Samples for analysis were selected from, 1) archived rotosonic cores drilled by the Minnesota Geological Survey and archived at the Lands and Minerals Drill Core Library, Minnesota Department of Natural Resources, Hibbing, Minnesota, USA; or b) freshly collected rotosonic cores, collected on-site at the time of coring. Cores in the sample archive are stored in wooden core-boxes in ambient air. Cores have supporting geology, stratigraphy, geochemistry, and hydrogeology data as published in County Geologic Atlases, Parts A and B, by the Minnesota Geological Survey (MGS) and the Minnesota Department of Natural Resources (MDNR); or in Regional Hydrogeologic Assessments, MGS. Included in this data release are: 1) Core_Chem_Locations.pdf: PDF format map illustrating core locations in Minnesota. 2) Sample_descriptions.csv: Sample IDs, laboratory IDs, x-y-z location, and brief physical description of each sample. 3) Major_and_trace_elements.csv: Major elements, trace elements, and carbon concentrations in solid materials. 4) Weak_leach_and_sequential_extractions.csv: Major elements, trace elements, and carbon; selected major and trace elements recovered from a deionized water leach extraction; selected major and trace elements recovered from each of 5 stages of sequential extraction. 5) Data_Table_Ranges.csv: Minimum and maximum data values for tables Major_and_trace_elements.csv and Weak_leach_and_sequential_extractions.csv.