Powder X-ray diffraction (XRD) data and estimates of mineral abundances determined using Rietveld refinement included in this data release were generated as part of the Earth Mapping Resources Initiative (Earth MRI; https://www.usgs.gov/special-topics/earth-mri). Earth MRI is a partnership between the U.S. Geological Survey (USGS) and state geological surveys and was developed by the USGS to evaluate critical mineral resources in the USA in response to Federal directives to address the shortfall in critical mineral supply for national defense and economic security. Earth MRI involves generating data to support a national critical mineral assessment of subsurface resources, such as mineralized rock, and above ground resources including mine wastes. The mine waste component of Earth MRI involves generating an inventory of mine waste features and the geochemical and mineralogical characterization of mine wastes collected by state geological surveys. The results of the mineralogical characterization of mine waste samples are provided in this data release and include XRD data for each mine waste sample, and the interpretation of those XRD data to estimate mineral abundances using the Rietveld method (Albinati and Willis, 2006). The results of the geochemical characterization of mine wastes are published in the following data release which contains additional sample attribute data: Geochemical data generated by projects funded by the USGS Earth Mapping Resources Initiative (https://doi.org/10.5066/P9WHRLXH). These data are being released in support of the ongoing Earth MRI mine waste characterization effort; additional mineralogical data will be released periodically as they are generated. Albinati, A., Willis, B.T.M., 2006, The Rietveld method. In: Prince, E. (eds) International Tables for Crystallography Volume C: Mathematical, physical and chemical tables. International Tables for Crystallography, v. C. Springer, Dordrecht. https://doi.org/10.1107/97809553602060000614, accessed July 24, 2024. U.S. Geological Survey, 2021, Geochemical data generated by projects funded by the USGS Earth Mapping Resources Initiative (ver. 10.0, June 2024): U.S. Geological Survey data release, https://doi.org/10.5066/P9WHRLXH, accessed July 24, 2024.