2011-06

2011-06

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Native Americans have been making ceramics for thousands of years. As they moved from place to place across the landscape, they brought their possessions (including ceramics) with them. While archaeologists have had some success identifying who made ceramics and where they made them, these techniques relied on removing a sample and complex instrumentation. Using grant funds awarded by NCPTT, the Virginia Department of Historic Resources (VDHR) used portable x-ray fluorescence (XRF) instrumentation as a tool to determine the geographic origin of Native American ceramics. Ceramic sherds like these are found all over the Mid-Atlantic region, which includes Delaware, the District of Columbia, Maryland, Pennsylvania, Virginia and West Virginia. Portable XRF instruments use x-rays to safely and easily collect compositional data directly from the object and without removing a sample. Material hardness, porosity, bulk density, microstructure, elemental and crystalline composition are critical parameters that affect sample interaction with X-ray beams.

The major goal of this project was to develop a set of low-fired reference materials that reflected the range of ceramic composition found in the archaeological record. Production of reference materials relied on characterizing ceramics found in the James and Potomac River basins in order to determine their physical properties and composition. These ceramics were selected because their archaeological and historic use is specific to a relatively small geographic area. In addition, they utilized a number of different temper types, which were added to improve ceramic strength. Unfortunately, the physical and chemical characteristics of the ceramics used in this study varied too widely. Measurements for ceramic hardness, porosity, bulk density and composition were inconsistent. This made it difficult to actually produce low-fired reference materials reflecting the archaeological samples analyzed. For this study, inconsistencies in ceramic production materials and methods, as well as the overall degree of preservation all affected collected data. Despite this setback, VDHR was able to contribute to our knowledge of the composition of these ceramics associated with the James and Potomac River basins.

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