Nicaraguan ceramics are famous for their beautiful decoration, using bold colors and intricate iconography. Since the late 19th century they have been used for chronology building as well as for speculations about cultural interactions with Mesoamerican and South American neighbors. However, relatively little has been done to understand the underlying principles of ceramic manufacture that could allow broader use of these ubiquitous artifacts for archaeological interpretation.
One significant exception is the Greater Nicoya Ceramic Project of the 1980s and 90s, conducted by Ronald Bishop and Frederick Lange, which collected and tested about one thousand fragments from throughout the region to postulate several production centers.
Recently, investigators from the University of Calgary have expanded this data base, incorporating such techniques as thin section petrography, neutron activation analysis, and x-ray diffraction to better understand the mineral composition of the pottery and thereby infer regional exchange networks.
Thin section petrography
Petrography uses a diamond saw to cut thin slices off of pottery fragments. When mounted for microscopic analysis these reveal the mineral inclusions within the clay body. The inclusions relate to the potting ‘recipes’ and tend to be unique to different manufacturing communities, thus offering a means of inferring ancient exchange patterns and production methods. Petrography also provides a quantitative means for analysis based on size, shape, and material of inclusions for empirical comparisons. For example, it can inform on specialized manufacturing processes relating to particular potting communities.
Neutron activation analysis
Neutron Activation Analysis irradiates powdered pottery and then reads the elemental signatures of the emitted neutrons from the clay base. This process has been done in collaboration with Dr. Ronald Bishop of the Smithsonian Institution. It is especially useful for identifying regions of pottery manufacture since it focuses on the clay matrix of the pottery. It has been useful in identifying the origins of different pottery types, such as the Granada Redware complex produced in the Granada region.
X ray diffraction
X-ray diffraction analysis is based on the unique crystal planes of different minerals in the clay matrix. Projecting x-rays onto powdered ceramics, the x-rays diffract onto a screen and the diffraction angle indicates the mineral material. This technique therefore records the composition of the clay material and is another way of characterizing different ceramic types. It has been used to demonstrate the tremendous variability of manufacturing sites across Pacific Nicaragua.
By Geoffrey McCafferty and Carrie Dennett, University of Calgary and Mi Museo.