The origins of two purportedly pre-Columbian Mexican crystal skulls

The well-known life-size rock crystal skull in the British Museum was purchased in 1897 as an example of genuine pre-Columbian workmanship, but its authenticity has been the subject of increasing speculation since the 1930s. This paper is concerned with the history, technology and material of the skull and another larger white quartz skull, donated recently to the Smithsonian Institution. Manufacturing techniques were investigated, using scanning electron microscopy to examine tool marks on the artefacts, and compared with Mesoamerican material from secure contexts. A Mixtec rock crystal goblet and a group of Aztec/Mixtec rock crystal beads show no evidence of lapidary wheels. They were probably worked with stone and wood tools charged with abrasives, some of which may have been as hard as corundum. Textual evidence for Mexican lapidary techniques during the early colonial period, supported by limited archaeological evidence, also indicates a technology without the wheel, probably based on natural tool materials. In contrast, the two skulls under consideration were carved with rotary wheels. The British Museum skull was worked with hard abrasives such as corundum or diamond, whereas X-ray diffraction revealed traces of carborundum (SiC), a hard modern synthetic abrasive, on the Smithsonian skull. Investigation of fluid and solid inclusions in the quartz of the British Museum skull, using microscopy and Raman spectroscopy, shows that the material formed in a mesothermal metamorphic environment equivalent to greenschist facies. This suggests that the quartz was obtained from Brazil or Madagascar, areas far outside pre-Columbian trade networks. Recent archival research revealed that the British Museum skull was rejected as a modern artefact by the Museo Nacional de Mexico in 1885, when offered for sale by the collector and dealer, Eugène Boban. These findings led to the conclusion that the British Museum skull was worked in Europe during the nineteenth century. The Smithsonian Institution skull was probably manufactured shortly before it was bought in Mexico City in 1960; large blocks of white quartz would have been available from deposits in Mexico and the USA.     

A new calibration of the XRD technique for the study of archaeological burned human remains

A new calibration of human bones as a function of programmed temperature (200–1000 °C) and time (0, 18 and 60 min) is presented and discussed in order to investigate the issues related to the study of cremated bone remains by using the powder X-ray diffraction approach. The experimental results confirm the growth of hydroxylapatite crystallites as a function of the applied temperature, with a sigmoid behaviour that has been parameterized to the experimental data points. Particularly, it was observed that the thermal treatments for 60 min anticipate of about 100 °C the effects that are otherwise observed after the treatments for 0 min. The developed procedure was subsequently applied to cremated remains of various archaeological sites of Spain and supplied precise information not only about the temperature reached during the funerary rites, but also on the presumed duration for the cremation.     

Synchrotron radiation-based x-ray analysis of bronze artifacts from an Iron Age site in the Judean Hills

Seven bronze bangles from Tell en-Nasbeh, northern Judah, were investigated to understand the phase composition and manufacturing process of the artifacts, and possibly suggest a provenance for their origin. Synchrotron x-ray radiation diffraction (XRD) and fluorescence (XRF) were used in the analysis to avoid any destructive sampling and at the same time penetrate through the surface into the core metal. These techniques enabled us to determine that the bangles were not just tin bronze, but leaded tin bronze. Based on excavation reports, it is unlikely that the metal objects were manufactured locally at Tell en-Nasbeh; rather, preliminary XRD and XRF data point towards the neighboring region of Edom as their origin. Despite their political enmity during the Iron Age II, the data suggest that Judahite social demands for bronze may have fostered a strong economic relationship between these two polities.     

ARCHAEOLOGICAL RESEARCH AT THE INSTITUTE OF NUCLEAR TECHNIQUES,BUDAPEST UNIVERSITY OF TECHNOLOGY AND ECONOMICS: SCHOLARLY ACHIEVEMENTS OF A PROSPEROUS LONG‐TERM COLLABORATION

The laboratory is part of a university institute with a nuclear reactor on the premises. NAA of archaeological materials started in the early 1980s, and has found continuous interest since then. Site‐specific characteristics of the NAA procedure are the long irradiation and counting times, due to the relatively low neutron flux, the single comparator method of standardization and the use of reference materials for quality control. The main research interest focuses on provenance studies of potteries; 90% of the analysed samples are ceramic materials. Most of the projects concentrate on the investigation of pottery finds from Roman Pannonia, and from different archaeological sites in Israel. The Qumran pottery project is presented as a typical example.     

ANOTHER ONE BITES THE DUST: QUALITY CONTROL AND FIRING TECHNOLOGY IN THE PRODUCTION OF MEDIEVAL GREYWARE CERAMICS IN CATALONIA,SPAIN

The following study sheds new light on the quality control procedures of ancient potters by comparing cooking vessels exported from the medieval kiln‐site of Cabrera d'Anoia (Barcelona) with ‘wasters' that were discarded at source. The firing temperature of examined sherds indicates that only pots subjected to a maximum temperature of 800–850°C were offered for sale. The potters at Cabrera d'Anoia appear to have been fully aware of the optimal balance between thermal and physical shock resistance of vessels fired within this range and strived to control firing in order to achieve better products than that of competing workshops.     

The Use of Small‐Angle X‐Ray Diffraction Studies for the Analysis of Structural Features in Archaeological Samples

X‐ray diffraction or scattering analysis provides a powerful non‐destructive technique capable of providing important information about the state of archaeological samples in the nanometer length scale. Small‐angle diffraction facilities are usually found at synchrotron sources, although the potential of a laboratory source is also described. Specific examples of analysis using X‐ray diffraction of historic parchment, archaeological bone, a Central Mexico style pictograph and microdiffraction of calcified tissues are used to show the scope and versatility of the technique. Diffraction data is capable of giving fundamental structural information as well as quantifying the remodelling of structures influenced by environmental factors.     

Manganese Black Pigments in Prehistoric Paintings: the Case of the Black Frieze of Pech Merle (France)

Different black pigments of natural origin (mineral or organic) have been examined by means of several analytical methods (colour measurements, elemental analysis and structural analysis). The results, after being compared with each other, then served as reference points in the study of the ‘Black Frieze’ of the cave of Pech Merle (Lot). After that, colour measurement was investigated in situ on the paintings as a means of displaying small differences (in hue or chroma) between the black colours. The aim of this study was to verify several hypotheses concerning the techniques used by the painters of Pech Merle, and specifically by the one(s) of the Black Frieze. A first objective was that of identifying the nature and, if possible, the origin of the black pigments used in these figures. A second objective was that of determining in which parts of the frieze one or the other (or one and the other) had been used; and the final objective was to provide new technical information that might help us better to understand how the Pech Merle frieze was produced, whether by a single painter and in one episode, for the most part, or, on the contrary, in several episodes and by a succession of different painters.     

Technological Characterization of Campanian Pottery of Type A,B and C and of Regional Products from Ancient Calabria (Southern Italy)

Sherds of Campanian pottery were studied by SEM‐EDX. SEM images show that slips of Campana C are scarcely sintered and are thicker than the well vitrified coatings of Campana A and B and imitations of Campana B. Slips of products with a grey slip on a grey body are very thin and well vitrified. EDX analyses indicate that slips are richer in aluminium and iron, and poorer in silicon and calcium, with respect to the bodies. Higher potassium is also found in all of the coatings except those of Campana A. Here relatively high sodium makes the total alkalis comparable with those of the other products, except Campana C, where it is somewhat lower. Measurement of thermal expansion and X‐ray powder diffractograms suggest that firing temperatures were mostly in excess of 900°C, but some samples of Campana C seem to have been fired below 800°C.     

Neutron Activation Analysis of Metal Artefacts from the Moche Site,North Coast of Peru

Neutron activation analysis has been used to characterize 60 metal objects from the Moche site, of which four are associated with the Chimú Period, two with the Early Chimú Period and the others with various Moche IV contexts. Different types of utilitarian and non‐utilitarian objects were analysed to identify the metals present, and to investigate their chemical composition and their eventual source. The results clearly indicate the distinction between Chimú and Moche artefacts and confirm the generalized opinion that arsenic bronze was popular after ad 900. They also indicate that gilding copper objects with gold was already a common practice during the Moche era.     

Investigation of chemical changes in bone material from South African fossil hominid deposits

The bone fragments of the Australopithecus Africanus from the dolomitic cave in the Cradle of Humankind in South Africa have been studied by the use of several spectral techniques. The aim was to establish their degree of preservation and possibilities of inferring the life conditions from them. X-ray diffraction studies revealed the transformation of the mineral components partially into fluoroapatite form with addition of goethite, birnessite and quartz phases and with surprisingly well preserved collagen remains. Several important chemical elements were detected by using the electron (EPMA) and synchrotron-based X-ray fluorescence (XRF) microprobes. Among them, Sr and Zn were distributed in a way following the distribution of Ca, the main element of the bones. We suspect the immanent crystallographic substitution of Ca in this case in native bone. Iron followed the distribution of Sr but while Sr is distributed in a continuous way in more rigid locations, iron occurs mainly in the edge zones of the bones and in spot-like inclusions inside. Some part of the spots located in a very edge of bone is also filled with Mn and Cu. It suggests that the porosity and fracture of bones plays a more significant role in the localization of Fe, Mn and Cu. They also form a rigid thin layer (100–250 μm) avoiding further penetration. As (as AsO₄³⁻?) distribution pattern is unique and seems to occur in those locations where the concentrations of Sr are small. The conditions for bone penetration as determined from Eh-pH diagrams suggest that is rather impossible to preserve the organic matter in locations of Mn and also that Mn and Fe hardly can meet in the same spots.