Thin Section/Petrography

Petrographic analysis is a technique developed by geologists for the study of rocks and minerals that has been applied to archaeological investigations of ceramics. It involves creating a "thin-section" of the material being studied, which is a thin slice exactly 0.03 mm thick and examining it under a polarising microscope. Minerals in the ceramic sample are identified by the optical properties of the component crystals, including relief, pleochroism, birefringence, and interference colour. The variety of minerals and rocks in the thin-section, in combination  with their texture and range of sizes, defines the petrofabric. The petrofabric of a particular vessel will be diagnostic of geology of region in which the ceramic was made. By identifying the patterns of production, important evidence regarding technology, economics, and social organization can be inferred.