Minnesota Geological Survey
Report of Investigations  RI-57.
Geochemical characterization of paleoProterozoic volcanic and hypabyssal igneous rocks, east-central Minnesota,
by D.L. Southwick, Terrence J. Boerboom, and Peter L. McSwiggen
2001

The pdf report should be viewed using Acrobat Reader 4.0 or higher
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Also available as a printed report; contact the MGS Map Sales office at 612-627-4780, ex. 238 for price and availability.