This data release provides electron microprobe analyses of ore minerals from the Copperwood sediment-hosted stratiform copper deposit in the Upper Peninsula of Michigan. The minerals include bornite, chalcocite, native copper, native silver, and pyrite. Minerals were analyzed for Ag, As, Co, Cu, Fe, Hg, Ni, Pb, S, Sb, and Zn. Results with acceptable totals that lie between 98.5 and 101.5% show that these minerals are stoichiometric, with very limited substitution of other elements. The Copperwood copper deposit is a sediment-hosted stratiform copper deposit in the Presque Isle Syncline of the Upper Peninsula of Michigan. The Lower Copper Bearing Sequence has a 2018 mineral resource estimate of 42.2 million metric tons (Mt) of measured plus indicated mineral resources at an average grade of 1.60% Cu and 3.84 g/t Ag. The measured plus indicated mineral resource in the Upper Copper Bearing Sequence is estimated to be 7.1 Mt at an average grade of 1.21% Cu and 3.26 g/t Ag (Gignac, 2018). The mineral reserves for the Copperwood Project are estimated at 25.4 Mt at an average grade of 1.43% Cu and 3.83 g/t Ag (Gignac, 2018).

This data release provides electron microprobe geochemical data that was collected as part of a scoping study to evaluate whether unconventional critical element resources may be associated with sediment-hosted copper systems in the Midcontinent Rift. We report abundances of trace elements in native copper and sulfide minerals in 12 thin sections from samples of the Mesoproterozoic lower Nonesuch Formation that were collected from underground exposures in the White Pine deposit. Approximately 350 spots were analyzed for Cu, Pb, Zn, Fe, Ni, Co, As, Sb, Ag, Hg, and S. The electron microprobe data were collected by personnel of the Central Region Minerals Program in Denver, Colorado, for the U.S. Geological Survey (USGS) Mineral Resources Program (MRP). An ASCII text file of results is provided in comma-separated by value (csv) format. The file has the name “White_Pine_EPMA_data.csv”.

This data release provides electron microprobe geochemical data that was collected as part of a scoping study to evaluate whether unconventional critical element resources may be associated with sediment-hosted copper systems in the Midcontinent Rift. We report abundances of trace elements in native copper and sulfide minerals in 12 thin sections from samples of the Mesoproterozoic lower Nonesuch Formation that were collected from underground exposures in the White Pine deposit. Approximately 350 spots were analyzed for Cu, Pb, Zn, Fe, Ni, Co, As, Sb, Ag, Hg, and S. The electron microprobe data were collected by personnel of the Central Region Minerals Program in Denver, Colorado, for the U.S. Geological Survey (USGS) Mineral Resources Program (MRP). An ASCII text file of results is provided in comma-separated by value (csv) format. The file has the name “White_Pine_EPMA_data.csv”.

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”.

The exploration for porphyry deposits in some parts of Alaska may require unconventional exploration geochemical methods, depending on type of cover. The Taurus deposit and others in the region are mostly concealed by residual soils that in part include ash and loess, and therefore traditional stream sediment samples typically contain subdued geochemical signatures. Indicator mineral studies include collection of stream sediment samples and analysis using automated SEM mineralogical techniques. The presence of select minerals in the stream sediments may indicate mineralization. In addition, the chemistry of specific minerals may be used to distinguish a hydrothermal origin as opposed to others, and include apatite, rutile, and titanite. The electron probe data in this data release were collected for apatite, rutile, and titanite by personnel of the Geology, Geophysics, and Geochemistry Science Center in Denver, Colorado, for the U.S. Geological Survey (USGS) Mineral Resources Program (MRP). Appreciable differences in chemistry were noted for these minerals in mineralized rock and stream sediment samples draining these rocks compared to sediment samples away from mineralization.

Electron microprobe analyses of sphalerite (ZnS) were collected on samples from current or past mining operations in the USA with a specific focus on germanium (Ge), a byproduct critical mineral recovered from sphalerite. Data and methods reported are part of a research study published here: Hayes SM, McAleer RJ, Piatak NM, White SJO, Seal RR II (2023), A novel nondestructive workflow for examining germanium and co-substituents in ZnS. Front. Earth Sci. 11:939700. doi: 10.3389/feart.2023.939700

Electron microprobe analyses of sphalerite (ZnS) were collected on samples from current or past mining operations in the USA with a specific focus on germanium (Ge), a byproduct critical mineral recovered from sphalerite. Data and methods reported are part of a research study published here: Hayes SM, McAleer RJ, Piatak NM, White SJO, Seal RR II (2023), A novel nondestructive workflow for examining germanium and co-substituents in ZnS. Front. Earth Sci. 11:939700. doi: 10.3389/feart.2023.939700

This data release provides multi-element data for drill core samples from the Mesoproterozoic Nonesuch Formation and Copper Harbor Conglomerate at the Copperwood copper deposit, Michigan, USA. Gold, platinum, and palladium data were collected by fire assay; copper and silver were collected by assay; and other elements were collected by inductively coupled plasma-optical emission spectrometry (ICP-OES) or inductively coupled plasma-mass spectrometry (ICP-MS) following a digestion that used hydrochloric, nitric, perchloric and hydrofluoric acids. The Copperwood copper deposit is a sediment-hosted stratiform copper deposit in the Presque Isle Syncline of the upper peninsula of Michigan. The deposit has a 2018 mineral resource estimate of 42.2 million metric tons (Mt) of measured plus indicated mineral resources in the Lower Copper Bearing Sequence at an average grade of 1.60 percent Cu and 3.84 grams per ton (g/t) Ag. The measured plus indicated mineral resource in the Upper Copper Bearing Sequence is estimated to be 7.1 Mt at an average grade of 1.21 percent Cu and 3.26 g/t Ag (Gignac, 2018). The mineral reserves for the Copperwood Project are estimated at 25.4 Mt at an average grade of 1.43 percent Cu and 3.83 g/t Ag (Gignac, 2018). Some sediment hosted deposits elsewhere produce significant amounts of gold, platinum, palladium, and (or) cobalt. However, in the Copperwood samples, these elements have geometric mean concentrations of 0.0022 ppm, 0.0021 ppm, 0.0029 ppm, and 24 ppm, respectively, so they are not enriched. Gallium, which is a critical mineral in the U.S., is enriched in some base metal deposits, but Copperwood samples have a geometric mean gallium concentration of 16 ppm, which is similar to average crustal concentrations. Although the data herein are limited to 34 determinations, they strongly suggest that the Copperwood copper deposit does not contain significant concentrations of byproduct critical minerals.

This data release provides multi-element data for drill core samples from the Mesoproterozoic Nonesuch Formation and Copper Harbor Conglomerate at the Copperwood copper deposit, Michigan, USA. Gold, platinum, and palladium data were collected by fire assay; copper and silver were collected by assay; and other elements were collected by inductively coupled plasma-optical emission spectrometry (ICP-OES) or inductively coupled plasma-mass spectrometry (ICP-MS) following a digestion that used hydrochloric, nitric, perchloric and hydrofluoric acids. The Copperwood copper deposit is a sediment-hosted stratiform copper deposit in the Presque Isle Syncline of the upper peninsula of Michigan. The deposit has a 2018 mineral resource estimate of 42.2 million metric tons (Mt) of measured plus indicated mineral resources in the Lower Copper Bearing Sequence at an average grade of 1.60 percent Cu and 3.84 grams per ton (g/t) Ag. The measured plus indicated mineral resource in the Upper Copper Bearing Sequence is estimated to be 7.1 Mt at an average grade of 1.21 percent Cu and 3.26 g/t Ag (Gignac, 2018). The mineral reserves for the Copperwood Project are estimated at 25.4 Mt at an average grade of 1.43 percent Cu and 3.83 g/t Ag (Gignac, 2018). Some sediment hosted deposits elsewhere produce significant amounts of gold, platinum, palladium, and (or) cobalt. However, in the Copperwood samples, these elements have geometric mean concentrations of 0.0022 ppm, 0.0021 ppm, 0.0029 ppm, and 24 ppm, respectively, so they are not enriched. Gallium, which is a critical mineral in the U.S., is enriched in some base metal deposits, but Copperwood samples have a geometric mean gallium concentration of 16 ppm, which is similar to average crustal concentrations. Although the data herein are limited to 34 determinations, they strongly suggest that the Copperwood copper deposit does not contain significant concentrations of byproduct critical minerals.

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.