With National Science Foundation support, Dr. Sarah Wisseman and her colleagues employ a small, Portable Infrared Mineral Analyzer (PIMA) to locate the sources of stone materials used to make pipes and figurines dating to the Middle Woodland (ca. 50 B.C. to A.D. 250) period and later in the eastern United States. This project unites archaeologists and geologists to better define the nature of materials used by prehistoric and historic societies in the Midwest and the relationships between raw material sources, production patterns, and trade of finished artifacts. The PIMA spectrometer is an accurate and precise addition to modern analytical instruments, with the advantages that it is easy to operate, fast (30 seconds per reading), and totally non-destructive. The PIMA is equally useable in field or museum settings, and has been successfully used to determine mineral composition and likely source of valuable artifacts that cannot be destructively sampled. For example, PIMA readings were taken of a museum figurine thought to be from Mississippi, but with no documentation of provenance. Surprisingly, analysis showed a good match with flint clay from quarries in eastern Missouri, known from the team's previous work as the source of most of the Middle Mississippian (ca. A.D. 1000 to 1400) "red goddess" figurines found at or near the site of Cahokia in East St. Louis. In another example, PIMA readings confirm a local source of pipestone for Hopewellian (Middle Woodland) pipes found in northern Illinois, negating the earlier theory that all such pipes were manufactured in Ohio and then traded to the west. The PIMA technique is complementary to X-ray diffraction (XRD), a well-established laboratory technique that is used by the team to check and refine compositional readings. The research team is using both techniques to build a reference database of stone materials specific to the Midwest.
The current project will focus on a) identification of source materials for pipes beyond those already identified in Scioto County, Ohio and Sterling, Illinois, and b) sourcing catlinite, a red pipestone that has been consistently misidentified in the literature. The catlinite problem has two key components: defining the range of variation of catlinite composition, both between sources and within a single source such as Pipestone National Monument, MN; and determining the extent of catlinite use by prehistoric and historic period Native Americans. Since many artifacts in museum collections have never been tested by either PIMA or XRD, the team's goal is to vastly expand the compositional database for pipes and figurines and to identify new, local sources of pipestones and catlinites that have not previously been documented. The results will radically alter the picture of long-distance trade and exchange of prestige items in the Eastern Woodlands.
