INDUCTIVELY COUPLED PLASMA-MASS SPECTROMETRY FOR THE ANALYSIS OF ANCIENT METALS*

Inductively coupled plasma-mass spectrometry (ICP-MS) is a relatively new analytical technique, growing in popularity, that offers many advantages over previously available instrumentation for the measurement of both the elemental and isotopic composition of metallic antiquities. The application of this method of analysis to archaeological metalwork is discussed and the technique compared with other methods of analysis commonly used in archaeometallurgy. Particular attention is drawn to the potential pitfalls and difficulties associated with ICP-MS and the need for extremely careful sample preparation and instrument operation.     

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.     

CHARACTERIZATION OF NATURAL PRODUCTS ON NATIVE AMERICAN ARCHAEOLOGICAL AND ETHNOGRAPHIC MATERIALS FROM THE GREAT BASIN REGION,U.S.A.: A PRELIMINARY STUDY

Although documentary evidence provided by ethnographers makes reference to the source of adhesives, sealants, dyestuffs and medicines used by the communities of the Great Basin, much of it is sporadic and unspecified. However, observations of amorphous deposits surviving on stone tools, ceramics, basketry and wooden artefacts have prompted an investigation of their identity, procurement and use. The aim initially is to study samples from a number of archaeological and ethnographic contexts from the region. Comparative material includes higher plant and insect resins. The study provides a unique opportunity to document use patterns in plant and animal resources in the Great Basin region.     

Geochemical Characterization of Lapita Pottery Via Inductively Coupled Plasma–mass Spectrometry (ICP–MS)

We have obtained high‐resolution elemental data on Lapita ceramics (3200–2700 cal year bp ) from Fiji, Tonga and New Ireland using chemistry‐based inductively coupled plasma–mass spectrometry (ICP–MS). These data show clear elemental distinctions between Lapita pottery manufactured in Fiji, Tonga and New Ireland, and demonstrate significant elemental variation in Fijian ceramics collected from settlements in close proximity to one another. Therefore, we anticipate that ICP–MS will become an effective technique for tracking the transfer of Lapita pottery within and between different island groups in Oceania.     

The Determination of Lead Isotope Ratios by Multiple Collector Icp‐Ms: A Case Study of Early Bronze Age Artefacts and their Possible Relation With Ore Deposits of the Erzgebirge*

Lead isotope analyses of Early Bronze Age metal artefacts from the Aunjetitz (Ún?tice) culture in central Germany and Bohemia were determined in order to find out whether they could be related to ore sources of the Erzgebirge. Historical mining began only in the 12th century ad , but despite the lack of convincing field evidence it has frequently been suspected that this region was already being exploited in prehistoric times. For the determination of the lead isotope ratios, the new technique of multiple collector inductively coupled plasma mass spectrometry (MC‐ICP‐MS) was employed, which combines relatively easy sample preparation with highly precise and accurate measurements. The results show that there is still no evidence for prehistoric mining in the Erzgebirge, but the Rammelsberg deposit in the Harz Mountains might have supplied some of the copper. Mining of stream tin in the Erzgebirge remains a possibility, but no positive evidence can be extracted from 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.     

DATING ARCHAEOMETALLURGICAL SLAGS USING THERMOLUMINESCENCE*

Thermoluminescence has a great potential for dating archaeometallurgical slags, because the smelting process leads to a well‐defined resetting of the ‘luminescence clock’. However, the complex compositions of slags have unpleasant consequences for TL measurements if the bulk slag substance is used. To overcome this problem, quartz has been separated out of slag matrices by chemical and physical procedures. The TL measurements were carried out on this defined mineral phase. This method was tested with seven slag samples from different locations and ages. In most cases, the TL ages determined show good agreement with reference data.     

RAMESSIDE GLASS-COLOURING CRUCIBLES*

The preparation of glass in New Kingdom Egypt heavily involved the use of crucibles. Shape, mode of operation and function of these vessels have been reconstructed on the basis of new, stratified material from the excavation at Qantir, eastern Nile Delta. The crucible fabric, the internal layer protecting the vessel from the charge, and the glass melted in the crucibles are characterized by chemical and petrographic studies. The crucibles were apparently employed mainly to add the colourants to the glass. The broader archaeological context strongly suggests that glass production in the Late Bronze Age has been a highly developed, specialized and organized craft, with different factories for glass production, for colouring, and for working, connected by a wide-ranging trade network.     

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.     

IDENTIFICATION OF AN ADHESIVE USED TO REPAIR A ROMAN JAR

A combination of micro-analytical techniques, including thin layer chromatography (TLC), gas chromatography (GC), and combined gas chromatography/mass spectrometry (GC/MS), was employed to study the lipid composition of an adhesive used to repair an Ecton ware jar, recovered from Roman sediments of the River Nene at West Cotton (Rounds, Northamptonshire, U.K.). GC of the total lipid extract of the adhesive showed a complex pattern which was difficult to interpret. TLC was used to fractionate the extract. The fractions were then trimethylsilylated and submitted to GC and GC/MS. Betulin, lupeol, lupenone, allobetul-2-ene, and several other pentacyclic triterpenoid compounds were shown to be present in the ancient material. The similarities between the lipid compositions of the adhesive and of contemporary birch bark tar and a birch bark total lipid extract led to the conclusion that the adhesive was derived largely from birch bark, thus providing the first firm evidence for the use of birch bark tar in ancient Britain.