This data release presents high-spatial resolution geochemical analyses collected from Mesoproterozoic apatite crystals in igneous rocks from the St. Francois Mountains terrane and coeval ore rocks from the Pea Ridge iron oxide-apatite-rare earth element (IOA-REE) and Boss iron oxide-copper-gold (IOCG) deposits. These deposits are located in the southeast Missouri iron metallogenic province. These data support a journal article entitled, “Apatite trace element geochemistry and cathodoluminescent textures—A comparison between regional magmatism and the Pea Ridge IOA-REE and Boss IOCG deposits, southeastern Missouri iron metallogenic province, USA” by Celestine N. Mercer, Kathryn E. Watts, and Juliane Gross, that is published in Ore Geology Reviews. The goal of these data is to use apatite geochemical data to elucidate the petrogenetic histories of the samples and help evaluate ore deposit models. Our sample suite comprises 25 samples, encompassing 8 regional rhyolite suite rocks, including rhyolite host rocks at Pea Ridge and Boss; 6 regional mafic- to intermediate-composition suite rocks, including one intermediate-composition host rock at Boss; 10 ore samples from the Pea Ridge deposit (amphibole-quartz zone, magnetite zone, hematite zone, and REE-bearing hard breccia pipe), and 1 ore sample from the Boss deposit (magnetite-rich ore zone). Prior to quantitative analysis, apatite was identified by petrographic microscope in thick sections and imaged by backscattered electron (BSE) microscopy to distinguish complex textural domains. Apatite crystals contain primary domains as well as secondary and tertiary altered domains. These data were collected at the U.S. Geological Survey (USGS) Denver Microbeam Laboratory using a FEI Quanta 450 field emission gun scanning electron microscope (SEM) equipped with an energy dispersive spectroscopy (EDS) detector operating at 15-20 kilovolts (kV) and a beam current of 0.1-0.5 nanoamperes (nA). Major and minor element analyses in apatite were analyzed at the USGS Denver Microbeam Laboratory using a JEOL 8900 electron microprobe (EMP). We report 283 spot analyses that were completed using a 15 kV accelerating potential, 20 nA beam current, and the largest spot size possible (about 3-10 micrometers [µm]) to analyze a particular apatite domain while minimizing elemental migration. Natural and synthetic minerals and glasses were used as standards for all EMP analyses. Average detection limits are typically about 200-300 parts per million (ppm) for P, Si, Na, and Cl; about 100 ppm for Ca, S; and about 900 for F. This analytical setup is adequate for routine analysis of Ca, P, Si, Na, and S in apatite, but provides F and Cl analyses with relatively larger uncertainties. Given these operating conditions, the generally F-rich, Cl-poor character of the apatite, the random crystallographic orientations of the grains analyzed, and the total beam exposure of 120 seconds (for F, Cl, Ca, and P), we expect there was an increase in F X-ray counts of up to about 30-40 percent and a decrease in Cl X-ray counts of up to about 20-30 percent (Goldoff and others, 2012). Our analytical accuracy for measurements of the F-rich Wilberforce apatite standard is within ≤3 percent for Ca, P, and Na, but high by about 33 percent for F, suggesting F (and presumably Cl) is inaccurate. Nonetheless, we report measured values of F and Cl data because even with these large uncertainties they clearly demonstrate the basic compositional variety between samples. Trace element concentrations in apatite were measured by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) using a Photon Machines Analyte G2 LA system (193 nanometer [nm], 4 nanosecond [ns] excimer) attached to a PerkinElmer DRC-e ICP-MS, housed at the USGS Denver Laser Ablation ICP-MS Laboratory. We report 37 minor and trace elements from 231 apatite spot analyses. Spot ablation was carried out using a 15 to 25 µm spot size at 10 joules per square

The ore from historic iron mines of the eastern Adirondack Highlands, New York, contain abundant quantities of rare earth element (REE)-bearing apatite crystals. These apatite crystals are especially enriched in Y, La, Ce, and Nd. In-ground ore, mine waste piles, and tailings piles that are associated with these mines could contain apatite and other REE-bearing phases at elevated concentrations indicating potential as REE resources. This is the first geochemical database for a regional subset of ore and mine waste products for these mines. Thirty-four ore, twenty-nine mine waste, seven host rock, two pegmatite, and one slag sample were collected from these iron oxide-apatite (IOA) mines in the eastern Adirondack Highlands near Mineville and Ticonderoga, New York. The waste pile samples included 25 samples collected from rubble-sized mine waste piles and four samples from processed tailings piles. Waste pile sampling was accomplished by adapting the sampling strategy outlined by Smith and others (2000, 2006), which included collecting 30 to 50 evenly distributed aliquots (subsamples) from across each waste pile that were composited to form a representative composite sample for the pile. The resulting samples ranged from 12.75 to 32.50 pounds (5.78 to 14.74 kilograms) of material, which were crushed, homogenized, and split prior to geochemical analysis. Major elements were analyzed by wavelength dispersive x-ray fluorescence (WDXRF) and 60-element analyses was completed by inductively coupled plasma-optical emission spectroscopy-mass spectroscopy (ICP-OES-MS). Ore samples were preferably collected in situ from the ore seams, but clasts were collected from waste piles if the ore seam was inaccessible. A wide range in chemical values exists for the ore and waste pile samples. Total REE (lanthanides plus yttrium) varies from 11 to greater than 22,000 parts per million (ppm) for waste piles and 15 to greater than 47,000 ppm for ore samples. All waste pile samples have light REE greater than heavy REE content, with light REE/heavy REE ratio ranging from 1.43 to 35.30, with a median value of 2.14. Ore samples with the highest total REE content have larger negative Eu anomalies, and samples with lower total REE have diminished negative Eu anomalies and more notable negative Ce anomalies. A positive correlation for all samples exists between REE and Th, indicating the potential for radiometric surveys as a tool for vectoring toward higher grade resources. The elevated REE found in some of these waste piles and ore samples is similar to or higher than grades found in some rare earth mines and advanced exploration projects. However, targeted selection of specific mines and waste piles would be required due to the large range in REE values found in the Adirondack IOA deposits. References: Smith, K.S., Ramsey, C.A., and Hageman, P.L., 2000, Sampling strategy for the rapid screening of mine-waste dumps on abandoned mine lands, in ICARD 2000—Proceedings from the Fifth International Conference on Acid Rock Drainage, Denver, Colorado, May 21-24, 2000: Society of Mining, Metallurgy, and Exploration, Inc., p. 1453–1461. Smith, K.S., Hageman, P.L., Ramsey, C.A., Wildeman, T.R., and Ranville, J.F., 2006, Reconnaissance sampling and characterization of mine-waste material, in Proceedings of the US Environmental Protection Agency Hard Rock Mining 2006 Conference, Tucson, Arizona, November 14-16, 2006, p. 1–14.

The ore from historic iron mines of the eastern Adirondack Highlands, New York, contain abundant quantities of rare earth element (REE)-bearing apatite crystals. These apatite crystals are especially enriched in Y, La, Ce, and Nd. In-ground ore, mine waste piles, and tailings piles that are associated with these mines could contain apatite and other REE-bearing phases at elevated concentrations indicating potential as REE resources. This is the first geochemical database for a regional subset of ore and mine waste products for these mines. Thirty-four ore, twenty-nine mine waste, seven host rock, two pegmatite, and one slag sample were collected from these iron oxide-apatite (IOA) mines in the eastern Adirondack Highlands near Mineville and Ticonderoga, New York. The waste pile samples included 25 samples collected from rubble-sized mine waste piles and four samples from processed tailings piles. Waste pile sampling was accomplished by adapting the sampling strategy outlined by Smith and others (2000, 2006), which included collecting 30 to 50 evenly distributed aliquots (subsamples) from across each waste pile that were composited to form a representative composite sample for the pile. The resulting samples ranged from 12.75 to 32.50 pounds (5.78 to 14.74 kilograms) of material, which were crushed, homogenized, and split prior to geochemical analysis. Major elements were analyzed by wavelength dispersive x-ray fluorescence (WDXRF) and 60-element analyses was completed by inductively coupled plasma-optical emission spectroscopy-mass spectroscopy (ICP-OES-MS). Ore samples were preferably collected in situ from the ore seams, but clasts were collected from waste piles if the ore seam was inaccessible. A wide range in chemical values exists for the ore and waste pile samples. Total REE (lanthanides plus yttrium) varies from 11 to greater than 22,000 parts per million (ppm) for waste piles and 15 to greater than 47,000 ppm for ore samples. All waste pile samples have light REE greater than heavy REE content, with light REE/heavy REE ratio ranging from 1.43 to 35.30, with a median value of 2.14. Ore samples with the highest total REE content have larger negative Eu anomalies, and samples with lower total REE have diminished negative Eu anomalies and more notable negative Ce anomalies. A positive correlation for all samples exists between REE and Th, indicating the potential for radiometric surveys as a tool for vectoring toward higher grade resources. The elevated REE found in some of these waste piles and ore samples is similar to or higher than grades found in some rare earth mines and advanced exploration projects. However, targeted selection of specific mines and waste piles would be required due to the large range in REE values found in the Adirondack IOA deposits. References: Smith, K.S., Ramsey, C.A., and Hageman, P.L., 2000, Sampling strategy for the rapid screening of mine-waste dumps on abandoned mine lands, in ICARD 2000—Proceedings from the Fifth International Conference on Acid Rock Drainage, Denver, Colorado, May 21-24, 2000: Society of Mining, Metallurgy, and Exploration, Inc., p. 1453–1461. Smith, K.S., Hageman, P.L., Ramsey, C.A., Wildeman, T.R., and Ranville, J.F., 2006, Reconnaissance sampling and characterization of mine-waste material, in Proceedings of the US Environmental Protection Agency Hard Rock Mining 2006 Conference, Tucson, Arizona, November 14-16, 2006, p. 1–14.

This data release is part of a 2016-2019 study on the geology, geochemistry and geochronology of ore systems in the eastern Yukon-Tanana Upland region, Alaska. Whole rock chemistry was conducted on 185 samples, mostly from Au prospects, with lesser samples from porphyry Cu prospects. Geographically, most samples are from gold prospects near the Pogo Au mine and east to Black Mountain in the Big Delta quadrangle. Fewer samples are from prospects in the Eagle and Tanacross Quadrangles. Samples were submitted to the USGS contract laboratory and analyzed for select trace elements and gold. Sixty elements were determined by inductively coupled plasma-optical emission spectroscopy-mass spectroscopy (ICP-OES-MS), sodium peroxide fusion (ICP-60). Gold was determined by lead fusion fire assay.

This data release is part of a 2016-2019 study on the geology, geochemistry and geochronology of ore systems in the eastern Yukon-Tanana Upland region, Alaska. Whole rock chemistry was conducted on 185 samples, mostly from Au prospects, with lesser samples from porphyry Cu prospects. Geographically, most samples are from gold prospects near the Pogo Au mine and east to Black Mountain in the Big Delta quadrangle. Fewer samples are from prospects in the Eagle and Tanacross Quadrangles. Samples were submitted to the USGS contract laboratory and analyzed for select trace elements and gold. Sixty elements were determined by inductively coupled plasma-optical emission spectroscopy-mass spectroscopy (ICP-OES-MS), sodium peroxide fusion (ICP-60). Gold was determined by lead fusion fire assay.

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.

Geochemical data from samples collected in 2022 for the Mount Harper geologic mapping project, Big Delta, Mount Hayes, and Eagle quadrangles, Alaska, Raw Data File 2023-24, presents whole-rock and major- and trace-element geochemistry of rock samples collected to support geologic mapping and mineral exploration in the Mount Harper area of the Melozitna mining district. During the 2022 field season, geologists from the Alaska Division of Geological & Geophysical Surveys (DGGS) conducted 1:100,000-scale bedrock geologic mapping of ~3,100 mi2 (~8,000 km2) within the Big Delta, Mount Hayes, and Eagle quadrangles. This project aims to produce more detailed and modern geologic maps and supporting datasets to promote mineral resource exploration in eastern Interior Alaska. The project area includes known gold (Au) mineralization, recently explored in the Richardson mining district, including the SAM project and the nearby Democrat Lode and associated prospects, and in the Goodpaster mining district at the LMS and Healy intrusion-related gold prospects. The Mount Harper area hosts a cluster of molybdenum (Mo) and tungsten (W) prospects, including porphyry Mo and W skarn styles, both of which have had industry interest over the decades. Ultramafic rocks occur in the South Fork and Volkmar river drainages; these bodies have an as-yet poorly understood potential to host platinum group elements (PGE), chrome (Cr), cobalt (Co), and nickel (Ni) resources. The DGGS map area includes a section of pre-Mississippian to Permian metasedimentary and metaigneous rocks and Triassic to Paleogene intrusive and volcanic rocks. Major- and trace-element geochemistry for these rocks was analyzed to further our understanding of the resources in the area, including distinguishing between igneous and sedimentary protoliths for metamorphic rocks and characterizing and differentiating Mesozoic and Cenozoic magmatic events in the area. Highlights of this geochemical report include sampling of the Healy and LMS projects and multiple prospects on Mount Harper and elsewhere in the map area. Sample 22Z336, collected south of the Brink prospect, yielded 1.52 ppm Au and 500 ppm W. A few samples collected at the LMS prospect yielded elevated silver (Ag) concentrations (for example, sample 22Z409 yielded up to 12.95 ppm). Additionally, sample 22Z406 yielded 1.48 ppm Au, 7.65 ppm Ag, and 1,787 ppm arsenic (As). Samples collected at Larsen Ridge/Lucky 13 prospect near the top of Mount Harper yielded high Ag and W values. For example, 22Z271 (a massive quartz vein) yielded 18.87 ppm Ag and 1,100 ppm W, 22TJN157 (a skarn) yielded 5.75 ppm Ag, 2,348 ppm copper, 4,422 ppm manganese (Mn), and 600 ppm W, and 22Z270 (a granite) yielded 2,356 ppm Mo and 200 ppm W. The Richardson mining district has been previously sampled by DGGS. This data file is released as a Raw Data File with an open end-user license. The data are available from the DGGS website: http://doi.org/10.14509/31089.