GEOCHEMICAL ANALYSIS OF VITREOUS ROCKS EXPLOITED DURING THE FORMATIVE PERIOD IN THE ATACAMA REGION,NORTHERN CHILE*

Petrographic analysis and geochemical characterization studies were carried out on vitreous dacite and/or rhyodacite artefacts from Formative period archaeological sites in the upper Salado River Basin in the Atacama Desert, northern Chile. These were compared with samples taken from two source areas located within the subregion, named Linzor and Paniri. Source samples and archaeological specimens were analysed by inductively coupled plasma – mass spectrometry (ICP–MS) combined with optical emission plasma – mass spectrometry (ICP–OES) and atomic absorption spectroscopy (AAS). Results from the limited number of samples analysed indicate that the Linzor source seems to have been the primary source exploited during the Early and Late Formative periods in the Salado River Basin.     

LEAD GLAZES IN ANTIQUITY—METHODS OF PRODUCTION AND REASONS FOR USE*

Transparent high lead and tin-opacified lead-alkali glazes have been extensively used throughout Europe and the Near East from their first appearance in the Roman era and the tenth- to eleventh-century Islamic world, respectively, up until the present day. Using, to a large extent, information which is widely scattered through a diverse range of literature, the methods employed in the production of these two glaze types are first outlined and their merits are then compared with those of alkali glazes in terms of ease of preparation of the glaze mixture, ease of application of the glaze, ease of firing, cost of production, glaze-body fit and visual appearance. The principal advantages of transparent high lead glazes as compared to alkali glazes are shown to be ease of preparation and application of the glaze suspension, low susceptibility to glaze ‘crazing’ and ‘crawling’ and high, optical brilliance. Factors that influence the choice of tin-opacified lead-alkali glazes include ease of production of tin oxide by melting tin and lead metals together; a reduced risk of reduction of lead oxide to lead metal and consequent blackening of the glaze; and, again, low susceptibility to ‘crazing’ and ‘crawling’. Limits of current knowledge regarding these two glaze types and requirements for future research are outlined.     

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.     

IDENTIFICATION OF FORGERIES BY MEASURING TIN ISOTOPES IN CORRODED BRONZE OBJECTS*

The reliable identification of fakes consisting of bronze often presents problems, because traditional methods such as stylistic studies, optical microscopy, chemical analysis or X‐ray diffraction of the corrosion may not be conclusive. We present a method that is based on the comparison of the tin isotope ratios ¹²²Sn/¹¹⁶Sn and ¹¹⁷Sn/¹¹⁹Sn in the metal and in the adherent corrosion layer. An artificial patina is usually generated within a short time period. It has been observed that such a procedure leads to a depletion of the light tin isotopes in the corrosion layer, while in naturally corroded authentic archaeological objects no isotopic fractionation has been detected. The method has also been applied to archaeological objects and it could be confirmed, among other examples, that the famous ‘Sky Disc of Nebra’ is authentic.     

GC–MS ANALYSIS OF LIPIDS IN PREHISTORIC ROCK PAINTS AND ASSOCIATED OXALATE COATINGS FROM THE LOWER PECOS REGION,TEXAS*

The presumption that lipids were used as binders/vehicles in pictograph paints from southwestern Texas was tested using gas chromatography–mass spectrometry (GC–MS). A one‐step transesterification/derivatization procedure was used to convert bound and unbound fatty acids to fatty acid methyl esters for the analysis. Approximately 30 organic compounds were detected in the natural rock coating that encapsulates the paints, but there were no compounds unique to the paints. Moreover, the C_16:0 and C_18:0 concentrations in the paint samples were similar to the concentrations of these fatty acids in the rock coating, indicating that the compounds are native to the patina. Thus, lipid binders were either not used in the original paint mixture or have since degraded.     

NEOLITHIC ZOOMORPHIC VESSELS FROM EASTERN MACEDONIA,GREECE: ISSUES OF FUNCTION*

Five fragments of Late Neolithic clay zoomorphic vessels from northern Greece have been analysed for organic residues by gas chromatography – mass spectrometry. The results showed that the containers had been used in connection with a number of substances, in particular lower terpenoids, an oil or fat, possibly fossil fuel and in one case possibly beeswax. The paper considers likely interpretations of such combinations of materials in relation to possible functions of these symbolically enhanced artefacts. It appears that substances may have been used in the vessels because of their aromatic and/or medicinal and combustible properties, possibly in order to produce light, fragrance and/or smoke.     

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).     

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.     

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.