LA–ICP–MS,SEM–EDS AND EPMA ANALYSIS OF EASTERN NORTH AMERICAN COPPER‐BASED ARTEFACTS: IMPACT OF CORROSION AND HETEROGENEITY ON THE RELIABILITY OF THE LA–ICP–MS COMPOSITIONAL RESULTS*

This study discusses the relevance of compositions obtained using laser ablation – inductively coupled plasma – mass spectrometry (LA–ICP–MS) for the purpose of identifying the provenance of copper‐based artefacts found in Virginia at Native American sites dated from the 16th to the 18th centuries. Ten artefacts were investigated by scanning electron microscopy – energy dispersive spectrometry (SEM–EDS) to visualize the corrosion and characterize the heterogeneities in the metal and electron probe micro‐analysis (EPMA) to determine separately the compositions of the intact metal and of the corrosion product. It is shown that the corroded surfaces are highly depleted in zinc but that representative concentrations can be determined by sampling the deeper, uncorroded metal. In contrast, lead values are highly variable because of the heterogeneous distribution of this metal within the bulk copper. Despite these problems, brass is easily identifiable and American native copper and European smelted copper can be unambiguously distinguished with LA–ICP–MS on unprepared artefacts using As, Ag, Ni and Sb trace elements.     

COLOUR ATTRIBUTES OF MEDIEVAL WINDOW PANES: ELECTRON PARAMAGNETIC RESONANCE AND PROBE MICROANALYSES ON STAINED GLASS WINDOWS FROM PAVIA CARTHUSIAN MONASTERY*

Stained glass windows from the Carthusian Monastery of Pavia, dating back to the 15th century, were studied by combining two analytical techniques: electron probe micro‐analysis (EPMA) and electron paramagnetic resonance (EPR). Chemical compositions and oxidation states of the transition ions, present as minor elements, were investigated by EPMA and EPR, respectively, in order to ascertain the role played by chromophorous ions in the glass coloration. The investigated glass can be defined as K–Ca glass, and the panes with red, green and blue colours were produced using flashing techniques.     

FINGERPRINTING OF ROMAN MINTS USING LASER‐ABLATION MC–ICP–MS LEAD ISOTOPE ANALYSIS*

In this paper we present data to demonstrate the applicability of laser‐ablation MC–ICP–MS isotope analysis to archaeological artefacts, in this case Roman silver coins. The technique requires no chemical preparation, does minimal damage to the sample and yields external reproducibility that is better than conventional TIMS analysis; ²⁰⁷Pb/²⁰⁶Pb =±0.015% 2σ in comparison with ²⁰⁷Pb/²⁰⁶Pb =±0.04% 2σ, respectively. We show that Pb isotope compositions give isotope fingerprints to mints despite the likely reworking of the metal during coin production.     

MICROSTRUCTURAL CHARACTERIZATION OF EARLY WESTERN GREEK INCUSE COINS*

In this research, we studied the compositional, crystallographic and microstructural properties of a series of incuse silver didrachmae stemming from the Achaean colonies of Metapontum and Caulonia. In this paper, we address the following points: (i) the metal sources, (ii) the fabrication process and (iii) degradation phenomena, such as incrustation and embrittlement. In this investigation, we employed energy‐dispersive X‐ray fluorescence spectroscopy, X‐ray diffractometry, and scanning electron and optical microscopies. The patina is mainly composed of chlorargirite. The coins consist of a silver‐rich alloy containing ～ 1% of Au and Cu. Metallographic and local compositional analyses revealed a complex scenario of inclusions. In one instance, unalloyed copper grains, two‐phase copper/bismuth globuli and high‐bismuth filaments were observed. In other cases, globular Cu ₂ S (chalcocite) inclusions were noticed. The presence of SiO ₂ and iron oxide inclusions is ubiquitous in these samples. Distorted twin lines and strain lines can be detected, denoting work‐hardening of recrystallized flans. Grain polygonalization can occasionally be noticed, hinting at secondary recrystallization processes. The irregularly shaped iron oxide particles often act as crack initiation sites. Fracture facets are generally intergranular. On some areas, intergranular decohesion is also observed. Open cracks sometimes contain AgCl. The strain lines that can be noticed on the fracture surfaces indicate work‐hardening and residual microstructural deformation. Information regarding inclusions and the presence of significant amounts of gold can be tentatively used to address provenancing and fabrication issues.     

DETECTING CHANGES OF CELTIC GOLD SOURCES THROUGH THE APPLICATION OF TRACE ELEMENT AND Pb ISOTOPE LASER ABLATION ANALYSIS OF CELTIC GOLD COINS*

This project follows on from an initial study of Celtic gold coins from the Middle Rhine/Moselle region, which was based on material found at the Martberg, a Late Iron Age/Roman sanctuary and settlement (River Moselle, western Germany; Bendall 2003 ). The earlier work was expanded to encompass over 100 examples of various other regional Celtic gold coinages from the collection of the Römisch‐Germanisches Zentralmuseum, Mainz. The alloy (Au–Ag–Cu) and trace element compositions (in particular Ni, Sb and Pt) were determined by EPMA and LA–ICP–MS, respectively, and their Pb isotope signatures were measured by LA–MC–ICP–MS. Of the 28 trace elements measured, only Ni, Sb and Pt were found to show meaningful variations and so only they are presented here. In particular, differences in the Pt/Au ratios between various groups of earlier coinage (imitations of Philippus and Alexander/Nike staters, Sch. 23 and some early Boian coins) on the one hand, and the majority of the Boian and the southern rainbow cup coinages on the other, indicate a significant difference in the gold sources exploited for these regional coinages. The Pb isotope data confirm previous conclusions that the contribution of gold to the total lead in the Au–Ag–Cu coin alloys can be detected, especially for coins with over 70% gold, and show that possible gold sources include both eastern Mediterranean and Alpine sources. Combining the Pb isotope data with the Pt/Au ratios allows the potential gold sources to be further differentiated.     

DETECTION OF NEAR-SURFACE SILVER ENRICHMENT ON ROMAN IMPERIAL SILVER COINS BY X-RAY SPECTRAL ANALYSIS*

A collection of 218 Roman imperial silver coins, covering three centuries, was analysed non-destructively by two variants of X-ray spectral analysis. Electron beam excitation and energy-dispersive spectrometry was used for the analysis of the uppermost thin layer (3 μm) of each coin, while X-ray tube excitation and wavelength-dispersive spectrometry was applied for the analysis of thicker layers (30 μm), Ag and Cu as major constituents and 18 minor elements were determined quantitatively. Comparing the silver content of the obverse and the reverse of a coin, inhomogeneities could be identified. By comparison of the silver content of the upper thin and the thick surface layers, near-surface silver enrichment could be detected. Inhomogeneities and enrichments increase in the second and more so in the third century. A large scatter of the silver content and silver enrichment for coins of the same emperor was attributed to varying abrasion of Ag-enriched layers of the individual coins during decades of circulation.     

CHARACTERIZATION OF THE AMPHORAE,STONE BALLAST AND STOWAGE MATERIALS OF THE SHIPS FROM THE ARCHAEOLOGICAL SITE OF PISA–SAN ROSSORE,ITALY: INFERENCES ON THEIR PROVENANCE AND POSSIBLE TRADING ROUTES*

In December 1998, during excavation for the construction of a new building near San Rossore railway station in Pisa, the remains of ancient ships were discovered. These findings have been dated (radiocarbon) to between the end of the 10th century bc and the fifth century ad ( Belluomini et al. 2002 ). Several transport amphorae belonging to the Hellenistic ship, samples of rocks (stone ballast) belonging to ships B, D and the Hellenistic ship, and stowage materials belonging only to ship B have been analysed. The mineralogical and petrographic data of the investigated samples provided information on the possible provenance of the raw materials utilized in the manufacture of the ceramic amphorae, as well as on the provenance of the rock materials found in the ships as ballast and stowage. The compositional data (obtained through XRD, XRF, OM and EPMA) and their statistical analyses suggest that the provenance of the Dressel amphorae belonging to the Hellenistic ship was the Middle Tyrrhenian coast of Italy, and more precisely the area between Tarquinia and Naples, according to the numerous kilns and wine production sites found in this area. The provenance of the volcanic rocks was from southern Tuscany, northern Latium and possibly the Pontine Islands, whereas the intrusive rock possibly comes from the Calabrian–Tyrrhenian coast and/or the Peloritani area. The impure limestones and the dolostone come from southern Tuscany and the Latium coast; the semi‐metamorphic rocks could come from the coast of southern Tuscany, the Tuscan Archipelago or possibly also from the Ligurian coast; only the sample of mylonitized granitoid possibly comes from either the Calabria–Peloritani arc or the Tuscan Archipelago. The stowage materials, consisting of lapilli and scoria of a pyroclastic nature, are sourced from the Neapolitan area. These data might shed some light on the centres of production of the amphorae and of the trading routes followed by the ships, according to the ports of call.     

Small change: economics and coin-trees in Britain and Ireland

Abstract

Throughout the c. 2,000-year period coins have been circulated in Britain, they have also been ritually employed, most notably as votive deposits. Focusing specifically on the understudied custom of the British coin-tree, whereby coins are ritually embedded into the barks of trees, this paper considers the coin’s role and applicability as a deposit. It aims to demonstrate that our understanding of the coin’s past, present and future ritual employment is not only aided by a consideration of economics and the coin’s secular function; it would be utterly incomplete without it.     

CUERDA SECA CERAMICS FROM AL‐ANDALUS,ISLAMIC SPAIN AND PORTUGAL (10TH−12TH CENTURIES AD): INVESTIGATION WITH SEM–EDX AND CATHODOLUMINESCENCE*

Since little is known about the cuerda seca technique, our aim has been to complete an initial analysis of 11th‐century cuerda seca by studying fragments from the 10th century (Pechina, Almería) and the 12th century (Mértola and Almería), so as to establish the diachronic evolution of this technique. Characteristics specific to cuerda seca ceramic glazes were investigated using scanning electron microscopy (SEM) and quantitative chemical analysis with energy‐dispersive X‐ray spectrometry (EDX). The chemical compositions of the different‐coloured glazes (green, black, yellow and white) have given us valuable indications about the evolution of the technique. The opacification mode and the firing process were also investigated. With the help of cathodoluminescence (CL) and the study of modern ‘cuerda seca’ glazed ceramics, new hypotheses regarding the number of firing stages, taking into account glaze and paste transformations and their interactions, are put forward.     

INCISED SLIPWARE PRODUCTION AT CASTELFIORENTINO (FLORENCE): THE ‘VIA BERTINI’ SITE (15TH–17TH CENTURIES)*

This study deals with the physical–chemical and mineralogical–petrographic investigations (OM, SEM–EDS, EPMA, ICP, XRpD, Mössbauer and IR) conducted on first‐ and second‐firing wasters belonging to two types of incised slipware (sgraffito), manufactured at Castelfiorentino between the late 15th and the early 17th centuries. Raw materials, colouring agents and firing products were analysed in order to establish the production technology of the ceramic coatings, by means of detailed microtextural and chemical investigations. The pottery underwent two firing processes: the firing of the white slip‐coated ceramic body and a further firing after application of the glaze. The homogeneity of the raw materials, white slip and glaze is remarkable, and demonstrates the use of well‐established recipes with a constant supply of raw materials from the same places. Highly efficient kiln management during both firings is revealed by body–glaze interface reactions.     

LEAD ISOTOPIC ANALYSIS FOR THE IDENTIFICATION OF LATE BRONZE AGE POTTERY FROM HALA SULTAN TEKKE (CYPRUS)

Lead isotopic compositions were measured for 65 sherds from five pottery wares (Plain White, Coarse, Canaanite, White Slip and Base‐ring) excavated from the Late Bronze Age site of Hala Sultan Tekke (Cyprus). The elemental composition and isotopic signature of the sherds were compared with those of 65 clay samples collected in south‐east Cyprus, mainly in the surroundings (<20 km) of Hala Sultan Tekke. This work shows the effectiveness of using lead isotopic analysis in provenance studies, along with other analytical techniques, such as X‐ray diffraction (XRD) and a scanning electron microscope (SEM) equipped with an energy dispersive X‐ray detection (EDX) facility, to identify the composition of pottery wares and the clay sources used for pottery ware production.     

SIMS‐SS,A NEW OBSIDIAN HYDRATION DATING METHOD: ANALYSIS AND THEORETICAL PRINCIPLES*

The water diffusion mechanism in obsidian has been revisited with the advent of a new dating approach employing secondary ion mass spectrometry (SIMS). The water diffusion SIMS(+) profile and the concept of a surface saturation (SS) layer in obsidians both provide a sound basis for the new diffusion age equation (SIMS‐SS) and are supported by dated world examples ( Liritzis et al. 2004 ). Here, we present the basic physical–chemical analysis of the mass transport phenomenon on which the new dating method is based. The crucial age parameter of the SIMS‐SS dating approach for archaeological obsidians—that is, the surface saturation (SS) layer—is supported by both theoretical and experimental data.     

The application of 3D‐microprofilometry as a tool in the surface diagnosis of fossil and sub‐fossil vertebrate hard tissue. An example from the Pliocene Upper Laetolil Beds,Tanzania

Non‐contact optical 3D‐profiling instruments are often used in the study of surface modifications on fossil mammalian bone. The advantage of optical laser scanning for the study of fossil and sub‐fossil bone is its non‐contact nature, allowing the investigation of fragile and poorly preserved surfaces. The high resolution and fast measuring rate of this method make it an alternative to scanning electron microscopy (SEM) investigation if topography is to be visualized. This study analyses clusters of incisions in a suid humeral fragment from the Pliocene Upper Laetolil Beds. The marks show a characteristic crest structure that is also frequently found in mandible marks produced by the Australian termite species Mastotermes darwiniensis. The marks from the Laetolil Beds are, therefore, interpreted as also being caused by insect mandible action. An as yet unknown large insect species capable of modifying bone with their mandibles is thus postulated in the palaeohabitat represented by the hominid‐bearing Upper Laetolil Beds. Copyright © 2001 John Wiley & Sons, Ltd.     

ANALYTICAL CHARACTERIZATION OF ROMAN PLASTERS OF THE ‘DOMUS FARINI’ IN MODENA*

The paper refers to the analytical characterization of Roman painted plasters dating back to the second century ad . The following techniques were used: optical microscopy (OM), scanning electron microscopy (SEM–EDS), micro‐Raman and Fourier transform infrared spectroscopies (µ‐Raman and FT–IR), X‐ray diffraction (XRPD), colorimetry and thermal analyses (TG/DTA). The investigation analysed the chemical composition and structure of the plasters, the chemical composition of the pigment layers, the use of binders and any chemical alteration of pigments as well as deterioration of the samples. Stratigraphic analysis of plasters allowed identification of their individual components, which proved helpful in finding out more about the mural painting technique employed.     

GLASS CORROSION ACROSS THE ALPS: A SURFACE STUDY OF CHEMICAL CORROSION OF GLASSES FOUND IN MARINE AND GROUND ENVIRONMENTS*

Ancient glasses deriving from differing environments (marine and ground) and areas (Mediterranean and Continental) have been investigated to understand their weathering processes. Although the glass technologies, developed in various ways, and the differing compositions of the glasses from the two areas, have generated differing durabilities, the weathering features of both typologies of glass are identical. Therefore, the corrosion phenomena are due to the action of water, and they are not related to the sample microclimate. Data have been collected using optical microscopy, RGA and surface analysis techniques: XPS, ESEM and SIMS.     

Determination of the Fineness of Medieval Coins—Evaluation of Methods in a Case Study of a Medieval Pfennig

The original fineness of coins is very important information that can help us to understand the commercial situation in a wide historical context. This paper deals with a comparison of analytical methods suitable for the evaluation of the actual and original fineness of coins based on a detailed case study of a medieval coin sample. Both non‐destructive (i.e., scanning electron microscopy/energy‐dispersive X‐ray spectroscopy, X‐ray fluorescence, atomic force microscopy and hydrostatic weighing) and destructive (i.e., inductively coupled plasma – mass spectrometry and the Volhard titration method) techniques were used. The original fineness can be also deduced from knowledge of the internal structure of the coin (limited miscibility of copper and silver). A new analytical method based on a combination of a micrograph of the metallographic cross‐section with consequent image analysis was developed for determination of the original fineness. The proposed approach is relatively simple and provides reliable values. Sample heterogeneity and its impact on the determination of fineness are also discussed.     

AN INVESTIGATION INTO THE RELATIONSHIP BETWEEN THE RAW MATERIALS USED IN THE PRODUCTION OF CHINESE PORCELAIN AND STONEWARE BODIES AND THE RESULTING MICROSTRUCTURES*

The microstructures of porcelain and stoneware bodies from north and south China, spanning the period from the Tang to the Ming dynasty (7th–17th centuries ad ), were examined in polished sections in a scanning electron microscope (SEM) after etching the sections with hydrofluoric acid (HF). Mullite, present as fine, mainly elongated crystals, is the dominant crystalline phase observed. The bulk chemical compositions of the bodies are determined by energy‐dispersive spectrometry in the SEM, and the relative amounts of mullite and quartz present in the different ceramics are estimated from X‐ray diffraction measurements. Mullite formed from areas of kaolinitic clay, mica particles and feldspar particles is distinguished through a combination of the arrangement of the mullite crystals, and the associated SiO₂/Al₂O₃ wt% concentration ratios. It is shown that very different microstructures are observed in ceramic bodies produced using kaolinitic clay from north China (Ding porcelain and Jun stoneware), porcelain stone from south China (qingbai and underglaze blue porcelain and Longquan stoneware), and stoneware clays from south China (Yue and Guan stonewares). Therefore, SEM examination of HF‐etched, polished sections of the bodies of high‐refractory ceramics has considerable potential for investigating the raw materials used in their production.     

SPECTROSCOPIC INVESTIGATION OF RED STAINS AFFECTING THE CARRARA MARBLE FAÇADE OF THE CERTOSA OF PAVIA

The nature of the large red stains exhibited on the Carrara marble elements of the Certosa of Pavia façade was investigated by means of spectroscopic techniques and scanning electron microscopy. Although previous microbiological analysis has demonstrated the presence on the stone of a bacterial strain identified as Micrococcus roseus, that is capable of carotenoid production, it has been ascertained in the present study that an inorganic pigment, namely Pb₃O₄, is responsible for the observed coloration. On small green spots, the presence of photosynthetic micro-organisms has been demonstrated by microbiological analysis and confirmed by resonance Raman spectroscopy.     

SIENESE ‘ARCHAIC’ MAJOLICA: A TECHNOLOGICAL STUDY OF CERAMIC BODIES AND COATINGS*

The aim of the present study is to reconstruct the production technology of Sienese ‘archaic’ majolica in the early decades of the 14th century ad . The integration of archaeological data with archived data revealed the presence of numerous workshops, suggesting that the Sienese tradition of majolica production was well developed up until the end of the 16th century. Sixty‐seven uncoated and coated waste products were analysed. The ceramic bodies were examined by OM, XRDp, SEM–EDS, XRF, ICP–OES, ICP–MS and INAA. The coatings (enamels and glazes) were analysed by SEM–EDS and Raman microspectroscopy. The results showed that ceramics were rejected due to poor control of the firing temperature (technological wastes), faulty production technology (wastes of uncertain classification) and accidents (post‐firing wastes). Finally, the analyses revealed extreme homogeneity of the ceramic bodies, indicating the continued use of the same raw material over the whole period studied.     

CHARACTERIZATION OF ARCHAEOLOGICAL AND IN SITU SCOTTISH WINDOW GLASS

Scottish window glass from both archaeological sites and historic buildings was examined using portable X‐ray fluorescence (pXRF) and scanning electron microscopy – energy‐dispersive X‐ray micro‐analysis (SEM–EDX). The elemental composition of the glass provides information regarding the materials used and, subsequently, an approximate range of dates of manufacture. pXRF is shown to be more vulnerable than SEM–EDX to the effects of surface corrosion and matrix effects in archaeological samples. The study showed that the production of window glass in Scotland from the 17th century onwards appears to closely parallel that in England. It also demonstrated the potential of pXRF for in situ studies of window glass in historic buildings. pXRF was used to assess two Scottish buildings; one in state care and one in private ownership. The building in state care, the Abbot's House at Arbroath Abbey, showed a uniform glass type, suggesting that the building was re‐glazed completely at some point during the late 19th or early 20th century. The building in private ownership, Traquair House, had a range of glass types and ages, demonstrating a different maintenance and repair regime. This type of data can be useful in understanding historic buildings in the future, particularly if re‐glazing is being considered.