ANOMALOUS CARBON-13 VALUES FOR FIBRE TEMPER IN CERAMICS*

Ceramic vessels from Later Stone Age sites in the Seacow river valley, South Africa, were heavily tempered with C4 grasses. However, most δ¹³C values of the temper fall between the known δ¹³C ranges for C4 and C3 grasses. Among possible C3 additives that could skew the signal, ground bone, animal dung, alpine grass, Karoo scrub ash, and humic acid contamination are eliminated. The sherd surfaces yield fatty chars with C3-like values. Although these are not enough to account for all the skewing, they represent only the final cooking event. They were preceded by many such events in which fat was absorbed into the C4 grass then charred to soot by later periods in the fire. Thus organic carbon with the isotope composition of the fat built up while the vessel remained in use.     

X-RAY FLUORESCENCE AND DENSITY MEASUREMENTS ON SURFACE-TREATED ROMAN SILVER COINS*

Some 630 Roman silver coins excavated at Augusta Raurica (Switzerland) have been analysed by non-destructive X-ray fluorescence and X-ray diffraction. Furthermore, the density and the weight have been determined. The measured average density of plated and massive depletion-silvered coins is lower than the density calculated from the chemical composition, whereas massive coins display equal values for both of the densities. Based on experimental X-ray investigations of modern silver (tempering, acid treatment, production of corrosion layers), the nature of corrosion products on silver, their impact on surface analysis, and aspects of wearing-off by circulation are briefly discussed.     

Chemical characterization of ancient pottery from sudan by x‐ray fluorescence spectrometry (xrf), electron microprobe analyses (empa) and inductively coupled plasma mass spectrometry (ICP–MS)*

Sixty‐four sherds and seven natural clays from prehistoric sites in northwestern Sudan have been submitted to petrological and chemical analysis using XRF spectrometry, EMPA and ICP–MS. According to their texture, the sherds form five different groups. The high contents of P₂O₅ (more than 0.5 wt%) discerned in 19 samples and the variation of the P₂O₅ content in two samples of the same vessel can be explained by post‐depositional processes or by the ancient organic contents (e.g., milk) of the vessel. Chemical classification of the pottery bulk suggests that vessels were made locally, as only sherds from the same area show homogeneity of data.     

FURTHER STUDIES IN THE COMPOSITIONAL VARIABILITY OF COLOURLESS ROMANO‐BRITISH VESSEL GLASS*

Previous studies of colourless Romano‐British vessel glasses have suggested that, regardless of vessel type, they show considerable compositional homogeneity. Intriguing differences in variability (as opposed to mean composition) have, however, also emerged. This paper reports on a compositional study of 243 vessels, that is larger and more carefully controlled than in previous studies of this kind. Unexpected compositional differences have been found both between and within the four vessel types studied. We discuss the implications of these results in the context of different models that have been proposed for glass‐making and glass‐working in the Roman world.     

CHEMICAL CHARACTERIZATION AND STATISTICAL MULTIVARIATE ANALYSIS OF ANCIENT POTTERY FROM MESSINA,CATANIA, LENTINI AND SIRACUSA (SICILY)*

This paper presents the chemical characterization of 79 fragments of Archaic and Hellenistic fine‐grained pottery from archaeological sites in Messina, Catania, Lentini and Siracusa (Sicily). The sherds were classified as ‘calcidian’, ‘banded’, ‘unvarnished’ and ‘black varnished’ pottery. The major and trace elements identified by X‐ray fluorescence (XRF) were statistically elaborated using the method proposed by J. Aitchinson in 1986 for the analysis of compositional data. From cluster analyses using element/SiO₂ log‐ratios, it was possible to group the pottery found in Catania, Lentini and Siracusa into highly linked clusters. Conversely, the Messina pottery was divided into two clearly distinct groups. With the aim of identifying any possible mineralogical differences between the two Messina groups, Fourier transform infrared (FT–IR) absorption measurements were made, showing only quantitative differences in plagioclase and muscovite. The specific groups of pottery with restricted chemical compositions are considered to be of local production, also on the basis of archaeological and petrographic evidence.     

ANALYSIS OF ROMAN WALL PAINTINGS FROM THE THERMAE OF ‘IULIA CONCORDIA’

Twenty‐six wall painting fragments and some plaster, ‘intonachino’ and stucco samples, discovered at Iulia Concordia, have been studied by different analytical techniques to gain information about the pigment nature and the composition of the materials. The presence of calcite, dolomite and aragonite allow the distinction of four groups of wall samples varying in the nature of pigments and in the application technique. These differences can be attributed to different execution times or, more probably, to the arrangement of the rooms in the building structure. The nature of the pigments found in the Thermae of Iulia Concordia appears similar to that found in other Roman villas of Venetia et Histria, with the use of precious pigments such as Egyptian blue and cinnabar.     

TECHNOLOGY AND PROVENANCE OF A COLLECTION OF ISLAMIC COPPER‐BASED OBJECTS AS FOUND BY CHEMICAL AND LEAD ISOTOPE ANALYSIS*

Chemical and lead isotope analyses were utilized to determine the composition, technology and origin of a collection of Islamic copper‐based objects found in Jordan. The atomic absorption spectrometry results show that the objects were made of different types of copper‐base alloys that contain various amounts of zinc, tin and lead. The use of brass, highly leaded brass and quaternary alloys of Cu‐Zn‐Sn‐Pb in the manufacture of everyday, household objects strongly points to Islamic traditions. The lead isotope compositions of the objects match very well that of the copper ore mined from the Dolomite‐Limestone‐Shale unit of the Arabah copper mines.     

CHEMICAL COMPOSITION OF A BOG BODY ADIPOCERE

Chemical analyses were carried out on adipocere obtained from a bog body recovered from a peat bog at Meenybradden, County Donegal, Ireland. Chromatographic (thin-layer chromatography and gas chromatography) and mass spectrometric analyses, combined with microanalytical chemical transformations, have yielded detailed compositional information. An absence of intact triacylglycerols, diacylglycerols and monoacylglycerols indicates that hydrolysis is complete. Consequently the adipocere is composed mainly of fatty carboxylic acids. The high proportion of palmitic and stearic acids, together with depleted oleic acid content, indicates that extensive reduction and, possibly, β-oxidation have occurred during burial in the peat bog. Hydration of the double-bond in oleic acid has also occurred, as is shown by the formation of 10-hydroxystearic acid. The monoenoic fatty carboxylic acids that are present, composed mainly of C₁₈ and C₁₆ compounds, comprise a mixture of positional isomers. The results are compared and contrasted with those obtained from previous studies of the lipid composition of other adipoceres and cadavers of archaeological interest.     

EVIDENCE FOR THE MIXING OF FATS AND WAXES IN ARCHAEOLOGICAL CERAMICS

Lipid residues from two Late Saxon/early medieval ceramic vessels recovered from excavations at West Cotton, Raunds, Northamptonshire, U.K., have been investigated by high-temperature gas chromatography (GC) and GC/mass spectrometry (GC/MS). The solvent extracts of sherds sampled from different points on each vessel (i.e., base, body and rim) were analysed quantitatively and qualitatively and compounds were identified which were characteristic of beeswax and animal fat. Furthermore, by determining the sites of accumulation of the specific lipid types and their concentrations in different parts of the vessels it can be inferred that the beeswax was added to the vessels prior to the addition of the fat. It was concluded that the two vessels performed different functions in antiquity.     

CYPRIOT BLACK-ON-RED WARE: TOWARDS A CHARACTERIZATION

Chemical analysis of Early Iron Age sherds from Cyprus and the Levant using atomic absorption spectrometry shows that Black-on-Red ware was manufactured only in Cyprus. Two types of fabric are isolated, calcareous and non-calcareous, and their technological significance discussed. The presence of trade links between the Cypriot sites of Kition and Amathus and sites in the Levant is suggested.