Pipestone artifacts have been recovered from numerous sites throughout the upper Midwest and eastern Plains. Geologic sources and glacial deposits of this argillite have distributions almost equally broad. Artifacts from a historic component and several prehistoric sites in the upper Mississippi River valley have been analyzed through X-ray powder diffractometry and compared to pipestones from geological sources. Similarity in mineral composition indicates that nearly all the artifacts are catlinite from southwestern Minnesota. None are manufactured from the more readily available Wisconsin pipestones. Catlinites
are not present on sites that predate AD 1260, indicating that trade or transport of this exotic pipestone in to the Upper Mississippi Valley began late in the thirteenth century. Frequency comparison of pipestones from various sites indicates an increased use of this exotic material AD 1550 to 1650 and a dramatic rise during the historic period.
