Analysis of precious metals from the tomb of the “Lady of Cao” by X-ray microtomography and digital radiography

Investigative analyses of metallic objects from the tomb of a queen of the Moche civilization, who lived around 100 to 300 AD in the northern coast of current Peru, known as Lady of Cao, have been carried out by researchers in the last 4 years using various destructive techniques. Many of these objects found inside the tomb are jewelry produced using silver, gilded copper, copper, and gold sheets. The application of X-ray microtomography (μCT) and X-ray digital radiography techniques using a portable system had the objective of obtaining more information on the structures of the objects studied, and thus to obtain some evidences about the production methods used by Moche artisans. In this way, radiographic and microtomographic images were acquired, and qualitative and quantitative analyses were performed. A fish in gold and a nose decoration in silver were examined by radiographic methods, whereas a silver earring and a gold needle were analyzed by μCT. Important information on the structure of these objects were gained.