The U.S. Geological Survey (USGS) collected rock physical property measurements to help understand causative sources of gravity and magnetic survey anomalies in the central Upper Peninsula of Michigan. A total of 1,460 measurements of magnetic susceptibility and density from 61 outcrops and 37 boreholes have been conducted on Precambrian rocks. The measurements aid in interpretation of gravity and airborne magnetic data that are helping to understand Precambrian geology and potential mineral resources. For outcrop measurements, lithologic info is provided. Sample locations were determined using handheld Global Position System units. Measurements from drill core samples at the State of Michigan public core facility in KI Sawyer and the Cleveland Cliffs Inc. drill core facility in Ishpeming are also presented. For these measurements, the drill hole name, depth, and lithologic unit are provided. We thank Cleveland Cliffs Inc. for allowing access to their drill core facility and outcrops on their lands.

This dataset supports the publication "Geophysical insights into Paleoproterozoic tectonics along the southern margin of the Superior Province, central Upper Peninsula, Michigan, USA." At a 1:100,000 scale, these data are in a geologic database in the Geologic Map Schema (GeMS) which includes spatial feature classes and non-spatial tables that contain the geologic information presented in figure 8 and S3 of appendix A, the supplemental map of the publication.

The U.S. Geological Survey (USGS) collected rock physical property measurements to help understand causative sources of gravity and magnetic survey anomalies in the Iron Mountain-Menominee region, Michigan-Wisconsin. A total of 2,356 measurements of magnetic susceptibility and density from 152 locations have been conducted on Precambrian rocks. The measurements aid in interpretation of newly acquired ground-based gravity and airborne magnetic data that are helping to understand concealed Precambrian geology and potential mineral resources. Multiple measurements were made at each location and sample lithology units were derived from existing USGS geologic maps noted in the supplemental information section of the metadata file. However, if no formal unit name exists, the rock lithology determined in the field were recorded. For outcrop measurements, sample locations were determined using handheld Global Position System units. Measurements from drill core samples at the State of Michigan public core facility in Harvey are also presented. For these measurements, the drill hole name, depth, and lithologic unit are provided.