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.