The genetic origin of many gold deposits, including Pogo in Alaska, remains controversial with questions as to whether they formed due to magmatic-hydrothermal or metamorphic-hydrothermal fluids. Gaining a better understanding of the formation mechanisms for these deposits is critical for defining proper exploration criteria in gold-bearing regions and production within these deposits. Monazite are light rare earth (LREE)-bearing and xenotime are heavy rare earth (HREE)-bearing phosphate minerals that are found as alteration products in many gold deposits. In addition to their importance in geochronological investigations, their minor element chemistry may be used to differentiate between metamorphic, magmatic, diagenetic, and hydrothermal origin. This data release provides electron microprobe geochemical data that is used to showcase differences in these phosphates when derived from magmatic-hydrothermal systems compared to metamorphic-hydrothermal systems. The electron microprobe data was collected by personnel of the Central Region Minerals Program in Denver, Colorado, for the U.S. Geological Survey (USGS) Mineral Resources Program (MRP). Appreciable differences in chemistry were noted for deposits associated with alkaline magmatic systems (Taurus, AK, and Cripple Creek, CO), calc-alkaline magmatic systems (Pebble, AK, and Butte, MT), and orogenic gold systems derived from metamorphic-hydrothermal systems (systems from Grass Valley, the Mother Lode, and the Klamath Mountains in CA). These characteristics were then applied to the controversially classified Pogo gold deposit, Alaska, in order to provide evidence for how it formed. Following initial study, new electron microprobe geochemical data for this updated data release were collected from reduced intrusion-related gold deposits at the Geology, Geophysics, and Geochemistry Science Center in Denver, Colorado, to add to the database. This new data allows better comparison between gold deposits formed from reduced magmatic-hydrothermal fluids, oxidized magmatic-hydrothermal fluids, and metamorphic-hydrothermal fluids.

This data release includes geochemical, x-ray diffraction mineralogical, and electron probe microanalysis (EPMA) data on rocks, soils, and sediments collected near the Orange Hill and Bond Creek porphyry copper deposits, Nabesna quadrangle, Alaska. Geochemical analyses were completed by a laboratory under contract with the U.S. Geological Survey (USGS). Electron microprobe and x-ray diffraction mineralogical analyses were completed by personnel of the Central Region Minerals Program in Denver, Colorado. The samples were collected and analyzed during 2014 to 2016, selected to help characterize the distribution and composition of mineralized and unmineralized geologic materials in this remote part of the eastern Alaska Range. These results provide important information for interpreting airborne imaging spectroscopy data that were collected as part of the U.S. Geological Survey (USGS) Mineral Resources Program (MRP) project, 'Hyperspectral Remote Sensing Data and a Multi-proxy Investigation for Characterizing Mineral Resources in Alaska'. A discussion and interpretation of these data and their relationship to the airborne spectroscopy results are provided in: Graham, G.E., Kokaly, R.F., Kelley, K.D., Hoefen, T.M., Johnson, M.R., and Hubbard, B.E., Application of imaging spectroscopy for mineral exploration in Alaska: A study over porphyry Cu deposits in the eastern Alaska Range, Economic Geology, in press.

This data release includes geochemical, x-ray diffraction mineralogical, and electron probe microanalysis (EPMA) data on rocks, soils, and sediments collected near the Orange Hill and Bond Creek porphyry copper deposits, Nabesna quadrangle, Alaska. Geochemical analyses were completed by a laboratory under contract with the U.S. Geological Survey (USGS). Electron microprobe and x-ray diffraction mineralogical analyses were completed by personnel of the Central Region Minerals Program in Denver, Colorado. The samples were collected and analyzed during 2014 to 2016, selected to help characterize the distribution and composition of mineralized and unmineralized geologic materials in this remote part of the eastern Alaska Range. These results provide important information for interpreting airborne imaging spectroscopy data that were collected as part of the U.S. Geological Survey (USGS) Mineral Resources Program (MRP) project, 'Hyperspectral Remote Sensing Data and a Multi-proxy Investigation for Characterizing Mineral Resources in Alaska'. A discussion and interpretation of these data and their relationship to the airborne spectroscopy results are provided in: Graham, G.E., Kokaly, R.F., Kelley, K.D., Hoefen, T.M., Johnson, M.R., and Hubbard, B.E., Application of imaging spectroscopy for mineral exploration in Alaska: A study over porphyry Cu deposits in the eastern Alaska Range, Economic Geology, in press.

This data release provides geochemical results of in situ electron probe microanalyses of hydrothermal muscovite associated with gold-bearing quartz veins from the Klamath Mountains, California. Samples were collected from eight different mines in the summer of 2013 and electron probe microanalyses were carried out May 27, 2014 and November 12, 2019.

This data release provides geochemical results of in situ electron probe microanalyses of hydrothermal muscovite associated with gold-bearing quartz veins from the Klamath Mountains, California. Samples were collected from eight different mines in the summer of 2013 and electron probe microanalyses were carried out May 27, 2014 and November 12, 2019.

This data release includes electron microprobe and 40Ar/39Ar collected at the U.S. Geological Survey for samples from the Sukari gold deposit in the Eastern Desert of Egypt. Rock samples were collected by Basem Zoheir--Benha University/University of Kiel. Muscovite from a polished thick section of sericitized wall rock was analyzed by electron probe microanalysis at the U.S. Geological Survey, Reston Electron Microbeam Laboratory. An aliquot of muscovite from this sample was microsampled from the thick section and analyzed by argon geochronology at the U.S. Geological Survey Bascom ARgon Dating (BARD) Laboratory in Reston, Virginia. The 40Ar/39Ar data constrain the timing of gold mineralization in the Sukari gold deposit.

This data release includes electron microprobe and 40Ar/39Ar collected at the U.S. Geological Survey for samples from the Sukari gold deposit in the Eastern Desert of Egypt. Rock samples were collected by Basem Zoheir--Benha University/University of Kiel. Muscovite from a polished thick section of sericitized wall rock was analyzed by electron probe microanalysis at the U.S. Geological Survey, Reston Electron Microbeam Laboratory. An aliquot of muscovite from this sample was microsampled from the thick section and analyzed by argon geochronology at the U.S. Geological Survey Bascom ARgon Dating (BARD) Laboratory in Reston, Virginia. The 40Ar/39Ar data constrain the timing of gold mineralization in the Sukari gold deposit.

The iron oxide-apatite (IOA) deposits near Mineville in the Adirondack Mountains, New York, have been of interest for their rich magnetite ore since the mid-1700s but have attracted renewed attention due to their potential as rare earth element (REE) resources (McKeown and Klemic, 1956; Lupulescu and others, 2016; Taylor and others, 2018). Apatite is the main REE-host and is found in variable concentrations within ore seams of the regional magnetite deposits. Some apatite crystals are unaltered, relatively homogenous, and inclusion-free, whereas other deposits contain heterogenous apatite with zones of abundant secondary mineral inclusions that were formed through metasomatic reactions with the apatite after initial precipitation. The heterogeneous apatite crystals may have inclusion-free bright zones and intermediate zones in back-scattered electron imagery (BSE), and dark BSE zones that contain inclusions of monazite and thorite. Apatite crystals from twenty-seven samples, including twenty-four ore and three rock samples from a total of nineteen different ore deposits, were analyzed by electron microprobe to obtain their major and minor element geochemistry. Additionally, some magmatic apatite crystals from the ore-hosting Lyon Mountain Granite Gneiss were analyzed for comparison with the ore apatite. The electron microprobe data was collected by personnel of the Southwest Region Geology, Geophysics, and Geochemistry Science Center in Denver, Colorado, for the U.S. Geological Survey (USGS) Mineral Resources Program (MRP). A JEOL 8900 Electron Microprobe with five wavelength dispersive analyzers operated at 20keV accelerating voltage, a 50-nA current (measured on the Faraday cup), and an electron beam diameter of 10 micrometers was utilized. All analyzed crystals are considered fluorapatite, with fluorine contents ranging from approximately 3.5 to 6.6%. Some apatite crystals from ore contain greater than 15% total REE, whereas some others contain less than 1%. Commonly, Y, La, Ce, and Nd are the most abundant REE in the apatite crystals. The magmatic apatite crystals are notably purer with low contents of actinides, REE, and other common minor impurities. Analyses that contained total elemental weight percentages between 97% to 103% were accepted; those analyses with poor totals falling outside of this range were rejected. The different zones within heterogeneous apatite crystals contained lower concentrations of REE and other minor element components in the dark BSE zones than in the bright BSE zones, but both zones had nearly parallel REE profiles. The zones of differing BSE brightness are interpreted to be caused by metasomatic alteration. Although the REE profiles were consistent for a given sample, variations in total REE content and overall chemistry were noted between different deposits and even different ore seams within a given deposit.

The iron oxide-apatite (IOA) deposits near Mineville in the Adirondack Mountains, New York, have been of interest for their rich magnetite ore since the mid-1700s but have attracted renewed attention due to their potential as rare earth element (REE) resources (McKeown and Klemic, 1956; Lupulescu and others, 2016; Taylor and others, 2018). Apatite is the main REE-host and is found in variable concentrations within ore seams of the regional magnetite deposits. Some apatite crystals are unaltered, relatively homogenous, and inclusion-free, whereas other deposits contain heterogenous apatite with zones of abundant secondary mineral inclusions that were formed through metasomatic reactions with the apatite after initial precipitation. The heterogeneous apatite crystals may have inclusion-free bright zones and intermediate zones in back-scattered electron imagery (BSE), and dark BSE zones that contain inclusions of monazite and thorite. Apatite crystals from twenty-seven samples, including twenty-four ore and three rock samples from a total of nineteen different ore deposits, were analyzed by electron microprobe to obtain their major and minor element geochemistry. Additionally, some magmatic apatite crystals from the ore-hosting Lyon Mountain Granite Gneiss were analyzed for comparison with the ore apatite. The electron microprobe data was collected by personnel of the Southwest Region Geology, Geophysics, and Geochemistry Science Center in Denver, Colorado, for the U.S. Geological Survey (USGS) Mineral Resources Program (MRP). A JEOL 8900 Electron Microprobe with five wavelength dispersive analyzers operated at 20keV accelerating voltage, a 50-nA current (measured on the Faraday cup), and an electron beam diameter of 10 micrometers was utilized. All analyzed crystals are considered fluorapatite, with fluorine contents ranging from approximately 3.5 to 6.6%. Some apatite crystals from ore contain greater than 15% total REE, whereas some others contain less than 1%. Commonly, Y, La, Ce, and Nd are the most abundant REE in the apatite crystals. The magmatic apatite crystals are notably purer with low contents of actinides, REE, and other common minor impurities. Analyses that contained total elemental weight percentages between 97% to 103% were accepted; those analyses with poor totals falling outside of this range were rejected. The different zones within heterogeneous apatite crystals contained lower concentrations of REE and other minor element components in the dark BSE zones than in the bright BSE zones, but both zones had nearly parallel REE profiles. The zones of differing BSE brightness are interpreted to be caused by metasomatic alteration. Although the REE profiles were consistent for a given sample, variations in total REE content and overall chemistry were noted between different deposits and even different ore seams within a given deposit.

This dataset contains results from electron microprobe analyses of cassiterite from the Sullivan Pb-Zn-Ag deposit, British Columbia. These data were collected from two samples and may not reflect the overall variability present at the deposit. An ASCII text file of results is provided in comma-separated by value (csv) format. The file has the name “2019-07-09_Sullivan_Cassiterite”.