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.     

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.     

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.     

EVALUATION OF THE ANALYTICAL POTENTIAL OF LASER‐INDUCED BREAKDOWN SPECTROMETRY (LIBS) FOR THE ANALYSIS OF HISTORICAL GLASSES*

The novel and—for archaeometrical applications—still rarely used Laser‐Induced Breakdown Spectrometry (LIBS) was tested on various standard glasses for its spectrometric performance. LIBS is an almost non‐destructive method based on the time‐resolved detection of optical emission following direct laser ablation. A frequency‐quadrupoled Nd:YAG laser at 266 nm was found to cause a hardly visible crater of c. 200 µm in diameter. The application of an innovative high‐resolution Echelle spectrograph allows the fast and simultaneous determination of up to 90 elements in the spectral range from 200 to 780 nm, with a resolution of 10–30 pm under ambient conditions. In principle, LIBS has a high analytical potential for archaeometry; in particular, for the determination of light elements (Li, Be, B and others). Because the measurement parameters (laser energy, delay time and number of pulses) do not independently influence the emission signal, their optimization proved to be complex and is rather a compromise for the range of elements. The effects of sample distance, surface roughness and the accumulation of depth profiles were studied. Problems arose for the determination of sodium and potassium in higher contents due to self‐absorption effects. Quantification tests using a silicon line as internal standard yielded a precision range between 3% and 20% relative, but in general no satisfying accuracy for a number of elements. However, these problems might be overcome in the near future by improved spectrometer set‐ups and matrix correction approaches.     

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.     

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 STUDY OF NABATAEAN ORGANIC RESIDUES FROM MADÂ’IN SÂLIH,ANCIENT HEGRA,BY GAS CHROMATOGRAPHY – MASS SPECTROMETRY*

Four Nabataean samples collected in some of the monumental tombs of Madâ’in Sâlih, ancient Hegra, in Saudi Arabia, have been studied by gas chromatography coupled with mass spectrometry. These samples are textile fragments that are either covered with a black layer or bound together with some black amorphous substance. Fatty acids and triterpenoic compounds were detected. Eight triterpenic compounds were identified: ursa‐9(11),12‐dien‐3‐ol, ursa‐9(11),12‐dien‐3‐one, olean‐9(11),12‐dien‐3β‐ol, β‐amyrone, β‐amyrin, α‐amyrone, α‐amyrin and lupeol. The resinous chemical composition and these pentacyclic alcohols, in considerable proportion, indicate a resin of the Burseraceae family, possibly of the genus Canarium.     

CHARACTERIZATION OF RED‐COLOURED SLIPS (ALMAGRA) ON ISLAMIC CERAMICS IN MUSLIM SPAIN*

Small objects found in Islamic (eleventh‐century) kilns excavated in Zaragoza (Spain) were studied to determine the nature of the red coating of almagra pottery. Ceramics with almagra decoration were completely coated with a glossy deep‐red layer, a slip, applied to the body before firing. Chemical and mineralogical studies were carried out, together with analysis of a surface treatment with organic compounds. The results of this study confirm that almagra ceramics were produced by means of a specific and elaborate process (slip preparation, firing and wax application), demonstrating the introduction of this slip into local production during the Islamic period.     

IDENTIFICATION OF ANCIENT LACQUER FILM USING TWO-STAGE PYROLYSIS-GAS CHROMATOGRAPHY/MASS SPECTROMETRY*

Oriental lacquer has been used as a surface coating for wood, porcelain and metal, and three different types are known: Japanese (or Chinese) lacquer (urushiol-based), Vietnamese lacquer (laccol-based) and Burmese lacquer (thitsiol-based). Identification of these types in ancient coatings is very important in conservation and restoration studies. A two-stage pyrolysis-gas chromatography/mass spectrometry method is effective for the analysis of lacquer films. This is shown here using an ancient lacquer film sample from medieval material excavated at Tobarikyu (Japan), The sample was identified, by comparison with linseed oil and authentic lacquer films, as an urushiol-based Rhus vernicifera (Japanese) lacquer which includes an added oil component.