AN ARCHAEOMETRIC STUDY OF MEDIEVAL GLASS FROM THE FIRST BULGARIAN CAPITAL,PLISKA (NINTH TO TENTH CENTURY AD)

Glass finds from the first Bulgarian capital, Pliska, have been analysed by instrumental neutron activation analysis. The analytical data, together with previous results from analysis of glass samples from the second Bulgarian capital, Preslav, were subjected to cluster and discriminant analysis. The local origin of part of the analysed samples was proven and some conclusions about the technology of production were possible.     

THE BEGINNINGS OF ISLAMIC STONEPASTE TECHNOLOGY*

A multidisciplinary programme of research on Islamic pottery has been focused on questions of the dating, provenance and technology of Islamic pottery. One particular question has been the development of stonepaste, a material made primarily of crushed quartz with added frit-glass and clay. The combination of the different approaches of this study has revealed early foundations for the technology in ninth-century AD Iraq, apparently originating in the clay ceramic rather than the ‘Egyptian faience’ tradition. Subsequent and final practice developed in tenth- and eleventh-century AD Egypt. This technology becomes the primary body for all fine Islamic ceramics.     

HISPANO-MORESQUE POTTERY PRODUCTION OF THE FOURTEENTH-CENTURY WORKSHOP OF TESTAR DEL MOLÍ (PATERNA,SPAIN)

Excavation of Testar del Molí, the only workshop found in the Manises-Paterna area, revealed the existence of a fourteenth-century ceramic workshop covering the remains of the thirteenth-century workshop. This study is concerned with the fourteenth-century production, and forthcoming papers will connect both epochs following the findings of current excavations. The chemical and mineralogical characterization of the ceramic production of this workshop shows the presence of three groups of ceramic pastes which could also be distinguished by, and, thus, related to, their daily use. The raw materials found in the excavation have also been mineralogically and chemically characterized, and a model of possible mixtures of raw materials has also been developed in order to determine their possible use in the manufacture of the pottery previously characterized.     

MULTICOIN: A TOOL FOR CLASSIFYING COINS IN A MULTIMEDIA ENVIRONMENT

Classifying coins found during excavation is a challenging task for the archaeologist. This paper describes a multimedia system designed to assist the archaeologist by enabling him either to classify coins based on a pre-existing catalogue or to draw up his own catalogue for specific purposes. The system can also be used to train novices in the field: following an initial screening, the archaeologist only has to examine coins specifically requiring his expertise. A case study uses coins minted in Salerno 800–1200 AD, but the system has been designed to classify any set of coins by simply changing the underlying knowledge base. Very little training is required to operate the user-friendly system, which runs on multimedia PCs, as it is written using the C++ language and makes full use of the advanced features of Windows 3.11.     

WHITE LUMPS IN FIFTH- TO SEVENTEENTH-CENTURY AD MORTARS FROM NORTHERN ITALY

Ancient mortars from northern Italy, dating from the fifth to the seventeenth century AD, were examined in order to formulate an hypothesis regarding the origin of the white lumps often observed in these mortars and in other samples of the same geographical provenance. Various characterization techniques were employed, including scanning electron microscopy, X-ray powder diffraction and Fourier transform infrared (FTIR) and micro-FTIR spectroscopy.     

TECHNOLOGY AND COLOUR DEVELOPMENT OF HISPANO-MORESQUE LEAD-GLAZED POTTERY

Lead-glazed pottery from the medieval workshop of Les Olleries Majors (Paterna, Spain) has been studied by Mössbauer spectroscopy, X-ray diffraction, X-ray fluorescence and optical spectroscopy. Yellow, brown and honey-coloured glazes occur on pots glazed on only one surface. They have virtually identical compositions and transmittance spectra, their apparent differences in colour are due to the colours of the underlying pastes. Yellow glazes occur on cream-coloured calcareous bodies, honey-coloured glazes occur on less calcareous bodies with some development of hematite, while brown glazes occur on red siliceous cooking-pots. Green glazes are found on pots glazed on both surfaces; the glazes trapped CO₂ evolved by decomposing carbonates, resulting in an internal reducing environment. This caused the reduction of iron to the ferrous state which coloured the glaze green by diffusion.     

METHODOLOGICAL DEVELOPMENTS IN THE LUMINESCENCE DATING OF BRICK FROM ENGLISH LATE‐MEDIEVAL AND POST‐MEDIEVAL BUILDINGS*

Fired clay brick samples, obtained from a group of seven high‐status late‐medieval and post‐medieval buildings in England ranging in age from c. ad 1390 to 1740, were dated by the luminescence method using an optically stimulated luminescence (OSL) technique. The results obtained indicate that, when applied to quartz extracted from brick, the technique is capable of producing dates that are in consistently good agreement with independent dating evidence for the buildings. For six samples taken from a group of four dating ‘control’ buildings the mean difference between the central values of luminescence and assigned ages was 5 ± 10 years (SD, n = 6). The methodology used is appropriate for application to other standing buildings in other temporal and geographic regions, and may be used with confidence where conventional dating methods are less certain. The study also examines the luminescence characteristics of quartz and the characteristics of the lithogenic radionuclides in brick samples and identifies various aspects related to the assessment of experimental uncertainty in testing the reliability of the method.     

THE PROVENANCE AND TECHNOLOGY OF NEAR EASTERN GLASS: OXYGEN ISOTOPES BY LASER FLUORINATION AS A COMPLEMENT TO STRONTIUM*

The ability to make rapid measurements on small samples using laser fluorination enhances the potential of oxygen isotopes in the investigation of early inorganic materials and technologies. δ¹⁸O and ⁸⁷Sr/⁸⁶Sr values are presented for glass from two primary production sites, four secondary production sites and a consumer site in the Near East, dating from Late Antiquity to the medieval period. δ¹⁸O is in general slightly less effective than ⁸⁷Sr/⁸⁶Sr in discriminating between sources, as the spread of measured values from a single source is somewhat broader relative to the available range. However, while ⁸⁷Sr/⁸⁶Sr is derived predominantly from either the lime‐bearing fraction of the glass‐making sand or the plant ash used as a source of alkali, δ¹⁸O derives mainly from the silica. Thus the two measurements can provide complementary information. A comparison of δ¹⁸O for late Roman – Islamic glasses made on the coast of Syria–Palestine with those of previously analysed glasses from Roman Europe suggests that the European glasses are relatively enriched in ¹⁸O. This appears to contradict the view that most Roman glass was made using Levantine sand and possible interpretations are discussed.     

GEOCHEMICAL CHARACTERIZATION OF ARCHAEOLOGICAL LIME MORTARS: PROVENANCE INPUTS*

Chemical and mineralogical analyses were carried out on historical lime mortars from the parish church of Santa María La Real (Guipúzcoa). The study included various periods ranging from Roman to modern times and allowed the identification of various types of raw materials. In order to obtain pure binder, free of carbonate aggregates and charcoal particles, an innovative binder separation method was implemented. The chemical composition of the binder allows discrimination of different provenance areas for the raw materials, although those areas do not correlate with specific historical periods. In addition, the influence of burial processes on the primeval chemical features has been assessed and reveals that modern mortars display greater chemical modification than the Roman mortars.     

X-RAY FLUORESCENCE CHARACTERIZATION OF THE CORONA FERREA*

X-ray fluorescence (XRF) analyses of metals, glasses and enamels from the Corona Ferrea, or Iron Crown, of Monza are reported. The method followed to obtain quantitative analysis of metal alloys was based on comparison with standards and it is framed on the more general problem of XRF quantitative analysis of irregularly shaped objects with a portable instrument. Preliminary radiocarbon dating results are also reported.