Tracing the origins of Eastern European enamelling: Chemical composition of glass and enamels from the Bryansk hoard (south‐western Russia)

The chemical composition of a series of Eastern European enamels from the Bryansk hoard from the third century ad and other sites was studied using scanning electron microscopy with energy‐dispersive spectroscopy (SEM‐EDS) and electron microprobe analysis (EPMA) techniques. Red opaque glass is homogeneous compositionally, suggesting not only common manufacturing traditions but also identical types and sources of raw materials and, consequently, a single origin. The glass is made in the Roman tradition of enamelling, which appeared in the mid‐first century ad , as was the case with orange glass. The difference in the lead content in glass of different colours, which determines the melting temperature, allows the reconstruction of polychrome enamelling techniques.     

Chemical Analysis of Starch‐Like Mineral Crystals to Eliminate Misidentification in Ancient Residue Research

To clarify issues involved in problematic identification of ancient starch granules, we investigated suspected granules found in residues from a Neolithic grinding stone in north‐east China. The chemical compositions of suspected granules and modern starch granules were tested via SEM–EDS. The results show that the elemental composition of the suspected granules mainly comprises O, S and Ca, which is similar to the composition of calcium sulphate, but quite different from that of real starch granules, which show high levels of C and O, with very low level of other elements. The findings in this study act as a warning that tiny mineral granules may be misidentified as starch, and also indicate that the method of SEM–EDS can be useful to confirm the nature of suspected granules in ancient starch analysis.     

DEEPLY COLOURED AND BLACK GLASS IN THE NORTHERN PROVINCES OF THE ROMAN EMPIRE: DIFFERENCES AND SIMILARITIES IN CHEMICAL COMPOSITION BEFORE AND AFTER ad 150*

In this work we attempt to elucidate the chronological and geographical origin of deeply coloured and black glass dating between 100 bc and ad 300 on the basis of their major and trace element compositions. Samples from the western and eastern parts of the Roman Empire were analysed. Analytical data were obtained by means of a scanning electron microscope – energy‐dispersive system (SEM–EDS, 63 samples analysed) and laser ablation – inductively coupled plasma – mass spectrometry (LA–ICP–MS, 41 samples analysed). Among the glass fragments analysed, dark brown, dark purple and dark green hues could be distinguished. Only among the dark green fragments could a clear compositional distinction be observed between fragments dated to the periods before and after ad 150. In the early samples (first century bc to first century ad ), iron, responsible for the green hue, was introduced by using impure sand containing relatively high amounts of Ti. In contrast, a Ti‐poor source of iron was employed, containing Sb, Co and Pb in trace quantities, in order to obtain the dark green colour in the later glass samples. The analytical results obtained by combining SEM–EDS and LA–ICP–MS are therefore consistent with a differentiation of glassmaking recipes, detectable in glass composition, occurring in the period around ad 150.     

PROVENANCE OF THE LIMESTONE USED IN TEOTIHUACAN (MEXICO): A METHODOLOGICAL APPROACH*

This work shows the preliminary results of an international project for the interdisciplinary study of the limestone used in the plasters of the ancient city of Teotihuacan. The limestone provenance was studied using a new approach based on the chemical analysis of the lime lumps that were selected because they represent the composition of the original limestone rock. The results show that the applied methodology was successful and that the limestone used to produce the lime employed to make the floor of the main courtyard at Teopancazco (Teotihuacan), comes from the region near Tula (Hidalgo).     

Vietnamese (15th Century) Blue‐And‐White,Tam Thai and Lustre Porcelains/Stonewares: Glaze Composition and Decoration Techniques*

EDS, X‐ray fluorescence, Raman spectroscopy, thermal expansion–shrinkage measurement and scanning electron microscopy were applied to determine the elemental components, structural phases and glazing temperatures of the transparent glazes, blue underglaze and overglaze tam thai (including gold‐like lustre) decorations from the 15th‐century Vietnamese porcelains/stonewares found at the Chu Ðâu–My Xa kiln site and in the Cù Lao Chàm (Hôi An) cargo. The ancient technology for colouring the glazes is discussed. The various blue tones in the underglazed décor result from cobalt‐containing manganese ore, with the intentional addition of iron oxide. The overglaze copper‐green and the gold‐like lustre were obtained by dispersing copper in lead‐based glass. The red colour was made using hematite dispersed in lead‐rich flux.     

Evaluation of Quantitative XRF Analysis Applied to Determine Cobalt Sources in Chinese Blue‐and‐White Porcelain

A method using the ratios between MnO, Fe₂O₃ and CoO to differentiate the cobalt sources for Chinese blue‐and‐white porcelain was developed in Oxford in the 1950s using X‐ray fluorescence (XRF) analysis directly on the glaze. In this paper, six blue‐and‐white porcelain sherds from the Luomaqiao kiln were analysed by XRF on the glaze and by scanning electron microscopy with energy‐dispersive spectrometry (SEM‐EDS) in cross‐section. The ratios between MnO, Fe₂O₃ and CoO calculated by quantitative XRF and EDS analyses are different. The analysis depths for MnO, Fe₂O₃ and CoO are < 60 μm by XRF analysis. However, the average glaze thickness of samples is > 400 μm, and the MnO, Fe₂O₃ and CoO mainly remain in the lower layer of the glaze, which is beyond the analysis depths of XRF analysis. The limitations of major and minor quantitative analyses for differentiating cobalt sources are discussed.     

Cooked Bones? Method and Practice for Identifying Bones Treated at Low Temperature

Is it possible to determine low‐temperature cooking in archaeological bones? The indirect exposure of bones to fire at low temperature (≤ 100 °C), linked to cooking, produces macroscopic modifications on these bones. These modifications have not been clearly or systematically described previously. Instead, physicochemical changes at nanometric level are only now beginning to be understood. In this paper, our principle aim is to explore new methods and techniques that correlate macroscopic features such as smoothness or light transparency with physicochemical characterization results that could aid towards detecting cooked bones in the archaeological record. This study then selected 11 archaeological samples, both human and non‐human. Bones were considered to be thermally treated or not, on the basis of macroscopic criteria. Complementary characterization techniques were used to study morphology (scanning electron microscopy and small angle X‐ray scattering), structure (X‐ray diffraction and transmission electron microscopy), local composition (energy‐dispersive X‐ray spectroscopy) and texture (gas adsorption). Indeed, fractal dimension, particle size, crystalline percentage or specific surface area may well explain some of the macroscopically observed modifications on these samples. The possibility that such apparent modifications may also be due to diagenesis is also considered. From an archaeological point of view, the results are promising. Our characterization of human and non‐human bones demonstrates that physicochemical techniques are complementary and provide good criteria against which to distinguish boiled from un‐boiled archaeological samples. Copyright © 2013 John Wiley & Sons, Ltd.     

Characterization of some ancient glass beads unearthed from the Kizil reservoir and Wanquan cemeteries in Xinjiang,China

A total of 33 ancient glass beads unearthed from the Kizil reservoir cemetery and Wanquan cemetery in Xinjiang are studied using Raman spectroscopy, scanning electron microscopy with energy‐dispersive spectrometry (SEM–EDS) and other methods. The detailed study of the glassy matrices, the crystalline inclusions and the microstructural heterogeneities for these glass beads has revealed some valuable information to help in the understanding of their possible manufacturing technology and provenance. At least two different types of glass were present in the two cemeteries. For the first time, antimony‐based colourant/opacifier—for example, Pb₂Sb₂O₇ or CaSb₂O₆—was systematically identified in some beads of plant‐ash type soda–lime glass dated to about 1000–500 bc . The limited number of potash glass beads from the Kizil reservoir cemetery, which were dated to about 500–300 bc , used tin oxide as an opacifier. The diverse resources of the soda–lime and potash glasses indicate the existence of a complex trade network between China and the West much earlier than the Western Han Dynasty.     

Fuel Efficiency of Ancient Copper Alloys: Theoretical Melting Thermodynamics of Copper,Tin and Arsenical Copper and Timber Conservation in the Bronze Age Levant*

The melting of pure or alloyed copper, tin and arsenical copper ingots or recycled objects was a drain on the timber and dung fuel resources of many cultures. This paper suggests formulae grounded in thermodynamic principles in an attempt to estimate the energy requirements necessary to melt copper alloys common to both Old and New World cultures, with the goal of identifying consumption and conservation patterns. It has been suggested that tin bronze metallurgy was first adopted in the Levant during the Early Bronze Age (EB) IV, at the onset of the Late Holocene climate episode (c.2300–2000 bc ), becoming the most desired alloy by the Middle Bronze Age (MB) II (2000–1530 bc ) due to the ease of melting tin. To test this hypothesis, the formulae are applied here to all published Levantine EB IV – MB II copper alloys. Fuel conservation rates are proposed based on the thermodynamic formulae. Tin bronze is demonstrably more fuel efficient than pure copper. Due to the inherent difficulties in predicting the behaviour of arsenical copper compounds, it is suggested that melting experiments with representative alloys are conducted to further test and refine these energy relationships.     

The Origin of the use of the Tin‐Glazed Earthenware Technique in the Production of the French Medieval Pavement of Suscinio

The medieval pavement found in its original state and place at the Breton castle of Suscinio is an interesting case study for answering questions about the origin of the tin‐glazed earthenware technique in France. Twenty‐eight decorated tiles (with transparent and tin‐opacified glazes) and eight clayey raw materials were examined using chemical and microstructural approaches involving petrographic, SEM–EDS and XRD analyses. By combining the results of provenance and technological studies with historical and archaeological data, it was possible to conclude that the pavement was a local product, made with imported technological skills, rather than an imported product or the result of local experimentation.