Can chemistry lead to better understanding of archeological objects? Ask Dr. Evan Peacock from the Cobb Institute of Archaeology at Mississippi State University. With funding from NCPTT, Peacock is using an analytical technique called Laser Ablation-inductively Coupled Plasma-Mass Spectrometry (LA-ICP-MS) analyzing spoons made of freshwater mussel shell. Spoons like these were used to smooth pottery during the Mississippian Period, between 300 to 1100 years ago. LA-ICP-MS is high precision technique that allows archeologists to determine the chemical makeup of objects. A laser is used to remove a microscopic amount of material, which is transported to an ablation cell where ions are extracted. This stream is fed into a mass spectrometer where the ions are separated according to their mass/charge ratio.
Using LA-ICP-MS Peacock and his colleagues looked to determine the source of shell used to make three spoons found at a prehistoric burial located at Lyon’s bluff, a site in eastern Mississippi. At least one of the spoons was considered an import from the Tombigbee River valley that is about 15 miles away. The team determined 46 elements making up the shell using the analytical technique. By comparing the ratios of elements found in these objects and comparing them to known shells from the Lyon’s bluff and Tombigbee River Valley regions, Peacock could determine that all spoons were made from mussel shell found locally.
New technologies are changing the way we study and understand cultural objects. The use of LA-ICP-MS allows researchers to study minute amounts of material in a virtually non-destructive manner. The new tools will aid in the testing of more hypotheses and ultimately a clearer understanding of the past.
To learn more about this project, see the following journal article:1
Peacock, E.; Palmer, R. A.; Xia, Y.; Bacon-Schulte, W.; Carlock, B.; Smith, J., Chemical Sourcing of a prehistoric Freshwater Shell Artifact using Laser Ablation-Inductively Coupled Plasma-Mass Spectrometry. Archeology of Eastern North America 2010, 38, 91-99.