X-RAY MICROANALYSIS OF ANCIENT GLASSY MATERIALS: A COMPARATIVE STUDY OF WAVELENGTH DISPERSIVE AND ENERGY DISPERSIVE TECHNIQUES*

Sensitivity, precision and accuracy of quantitative microanalysis of major, minor and trace elements present in ancient glasses by energy dispersive spectrometry (EDS) is compared to that by wavelength dispersive spectrometry (WDS). Although there are certain problems with EDS due to peak overlaps and background noise, the precision and minimum detection limits of EDS for most of the important elements in ancient glasses were found to compare favourably to those of WDS. Both EDS and WDS, when quantified by comparison to glass standards, can produce reliable results which are adequate for most technological questions.     

Aspects of the Production of Cobalt‐blue Glass in Egypt

Cobalt‐blue glass of the Near and Middle Eastern Late Bronze Age has long been recognized as compositionally distinct from other contemporary glasses (Sayre 1967; Lilyquist et al. 1993). It has been suggested recently by Shortland and Tite (2000) that this chemical distinction reflects the use of Egyptian raw materials for making these glasses, different from those used to make glass in Mesopotamia, or its manufacture by Mesopotamian workmen, possibly in Egypt. This assumed that cobalt‐bearing alum from the Western Oases and mineral natron from the Wadi Natrun were used for the cobalt‐blue glass, while the other, probably Mesopotamian, glasses were made using plant ash as the main alkali source. This note discusses some technical aspects of the possible ways in which the cobalt could have been added to the glass, and how this relates to the likely raw glass used in its making. Combining earlier suggestions by Noll (1981) and Brill in Lilyquist et al. (1993), an alternative explanation of the chemical characteristics is suggested, maintaining that all the glasses under discussion were made using plant ash. Differences in alkali concentrations probably reflect different soil and plant chemistries, and the colorant was probably added to the glass after being precipitated from the alum as a complex cobalt aluminium hydroxide.     

COMPARING GLASS COMPOSITIONAL ANALYSES*

In a recently published study of Romano‐British colourless glass compositions, using inductively coupled plasma spectroscopy, 28 glasses from Colchester sampled in a previous study were resampled. This was done deliberately, with a view to examining the repeatability of results from sampling on different occasions. We report on our results here, developing in the process some simple statistical methodology that could be applied in similar situations. The potential for combining analyses undertaken at different times is discussed and illustrated.     

APPLICATION OF LEAD ISOTOPE ANALYSIS TO A WIDE RANGE OF LATE BRONZE AGE EGYPTIAN MATERIALS*

Lead isotope analysis was applied to Egyptian materials from the Late Bronze Age in order to investigate the relationship between these different materials, many of which have lead as a significant component. The galena kohls analysed can be provenanced to Gebel Zeit, a large mining site known to have been active during the period. However, the source of lead metal is different and seems to be outside Egypt, along with the source of copper. Lead‐based pigments such as lead antimonate that were used in glass and glazes seem mostly to come from Egypt, although they may well contain a component of ‘Mesopotamian’ lead. In the Predynastic period, galena from many sources is being exploited for use as kohl. However, by the Middle Kingdom (2055–1650 bc ), extraction has concentrated on one source, Gebel Zeit, perhaps reflecting increasingly centralized control and/or the use of large‐scale exploitation. It therefore appears that a complex pattern of trade in lead‐based materials was evident, with lead metal and galena being separate commodities from separate sources and treated as such.     

DIRECT EVIDENCE OF PRIMARY GLASS PRODUCTION IN LATE BRONZE AGE AMARNA,EGYPT

This paper presents direct archaeological evidence for the primary production of glass at the LBA site of Tell el‐Amarna, in the form of numerous finds of semi‐finished glass. The diagnostic microstructural and chemical composition of these finds is presented alongside macroscopically similar finds, of shapeless lumps of finished white glass. The semi‐finished glass was found to contain numerous inclusions of residual quartz and newly formed lime‐rich crystal phases, but no added colorant. However, several samples of semi‐finished glass have antimony oxide levels comparable to those of finished white glass, suggesting that the opacifier was added to the initial glass‐making batch. The results are discussed in comparison with the evidence for glass‐making from Qantir – Pi‐Ramesse, identifying some close technical similarities, which indicate that the same technological processes were used at both sites for the production of glass.     

ISOTOPIC DISCRIMINANTS BETWEEN LATE BRONZE AGE GLASSES FROM EGYPT AND THE NEAR EAST

This paper presents oxygen, strontium and neodymium isotopic analysis from a series of Late Bronze Age glasses from Egypt and Mesopotamia. It was found that oxygen and neodymium isotopes alone cannot readily distinguish between glasses from the various sites. However, combined Sr and Nd isotope analysis separate the data into three groups: an Egyptian group with relatively low Sr and Nd ratios; a Late Bronze Age (LBA) Nuzi group with high Sr and low Nd ratios; and an intermediate Sr and high Nd ratio grouping of glasses from Tell Brak. These findings suggest that most of the glass from Nuzi and Tell Brak had different raw materials and hence the glass was probably produced at different manufacturing sites. However, one glass ingot found at Tell Brak (TB1) appears to have Nuzi‐type Sr–Nd characteristics. This is the first positive identification of multiple production sites in LBA Mesopotamia and an exceptional example of a glass that may have been exchanged from one LBA site to another.     

THE COMPOSITION OF COPPER-BASED SMALL FINDS FROM A WEST PHOENICIAN SETTLEMENT SITE AND FROM NIMRUD COMPARED WITH THAT OF CONTEMPORARY MEDITERRANEAN SMALL FINDS

About 100 Phoenician copper alloy artefacts from Morro de Mezquitilla (Spain) have been analysed by inductively coupled plasma spectrometry and atomic unpublished analyses of contemporary material from Nimrud and with small finds of the same period from several Mediterranean areas. There are no published large-scale analyses of Phonenician metalwork and few analyses of the copper-based, very minor objects of the sort typically recovered from excavation and the comparisons show both similarities and differences in techniques and alloys of the various civilizations and classes of objects.     

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.     

A PRELIMINARY PETROGRAPHIC ANALYSIS OF CYPRIOT WHITE SLIP II WARE*

Samples of Late Bronze Age White Slip II ware from Cyprus were analysed using optical and scanning electron microscopy in conjunction with energy and wavelength dispersive analyse The slip has a novel granular nature and the coarser aggregates are impressed into the outer surface of the body, indicating that it was applied to a moist surface before the vessels were fired. It has a consistent mineral assemblage (Mg‐chlorite + illite‐smectite + sphene + anatase/rutile ± albite) which is very similar to that of hydrothermally altered zones associated with copper orebodies in the Troodos Massif which were mined in antiquity Our analysis suggests that the raw material for the slip was not found at the ground surface, because the alteration assemblage is unaffected by oxidation and copper carbonate or iron staining. It may, therefore, be a by‐product of sub‐surface ore extraction     

COMPOSITIONAL VARIABILITY IN COLOURLESS ROMAN VESSEL GLASS

A statistical re-analysis is undertaken of 118 inductively coupled plasma spectrometry analyses of Romano-British glass specimens found in excavations at Colchester. There are four vessel types present, some of which are associated with chronologically distinct periods. Previous research has suggested little difference in the mean composition of different types. The present paper shows that there are interesting differences in the variation of compositions within types, with some showing much greater compositional stability then others. Some possible models to explain this phenomenon are discussed.     

ON STATISTICAL APPROACHES TO THE STUDY OF CERAMIC ARTEFACTS USING GEOCHEMICAL AND PETROGRAPHIC DATA*

The scientific analysis of ceramics often has the aim of identifying groups of similar artefacts. Much published work focuses on analysis of data derived from geochemical or mineralogical techniques. The former is more likely to be subjected to quantitative statistical analysis. This paper examines some approaches to the statistical analysis of data arising from both kinds of techniques, including ‘mixed‐mode’ methods where both types of data are incorporated into analysis. The approaches are illustrated using data derived from 88 Late Bronze Age transport jars from Kommos, Crete. Results suggest that the mixed‐mode approach can provide additional insight into the data.     

ROMAN GLASS‐MAKING AT COPPERGATE,YORK? ANALYTICAL EVIDENCE FOR THE NATURE OF PRODUCTION*

Ceramic vessels and associated vitreous debris, excavated at Coppergate, York, UK, have been interpreted as the remains of Roman glass‐making from the raw materials. This paper reports the results of analysis of this assemblage by XRF, ICPS, XRD, SEM– EDAX and thin‐section petrography. These findings suggest that some ceramic vessels, used as crucibles, have been subjected to temperatures up to 1200°C, well above the firing temperatures of the local domestic assemblage from which they were selected. Analysis of quartz‐rich debris, intimately mixed with glass in some samples and in others interleaved with glassy phases, indicates partially reacted glass‐making raw materials, with α‐quartz, tridymite and cristoballite phases represented. This could represent evidence either of a failed attempt to frit the raw materials, or a batch that had not fully fused. Variability in the composition of glass at the site is viewed in the light of glass‐making technology, and possible interpretations concerning this episode are discussed in the light of the archaeological evidence.     

TEPHRA SAMPLES FROM MOCHLOS AND THEIR CHRONOLOGICAL IMPLICATION FOR NEOPALATIAL CRETE

Five deposits of Santorini tephra have been found in the excavations currently under way at the site of Mochlos which lies on the north coast of Crete about 140 km to the south of Santorini. This paper provides refractive index and trace element analyses for the largest of these deposits, examines the stratigraphy of all five deposits, and notes the chronological implication of this stratigraphy for the Late Minoan IB period, the floruit of Minoan civilization.     

A CHARACTERIZATION OF THE COMPOSITIONAL VARIATIONS OF ROMAN SAMIAN POTTERY MANUFACTURED AT THE LEZOUX PRODUCTION CENTRE

The study addresses the chemical variations for Roman Samian wares manufactured during various periods at different workshops within the Lezoux production centre. Instrumental neutron activation analysis and inductively coupled plasma spectrometry were used to determine the chemical constituents of the pottery. The two techniques were evaluated based on the capacity of each to identify the same compositional groups for Lezoux Samian with the use of multivariate statistics. The compositional analysis redefines and clarifies how potters used the clay sources at the site to produce fine wares. The results indicate that the majority of potters from different workshops at Lezoux shared the same clay source during the second century AD.     

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.     

CAMPANIAN POTTERY FROM ANCIENT BRUTTIUM (SOUTHERN ITALY): SCIENTIFIC ANALYSIS OF LOCAL AND IMPORTED PRODUCTS*

One hundred and fifty-seven sherds of Campanian pottery were analysed by inductively coupled plasma optical emission spectroscopy (ICP-OES) and flame emission spectroscopy (FES). The sherds were found in the course of archaeological excavations carried out at the sites of Sibari, Cosenza, Crotone, Locri, Reggio and Oppido Mamertina in southern Italy (ancient Bruttium, today Calabria). Analyses were carried out on dissolved samples, determining 15 elements per sample (Al, Fe, Ca, Mg, Ti, Mn, Sr, Ba, Cr, Cu, Y, La and Sc by ICP-OES, and Na and K by FES). Analytical data were subject to multivariate statistical treatment by hierarchical cluster analysis and principal components analysis. Results indicated different compositional groups, allowing one to separate suspected imports from Campania, Etruria and Sicily from each other and from likely local products. The latter could be further classified into different groups, comprising imitations of foreign forms as well as original local products.     

Chemical characterization of ancient pottery from sudan by x‐ray fluorescence spectrometry (xrf), electron microprobe analyses (empa) and inductively coupled plasma mass spectrometry (ICP–MS)*

Sixty‐four sherds and seven natural clays from prehistoric sites in northwestern Sudan have been submitted to petrological and chemical analysis using XRF spectrometry, EMPA and ICP–MS. According to their texture, the sherds form five different groups. The high contents of P₂O₅ (more than 0.5 wt%) discerned in 19 samples and the variation of the P₂O₅ content in two samples of the same vessel can be explained by post‐depositional processes or by the ancient organic contents (e.g., milk) of the vessel. Chemical classification of the pottery bulk suggests that vessels were made locally, as only sherds from the same area show homogeneity of data.     

A COMPARISON OF METHODS FOR ESTABLISHING FATTY ACID CONCENTRATION GRADIENTS ACROSS POTSHERDS: A CASE STUDY USING LATE BRONZE AGE CANAANITE AMPHORAE*

Canaanite amphorae fragments in fabrics believed to be associated with the bulk transport of vegetable oils from the fourteenth‐century BC site of Amarna, Egypt, have been examined. A comparison is made between solvent extraction, saponification and the use of TMTFTH (m‐trifluoromethylphenyl)trimethylammomum hydroxide, used here for the combined extraction and derivatization of ceramic‐absorbed organic residues. Extracts were studied using gas chromatography and gas chromatography‐mass spectrometry. The extraction of fatty acids from small ceramic samples has established concentration gradients of absorbed organic matter from the inner to the outer surfaces of the sherds.     

FINGERPRINTING ANCIENT EGYPTIAN QUARRIES: PRELIMINARY RESULTS USING LASER ABLATION MICROPROBE-INDUCTIVELY COUPLED PLASMA-MASS SPECTROMETRY*

Microchemical analysis of minerals present in pottery and stone artefacts may help determine their provenance. Electron microprobe major element analyses of augite suggest that minor elements (Ti0₂,MnO, Aa₂O) are important in fingerprinting basalts. This points to the potential usefulness of trace elements. Augite present in six basalt samples (representing all known/suspected Pharaonic basalt quarries in northern and middle Egypt) and basaltic temper fragments in two New Kingdom pottery sherds was analysed for 28 trace elements (Sr, Ba, Th, U, Zr, Hf, Nb, Ta, Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu. Sc, V, Cr, Ni, Ga) by laser ablation microprobe-inductively coupled plasma-mass spectrometry (LAM-ICP-MS, laserprobe). Cluster and discriminant analysis indicate that (1) laserprobe trace element data are more effective at fingerprinting basalts than conventional electron-microprobe data and (2) basaltic temper in the two sherds does not match any of the quarries. Microbeam techniques providing trace element data may represent the future for mineral-based provenance studies.     

PREHISTORIC COPPER PRODUCTION IN THE INN VALLEY (AUSTRIA), AND THE EARLIEST COPPER IN CENTRAL EUROPE*

In recent years archaeological finds and scientific analyses have provided increasing evidence for a very early beginning of copper production in the rich mining area of the Tyrolean Alps. The earliest findings derive from an excavation of a multi‐phase settlement on the Mariahilfbergl in Brixlegg, which revealed evidence that a small amount of fahlores, probably of local provenance, was at least heated if not even smelted there in the Late Neolithic Münchshöfen culture (the second half of the fifth millennium bc ). However, most copper finds of this horizon consist of low‐impurity copper that most probably derives from Majdanpek in Serbia. This long‐distance relationship is corroborated by typological features that link some aspects of the Münchshöfen culture with the Carpathian basin. Thus it is not yet clear if, at Brixlegg, actual copper production took place or, rather, an experimental treatment of the local ores. The typical fahlore composition, with arsenic and antimony in the per cent and silver and bismuth in the per mille ranges, appears in quantity only in the Early Bronze Age. Many thousands of Ösenringe are known from many central European Early Bronze Age sites, with a chemical composition typical of fahlores. At Buchberg near Brixlegg, a fortified settlement with slags from fahlore smelting proves that the local ores were indeed exploited. The lead isotope ratios of Ösenringe from the Gammersham hoard in Bavaria, which consist of fahlore copper, confirm this and suggest that copper mining and production in the Inn Valley reached a first climax during that period. In the Late Bronze Age, copper was produced at an almost industrial level.