RAPID CHEMICAL CHARACTERIZATION OF OBSIDIAN ARTIFACTS BY ELECTRON MICROPROBE ANALYSIS

The potential of the electron microprobe to analyse chemically obsidian artifacts for source provenance studies is demonstrated using artifacts from four archaeological sites in Kenya.     

CHARACTERIZATION OF PACIFIC NORTHWEST COAST OBSIDIAN BY X-RAY FLUORESCENCE ANALYSIS

Several geological sources of obsidian in the Pacific Northwest have been characterized by means of their trace element concentrations, as measured by X-ray fluorescence analysis. The technique is fast and completely non-destructive, making it well-suited for identifying the sources of obsidian from which artifacts were fabricated.     

GEOCHEMICAL PROVENANCE OF OBSIDIAN ARTEFACTS FROM THE MSA SITE OF PORC EPIC,ETHIOPIA*

Obsidian geochemical analysis has become an indispensable tool in archaeological research and has wide applications. However, in spite of the abundance of geological and archaeological obsidian, there has been virtually no such investigation in Ethiopia. Recent instrumental characterization of 31 obsidian artefacts from the Middle Stone Age site of Porc Epic and numerous obsidian geological sources show that artefacts were being transported from as far as 250 km away. We believe this has relevance to the understanding of the emergence of modern human behaviour.     

TEMPORAL ORDERING OF SURFACE-COLLECTED OBSIDIAN ARTIFACTS BY HYDRATION MEASUREMENT

Two samples of obsidian projectile points from northwestern Nevada, one surface collected and the other excavated, were subjected to obsidian hydration measurement. The temporal ordering of the three projectile-point types in each of the two samples was demonstrated to be the same on the basis of their hydration measurements. The validity of this temporal ordering of the projectile-point types in the two samples was confirmed by the stratigraphic sequence of the types in the excavated sample. We have found that surface-collected obsidian artifacts can be relatively dated by hydration measurement. In northwestern Nevada they hydrate at a rate almost double that of their excavated typological counterparts, but their relative ordering remains the same.     

POST-COLONIZATION INTERACTION BETWEEN VANUATU AND FIJI RECONSIDERED: THE RE-ANALYSIS OF OBSIDIAN FROM LAKEBA ISLAND, FIJI*

PIXE–PIGME analysis of 19 obsidian artefacts from Lakeba Island in east Fiji identified contact with northern Vanuatu in the post-colonization period ( c. 2500–1000 bp ) of Fiji. The Lakeba obsidian is the only physical evidence for interaction across the 850 km water gap separating the archipelagos of Vanuatu and Fiji in the first millennium ad . New research on the Vanuatu obsidian sources with laser ablation – inductively coupled plasma – mass spectrometry (LA–ICP–MS) casts serious doubt on the validity of a long-distance inter-archipelago connection in the post-Lapita era. This paper presents the re-analysis of 18 obsidian artefacts from Lakeba using LA–ICP–MS and radiogenic isotope results that demonstrate that the Lakeba obsidian is not from Vanuatu, and it most likely derives from the Fiji–Tonga region. Geochemical evidence for long-distance interaction and migration between the West and Central Pacific in the post-Lapita era has yet to be identified.     

PROVENANCE STUDIES OF CHALCOLITHIC OBSIDIAN ARTEFACTS FROM NEAR LAKE URMIA, NORTHWESTERN IRAN USING WDXRF ANALYSIS

In 2005–2006 we initiated a major archaeological survey and chemical characterization study to investigate the long-term use of obsidian along the eastern shores of Lake Urmia, northwestern Iran. Previous research in the area suggested that almost all archaeological obsidian found in this area originated from the Nemrut Daĝ source located in the Lake Van region of Anatolia (Turkey). More recent research on obsidian artefacts from the Lake Urmia region has identified a significant number of obsidian artefacts with compositions different from the sources near Lake Van. This suggests that the obsidian artefacts are from a yet to be identified geological source, but possibly one that was not too distant. In order to advance our knowledge of Iranian obsidians and eventually refine provenance criteria we analysed obsidian from 22 Chalcolithic sites and some source areas. The compositions of both obsidian source samples and artefacts were determined using wave length dispersive X-ray fluorescence spectrometry (WDXRF). This paper presents results from the trace elemental analysis of both geological and archaeological obsidians, providing important new data concerning the diachronic relationship between lithic technology and raw material in the north-west of Iran.     

ELEMENTAL ANALYSES OF A GROUP OF GLAZED TERRACOTTA ANGELS FROM THE ITALIAN RENAISSANCE,AS A TOOL FOR THE RECONSTRUCTION OF A COMPLEX CONSERVATION HISTORY*

A group of Italian glazed terracotta sculptures, attributed to the della Robbia workshop of Florence, is partly displayed in the Louvre Museum. Analyses of the apparently homogeneous sculptures by techniques such as PIXE, SEM, ICP/AES and ICP/MS have identified differences in the materials used. The data provide a subdivision of the sculptures, which is compatible with what is known from historical documents and artistic considerations, and suggest a date for this ensemble at the end of the 15th century, when the della Robbia family was involved in the decoration of the San Frediano church in Florence.     

CHARACTERIZATION OF TAKATORI STONEWARE FROM CHIKUZEN PROVINCE,JAPAN*

This study reports the findings of an examination of stonewares from the Takatori kilns of seventeenth- to nineteenth-century Chikuzen Province, Kyushu, Japan. Scanning electron microscopy and inductively coupled plasma atomic emission spectroscopy were used to determine the mineralogy and chemical compositions of the ceramic bodies. The results of this broad characterization are used to comment on the relationships between these wares and the raw materials used. Despite close similarities in some cases, it is possible to distinguish the wares of many of these kilns from each other and from outwardly similar wares from contemporary kilns in adjacent provinces.     

MICROCHEMICAL CHARACTERIZATION OF BUILDING STONE FROM SEVILLE CATHEDRAL,SPAIN

Enrichment diagrams for trace elements have been proposed as a useful and straightforward procedure to identify ores and stones. The identification of the diverse stone of the exterior of the Cathedral of Seville has been achieved by this means. Fourteen trace elements have been analysed, from both quarry and building material samples, using atomic absorption and flame emission spectrometry in order to apply enrichment diagrams for identification purposes.     

THE ELEMENTAL COMPOSITION OF BENIN MEMORIAL HEADS*

Among the Nigerian cast copper‐alloy artefacts, the chronology of the Benin memorial heads has been the most fully worked out. Therefore, a study focused upon their elemental compositions is particularly likely to be interpretable in terms of development of the alloys used in their making. The elemental analyses, both published and unpublished, of 66 Benin heads, supplemented with seven analyses of some artefacts excavated from a well‐dated, very early Benin site, have been collected, analysed statistically and computed to the elemental analyses of 11 heads and figures from Udo. All but a very few of the Benin heads and artefacts separate into five compositional groups, indicating a chronological sequence of different alloying traditions. All but one of the Udo objects fall into a distinctly separate compositional group, together with two Medicine heads. The compositional groups correlate remarkably well with the stylistic types proposed by Dark.     

A MULTIDISCIPLINARY APPROACH TO THE CHARACTERIZATION OF ROMAN GRAVESTONES FROM AQUILEIA (UDINE,ITALY)*

The results of an archaeometric study on gravestone production in Aquileia (northeastern Italy) during Roman Republican times are reported here. The artefacts are made of limestone, quarried from the sedimentary sequence of the Trieste Karst (Carnican Alps, northeastern Italy), as testified by historical sources which refer to the ‘Roman Quarry’ at Aurisina. The rock types used for the gravestones are petrographically, geochemically and geochronologically homogeneous, and display similar faunal assemblages. In addition, their age is restricted to the Santonian – Lower Campanian. Comparisons between archaeological finds and rock specimens from various active and inactive quarries in this area suggest that quarrying during Roman Republican times was limited to a specific stratigraphic horizon of the sedimentary sequence, corresponding to the higher part of the ‘Roman Quarry’.     

SCIENTIFIC CHARACTERIZATION OF THE POHORJE MARBLES,SLOVENIA

As a former part of the great Roman Empire, Slovenia has many archaeological sites featuring buildings and objects entirely or partly constructed from marble whose provenance is doubtful. In Slovenia, the most probable source of such marble is the Pohorje Mountains. For the purpose of supporting further provenance studies, these marbles are fully scientifically characterized. The techniques used are petrographic and geochemical analysis, stable isotope ratio analysis and EPR spectroscopy. The results show that the Pohorje marbles are highly heterogeneous in both their isotopic and geochemical parameters as well as grain sizes. The parameters of the different Pohorje marble outcrops are compared between themselves and with the parameters of known ancient quarries in the Mediterranean and Austria. The use of a multi‐technique approach with combined parameters allows the best possible discrimination.     

OBSIDIAN HYDRATION DATING: AN IMPROVED OPTICAL TECHNIQUE FOR MEASURING THE WIDTH OF THE HYDRATION RIM

A simple optical method is described that will enhance the color contrast between the outer birefringent hydration rind and the inner unhydrated core on obsidian thin sections used for hydration dating. The technique utilizes a gypsum nccessory plate. The gypsum plate rotates all incoming light by 550nm causing the black isotropic core of the nhsidian to become transparent first-order pink and interacting with the transmitted light from the birefringent rind, by either addition or subtraction. to produce a second-order blue or a first-order yellow color.     

THE IMPORTANCE OF THE ‘BEST RELATIVE FIT FACTOR’ WHEN EVALUATING ELEMENTAL CONCENTRATION DATA OF POTTERY DEMONSTRATED WITH MYCENAEAN SHERDS FROM SINDA,CYPRUS

Neutron activation analysis of pottery was established at Bonn in 1983 and has since become one of the primary archaeometry‐based analytical techniques at the facility. A brief history of the laboratory and a discussion of the best relative fit procedure for pottery is provided. When comparing concentration data for pottery, a best relative fit should always be considered. This mathematical procedure generally results in ‘sharper’ concentration patterns and improves the separability of chemically not very different compositional groups. This is demonstrated for a set of 30 Late Cypriot (Myc. IIIC1) pottery samples from Sinda, Cyprus, which allow formation of a good reference pattern for this site. Applying factors in the range of 0.82–1.43, a number of samples from Egypt and Palestine can be assigned with high probability to a Cypriot origin.     

INDUCTIVELY COUPLED PLASMA ATOMIC EMISSION SPECTROSCOPY ANALYSES OF ROMAN MILITARY COPPER-ALLOY ARTEFACTS FROM THE EXCAVATIONS AT MASADA,ISRAEL*

A selection of Roman military fittings and associated copper-alloy artefacts was analysed by inductively coupled plasma-atomic emission spectroscopy. The method used was a variant on those previously published and gives very good precision and accuracy. The Roman metalwork analysed conforms extremely well to similar artefacts analysed from, contemporaneous European sites and suggests, despite the strongly ‘local’ nature of the Judaean legions, a considerable uniformity of alloying practice within the Roman army during the first century AD.