José Luis Ruvalcaba

Non Destructive In Situ Study of Mexican Codices: Methodology and First Results of Materials Analysis for the Colombino and Azoyu Codices

Little is known about manuscript writing and painting practices in pre-Hispanic Mesoamerica. Around the world, only 16 codices from pre-Hispanic Mexico survived the Spanish conquest, most of them preserved in European collections. Even though the manufacture of codices was widespread during the post-Classical period (1325–1521 AD), the features of the surviving pre-Hispanic and Early Colonial documents show some technical differences that can be related to local traditions. The only pre-Hispanic codex held at a Mexican Collection is the Colombino Codex from the Mixtec coast in the south of Mexico. Nevertheless, many manuscripts produced in New Spain preserved the indigenous codices traditions and practices. These manuscripts are an outstanding information source in terms of the materials used in the writing and colouring traditions. Usually, organic colours obtained from local plants and carbon inks on calcium-rich preparation layers were employed. However, there are few studies of original manuscripts, carried out on a limited number of samples (Gonzalez Tirado 1998), and scarce information has been made available on this subject to date.

The Grolier Codex: A Non Destructive Study of a Possible Maya Document using Imaging and Ion Beam Techniques

The Grolier Codex has been a controversial document ever since its late discovery in 1965. Because of its rare iconographical content and its unknown origin, specialists are not keen to assure its authenticity that would set it amongst the other three known Maya codes in the world (Dresden, Paris Codex and Madrid Codex). The document that has been kept in the Museo Nacional de Antropologia in Mexico City, after its exposure in 1971 at the Grolier Club of New York, has been analyzed by a set of non-destructive techniques in order to characterize its materials including paper fibers, preparation layer and color compositions. The methodology included UV imaging, IR reflectography and optic microscopy examinations as well as Particle Induced X-ray Emission (PIXE) and Rutherford Backscattering Spectrometry (RBS) using an external beam setup for elemental analysis. All the measurements were carried out at 3MV Pelletron Accelerator of the Instituto de Fisica, UNAM. The aim of this work is to verify if the materials in the Grolier Codex match those found in other pre-Hispanic documents. From the elemental composition we concluded that the preparation layer shows the presence of gypsum (CaSO4), color red is due to red hematite (Fe2O3) and black is a carbon-based ink. These results agree with previous analyses carried out by Scanning Electron Microscopy (SEM-EDX) on few samples. However, the presence of Maya Blue in the blue pigment cannot be assured. The examination using UV and IR lights shows homogeneity in the inks and red color but dark areas that contain higher amounts of K in the preparation layer. This paper discusses the results obtained for the UV-IR examinations and the elemental analysis. A comparison with other studies on pre-Hispanic and early colonial codex is presented.

The Reduction Welding Technique Used in Pre-Columbian Times: Evidences from a Silver Ring from Incallajta, Bolivia, Studied by Microscopy, SEM-EDX and PIXE

A pre-Columbian silver ring from Incallajta, Bolivia, recovered from an archaeological excavation is composed of a thin sheet of silver bent to form the ring. Two small wires in the shape of the infinity sign are joined to the surface of the ring. Four green stone beads were laid inside the four cavities formed by the wires. Energy dispersive spectroscopy (EDX) and Particle Induced X-rays Emission (PIXE) analyses of the beads proved that they were turquoise. Examination with a stereoscopic binocular microscope indicated that the two wires could have been soldered to the ring by reduction welding, because copper corrosion products were found in the interface of the welding, similar to those seen on two modern silver objects from Indonesia, decorated with granulation. Since reduction welding is a technique not reported before in preColumbian metallurgy, further analyses were carried out to prove that it was used here. Thus, the ring was analyzed with Scanning Electron Microscopy (SEM-EDX) and external beam PIXE, showing with certainty that the copper content in the area of the welding was higher than in any other part of the ring, with increasing copper amounts towards the center of the weld.