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CHEMISTRY 155 - Archaeological Chemistry

Fall 2002, Fall 2003 (this page), Spring 2004, Fall 2004, Spring 2010

The scanning electron microscope (SEM) equipped with x-ray energy dispersive spectrometry (XEDS) is an important tool that can provide information about the fine structure of surfaces as well as the chemical composition of archaeological materials. Studying the elemental composition of such materials aids the archaeologist in pinpointing the age and source (geographic region) of a specimen.

The following images are EDX spectra and SEM micrographs collected from ancient and modern pottery samples.

EDX of Modern Pottery (below, left) and Ancient Pottery (below, right):

Note the prominent silicon (Si), aluminum (Al), calcium (Ca), and iron (Fe) peaks. The presence of gold (Au) is attributable to the preparation technique, in which a thin film of gold is applied to make the specimen electrically conductive. Other elements are present in lesser amounts: oxygen (O), magnesium (Mg), chlorine (Cl), potassium (K), and titanium (Ti). In the modern pottery sample, the Si peak is largest, indicating that it is the highest percentage element in the sample. Compare this with the ancient sample, and note the difference in proportional amounts of Si and Ca in particular.

SEM of Modern Pottery (below, left) and Ancient Pottery (below, right):
In the modern pottery sample, the surface appears fairly homogeneous, with plateau regions between small lacy voids. In the ancient sample, the surface appears more uneven, and there are large smooth-surfaced inclusions scattered randomly.