Local recipes or distant commodities? Lead isotope and chemical compositional analysis of glaze paints from the Salinas pueblos,New Mexico

For nearly four hundred years, Pueblo potters in the Rio Grande Valley of New Mexico produced technologically innovative glaze-decorated bowls and exchanged them widely among different villages. While potential sources of lead ores used to make glaze paints are found throughout the Rio Grande Valley region, researchers have only recently begun to identify which ore sources potters exploited and to understand the social and economic factors underlying patterns of ore resource use. In this paper we use stable lead isotope and electron microprobe analysis of glaze paints on Rio Grande Glaze Ware made at two Salinas pueblos to identify ore sources and glaze recipes used by their potters. Despite some isotopic overlap of ore sources, the lead isotope data point to regular exploitation of ores from the Socorro area of the southern Rio Grande. Salinas potters apparently used other sources as well, and likely mixed ores from different sources. We also identify four local glaze recipes that appear to incorporate multiple ore sources, suggesting that Salinas potters obtained raw ores rather than finished glaze paints.     

LEAD ISOTOPE ANALYSIS OF TANG SANCAI POTTERY GLAZES FROM GONGYI KILN,HENAN PROVINCE AND HUANGBAO KILN,SHAANXI PROVINCE

Through the use of MC–ICP–MS, this study analyses the lead isotope ratios of 19 Tang Sancai pottery glazes unearthed from the Gongyi and Huangbao kiln sites. According to their different lead isotope ratios, the two kilns can be grouped separately. The research also suggests that the Gongyi and Huangbao kilns are independent production centres of Tang Sancai in the Tang Dynasty. The data from the Huangbao kiln indicates that the lead in the glazes originates from the Northern China geochemical province, while the data from Gongyi kiln suggests its source as the Yangtze geochemical province. Furthermore, the results obtained for the Tang Sancai pottery indicate that the lead sources for glaze making of these two kilns were very consistent, which suggests that lead isotope analysis could be a helpful method to identify the kilns producing Tang Sancai artefacts.     

Chemical and Textural Characterization of Tin Glazes in Islamic Ceramics from Eastern Spain

Several productions of Islamic tin glazed pottery from eastern Spain have been studied under the chemical and microstructural points of view by means of WDS, SEM/EDX, XRD and XRF analyses. Samples of Islamic pottery from the workshops of Murcia 10th, Zaragoza 11th, Mallorca 11th, Denia 13th, Granada 14th and Córdoba 10th, which represent a wide range of local productions from medieval eastern Spain, have been studied in order to obtain the trends of the technical and compositional evolution. From the experimental data, some common features can be established, as well as some differences. All the Islamic Spanish opaque glazes are lead glazes with PbO contents from 37 to 56%, opacified with tin oxide in the range 4–15%. In all the cases, they were applied on a previously biscuited body made with a Ca-rich clay, probably to produce a buff colour less apparent through the glaze. The thicknesses range from 100 to 150 microns and the opacification is achieved by small crystals of SnO₂(under a micron of size). The main differences are the size and distribution of such small crystals, being smaller in the early Islamic productions (Zaragoza and Murcia) and bigger in the late productions.     

Chemical Composition and Manufacturing Technology of a Collection of Various Types of Islamic Glazes Excavated from Jordan

A collection of Islamic glazed pottery shards that were excavated from the archaeological site of Dohaleh/Northern Jordan were chemically analysed. The glazes belong to three different decorative styles. The chemical analysis of the glazes was carried out using energy dispersive x-ray fluorescence. The chemical analysis results enable the classification of the glazes into the three distinct compositional groups with reference to their principal modifier, these are: the alkaline glazes, the high lead glazes and the lead–alkali glazes. In some cases the body fabric was analysed by a combination of petrographic and chemical analysis techniques. The study show that inherited traditional techniques were combined with innovative Islamic techniques were used for the production of the glazes.     

DISCOVERY,PRODUCTION AND USE OF TIN‐BASED OPACIFIERS IN GLASSES,ENAMELS AND GLAZES FROM THE LATE IRON AGE ONWARDS: A REASSESSMENT*

Tin‐based opacifiers (lead stannate yellow and tin oxide white) were first used in glass production for a short period in Europe from the second to the first centuries bc , and then again throughout the Roman and Byzantine Empires from the fourth century ad onwards. Tin oxide was also used in the production of Islamic opaque glazes from the ninth century ad , and subsequently in enamels applied to Islamic and Venetian glasses from the 12th century ad onwards. A selection of published analytical data for the tin‐opacified glasses, enamels and glazes is summarized, and the methods used in their production are reassessed. The phase transformations occurring when mixtures of lead oxide, tin oxide and silica are fired are investigated with high temperature X‐ray diffraction (XRD) using a synchrotron radiation source, and these results are used to explain the observed differences in the glass, enamel and glaze compositions. Possible reasons for the use of tin‐based opacifiers in the second to first centuries bc , and for the switch from antimony‐ to tin‐based opacifiers in the fourth century ad are suggested, and the possible contexts in which tin‐based opacifiers might have been discovered are considered. The introduction of tin‐opacified glazes by Islamic potters in the ninth century ad is discussed in terms of technological transfer or independent invention.     

Testing technological practices: neutron activation analysis of neolithic ceramics from Valencia,Spain

Using instrumental neutron activation analysis (INAA) of prehistoric pottery, daub, and modern clay samples from Valencia, Spain, we tested expectations on changes in raw material use with socio-economic shifts during the Neolithic (ca. 5600–2800 BC). Elemental analysis identified three distinctive clay source groups used by Neolithic potters. Contrary to expectations, a shift in raw material use was identified between the Early and Middle Neolithic despite general similarities in technological practices. In the Late Neolithic, pottery production became more specialized, but potters used the same range of clay sources documented earlier. This study illustrates the utility of INAA for testing hypotheses of prehistoric craft production.     

APPLICATION OF LEAD ISOTOPE ANALYSIS TO A WIDE RANGE OF LATE BRONZE AGE EGYPTIAN MATERIALS*

Lead isotope analysis was applied to Egyptian materials from the Late Bronze Age in order to investigate the relationship between these different materials, many of which have lead as a significant component. The galena kohls analysed can be provenanced to Gebel Zeit, a large mining site known to have been active during the period. However, the source of lead metal is different and seems to be outside Egypt, along with the source of copper. Lead‐based pigments such as lead antimonate that were used in glass and glazes seem mostly to come from Egypt, although they may well contain a component of ‘Mesopotamian’ lead. In the Predynastic period, galena from many sources is being exploited for use as kohl. However, by the Middle Kingdom (2055–1650 bc ), extraction has concentrated on one source, Gebel Zeit, perhaps reflecting increasingly centralized control and/or the use of large‐scale exploitation. It therefore appears that a complex pattern of trade in lead‐based materials was evident, with lead metal and galena being separate commodities from separate sources and treated as such.     

The early roman imperial AES coinage II: Tracing the copper sources by analysis of lead and copper isotopes—copper coins of Augustus and Tiberius*

Lead and copper isotopes of Roman Imperial copper coins (denominations as and quadrans) were analysed by MC–ICP–MS. We concentrated on well‐dated coins minted at the official mint of Rome under the Emperors Augustus and Tiberius (between 16 bc and ad 37). The lead isotope results were compared with published lead isotope data of ore bodies from the Aegaean, Cyprus, Italy and Spain, in order to fingerprint the sources of Roman copper. During the Augustan period the main copper supply, as judged from the copper coins, is from Sardinia and south‐east Spain, with minor contributions from Tuscany. Except for Tuscany, this continued into the Tiberian period, when Cypriot copper also appears. Augustan quadrantes and late Tiberian asses came solely from the Rio Tinto area in south‐west Spain. Copper isotopes were applied here for the first time to systematic archaeometric studies. They are supplementary to lead isotopes and allow further grouping and classification of the copper coins.     

THE TECHNOLOGY OF GLAZED ISLAMIC CERAMICS USING DATA COLLECTED BY THE LATE ALEXANDER KACZMARCZYK

During the 1980s, the late Alexander Kaczmarczyk undertook the analysis of some 1200 glazed Islamic ceramics from Egypt, Iran, Iraq and Syria spanning the period from the eighth to the 14th centuries ad , using a combination of XRF for the glazes, and AAS or PIXE for the bodies. The aim of the present paper is, first, to bring to the attention of researchers into Islamic ceramics the fact that these analytical data are available on the Research Laboratory for Archaeology and the History of Art website, and also that some 400 of the analysed sherds are held in the Research Laboratory. Second, the paper provides a preliminary interpretation of the analytical data in terms of the choice of glaze type (i.e., alkali–lime, lead–alkali and high‐lead), tin‐opacification, body type (i.e., quartz or stonepaste, calcareous clay, and non‐calcareous clay), and colorants.     

The production technology of Iznik pottery—a reassessment*

Previous research has established that Iznik pottery differs from other Islamic stonepaste pottery in that its stonepaste bodies contain lead oxide as well as soda and lime, and that a significant proportion of the tin oxide in its glaze is present in solution rather than as tin oxide particles. In order to better understand these distinguishing features, the chemical compositions and microstructures of Iznik pottery and tile samples, together with those of lumps of glass found in association, were investigated using both scanning electron and optical microscopy. These data have been supplemented by the study of replicate lead–alkali glazes produced in the laboratory with a range of different compositions. The results demonstrate that separate soda–lime and high‐lead glasses were used in the production of Iznik stonepaste bodies, and that the total glass contents of the bodies were significantly higher than those quoted by Abū’l‐Qāsim, who was writing in about ad 1300. The very high purity of the lead–soda Iznik glazes indicated that the alkali flux used was either a purified plant ash or an as yet unidentified mineral source of soda. Replication experiments established that the high solubility of tin oxide in the glaze was due to the high purity of the glaze constituents. Furthermore, it is suggested that tin oxide was added to the glaze in order to give it a very slight opacity and thus obscure any blemishes in the underlying body.     

CHEMICAL AND MINERALOGICAL CHARACTERIZATION OF SASANIAN AND EARLY ISLAMIC GLAZED CERAMICS FROM THE DEH LURAN PLAIN,SOUTHWESTERN IRAN*

One hundred and seventy‐five glazed ceramics from Sasanian and Early Islamic period sites located on the Deh Luran Plain in southwestern Iran were examined by instrumental neutron activation analysis for characterizing differences in ceramic pastes and by laser‐ablation inductively coupled plasma mass‐spectrometry for identifying the constituents of the ceramic glazes. The results of the analysis reveal that alkaline‐based glazed ceramics have paste compositions that are distinct from contemporary and later ceramics decorated with alkaline–low‐lead and lead‐based glazes.     

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.     

LEAD ISOTOPIC EVIDENCE FOR A MIXED PROVENANCE FOR ROMAN WATER PIPES FROM POMPEII*

Lead isotope analysis has been applied to the investigation of some Roman objects found in the town of Pompeii, consisting mostly of fistulae from the Augustan water supply system. The results of the analyses have produced ratios between 18.10 and 18.66 for ²⁰⁶Pb/²⁰⁴Pb, between 15.63 and 15.72 for ²⁰⁷Pb/²⁰⁴Pb and between 38.21 and 38.98 for ²⁰⁸Pb/²⁰⁴Pb. These data point to a fairly complex origin for the lead artefacts, probably involving several successive meltings and recyclings of a rather heterogeneous lead supply. The spread of lead isotope ratios can only be reconciled with a multiplicity of end‐members, at least three, but very probably more. There is one certain Sardinian ore, other indistinguishable Hercynian ores of Sardinia and/or Spain, and several different Alpine Mesozoic‐Tertiary mineralizations of the Mediterranean basin (Spain, Greece, Tuscany).     

INVESTIGATION ON ROMAN LEAD GLAZE FROM CANOSA: RESULTS OF CHEMICAL ANALYSES*

Five sherds of green glazed pottery excavated at Canosa (Apulia) in Italy have been analysed by scanning electron microscopy. The aim of the investigation was to determine the chemical composition of the glazes and thus obtain information on the methods used in their production. The glazes were all of the high‐lead type, coloured green by the addition of copper. Intermediate layers, observed at the interface between the glaze and body and giving the appearance of an applied white slip, were the result of the crystallization of lead feldspar from the molten glaze. Non‐calcareous clays were used in the production of the pottery bodies. Concentration profiles from the glaze exterior to the body suggested that the glazes were produced by applying a suspension consisting of lead oxide plus silica to the bodies. On the basis of the glaze and body compositions, it is suggested that the Canosa glazed pottery was produced locally.     

Local mining or lead importation in the Roman province of Africa Proconsularis? Lead isotope analysis of curse tablets from Roman Carthage,Tunisia

This study attempts to determine if there was Roman lead mining in Africa Proconsularis, approximately the area of modern day Tunisia, using lead isotope analysis. Another important aspect of the study is the innovative use of electron microprobe analysis (EMPA) as a screening tool to greatly reduce the number of expensive lead isotope analyses needed for the study. The EMPA X-ray mapping for arsenic, antimony, copper, and silver narrowed the sample of curse tablets to those most likely produced from Tunisian ores; these tablets were then tested using thermal ionization mass spectrometry (TIMS) analysis. A total of 96 Roman lead curse tablets from Carthage, Tunisia were screened with EMPA and twenty selected for TIMS to determine the ore sources of the lead used to manufacture the tablets. Comparing the lead isotope ratios of twelve of the sixteen tablets most likely to be made of Tunisian lead to samples of Tunisian ores suggests that the Romans were mining lead in Africa Proconsularis and were not relying solely on imports.     

A study of the glazing techniques and provenances of Tang sancai glazes using elemental and lead isotope analyses

This study discusses the elemental compositions and lead isotope ratios of Tang sancai glazes unearthed from the Huangpu kiln, Huangye kiln and two Tang sancai tomb sites. The various glazes feature distinct lead isotope ratios and trace element characteristics, which can be interpreted as evidence for the use of different lead ore deposits and siliceous raw materials in the glazes. This is a strong indication that lead isotopes combined with trace element analysis could be used as a viable approach for identifying the provenance of Tang sancai of unknown origin by linking them to kiln sites, This provenance technique could be significant in the interpretation of ancient ceramic trade and communication patterns. In this study, the provenance of several Tang sancai glazes of uncertain origin were determined using this method: some Tang sancai wares unearthed in Xi'an City were produced in the kiln near Luoyang City and then traded to Xi'an City, providing an idea of ancient Tang sancai ceramic trade routes.     

Revisiting the Exploitable Threshold Model: 14th century resource procurement and landscape dynamics on Perry Mesa,Arizona

Abstract

This study presents a revision of Dean E. Arnold’s (1985, 1993) Exploitable Threshold Model, which attempts to explain the selection of raw materials for pottery production. Arnold’s model posits that potters’ preferences for materials are largely determined by the linear distance to individual resources. We argue, however, that potters’ choices are, at least in part, determined by spatial relationships among the necessary resources rather than the distances to them. This study of 14th century pottery production on Perry Mesa, Arizona demonstrates that potters selected materials based on the co-occurrence of readily available sources of temper, clay, and fuel. Lack of water and fuel sources on the mesa top compelled local residents to eschew the use of readily available basaltic sands to temper their plainware pottery. Instead, Perry Mesa potters selected granitic sands from the river valley nearly 300 vertical meters below their settlements.     

A TECHNOLOGICAL EXAMINATION OF NINTH–TENTH CENTURY AD ABBASID BLUE‐AND‐WHITE WARE FROM IRAQ,AND ITS COMPARISON WITH EIGHTH CENTURY AD CHINESE BLUE‐AND‐WHITE SANCAI WARE*

Eight sherds of ninth–tenth century ad Abbaesid blue‐and‐white glazed earthenware, excavated in 1931 at Hira in western Iraq, were analysed using, variously, quantitative wavelength‐dispersive spectrometry (WDS) and energy‐dispersive spectrometry (EDS) in association with scanning electron microscopes (SEM), and semi‐quantitative X‐ray fluorescence spectrometry (XRF). In order to compare the compositions of the cobalt pigments used, the glazes of seven complete vessels of eighth century ad Chinese Tang blue‐and‐white sancai were also analysed semi‐quantitatively using XRF. The Abbasid wares were shown to have used traditional Mesopotamian alkali–lime glazes applied to calcareous clay bodies. Half the glazes examined were opacified with tin oxide. Three types of blue decoration (i.e., raised; spreading; and flat, non‐spreading) were produced using a variety of formulations, including a mixture of cobalt pigment with lead oxide. The sources of the ores used for the cobalt pigments have not been identified. However, the analytical data showed that the cobalt ore used for the Abbasid blue‐and‐white ware could be distinguished from that used for the Tang blue‐and‐white sancai by its higher iron content and by the presence of a significant amount of zinc. The use of cobalt‐blue decoration on the ninth–tenth century ad Abbasid ware was anticipated in China by eighth century ad Tang blue‐and‐white sancai wares. However, whether its introduction by the Abbasid potters should be seen as an independent invention that followed the introduction of tin‐opacified glazes in Iraq, or whether it was influenced in some way by Chinese originals, is still unresolved.     

Probing the provenance of archaeological glaze colorants: Polychrome faunal reliefs of the Ishtar Gate and the Processional Way of Babylon

The polychrome glazes from the Processional Way and the Ishtar Gate of Babylon are among the best preserved from antiquity. Yet, little is known about the logistical choices involved in their production. Variations in isotope ratios can be useful for complementing an archaeological investigation of potential geological sources of raw materials. Consistent with archaeological evidence and ancient texts on trade in metals, Turkish ore deposits are thus tentatively proposed as possible sources of the metal oxide colorants used for the investigated polychrome glazes of three Neo‐Babylonian faunal reliefs that are now part of the collection of the Ny Carlsberg Glyptotek, Copenhagen.     

中国钴着色材料的分类和来源

中国历史上的钴显色材料有颜料、玻璃、陶瓷釉。花绀青、钴蓝属历史颜料;钴显色蓝色玻璃可能始于西汉;钴显色蓝色陶瓷釉始于战国陶胎釉珠,唐朝唐三彩陶瓷釉发展成多个品种。钴显色材料有国产钴土矿类和进口Smalt类。原料矿中带入的锰、铁、镍、砷、铋等杂质对色彩有一定影响。