PIMA Spectroscopy PIMA PROJECT

Below is a description of a two-year project. This material is based upon work supported by the National Science Foundation under Grant No. 02-03010. The principal investigator is Sarah Wisseman (Director of ATAM) with co-principal investigators Thomas Emerson (Illinois Transportation Archaeological Research Program and Anthropology) and Randall Hughes (Illinois State Geological Survey).

Sourcing stone artifacts using mineral characterization by PIMA (Portable Infrared Mineral Analyzer) spectroscopy and XRD (X-ray diffraction) has already proven effective for Cahokia figurines dating to the Middle Mississippian period and Hopewellian pipes dating to the Middle Woodland period. As we have demonstrated under our previous grant NSF 9971179, PIMA spectroscopy is an accurate and precise addition to the archaeometrist's arsenal of techniques, with the advantages that the instrument 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 of valuable artifacts that cannot be destructively sampled. Our previous work with the PIMA1) validated the technique by finding good agreement between results obtained by PIMA and those obtained by XRD, 2) measured precision and accuracy of the PIMA, and 3) established PIMA and XRD spectral databases for Midwestern pipestones and flint clays. We also established that PIMA spectroscopy, while useful as a diagnostic first analysis or a stand-alone technique when artifacts cannot be sampled, provides maximum information when used as a companion technique with other methods such as XRD.

Since the task of sourcing Cahokia figurines is essentially complete, this renewal grant will focus on

a) identification of source materials for Hopewellian 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.

The new grant has four primary goals:

1) to continue testing both museum artifacts and potential source materials by both PIMA and XRD;
2) to add to our already established databases of Midwestern pipestones;
3) to improve our reference libraries of PIMA spectra for automatic identification of minerals, and
4) to refine our quantification methods so we can better compare the mineralogical results obtained using these two techniques.

Copyright 2002. University of Illinois at Urbana-Champaign.