Objects made of copal resin: a radiological analysis

since pre-hispanic times, copal (bursera bipinnata resin) has been used for different purposes, from medical to ritual or religious, which promoted its transportation from what is now the state of guerrero to morelos, puebla, and mexico city, as has been verified by ethnographic studies. during the late post-classic period, the resin was transported to tenochtitlan where it was transformed into different objects such as bars, spheres, conglomerates, bases of sacrificial knives, anthropomorphic figurines and diverse amorphous fragments. the macroscopic and microscopic study of more than 300 copal objects from the offerings of the great temple archaeological zone (templo mayor) permitted the establishment of a methodology in the manufacturing processes of several formal groups, which were then corroborated by computerized axial tomography, more commonly known by its abbreviated names, ct scan or cat scan. this radiological technique, created for the study of living human organisms, is very effective in archaeological applications, since it is not invasive but still allows observation of the surface of an object as well as its interior by means of virtual slices. additionally, it allows the detection of different densities of the components of the object, making it possible to know the composition of different materials.