the Triassic Shublik Formation, Northeastern Alaska".