DETERMINING POTTERY PROVENANCE: APPLICATION OF A NEW HIGH-PRECISION X-RAY FLUORESCENCE METHOD AND COMPARISON WITH INSTRUMENTAL NEUTRON ACTIVATION ANALYSIS*

A recently developed high-precision X-ray fluorescence (XRF) method, applied for the first time to the study of archaeological pottery, determines the abundances of 13 trace and four major elements from one X-ray spectrum acquired over a 1000 second counting interval. For replicate archaeological samples, the short-term and long-term measurement precisions were close to 1% for the ten elements measured with highest precision. These are comparable to the best results achieved on replicates of clay and pottery standards, and obsidian, using instrumental neutron activation analysis (INAA). High-precision XRF analysis, however, does not require a nuclear facility, and is markedly preferable to INAA in terms of the ease of both sample preparation and analytical procedure. Consequently, element abundance data can usually be provided by a single analyst within a few hours after the start of sample preparation. The accuracy of the method, determined by comparison with data of other workers on eight standard reference materials, averaged 2.4% for the ten best-agreeing elements. The effectiveness of the method for determining pottery provenance is demonstrated for a difficult problem, in which high-precision XRF analysis successfully distinguished the products of two nearby pottery manufacturers in Roman Galilee (Shikhin and Nahif) that had not been clearly differentiated by INAA. The greater effectiveness of high-precision XRF than INAA in this provenance study is a result of the different array of elements measured, and the higher precision obtained for certain elements, by XRF. These results suggest that high precision XRF has potential broad applicability for pottery provenance studies.     

STEATITE SOURCE CHARACTERIZATION IN EASTERN NORTH AMERICA: NEW RESULTS USING INSTRUMENTAL NEUTRON ACTIVATION ANALYSIS*

Doubts have recently been cast on the ability to characterize steatite sources using rare earth elements (REEs). By increasing the number of samples and elements examined using instrumental neutron activation analysis (INAA) and multivariate statistics, this study shows that, with unhomogenized samples, transition metals, not REEs, make the greatest contribution in characterizing steatite sources in the Middle Atlantic region of eastern North America. Preliminary results suggest that INAA has the potential to assign provenance to steatite artefacts, at least at a regional level.     

The distribution and sources of archaeological pitchstone in Britain

Pitchstone is a glassy volcanic rock, distinguishable from obsidian by having a higher water content. It forms lava flows and minor intrusions at several centres within the British Tertiary Volcanic Province (BTVP) in the west of Scotland and Ireland. Pitchstone artifacts and waste pieces have been recorded from 101 archaeological localities in Scotland and northern England, ranging in time from possibly Mesolithic to Bronze Age. To characterize the sources, 17 pitchstone samples from 11 sources within the BTVP were analysed for major elements by energy-dispersive X-ray fluorescence (EDXRF), and for trace elements by instrumental neutron activation analysis (INAA). 28 pitchstone pieces from 22 archaeological sites were analysed, mainly non-destructively, by INAA and interpreted as having originated from Arran sources. The Arran sources are divided into four petrographic types; the Corrygills, Tormore, Glen Shurig and Glen Cloy Types. Petrographic study of 15 archaeological samples indicated that three were of Corrygills type and two were of Tormore type. The remainder were less confidently attributed to the petrographic types distinguished. Arran pitchstone is found as far as 300 km from the Arran sources, at the chambered tomb of Ord North in Highland.     

THE HISTORY OF THE LAWRENCE BERKELEY NATIONAL LABORATORY INSTRUMENTAL NEUTRON ACTIVATION ANALYSIS PROGRAMME FOR ARCHAEOLOGICAL AND GEOLOGICAL MATERIALS

The Lawrence Berkeley National Laboratory pottery provenance group developed standards and instrumental neutron activation analysis (INAA) methods that are used at many archaeometry laboratories around the world. The background and development of ‘Standard Pottery’ and of methods for INAA are described. Early pottery provenance studies are described, and other research programmes, involving obsidian and magmatic mixing, the origin of the stone used for the Colossi of Memnon, and the ‘Plate of Brass’, are mentioned. Research work by the Laboratory included the discovery of the world‐wide iridium anomaly and extensive subsequent research on what has come to be known as the ‘Asteroid Impact Theory’. Characteristics of the analytical programme for pottery provenance work, including overall aims, precision and accuracy, intercalibration, and irradiation and measurement protocols, are discussed. New research areas developed in the past 15 years, to broaden the usefulness of chemical compositional data for archaeological investigation, and examples of recent work, are described. This research, which makes use of high‐precision X‐ray fluorescence analysis in addition to INAA measurements on sample splits, includes distinguishing the products of different workshops located at the same production site, studies on the significance of the distribution of silver in archaeological pottery and the use of high‐precision chemical compositional data as an aid for making chronological distinctions.     

Osteometric Analysis of South American Sea Lions (Otaria flavescens) Pups From Patagonia. An Assessment of Their Use as Indicators for Seasonality in Archaeological Sites

Zooarchaeological analyses of pinniped remains have been scarce in South America because of lack of specific studies of species determination and estimation of age and sex. Nonetheless, the presence of small and unfused bones (assigned as pup remains) of Otaria flavescens (O. flavescens) in the Patagonian archaeological record has been frequently used as an indicator of summer occupation accomplished by ecological analogues. For this reason, we carried out a postcranial skeletons osteometric study of modern pups of South American sea lions (O. flavescens) with known sex and aged 0–12 months, allowing a more precise age estimation of archaeological samples. Then, we revisited the evidence for seasonality in the Cabo Virgenes 6 site at Cabo Virgenes locality, one of the archaeological localities in Patagonia where the seasonality has been determined only on the basis of the presence of unfused pup bones. Our metric data study on a modern sample shows that the regression analyses generated a complementary and dependable age estimation model for unfused appendicular bones of O. flavescens between 0 and 12 months old that can be applied to samples recovered from archaeological sites. These osteometric studies of postcranial elements allow us to adjust the age estimation of the animal's death and re‐examine seasonality of the Cabo Virgenes 6 site (Santa Cruz, Argentina). Copyright © 2014 John Wiley & Sons, Ltd.     

CHALLENGES IN THE ANALYSIS OF HETEROGENEOUS POTTERY BY LA–ICP–MS: A COMPARISON WITH INAA*

Tempers added to pottery have the potential to obscure geographical variation in the chemistry of exploited clay resources when analysed using bulk methods. A pilot study was conducted to assess the possibility of using LA–ICP–MS to analyse clay matrix in pottery with extremely subtle partitions between INAA chemical groups. LA–ICP–MS was used to analyse the clay matrix of 32 pottery samples from seven Middle and Late Woodland period (c. ad 200–800) sites in north‐east Florida and results were compared to data from INAA of the same samples. The results reveal many of the challenges in analysing highly heterogeneous materials with LA–ICP–MS. However, the study also generated data that are potentially useful in the determination of pottery provenance. In some respects, LA–ICP–MS of clay matrix replicated the chemical variation recorded by INAA, and in other respects the results are divergent. The similarities and differences between these results are explained by specific differences between the methods and the materials analysed (matrix versus bulk analysis). Suggestions for improving the method are discussed.     

ACKNOWLEDGING FIFTY YEARS OF NEUTRON ACTIVATION ANALYSIS IN ARCHAEOLOGY

Neutron activation analysis has been an important analytical technique for chemical characterization studies of archaeological materials since 1957, and remains one of the best analytical approaches for bulk chemical characterization of archaeological ceramics and other materials. This paper introduces a series of reports that document the history of NAA applied to archaeological materials.     

NON‐DESTRUCTIVE ANALYTIC METHOD USING XRF FOR DETERMINATION OF PROVENANCE OF ARCHAEOLOGICAL OBSIDIANS FROM THE MEDITERRANEAN AREA: A COMPARISON WITH TRADITIONAL XRF METHODS*

A non‐destructive analytical method using wavelength‐dispersive X‐ray fluorescence (WDXRF) that allows the establishment of the provenance of archaeological obsidians was developed and a comparison with the classical XRF method on powders is discussed. Representative obsidian samples of all the geological outcrops of archaeological interest of the Mediterranean area (Lipari, Pantelleria, Sardinia, Palmarola and the Greek islands of Melos and Gyali), were analysed with the normal procedures used in rock analysis by XRF (crushing, powdering and pelletizing). The non‐destructive XRF analysis was instead conducted on splinters taken from the original geological pieces, with the shape deliberately worked to be similar to the refuse usually found at archaeological sites. Since the analysis was conducted on the raw geological fragment, intensity ratios of the suitably selected chemical elements were used, instead of their absolute concentrations, to avoid surface effects due to the irregular shape. The comparison between concentration ratios (obtained by traditional XRF methods) and the intensity ratios of the selected trace elements (obtained from the non‐destructive methodology) show that the different domains of the chemical composition, corresponding to the geological obsidians of the source areas, are perfectly equivalent. In the same way, together with the geological splinters, complete archaeological obsidians, from Neolithic sites, may be analysed and their provenance may be determined. The proposed non‐destructive method uses the XRF method. Due to its sensitivity, low cost and high speed, it is surely an extremely valid instrument for the attribution of the provenance of the archaeological obsidian from Neolithic sites.     

Sourcing ceramics with portable XRF spectrometers? A comparison with INAA using Mimbres pottery from the American Southwest

Seventy-five intact Mimbres and Jornada pottery sherds from the American Southwest were analyzed by portable XRF and instrumental neutron activation analysis (INAA). Examination of the data demonstrates that INAA and portable XRF results for elements common to both analyses can be used to construct similar compositional groups. When individual compositional groups are compared to one another, it is apparent that unambiguous separation of compositional groups is challenging by portable XRF given (1) the limited number of key discriminating elements that can be measured relative to INAA, and (2) the relative analytical precision and accuracy of portable XRF for measurements of intact heterogeneous ceramics. We conclude that sourcing intact ceramics by portable XRF is challenging and that bulk analytical measurements, such as INAA, remain a better approach for sourcing archaeological pottery.     

THE ANALYSIS OF DYESTUFFS FROM FIRST‐ TO SECOND‐CENTURY TEXTILE ARTEFACTS FOUND IN THE MARTRES‐DE‐VEYRE (FRANCE) EXCAVATIONS*

A series of Gallo‐Roman clothes and miscellaneous textile fragments from the first and second centuries from the Martres‐de‐Veyre necropolis (Puy‐de‐Dôme, France) was investigated. The objects studied were excavated between 1851 and 1923, during successive rounds of archaeological work. Since that time, they have been conserved in the Barguin Museum at Clermont‐Ferrand. The target of our research was dye identification, as it gives very interesting and useful information regarding the ancient technology. This approach has until now not been considered to be relevant and, unfortunately, is not systematic. The analysis was carried out by high‐performance liquid chromatography with photodiode array detection (HPLC–PDA). The small samples (threads up to 0.6 mg, less than 1 cm long) of coloured textile fibres were submitted to this technique. In one case, X‐ray fluorescence (XRF) analysis was applied. According to the analysis, the dyeing sources proposed are the Rubiaceae family for red, a luteolin ‘base’ for yellow, ellagitannins for brown and indigo for blue colours. Several samples did not seem to contain any dye. We point out possible factors for the partial dye source determination: instrumental limits, sample size, low dyestuff content in analysed samples and the dyes’ decomposition during ageing. Some improvements of dye analysis in archaeological samples by separation techniques based on recent analytical instrumentation and combined approaches are proposed.     

GEOCHEMICAL ANALYSIS AND SOCIOCULTURAL COMPLEXITY: A CASE STUDY FROM EARLY IRON AGE MEGIDDO (ISRAEL)*

Few archaeological sites can claim a more celebrated position than Megiddo, the Armageddon of biblical revelation. Guardian to a strategic pass on the ancient land bridge that traverses the region, it has long been known that Megiddo played a prominent role in the emergence of the Iron Age nation‐states of biblical fame. Given its pivotal location, Megiddo provides an ideal opportunity to examine the experience of a community that found itself at the centre of these developments. The archaeological and textual evidence indicates a community that enjoyed extensive contact with an array of culturally distinct sociopolitical groups emerging in its hinterland. To further explore the nature and extent of this interaction, an assemblage of 86 ceramic sherds was analysed by instrumental neutron activation analysis (INAA). This paper presents the results of this analysis, together with an evaluation of potential geochemical and archaeological interconnections. Based on this comparative analysis, implications are drawn regarding Megiddo's role in the changing cultural and political landscape of this formative period in the history of the region.     

Assessing Ceramic Compositional Data: A Comparison of Total Reflection X‐ray Fluorescence and Instrumental Neutron Activation Analysis On Late Iron Age Spanish Celtiberian Ceramics

A solid‐phase, non‐chemical processing protocol was recently developed as a means of chemically characterizing archaeological ceramics by total reflection X‐ray fluorescence (TXRF). Following this methodology, TXRF can provide semi‐quantitative determinations for 18 elements with comparable levels of precision and accuracy for the majority of them in comparison with a clay reference material analysed by instrumental neutron activation (INAA). In order critically to assess the analytical capabilities of TXRF, a large sample set of Late Iron Age Spanish Celtiberian ceramics and modern clays was analysed both by TXRF and INAA. Semi‐quantitative chemical data provided by TXRF and quantitative data provided by INAA were subjected to commonly used multivariate statistical methods as a way of evaluating the ability of the new technique to discriminate among different compositional groups. The comparison of the two data sets shows no significant discrepancies, thereby allowing support for the same archaeological interpretation. These results suggest that TXRF has potential applicability for compositional characterization of archaeological ceramics, providing data that are useful for provenance studies.     

ARCHAEOLOGICAL RESEARCH AT THE INSTITUTE OF NUCLEAR TECHNIQUES,BUDAPEST UNIVERSITY OF TECHNOLOGY AND ECONOMICS: SCHOLARLY ACHIEVEMENTS OF A PROSPEROUS LONG‐TERM COLLABORATION

The laboratory is part of a university institute with a nuclear reactor on the premises. NAA of archaeological materials started in the early 1980s, and has found continuous interest since then. Site‐specific characteristics of the NAA procedure are the long irradiation and counting times, due to the relatively low neutron flux, the single comparator method of standardization and the use of reference materials for quality control. The main research interest focuses on provenance studies of potteries; 90% of the analysed samples are ceramic materials. Most of the projects concentrate on the investigation of pottery finds from Roman Pannonia, and from different archaeological sites in Israel. The Qumran pottery project is presented as a typical example.     

AN INVESTIGATION OF THE PROVENANCE OF THE ROMAN AMPHORA CARGO FROM THE PLEMMIRIO B SHIPWRECK

Eighty-six Roman amphora sherds from the Plemmirio B shipwreck, off Sicily, have been analysed by neutron activation analysis. A large group representative of the amphora cargo, mainly of forms Africana 1 and Africana 2A (from the area of modern Tunisia), was subsequently defined. No differences between Africana 1 and Africana 2A samples were observed, thus implying a similar origin for both forms. The provenance of this cargo group was then investigated by comparison with a Roman amphora kiln data base. After elimination of the more mobile elements it was shown that the cargo amphorae were more likely to have been manufactured at kilns around Sullecthum rather than Leptis Minor. The analytical conclusions are thoroughly consistent with the known archaeological information.     

COMPOSITION AND ORIGIN OF IAPYGIAN POTTERY FROM ROCA VECCHIA,ITALY

We have studied 35 samples of fragments of ceramic containers dated between the eleventh and the eighth centuries BC, found at the archaeological site of Roca Vecchia, some 20 km from Lecce along the Adriatic (Salentine) coastline. Analysis of the elemental composition of the finds has been performed by means of atomic emission spectroscopy in plasma and the results obtained have been treated with diverse multivariate statistical techniques. Except for some minor differences, the statistical analysis confirms the grouping structures indicated by typological and stylistic evaluations of the samples, in accordance with the validity of the above methods.     

Long-distance provenance for obsidian artifacts of Mesoamerica Preclassic and Early Classic periods found in the Los Naranjos Archaeological Park (Honduras)

Los Naranjos is one of the most important pre-Columbian human settlements of Honduras related to the south-easternmost border of the Mayan civilization. Although the archaeological site mostly spans from 850 BC to 1250 AD, the present obsidian study was only focused on the Preclassic and Early Classic periods (Jaral, 800–400 BC and Edén, 400 BC–550 AD) where undamaged blades and/or retouched obsidian flakes are rare. In this way, the INAA analyses of 17 obsidian samples, compared with major-trace elements data of Honduran and Guatemalan obsidian sources, are mostly representative of waste flakes. Lithic artifacts of Los Naranjos such as sandstones, basalts, and quartzites come from local geological outcrops; whereas, obsidian provenance has to be searched from sources which are located within a radius up to 300 km far away. San Luis, La Esperanza, and Güinope obsidian sources are located in Honduras while the three most exploited Highland Guatemalan obsidian outcrops, which have been dominating long-distance trade in the Maya area mostly for the Classic-Postclassic periods, are San Martin de Jilotepeque, El Chayal, and Ixtepeque. An Ixtepeque provenance, for all the investigated obsidian samples of Preclassic and Early Classic periods found in the Los Naranjos Archaeological Park, was established, thus emphasizing a long-distance source (180 km). This also confirms that Ixtepeque represents the most important provenance of the obsidian artifacts found in archaeological sites of Western and Central-Western Honduras. The possible role played by some of the most important rivers of Guatemala and Honduras as waterway networks of transport was finally pointed out. New INAA chemical data from the Honduran obsidian source of La Esperanza (“Los Hoyos”, 4 samples) are also reported in this paper.     

INAA OF ARCHAEOLOGICAL SAMPLES AT THE UNIVERSITY OF MANCHESTER

INAA at Manchester began almost by chance, and amid scepticism, with a request for help from the university's Department of Archaeology in the early 1970s. Over the years, the method of selecting pottery to be sampled was refined from the simple assumption that sherds found at a site were typical of those made there, to a greater focus on kiln sites and wasters. An important element in Manchester's approach was that this was a teaching department: in the quarter‐century during which the laboratory practised INAA over 6000 samples were analysed in a wide range of projects by postdoctoral researchers, Ph.D. students and even final‐year undergraduates. Although there were sometimes problems of comprehension on both sides, close collaboration with archaeologists encouraged methodological comparisons, and often INAA was seen as an additional weapon in the archaeologists’ arsenal as much as a developing scientific technique. The university's place as the inventor of the computer encouraged the development of statistical programs, which in turn facilitated ready collaboration and exchange of information with other laboratories, such as those at Bonn and Berkeley.     

Increasing data (INAA) on Ecuadorian obsidian artifacts: preliminary provenance and a clue for pre-Columbian eastward trade

In this work we carried out INAA major (Na, K, Ca and Fe %) and trace (ppm) elements (plus Mn by FAAS analysis) of 15 obsidian samples (waste flakes) coming from an unknown archaeological site (¹⁴C-AMS age of 1425 AD) located on the south-eastern flank of the back-arc Sumaco volcano (to the east of the Cordillera Real) and from two already known pre-Columbian archaeological localities: La Florida (Quito) and Milan (Cayambe). Literature compositional data of the Ecuadorian obsidian outcrops provide some constraints on the provenance of the analyzed waste flakes, even though different methods of analyses make comparisons a difficult task. Concerning the obsidian artifacts of La Florida and Milan, they come from the well known Sierra de Guamanì obsidian sources (Cordillera Real). By contrast, the obsidian fragments of the Sumaco settlement show some compositional characters compatible with obsidian erratic pebbles recently discovered in some river banks of the Amazonian foothills draining the easternmost flanks of the Antisana volcano in the Cordillera Real as well. In this way, the obsidian artifacts found at the Sumaco site reinforce the opinion that Ecuadorian source inventory is not yet exhaustive. Although the Antisana volcano seems to be the best candidate to find out additional primary outcrops of obsidian sources, it cannot be also excluded that sub-Andean and Amazonian people directly took advantage from obsidian secondary sources (e.g. river banks), rather than procurements from primary outcrops in the Cordillera Real. The new archaeological findings at the Sumaco volcano are really of paramount importance in tracing the ancient routes of a possible obsidian eastward trade toward the Amazonian region.     

Comparison of analytical techniques for analysis of archaeological bronze

While many analyses of archaeological bronzes have been reported in the literature, in practice it is very difficult to compare them. To assess the present status of the chemical analysis of bronze two ancient objects—a flat axe (arsenic bronze) and a sickle (tin bronze)—were cut into pieces weighing about 2 g each and were distributed to 11 laboratories. The participants used the following methods for analysis: INAA, ED–XRF, PIXE, TRXRF, FAAS, ICP–AES, ICP–MS, SEM–EDS, LA–ICP–MS and PGAA. The samples were analysed in at least quadruplicate. Dixon's and Iglewicz and Hoaglin's tests were used to detect outliers. The majority of methods provided comparable results, especially for macroelements, independent of the technique and standards used. The number of determined elements depended on the method and, naturally, on the concentration level. Therefore an important recommendation that can be made is to supply, with each archaeometric investigation, data from the analysis of appropriate Certified Reference Materials (CRMs) used in the study.