Petrography lower if wholly or partly vitreous. The specific gravity of the more common rocks range from about 2.5 to 3.2. Archaeologists use petrography to identify mineral components in pottery. This information ties the artifacts to geological areas where the raw materials for the pottery were obtained. In addition to clay, potters often used rock fragments, usually called "temper" or "aplastics", to modify the clay's properties. The geological information obtained from the pottery components provides insight into how potters selected and used local and non-local resources. Archaeologists are able to determine whether pottery found in a particular location was locally produced
Ceramic petrography Ceramic petrography Ceramic petrography (or ceramic petrology) is a laboratory-based scientific archaeological technique that examines the mineralogical and microstructural composition of ceramics and other inorganic materials under the polarised light microscope in order to interpret aspects of the provenance and technology of artefacts. Samples are ground to a thickness of 0.03 mm and mounted on a glass slide. The approach relies heavily on the geological principles of optical mineralogy, thin section petrography and soil micromorphology. It combines these with an appreciation of the craft of ceramic manufacture and interprets data within an archaeological framework. Ceramic petrography is used in academic