Geochemical Data for Bulk Samples and Their Derivative Size and Density Fractions from Placer Tailings in Alaska

This data release contains elemental concentration data from geochemical analysis of eight bulk placer tailing sediment samples and of size and density fractions derived from those eight samples. All placer tailing material collected for this data release originated from samples that were collected in Alaska. The samples collected from one fifth yard of tailings material, sieved to -1/4 inch (6.35 mm). Small scoops of this material were collected at intervals during the sieving process to accrue a seven kilogram “bulk” sample for geochemical analysis. Approximately seventy kilograms of -1/4 inch sediment per sample were shipped to the Colorado School of Mines and processed in the Kroll Institute for Extractive Metallurgy (KIEM) laboratories. The 70 kg samples were weighed and classified into size fractions, and the size fractions were separated by gravity methods into light tail, middling, and concentrate fractions and weighed, as recorded in the sample descriptions in the data files. The size and density fractions prepared in the KIEMS labs were submitted to the US Geological Survey Geochemistry Laboratory in Lakewood, Colorado. Sample splitting was performed in the USGS Mineral Program's sample preparation facilities in Lakewood. The seven kg bulk samples and the size and density fractions from the 70 kg samples were analyzed in USGS contract chemistry labs by the same methods and for the same elements. The analytical methods include: 1) mercury by Cold Vapor Atomic Absorption Spectrometry, 2) gold, palladium and platinum by Inductively Coupled Plasma-Optical emission Spectroscopy and Inductively coupled Plasma-Mass Spectroscopy after collection by fire assay, 3) sixty elements by sodium peroxide fusion and ICP-OES and ICP-MS, 4) major elements by wavelength dispersive x-ray fluorescence spectrometry, 5) fluoride by Ion-Selective Electrode, and 6) total carbon and total sulfur by combustion and infrared detections. All contract analyses were performed in 2023 and 2024 by SGS laboratories: SGS was the USGS contract laboratory during the period of analysis.