Frederick Norman Pryce and Michael Vickers
David William John Gill
Petrographical and chemical analysis are the two main ways to characterize pottery. The former treats the pottery as a geological sediment which has been used for a particular purpose. Thus by scanning thin sections of pottery under a polarizing microscope, mineral inclusions can be visually identified; this allows a parallel to be drawn with other ceramic material, which may lead in turn to an identification of the clay source. This technique is particularly useful for coarse wares such as transport *amphorae. However in the case of fine pottery where inclusions have been removed, the clay can be treated as a bulk material. The sample can be studied by three main means: neutron activation analysis, optical emission spectroscopy, and atomic absorption spectrophotometry. In addition to the three main elements within clay (silicon, aluminium, and oxygen), an analysis will seek to determine the percentage of other elements in the composition: iron, calcium, magnesium, potassium, sodium, and titanium. These proportions can then be plotted and the results compared with other tests from pottery or indeed from clay sources.