TIN ISOTOPY—A NEW METHOD FOR SOLVING OLD QUESTIONS

Tin was a vital commodity in times past. In central Europe, the earliest finds of tin‐bronze date to about 2200 bc , while in Greece they are c. 400–500 years earlier. While there is evidence for prehistoric copper mining—for example, in the Alps or mainland Greece, among other places—the provenance of the contemporary tin is still an unsolved problem. This work deals with a new approach for tracing the ancient tin via tin isotope signatures. The tin isotope ratios of 50 tin ores from the Erzgebirge region (D) and 30 tin ores from Cornwall (GB) were measured by MC–ICP–MS. Most ore deposits were found to be quite homogeneous regarding their tin isotope composition, but significant differences were observed between several deposits. This fact may be used to distinguish different tin deposits and thus form the basis for the investigation of the provenance of ancient tin that has been sought for more than a century. Furthermore, the tin‐isotope ratio of the ‘Himmelsscheibe von Nebra’ will be presented: the value fits well with the bulk of investigated tin ores from Cornwall.     

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.     

A LEAD ISOTOPE DATABASE: THE LOS PEDROCHES – ALCUDIA AREA (SPAIN); IMPLICATIONS FOR ARCHAEOMETALLURGICAL CONNECTIONS ACROSS SOUTHWESTERN AND SOUTHEASTERN IBERIA*

One hundred and twenty‐five new lead isotopic analyses on galena, mainly from the Los Pedroches – Alcudia Valley area of southern Iberia, are presented. These data allow us to define four compositional groups in the ²⁰⁷Pb/²⁰⁶Pb versus ²⁰⁸Pb/²⁰⁶Pb and ²⁰⁷Pb/²⁰⁶Pb versus ²⁰⁶Pb/²⁰⁴Pb diagrams. Group I compositions are intermediate between those previously reported for southeastern and southwestern Iberian ore mineral locations. The compositions of Group II, the largest group, overlap with ore data from southwestern Spain. Groups III and IV have compositions that have never before been identified in this region and are comparable to those from the Sardinian Cu ores, which might explain the previously assumed exotic origin for local Bronze Age artefacts.     

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.     

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.     

THE POSSIBLE FRACTIONATION OF LEAD ISOTOPES IN ANCIENT METALLURGICAL PROCESSES

The possibility of lead isotope fractionation in ancient lead production is examined. Kinetic theory relating to isotopic fractionation in non-equilibrium evaporation is considered and the feasibility of the alteration of lead isotope abundance ratios in ore roasting and smelting is assessed. Previous experimental work is shown to have been inconclusive and conclusions are drawn on the need for further research to quantify the possible extent of fractionation in practice.     

THERMOLUMINESCENCE DATING OF A CRUCIBLE FRAGMENT FROM AN EARLY TIN PROCESSING SITE IN TURKEY

Archaeological exploration in the Taurus mountains at Göltepe in south-central Turkey has uncovered a site indicating the presence of extensive tin ore mining and smelling operations The most recent find of smelting crucible fragments allowed for a thermoluminescence-hased age determination spanning a late fifth to early third millennium BC date. This result is consistent with a number of radiocarbon dates derived for charcoal also found at the site. The importance of this site relates to the possible tin production and subsequent trade with southwestern Asia which would have provided this otherwise scarce ingredient to bronze technology in that area. This date is directly for crucible material and thus confirms the antiquity of tin smelting at Göltepe.     

A CASE STUDY OF ARTHROPODS PRESERVED ON ARCHAEOLOGICAL BRONZES—MICRO‐ARCHAEOLOGICAL INVESTIGATION HELPS RECONSTRUCTING PAST ENVIRONMENTS

This paper offers new perspectives for improving our knowledge of arthropods in wet and aerobic archaeological contexts. The very‐near environment of uncleaned buried bronze artefacts, two ronde‐bosse ornaments of a Celtic grave from the Iron Age (275 to 250 bc , La Fosse‐Cotheret, Roissy‐en‐France), was studied by means of optical and scanning electron microscopies. Taking into account recent knowledge on bronze corrosion (decuprification), this micro‐investigation (micro‐archaeology) allowed identification of two fossilized arthropods—Cryptophagus sp. (Insecta, Coleoptera, Cryptophagidae) and Coccotydaeolus sp. (Acari, Tydaeoidea, Iolinidae)—which sheds some light upon the complex taphonomic process that occurred after the burial of a Celtic chariot. These first results support the idea that the local corroded metal/soil system has to be investigated for a better understanding of archaeological microenvironments. Efficient minute investigation of soiled bronzes could be performed prior to systematic cleaning of artefacts.     

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.     

ORGANIC RESIDUE ANALYSIS IN ARCHAEOLOGY: THE ARCHAEOLOGICAL BIOMARKER REVOLUTION*

Organic residue analysis utilizes analytical organic chemical techniques to identify the nature and origins of organic remains that cannot be characterized using traditional techniques of archaeological investigation (because they are either amorphous or invisible). The field is founded upon the principle that the biomolecular, or biochemical, components of organic materials associated with human activity survive in a wide variety of locations and deposits at archaeological sites. The archaeological information contained in organic residues is represented by the biomolecular components of the natural products that contribute to the formation of a given residue. By applying appropriate separation (chromatographic) and identification (mass spectrometric) techniques, the preserved, and altered, biomolecular components of such residues can be revealed. Once identified, the Archaeological Biomarker Concept can be applied, wherein the structure and even isotopic composition(s) of a given biomolecule or suite of biomolecules (the ‘chemical fingerprint’) can be related to the compositions of organisms exploited by humans in the past. As the organic residue field emerges from its pre‐paradigmatic phase, and the organic residue revolution gathers pace, the way is open for challenging many long‐held archaeological hypotheses and offering new perspectives on the study of human activity in the past.     

On Pins and Needles: Tracing the Evolution of Copper-base Alloying at Tepe Yahya, Iran, via ICP-MS Analysis of Common-place Items

From 1967 to 1975 a team of archaeologists excavated the site of Tepe Yahya in southeastern Iran under the direction of C. C. Lamberg-Karlovsky. Although there are two forthcoming “final reports” (Hiebert (in progress), and Magee (in press); see also Lamberg-Karlovsky & Potts, 2001), analysis of the materials continues as opportunities allow. Metal artefacts, most especially those made of copper and its alloys, are found at this site from the late Neolithic through the Iron Age. Archaeometallurgical analysis, radiocarbon chronologies, and archaeological interpretation allow one to state when and how a type of metal or a style of object was invented, its use as a trade item, and its function and value to an ancient community. In the hopes of establishing a framework for future archaeometallurgical studies, most of the metal artefacts from Tepe Yahya, Iran, stored in the Peabody Museum of Harvard University, were analysed for elemental composition to complement stylistic and metallographic data.     

LEAD ISOTOPE ANALYSES OF BRONZE AGE COPPER‐BASE ARTEFACTS FROM AL‐MIDAMMAN,YEMEN: TOWARDS THE IDENTIFICATION OF AN INDIGENOUS METAL PRODUCTION AND EXCHANGE SYSTEM IN THE SOUTHERN RED SEA REGION*

The results of the lead isotope analysis (LIA) of 15 copper‐base artefacts from the Bronze Age site of al‐Midamman, Yemen, are reported. The LIA data suggest the existence of an indigenous Bronze Age metal production and exchange system centred on the southern Red Sea region, distinct from those in neighbouring regions of Arabia and the Levant. These preliminary results are highly significant for the archaeology of the region, suggesting that local prehistoric copper extraction sites have thus far gone unrecorded, and highlighting the need for systematic archaeometallurgical fieldwork programmes in the countries surrounding the southern Red Sea.     

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.     

COMPOSITIONAL VARIATIONS IN AGED AND HEATED PISTACIA RESIN FOUND IN LATE BRONZE AGE CANAANITE AMPHORAE AND BOWLS FROM AMARNA,EGYPT*

This study examines resinous deposits from the interior surfaces of sherds of imported Canaanite amphorae and locally produced bowls from the 18th Dynasty site of Tell el‐Amarna, Egypt. Archaeological evidence indicates that the Canaanite amphorae were used for resin transport, whilst the bowls are associated with burning resin as incense. A number of characteristic triterpenoids identify all the resinous deposits from both vessel types as Pistacia spp. No other resins were observed and there was no evidence of mixing with oils or fats. The composition of the archaeological resins is more complex than that of modern pistacia resin, due to degradation and generation of new components. Experimental heating alters the relative abundance of the triterpenoid composition of modern pistacia resin. One component, the triterpenoid 28‐norolean‐17‐en‐3‐one, is produced by such heating; however, an increase in its relative abundance in ancient samples is not matched by the archaeological evidence for heating. It is therefore not possible to use this component reliably to identify heated resin. However, additional unidentified components with a mass spectral base peak at m/z 453 have been associated with seven (out of 10) bowls and are not observed in resins associated with Canaanite amphorae. It is proposed that these components are more reliable molecular indicators of heating.     

ESTIMATION OF THE AGE OF A PRE‐INDUSTRIAL IRON SITE IN KOREA*

A pre‐industrial iron‐smelting site in Korea, whose period of active use is placed on typological grounds between the eighth and 18th centuries ad , has been dated using accelerator mass spectrometry and thermoluminescence. The ages of two charcoal samples were 77 ± 25 and 81 ± 25 years bp , with the calibrated date for both ranging from ad 1700 to ad 1955, while a clay fragment dated to ad 1650 ± 50. The results from typology and radiocarbon seem insignificant due to the considerable uncertainties involved, but in combination with the thermoluminescence result they place the most probable date of the site at around ad 1700.