Pipestone Quarries (image) University of Illinois at Urbana-Champaign Caption Researchers tested the mineralogical profiles of stone from sites across the upper Midwest to determine the origin of stone pipes found at Tremper Mound in Ohio, a Hopewell site. Credit MAP courtesy ISAS Usage Restrictions Image may be used only to accompany stories about the research described in this release. Credit: ISAS Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.