DISCOVERY AND CHARACTERIZATION OF AN UNKNOWN BLUE‐GREEN MAYA PIGMENT: VESZELYITE*

Blue‐green mosaic and polychrome masks and funerary offerings from the royal tombs of Calakmul, Mexico, were analysed by scanning electron microscope equipped with energy dispersive X‐ray spectroscopy (SEM‐EDS), X‐ray diffraction (XRD), and particle induced X‐ray emission (PIXE). This led to the first identification of the use of veszelyite, a rare hydrated copper‐zinc phosphate, as green pigment. Analyses of a geological sample of this mineral have been done to confirm the characterization of this Mayan pigment, which might help determine pre‐Columbian trade routes of precious and luxury objects in the ancient Maya Classic period (ad 250–800).     

Coloured Prints of the 16th Century: Non‐Destructive Analyses on Coloured Engravings from Albrecht DÜrer and Contemporary Artists

Qualitative investigations of pigments and dyes using micro X‐ray fluorescence spectrometry (micro‐XRF) and visible spectrophotometry (VIS) are suitable non‐destructive methods for the characterization of different colorants in art objects. In this study, several rare coloured engravings from the work of Albrecht Dürer—and, in addition, from the work of Cornelis Cort, Servatius Raeven and Johannes Sadeler—were investigated. The analyses result in specific palettes of colours that were used by different artists or in different workshops for the coloration of engraved images. Starting from these different palettes, it is possible to distinguish coeval colorations that were added in the 16th century from those that were carried out at a later date (e.g., the 19th century).     

CYPRIOT BYZANTINE GLAZED POTTERY: A STUDY OF THE PAPHOS WORKSHOPS

Twenty‐five samples of Byzantine glazed pottery from two archaeological sites between Limassol and Paphos region (Cyprus), dated between the 12th and 15th century ad were studied using micro X‐ray fluorescence spectroscopy, scanning electron microscopy and X‐ray diffraction analysis. It was found that all the glazes contain lead, following the main manufacturing process of medieval pottery in the Mediterranean territory, while some of them contain tin, possibly for better opacity. Furthermore, it is shown that copper, iron and cobalt with nickel are responsible for the decoration colours. Finally, the application of principal component analysis revealed significant differentiation for some of the samples.     

COLOURED OPAQUE GLASS BEADS OF THE MEROVINGIANS*

Monochrome coloured opaque glass beads of the Merovingians have been examined by different analytical methods. A large number of mostly unprepared beads have been measured by X‐ray fluorescence analysis. X‐ray diffraction was used for the identification of the crystalline colouring and opacifying pigments, and electron probe micro‐analysis as well as scanning electron microscopy were applied to study the composition and the microstructure of a white, brown, green, orange and yellow glass bead. After subtracting the content of colouring oxides of the glass beads and normalizing the residual values to 100% an identical soda‐lime‐glass matrix was obtained. The origin of the colouring metal oxides is discussed.     

The Application of Scanning X‐ray Fluorescence Microanalysis in the Examination of Cultural Materials

The use of a new analytical technique for the elemental characterization of artefacts is described. The new equipment is capable of X‐ray fluorescence analysis in conventional mode as well as for elemental scanning of small objects, fragments or microsamples. The Omicron, manufactured by Kevex Instruments Inc., is equipped with a microfocused X‐ray tube, which can be collimated to a 50 μ beam and used to scan objects over a maximum range of 256 × 256 pixels. False‐colour elemental distribution maps allow the user to image small features, differently pigmented areas, or whole objects in the machine completely non‐destructively. Analyses can be carried out in air, under helium or in vacuum. Two examples of the application of the new technique are described: first, to the surface decoration on a Greek Attic white ground lekythos; and, second, to the pigments used on a small painting, a ‘Pittura’, on copper by the Dutch artist, Frans van Mieris (1635–81) in the collections of the J. Paul Getty Museum.     

The production and technology of glazed ceramics from the middle ages,found in the saepinum territory (Italy): a multimethodic approach*

A collection of ceramics from the Middle Ages found in Altilia and Terravecchia (the Saepinum area, Campobasso, Italy) were characterized by using different mineralogical analyses to investigate their provenance and production techniques. The body ceramic was investigated using Rietveld phase analysis of X‐ray powder diffraction patterns, X‐ray fluorescence spectrometry and scanning electron microscopy. The chemical compositions of the coatings were measured by scanning electron microscopy and their mineralogical compositions were determined using a particular technique of X‐ray small‐angle scattering (SAS) optimized for studies of thin films. Moreover, the material used for decoration was studied using micro‐Raman spectroscopy. The archaeometric results confirmed the distinction into two different ceramic classes, already individuated from archaeological analysis: the Altilia objects belong to the protomajolica class, whereas the objects from Terravecchia are RMR (ramina‐manganese‐red) ceramics. A comparison between the chemical and mineralogical compositions of good‐quality ceramic objects and those of waste products indicated local production of the ceramics. A sharp distinction was found in the chemical composition of the coatings: the Altilia products have tin‐opacified lead glazes, while the Terravecchia ones have transparent high‐lead glazes. Among the Altilia products, the unsuccessful process that produced a large quantity of discarded materials was attributed to the high lead content of the glazes. In fact, the principal advantage of the high lead content was to make the preparation and application of the glaze suspension easier, but the risk of reduction of lead oxide to metallic lead was greatly increased. Using micro‐Raman spectroscopy, the following minerals were identified as pigments: pyrolusite for the dark colour, malachite for green, lepidocrocite for yellow and hematite for red.     

ANALYSING ARCHAEOLOGICAL BASALT USING NON‐DESTRUCTIVE ENERGY‐DISPERSIVE X‐RAY FLUORESCENCE (EDXRF): EFFECTS OF POST‐DEPOSITIONAL CHEMICAL WEATHERING AND SAMPLE SIZE ON ANALYTICAL PRECISION*

Energy‐dispersive X‐ray fluorescence (EDXRF) has been commonly used to determine geological sources of volcanic glass artefacts, but its ability to discriminate between basaltic sources is less developed. We examine the precision and accuracy of non‐destructive EDXRF for basalt artefacts by analysing varying size and weathering characteristics. The experiments identified no appreciable effect in reproducibility or measured composition due to thickness (down to 1 mm) or natural weathering of pre‐contact flake scars for the 17 elements measured in this study. Samples with surface area less than 100 mm², however, show significant variability in measured composition and reproducibility.     

THE COMPLEMENTARY USE OF NEUTRONS AND X‐RAYS FOR THE NON‐DESTRUCTIVE INVESTIGATION OF ARCHAEOLOGICAL OBJECTS FROM SWISS COLLECTIONS*

This paper shows the possibilities offered by the combined use of non‐destructive neutron and X‐ray beams in archaeological research on metallic finds. The following five artefacts from Swiss excavations were submitted to investigation, each with dedicated aims: a Roman sword, a Roman dagger, an Iron Age bucket, Iron Age spearheads and a Roman finger ring. The images obtained with both methods—neutrons and X‐rays—are discussed in length in this paper. The investigations took place at the Paul Scherrer Institute and the archaeologists who studied the objects come from the Universities of Lausanne and Zurich.     

CLIMATE FORCINGS AND THEIR INFLUENCE ON ALPINE HISTORY AS RECONSTRUCTED THROUGH THE APPLICATION OF SYNCHROTRON‐BASED X‐RAY MICROFLUORESCENCE ON LAYERED STALAGMITES*

Solar variability and volcanic activity strongly interact with climate and the environment. Synchrotron radiation X‐ray microfluorescence (micro‐XRF) to an annually laminated Alpine stalagmite confirmed that annual laminae result from hydrological variability and changes in the duration of soil microbial degradation. The latter is modulated by solar variability. At the centennial timescale, growth rate and solar activity appear to be correlated with temperature change, with low temperatures at solar minima. By combining micro‐XRF and absorption spectroscopy techniques (XANES), we also found that speleothems are a new archive of aerosol sulphate related to volcanic activity. Peaks in S‐concentration from c. 5.2 to 5.0 ka bp in an Alpine stalagmite suggest that multiple volcanic sulphate aerosol emissions enhanced Mid‐Holocene summer cooling, thus favouring the preservation of the Alpine Iceman mummy in a persistent ice casket.     

A SCIENTIFIC INVESTIGATION ON THE PROVENANCE AND TECHNOLOGY OF A BLACK‐FIGURE AMPHORA ATTRIBUTED TO THE PRIAM GROUP*

The restoration of a Greek black‐figure amphora provided an opportunity to study the provenance and production technology of the vase. The composition of the ceramic body, determined by inductively coupled plasma optical emission spectroscopy (ICP–OES), matches that of Attic products. Investigation by X‐ray diffraction and reflectance spectroscopy suggests a maximum firing temperature around 900°C and a body re‐oxidation temperature around 800°C, respectively. The morphology and composition of black, red and dark red surface areas were studied by scanning electron microscopy and X‐ray energy‐dispersive analysis; the black areas show the features of a typical well‐vitrified black gloss, while the red areas were most probably obtained by simple burnishing of the body; the dark red additions, on the other hand, are the likely result of a partial re‐oxidation of a clay–ochre mixture.     

Compositional Analysis by p‐XRF and SEM–EDX of Medieval Window Glass from Elgin Cathedral,Northern Scotland

Thirty shards of medieval window glass from Elgin Cathedral in north‐east Scotland have been subjected to compositional analysis by portable X‐ray fluorescence and scanning electron microscopy – energy‐dispersive X‐ray spectroscopy. Comparison with previous analytical studies suggests that the majority of the glass was probably produced in France, while a smaller group may have been made in Germany. Significant differences in base glass composition were observed between colours. Two distinct blue glasses compositions were identified. The composition of the grisaille paint differs from paint on the continent, providing the first evidence that it was made using local Scottish lead and iron pigments. This work represents the largest analytical study of Scottish medieval window glass yet undertaken and presents insights into the transfer of medieval materials, technologies and trade routes.     

CHARACTERIZATION OF ARCHAEOLOGICAL AND IN SITU SCOTTISH WINDOW GLASS

Scottish window glass from both archaeological sites and historic buildings was examined using portable X‐ray fluorescence (pXRF) and scanning electron microscopy – energy‐dispersive X‐ray micro‐analysis (SEM–EDX). The elemental composition of the glass provides information regarding the materials used and, subsequently, an approximate range of dates of manufacture. pXRF is shown to be more vulnerable than SEM–EDX to the effects of surface corrosion and matrix effects in archaeological samples. The study showed that the production of window glass in Scotland from the 17th century onwards appears to closely parallel that in England. It also demonstrated the potential of pXRF for in situ studies of window glass in historic buildings. pXRF was used to assess two Scottish buildings; one in state care and one in private ownership. The building in state care, the Abbot's House at Arbroath Abbey, showed a uniform glass type, suggesting that the building was re‐glazed completely at some point during the late 19th or early 20th century. The building in private ownership, Traquair House, had a range of glass types and ages, demonstrating a different maintenance and repair regime. This type of data can be useful in understanding historic buildings in the future, particularly if re‐glazing is being considered.     

X‐RAY SUB‐MICRON TOMOGRAPHY AS A TOOL FOR THE STUDY OF ARCHAEOLOGICAL WOOD PRESERVED THROUGH THE CORROSION OF METAL OBJECTS

Wood preserved in the corrosion layer of two early medieval iron objects was examined using X‐ray tomography. A state‐of‐the art multi‐resolution X‐ray tomography set‐up ( http://www.ugct.ugent.be ) provided virtual cross‐sections of the archaeological wood samples at sub‐micron resolution. These were compared with scans of samples of similar modern wood. These scans demonstrate the power of sub‐micron X‐ray tomography for wood identification, although the process of mineralization pushes this technique to its limits. Furthermore, this technique facilitated appraisal of the mineral content of the archaeological wood, which is useful in selecting the most appropriate strategy for the (preventative) conservation of the archaeological object.     

RESEARCH ON THE PIGMENTS FROM PAINTED CERAMICS EXCAVATED FROM THE YANGQIAOPAN TOMBS OF THE LATE HAN DYNASTY (48 BC – AD 25)

The analysis of pigments on painted ceramics excavated from the Yangqiaopan Tombs of the late Western Han Dynasty was undertaken using optical microscopy (OM), micro‐Raman spectroscopy (μ‐RS), scanning electron microscopy with energy‐dispersive X‐ray spectrometry (SEM–EDS), X‐ray diffraction (XRD) and Fourier‐transform infrared spectroscopy spectra (FTIR). The pigments were identified as red lead (Pb₃O₄), carbon (C), malachite [Cu₂CO₃(OH)₂], Chinese purple (BaCuSi₂O₆) and illite {[K,H₃O]Al₂Si₃AlO₁₀(OH)₂}. Fibrous materials were observed in some pigment samples. When observed by SEM, one showed a large amount of fibre in solidified gum, which indicated that gum of ramie could have been used as the binding medium to make the pigment particles adhere together. These results provide significant insights into the characteristics of these pigments in the Qin and Han Dynasties.     

PETROGRAPHIC AND CHEMICAL CHARACTERIZATION OF POTTERY PRODUCTION OF THE LATE MINOAN I KILN AT HAGHIA TRIADA,CRETE*

Pottery from the Late Minoan I kiln at Haghia Triada in the Mesara Plain, southern Crete, was analysed by a range of techniques, comprising thin‐section petrography, scanning electron microscopy, X‐ray diffraction, X‐ray fluorescence and neutron activation analysis. The project characterizes the ceramic fabrics and probable raw materials, correlates paste recipes with shape, reconstructs the firing conditions of the kiln and establishes a chemical reference group, taking into account post‐burial alteration and contamination. Comparison of the reference group formed with that from the neighbouring, broadly contemporary, kiln at Kommos shows an unexpected differentiation of the two kilns.     

X‐ray Diffraction and SEM Investigation of Wall Paintings Found in the Roman Temple Complex at Horvat Omrit,Israel

In the present study, the fragments of wall painting found in the Roman Temple Complex at Horvat Omrit were analysed for the first time using the non‐destructive techniques of X‐ray diffraction (XRD) and scanning electron microscopy (ESEM) equipped with energy‐dispersive X‐ray spectroscopy (EDS). The application of these methods enabled unambiguous identifications of the pigments and plaster components of the samples. Quantitative information on mineral composition, crystallite size and elemental composition of each studied paint layer and plaster was collected. Based on the results of the XRD and EDS analyses, the green pigment was identified as celadonite. It was revealed that the Egyptian blue pigment does not contain impurities of tin and lead, and this excludes the use of bronze scrap in its synthesis. Comparison of the mineral composition of the paint layers indicates that a wider palette of colours was obtained by mixing the available mineral pigments. The study of cross‐sections of painted specimens revealed the usage of slaked lime for plastering. The obtained results give a new insight into the wall painting technique employed by ancient artists at Horvat Omrit, in northern Israel.     

Wavelength‐dispersive X‐ray fluorescence analysis of ancient glasses*

The application of X‐ray fluorescence to the study of the composition of ancient glasses has been limited by the large amount of material required for samples. In this paper the setting of a reduced sampling XRF method for the analysis of ancient glasses is described. The method involves the preparation of glass beads by melting the sample with lithium tetraborate flux. By means of reference and synthetic samples, the method allows regression curves to be set, covering broad ranges from ppm to high concentrations. By means of a single program, up to 31 elements of interest in the study of ancient glass are analysed. The reproducibility, sensitivity and reliability of the method are discussed. The results demonstrate that 0.2 g of glass is sufficient to obtain accurate and sensitive analyses for most of the elements of interest.     

SCIENTIFIC ANALYSIS OF SEVENTH‐CENTURY GLASS FRAGMENTS FROM THE CRYPTA BALBI IN ROME*

Inductively coupled plasma emission spectroscopy, reflectance spectroscopy and X‐ray diffraction were used to study seventh‐century AD glass fragments from the Crypta Balbi in Rome. All the samples were found to be silica‐soda‐lime glasses. Iron determines the colour of blue‐green, green and yellow‐green transparent glasses; chemical composition suggests deliberate addition of iron and/or manganese in about half the samples. Copper was found as the main colourant in red, pale blue and blue‐green opaque fragments; elemental copper acts as an opacifier in red glass, and calcium antimonate in white, pale blue and blue‐green glasses. Detection of antimony in transparent fragments suggests recycling of opaque mosaic tesserae.     

Investigation of Organic Materials From the ‘Royal’ Burials of Xiongnu (Noin‐Ula,Mongolia) by Srxrf and XAFS Methods

The burials of famous Xiongnu people are a unique source of information about Xiongnu culture, due to the variety of organic findings. SRXRF analysis of hair, clay, bones, teeth and woollen cloth was carried out. An anomalously high copper content was observed in all hair samples, whereas the levels of copper in bone and clay were low. To define the hair morphology and the elemental distribution in the hair cross‐section, high‐resolution X‐ray computed tomography (HRXCT) and energy‐dispersive spectroscopy (EDS) with scanning electron microscopy (SEM) were used. The X‐ray absorption fine‐structure method (XAFS) was applied to determine the local copper environment. The majority of the copper species in the hair and enamel samples are present as Cu²⁺ cations in a distorted octahedral (4 + 2) coordination, surrounded by light ligands (oxygen/nitrogen). A similar distorted octahedral coordination is typical for both inorganic mixed oxide/hydroxide Cu nanosystems and metal–organic Cu complexes (with oxygen/nitrogen).     

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.