SCANNING ELECTRON MICROSCOPY-ENERGY DISPERSIVE SPECTROMETRY AND PROTON INDUCED X-RAY EMISSION ANALYSES OF MEDIEVAL GLASS FROM KOROINEN (FINLAND)*

Thirteenth- to fourteenth-century ecclesiastical window glass, excavated from the administrative centre of Koroinen, Finland, represents the earliest window glass in the country and includes the only emerald green window glass known from Finland at this time. This was examined, together with some excavated vessel glass. X-ray analysis, using scanning electron microscopy-energy dispersive spectrometry and proton induced X-ray emission, reveals that while the vessels are made from potash-lime, soda-lime, mixed alkali and lead-silica glasses, the window glasses are lead-silica and wood ash-lead-silica glasses; they resemble similar glasses from central Europe and suggest that Koroinen shared the trading network of other European religious centres.     

ENERGY DISPERSIVE X-RAY FLUORESCENCE ANALYSIS OF ANCIENT COPPER ALLOYS: EMPIRICAL VALUES FOR PRECISION AND ACCURACY

Energy dispersive X-ray fluorescence (EDXRF) analyses are compared with neutron activation as well as atomic absorption analyses of ancient copper-based alloys in order to examine their accuracy and to estimate realistic values for precision and sensitivity of EDXRF. The results show that it is possible to obtain reliable data of the surface composition of objects non-destructively. Better results for bulk composition are usually obtained with drill samples where the sensitivity of the method is at least competitive with atomic absorption spectroscopy with flame atomization.     

A TECHNOLOGICAL EXAMINATION OF NINTH–TENTH CENTURY AD ABBASID BLUE‐AND‐WHITE WARE FROM IRAQ,AND ITS COMPARISON WITH EIGHTH CENTURY AD CHINESE BLUE‐AND‐WHITE SANCAI WARE*

Eight sherds of ninth–tenth century ad Abbaesid blue‐and‐white glazed earthenware, excavated in 1931 at Hira in western Iraq, were analysed using, variously, quantitative wavelength‐dispersive spectrometry (WDS) and energy‐dispersive spectrometry (EDS) in association with scanning electron microscopes (SEM), and semi‐quantitative X‐ray fluorescence spectrometry (XRF). In order to compare the compositions of the cobalt pigments used, the glazes of seven complete vessels of eighth century ad Chinese Tang blue‐and‐white sancai were also analysed semi‐quantitatively using XRF. The Abbasid wares were shown to have used traditional Mesopotamian alkali–lime glazes applied to calcareous clay bodies. Half the glazes examined were opacified with tin oxide. Three types of blue decoration (i.e., raised; spreading; and flat, non‐spreading) were produced using a variety of formulations, including a mixture of cobalt pigment with lead oxide. The sources of the ores used for the cobalt pigments have not been identified. However, the analytical data showed that the cobalt ore used for the Abbasid blue‐and‐white ware could be distinguished from that used for the Tang blue‐and‐white sancai by its higher iron content and by the presence of a significant amount of zinc. The use of cobalt‐blue decoration on the ninth–tenth century ad Abbasid ware was anticipated in China by eighth century ad Tang blue‐and‐white sancai wares. However, whether its introduction by the Abbasid potters should be seen as an independent invention that followed the introduction of tin‐opacified glazes in Iraq, or whether it was influenced in some way by Chinese originals, is still unresolved.     

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.     

CHEMICAL AND MINERALOGICAL ANALYSES OF GALLO-ROMAN WALL PAINTING FROM DIETIKON,SWITZERLAND

Around 90 samples of Roman wall painting dating from the first to the third century AD were analysed using different analytical techniques: X-ray diffraction, X-ray fluorescence, infrared spectrometry, scanning electron microscopy, energy dispersive spectrometry, optical microscopy and physico-chemical tests. The identified pigments are: ash, calcite, carbon black, celadonite, cinnabar, Egyptian Blue, glauconite, goethite, hematite and red lead. Pigment mixtures were used to get other colours such as brown, pink or purple. Three types of plaster were used: a first, and most dominant, with river sand, a second with crushed tile for damp places and a third, to which cinnabar was exclusively applied, was prepared with crushed calcite crystals.     

MULTIVARIATE ANALYSIS OF THE ENERGY DISPERSIVE X-RAY FLUORESCENCE RESULTS FROM BLUE AND WHITE CHINESE PORCELAINS*

The energy dispersive X-ray fluorescence technique was employed to study non-destructively the surface of 66 samples of Chinese porcelain, of different periods and origins, and determine the contents of 13 chemical elements, namely, Ti, Mn, Fe, Co, Ni, Cu, Zn, Ga, Pb, Rb, Sr, Y and Zr. Principal components analysis was performed on these 13 variables, and scatter plots, incorporating the first, second and third principal components, used to study the clustering behaviour of the data. Based on these results, discriminant analysis was then performed on the data, and discriminant functions established for attributing the period and origin of the porcelains.     

A COMPARISON OF INDUCTIVELY-COUPLED PLASMA EMISSION SPECTROMETRY AND ATOMIC ABSORPTION SPECTROMETRY ANALYSIS ON STANDARD REFERENCE SILICATE MATERIALS AND CERAMICS

Analyses by inductively coupled plasma atomic emission spectrometry and atomic absorption spectrometry of 22 ceramic standards and sherds are compared. Further data from analyses of one of the ceramic standards analysed by both methods are also discussed. The results show that for most major elements, the methods are comparable, but that use of common standards would be advisable if data from the two methods are to be compared.     

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).     

THE ANALYSIS OF SECOND MILLENNIUM GLASS FROM EGYPT AND MESOPOTAMIA,PART 1: NEW WDS ANALYSES*

A recent analytical study by SEM–WDS was carried out on 226 glasses from the Late Bronze Age, analysing each of the glasses for a total of at least 22 elements, the largest such analytical study conducted on these glasses. The aim of the analysis was first to identify which elements were brought in with each of the raw materials and, second, to accurately characterize those raw materials. Since different glassmaking sites in Egypt and the Near East would probably use at least some local raw materials and these raw materials will vary slightly from site to site, this has potential for provenancing the glass. Analysis showed new patterns in the compositions of glass from the various sites and led to new conclusions about the supply of raw materials and personnel for the glass workshops. This forms the basis for further work by LA–ICPMS to be presented in part 2 of this paper.     

BYZANTINE OPAQUE RED GLASS TESSERAE FROM BEIT SHEAN,ISRAEL*

This paper presents the results of analysis of Byzantine opaque red glass tesserae derived from three separate locations in the ancient city of Beit Shean, Israel. Investigation proceeded using reflective light microscopy, energy dispersive X‐ray fluorescence and energy dispersive scanning electron microscopy. The glass matrix of the tesserae was found to be heterogeneous, with many inclusions. Similarities and differences between tesserae from the two mosaics are examined and discussed. Implications for locale of manufacture and production techniques are considered. Comparisons between the three locations led to conclusions about the use of the tunnel as a storage site and the implications of this for future research on mosaics.     

LA–ICP–MS,SEM–EDS AND EPMA ANALYSIS OF EASTERN NORTH AMERICAN COPPER‐BASED ARTEFACTS: IMPACT OF CORROSION AND HETEROGENEITY ON THE RELIABILITY OF THE LA–ICP–MS COMPOSITIONAL RESULTS*

This study discusses the relevance of compositions obtained using laser ablation – inductively coupled plasma – mass spectrometry (LA–ICP–MS) for the purpose of identifying the provenance of copper‐based artefacts found in Virginia at Native American sites dated from the 16th to the 18th centuries. Ten artefacts were investigated by scanning electron microscopy – energy dispersive spectrometry (SEM–EDS) to visualize the corrosion and characterize the heterogeneities in the metal and electron probe micro‐analysis (EPMA) to determine separately the compositions of the intact metal and of the corrosion product. It is shown that the corroded surfaces are highly depleted in zinc but that representative concentrations can be determined by sampling the deeper, uncorroded metal. In contrast, lead values are highly variable because of the heterogeneous distribution of this metal within the bulk copper. Despite these problems, brass is easily identifiable and American native copper and European smelted copper can be unambiguously distinguished with LA–ICP–MS on unprepared artefacts using As, Ag, Ni and Sb trace elements.     

THE CHEMICAL COMPOSITION OF SOME ARCHAEOLOGICALLY SIGNIFICANT FLINT FROM DENMARK AND SWEDEN

Flint was one of the most widely employed raw materials for artefact manufacture in Denmark and Sweden during the Stone Age, and it continued to be used during subsequent periods. Prehistoric flint mining and lithic manufacturing studies in these countries have attracted considerable attention, but there have been no recent attempts to chemically characterize the geological source materials. This paper builds on a pilot study ( Hughes et al. 2010 ) and uses energy‐dispersive X‐ray fluorescence (EDXRF) analysis to determine quantitative composition estimates for nine major, minor and certain trace elements in seven archaeologically significant flint sources in Denmark and Sweden, along with new data on a number of other sources of prehistoric significance. These data provide a geochemical foundation for ongoing research devoted to determining contrasts and continuities in the time and space utilization of flint sources in Scandinavian prehistory.     

A STUDY OF ANCIENT CHINESE PORCELAIN WARES OF THE SONG‐YUAN DYNASTIES FROM CIZHOU AND DING KILNS WITH ENERGY DISPERSIVE X‐RAY FLUORESCENCE*

Multi‐variable statistical analysis based on energy dispersive X‐ray fluorescence measurements on both porcelain body and glaze is employed to give clear and consistent classification of porcelain sherds from northern China of different styles from the Song‐Yuan dynasties (Ding and Cizhou styles), and also from the Sui‐Tang dynasties (Xing style). However, the observed separation is less clear for Cizhou style sherds produced at neighbouring kiln sites. Imitation Ding porcelain samples produced by ancient Cizhou potters are also analysed.     

ICP–MS ANALYSIS OF GLASS FRAGMENTS OF PARTHIAN AND SASANIAN EPOCH FROM SELEUCIA AND VEH ARDAŠ?R (CENTRAL IRAQ)*

Forty‐one glass fragments were analysed by inductively coupled plasma – mass spectrometry, determining 40 major, minor and trace elements, including rare earth elements. The fragments came from excavations carried out at the archaeological sites of Seleucia and Veh Arda??r in modern Iraq, and were dated to the Parthian and Sasanian epochs. Analytical data indicate that all the samples are silica–soda–lime glasses. Magnesium and potassium oxide contents below 1% suggest that eight out of nine glasses from Seleucia, dating from between the first and the third century ad , could have been obtained by use of an evaporite as a flux; the same conclusion can be drawn for some of the Sasanian glasses dating from the fourth and fifth centuries ad . The other glasses from Veh Arda??r, as well as the remaining sample from Seleucia, are characterized by higher contents of magnesium and potassium, which suggests recourse to plant ash; different magnesium and phosphorus contents allow one to separate these samples into two main groups, pointing to the use of different kinds of plant ash. Aluminium and calcium contents, together with trace element data, may indicate that different sands were used for preparing glasses of different composition. Samples from Seleucia and Veh Arda??r are mainly blue–green and green to yellow–green, respectively; iron and manganese contents suggest that the furnace atmosphere was mainly responsible for the development of these hues.     

AN INVESTIGATION INTO THE RELATIONSHIP BETWEEN THE RAW MATERIALS USED IN THE PRODUCTION OF CHINESE PORCELAIN AND STONEWARE BODIES AND THE RESULTING MICROSTRUCTURES*

The microstructures of porcelain and stoneware bodies from north and south China, spanning the period from the Tang to the Ming dynasty (7th–17th centuries ad ), were examined in polished sections in a scanning electron microscope (SEM) after etching the sections with hydrofluoric acid (HF). Mullite, present as fine, mainly elongated crystals, is the dominant crystalline phase observed. The bulk chemical compositions of the bodies are determined by energy‐dispersive spectrometry in the SEM, and the relative amounts of mullite and quartz present in the different ceramics are estimated from X‐ray diffraction measurements. Mullite formed from areas of kaolinitic clay, mica particles and feldspar particles is distinguished through a combination of the arrangement of the mullite crystals, and the associated SiO₂/Al₂O₃ wt% concentration ratios. It is shown that very different microstructures are observed in ceramic bodies produced using kaolinitic clay from north China (Ding porcelain and Jun stoneware), porcelain stone from south China (qingbai and underglaze blue porcelain and Longquan stoneware), and stoneware clays from south China (Yue and Guan stonewares). Therefore, SEM examination of HF‐etched, polished sections of the bodies of high‐refractory ceramics has considerable potential for investigating the raw materials used in their production.     

NON-DESTRUCTIVE ANALYSIS OF JINGDEZHEN BLUE AND WHITE PORCELAINS

The energy dispersive X-ray fluorescence method is used for the non-destructive qualitative analysis of Jingdezhen blue and white porcelains, which include the imperial wares of the Yongle, Xuande, Chenghua, Jiajing and Wanli periods of the Ming dynasty, the imperial wares of the Kangxi, Yongzheng, Qianlong, Jiaqing, Daoguang and Guangxu periods of the Qing dynasty, and those of the Republic and the contemporary period. The distribution pattern of the X-ray fluorescence intensities of the six characteristic elements for porcelain manufactured at different times has been investigated.     

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.     

THE ISOTOPIC COMPOSITION OF TIN IN SOME ANCIENT METALS AND THE RECYCLING PROBLEM IN METAL PROVENANCING

A recent suggestion that some ancient metallurgical processes might give rise to large changes (> 0.5%) in the isotopic composition of tin gave hope that it might be possible to identify ancient bronze samples which had undergone recycling and mixing processes. This paper describes a method for the analysis of the isotopic composition of tin by thermal ionization mass spectrometry and applies it to analyse a number of ancient bronzes and tin metal objects from the Bronze Age Mediterranean. No observable isotopic fractionation of tin was found above $0.1% in the ratio¹²² Sn/¹¹⁶. Consequently, either recycling of bronze in the Late Bronze Age Mediterranean was not so common as supposed, or the isotopic composition of tin is not fractionated by anthropogenic metallurgical processes to the extent predicted by the Bradford group.     

CHEMICAL ANALYSES OF GLASS BEADS FOUND IN TWO SARMATIAN BURIALS*

The chemical compositions of 14 glass beads from two Early Sarmatian-period burials were determined. Al, Ca, Fe, Mg, K, Na, and Si were measured by electron probe microbeam analysis, while the Co, Cu, Ga, Mn, Ni, Pb, Rb, Sr, Th, Ti, Y, Zn, and Zr contents were measured using energy dispersive X-ray fluorescence. All the beads can be classed as low-magnesia soda-lime-silica glasses. The blue glass beads examined in this study were coloured with Co and Cu containing minerals. Cluster analysis and principal components analysis suggest that two distinct glass recipes were used to manufacture these beads.