Characterization and origin of black and red Magdalenian pigments from Grottes de la Garenne (Vallée moyenne de la Creuse-France): a mineralogical and geochemical approach of the study of prehistorical paintings

Pigments sampled from wall paintings and from crayons taken on the floor, at the Grottes de la Garenne (Saint-Marcel – Indre, France) have been analyzed and characterized by infrared spectroscopy, Raman micro-spectroscopy, X-ray diffraction, ICP/MS and analytical TEM. The red pigment used for the wall paintings is mainly composed by hematite, clays, carbon matter and carbonates. Results on the red pigments show that the compositions of the paintings are similar to that of some crayons. Regarding these analyses, their origin is compatible with local siderolithic facieses. Analysis of black pigments shows that they are made of cryptomelane, pyrolusite, clays, carbonates and carbon matter. It shows also that paintings and some crayons compositions are compatible. On the contrary of red pigments, the origin of black pigments is probably allochtonous. Indeed, the traces of thallium detected in cryptomelane, the cerium anomaly and the absence of iron are not compatible with local facieses or other sites from the French Massif Central.     

Changes in the body,glaze and enamel compositions of early Meissen porcelain, 1723–c.1740

The evolution of early Meissen body, glaze and colorant compositions is examined using X-ray fluorescence spectroscopy (XRF) measurements on three artefacts that can be accurately dated to the period 1723–c.1740. The results are interpreted based on recipes recorded in the earliest documents of the Meissen archives. The pure Aue kaolinite contains low levels of Ti and can be distinguished from secondary clays, for example, clay from Colditz. The excess Ti in the glaze versus the body reported earlier and confirmed by the present authors is explained by the exclusive use of Colditz clay for the glaze, as described in the recipes before 1730, providing a terminus ante quem for Meissen porcelain exhibiting this particular asymmetry. After 1730, the presence of elevated Ti in the body could serve as a marker for the experimental admixture of clays to Aue kaolinite to alter its properties. Based on the detection of As, Ba and Bi, it is suggested that smalt from Erzgebirge was the colorant for blue enamels until at least 1725.     

Multi-method (FTIR,XRD, PXRF) analysis of Ertebølle pottery ceramics from Scania,southern Sweden

A combination of Fourier-transform infrared spectroscopy (FTIR), powder X-ray diffraction (XRD) and portable X-ray fluorescence spectroscopy (PXRF) was used on the clay fraction of Ertebølle ceramics from several Late Mesolithic sites in Scania, southern Sweden. The aim was to provide up-to-date information about clay types used during that period within the Scanian Ertebølle cultural unit, and to elucidate social aspects relevant to the organization of pottery production and the role of ceramics in the local societies. The results suggest similar clay preferences across the sites, site-based pottery production using local clays and zero mobility of ceramics between the sites. The chemical separation of the ceramics from the site of Soldattorpet into two compositional groups suggests possible multigroup occupation. The origins of aromatic hydrocarbons, extracted previously from the ceramic matrix of the vessels during a lipid residue study, were also investigated, and a discussion is provided.     

Archaeometric analysis of ceramic production in Tiwanaku state (c.500–1000 ce): An exploratory study

The chemical and mineralogical characterization of seven ceramic fragments produced within Tiwanaku state (c.500–1000 ce ) is reported. The instrumental techniques used included X‐ray elemental and mineralogical chemical analysis, Raman spectroscopy, and scanning and light microscopy. The results indicate there are several clay types, although they show similarities, such as the use of a plant‐based temper. The red colour of the decoration is hematite, and manganese oxides such as jacobsite are present in the black. The white colour is a mixture of gypsum and clay, and the orange is a mixture of hematite and clay. The use of colours, the quality of the clays and the temperatures reached during pottery firing point to expertise in ceramic production and to complex decision‐making processes. The multi‐elemental archaeometric approach documented here could become an important tool to shed a light on ancient ceramic technology and the internal variance of Tiwanaku pottery.     

The geochemical diversity of neogene clay deposits in Crete and its implications for provenance studies of Minoan pottery*

The determination of provenance probably forms the primary role of geochemical analyses in archaeological ceramic studies. In what has comprised a successful field of study, the ultimate basis for such research has been the comparison of pottery compositions with the geochemical diversity displayed by clay deposits within a given study area. Although such studies are now common, the understanding of chemical and mineralogical variability in ceramic raw materials has been somewhat neglected, with the dominance of assumptions rather than the actual analysis of clays. In this paper, a study is presented of Neogene clays in Crete (Greece), a clay type commonly used in ancient and modern pottery production. Sixty‐one samples were taken from 28 locations in the central and eastern parts of the island, to reveal both intra‐ and inter‐deposit variability. In one deposit chosen for multiple sampling, the 14 samples display great variability in the alkali elements, Fe and Co, and to a lesser extent in the REEs. Many of the geographically separate deposits differ from each other in chemical composition, with Eastern Cretan deposits showing higher REE concentrations and higher Th/Sc ratios, whereas Central Cretan deposits of younger geological stages are characterized by a lower Th/U ratio. Mineralogical analysis by XRD is used to explain aspects of the geochemical variability of the clays.     

ON THE INFLUENCE OF DRYING AND FIRING OF CLAY ON THE FORMATION OF TRACE ELEMENT CONCENTRATION PROFILES WITHIN POTTERY*

On experimentally fired briquettes made of five chemically and mineralogically different clays, trace element concentration profiles from the centre to the surface of the briquettes have been measured by Neutron Activation in order to examine if drying and firing of the clays lead to a mobilization and subsequent migration of single components within a sherd. Mineralogical changes during firing have been determined by X‐ray diffraction. Generally, no such migration could be found. For two clays, arsenic was lost from the briquette during firing, forming non‐constant concentration profiles. If NaCl is present in the clay paste, sodium migrates towards the surface. Additionally, in the special case in which the presence of NaCl coincides with that of calcite, the heavier alkali elements evaporate, forming significant concentration profiles within the sherd.     

MÖSSBAUER SPECTRA OF IRON IN CERAMICS AND THEIR RELATION TO POTTERY COLOURS

The chemical states of iron in a few selected clays and ceramics have been ascertained employing the technique of Mössbauer absorption. The effects upon the iron in firing the clays under different conditions have also been measured. Colour changes are correlated with the various chemical states of iron before and aftefiring.     

A Multidisciplinary Approach to the Study of Archaeological Mortars from the Town of Ammaia in the Roman Province of Lusitania (Portugal)

The Roman town of Ammaia (in Marvão Region) is considered one of the most important recent findings of the Roman presence in Portuguese territory. It was settled in Republican times and abandoned in the seventh century. In this research, 17 masonry mortars and renders from the West Tower (South Gate), the residential area near the West Tower, the macellum, the peristylium, the public bath building, the podium of the temple and the portico of the forum were analysed. The methodology of chemical, mineralogical and microstructural characterization has involved several complementary techniques, including stereomicroscopy, X‐ray diffraction, thermal analysis and scanning electron microscopy coupled with energy‐dispersive X‐ray spectroscopy. The results indicate that the mortars from the beginning of the town's edification were mainly composed of soil (clays). Later, during the main Roman building period, mortars were composed using a calcitic binder and the mortar composition varied according to their use and function. The samples from a period subsequent to the Roman occupation are based on a dolomitic binder. From the present study, relevant information has been acquired about the technological evolution of Roman construction in Ammaia, the historical context of the archaeological structures and guidelines for the conservation and restoration of mortars.     

Firing Techniques of the Impasti from the Protohistoric Site of Concordia Sagittaria (Venice)

⁵⁷Fe Mössbauer spectroscopy provided relevant information on the firing techniques employed in manufacturing concotto and coarse pottery, two types of fired clay mixtures (impasti) of the protohistoric settlement site of Concordia Sagittaria. The firing techniques of Concordia were reconstructed by comparing the Mössbauer patterns of the artefacts with those of the local raw clays fired in the laboratory. The concotto was produced in kilns by firing clay mixtures under oxidizing conditions at 700–1000°C, or at lower temperatures in the open air. The firing of these clay mixtures containing mainly ground pieces of waste pottery, resulted in hard and variously coloured construction materials, particularly suitable for humid environments. In turn, the coarse pottery was produced by firing clay mixtures more homogeneous than those used for the artefacts of concotto. The firing of coarse pottery was performed under reducing conditions at about 900°C with a final exposure to air by opening the hot kiln. Light and agreeable coarse pottery, with a red surface on the grey-black core, was obtained when the effective temperature of air was higher than 500°C.     

Petrographic and geochemical analysis on the provenance of the Middle Bronze and Late Bronze/Early Iron Age ceramics from Didi Gora and Udabno I, Eastern Georgia

We report thin section petrographic and geochemical analysis of a total of 20 Middle Bronze, Late Bronze/Early Iron Age ceramics excavated from Didi Gora and Udabno I located in the Eastern part of the Republic of Georgia and 31 clay samples from eight different regions in the surrounding areas of the sites. The major and trace element compositions of the ceramics and clays were determined using a wavelength dispersive X-ray fluorescence technique. The results indicate that the ceramics were manufactured from local clays in Eastern Georgia, mainly from two local clays without any preference of one of the sources during the Middle Bronze, Late Bronze/Early Iron Age.     

Pottery production and distribution in prehistoric Bronze Age Cyprus. An application of pXRF analysis

Portable X-ray Fluorescence (pXRF) analysis of over 400 samples of Early and Middle Bronze Age Cypriot pottery from four widely separated sites identifies both local and non-local products at each. A series of analyses of sub-sets of the data highlights differences in the clays used at each site and for some distinctive types and wares. When assessed in the context of general typological, technological and stylistic factors these variations provide the basis for considering patterns of local production and inter-regional relationships across the island. Although the great majority of pots were locally made, particular wares and shapes were brought in from elsewhere. For some sites finer, more highly decorated vessels are mostly imports, but at others both simpler and more complex vessels were made of the same local clays. While small juglets or flasks may have been containers for transporting small quantities of rare substances, larger vessels are likely to have held less precious material. Open vessels, especially small bowls – some of which are plain, utilitarian items – represent another aspect of social behaviour and inter-regional relationships.     

Technological examination of Neolithic-Bronze Age pottery from central and southeast Europe and from the Near East

Scanning electron microscopy is used to examine sequences of pottery sherds from central and southeast Europe, Greece and the Near East spanning the period from the Neolithic to the Bronze Age, in order to obtain information on the ceramic technologies employed in antiquity. On the basis of the vitrification observed and the chemical composition, the types of clay and firing procedures (temperature and atmosphere) employed in the manufacture of the pottery are defined. Two under-lying trends in the associated ceramic technologies are thus identified. The first is based on the use of non-calcareous or “unstable” calcareous clays fired in a reducing atmosphere at temperatures below 800 °C and the second on the use of “stable” calcareous clays fired in an oxidizing atmosphere at temperatures in excess of 800 °C.     

Diatoms as indicators of provenance in Finnish sub-neolithic pottery

The clays of Finland originated from glacial deposits formed during the deglaciation of the Weichselian ice-sheet and during the different stages of the Baltic Sea. The analysis of the fossil diatom flora is of central importance in the study of its developmental history. The diatoms in the clay indicate its sedimentary environment, which can be linked to the stages of the Baltic Sea. The siliceous valves of diatoms tolerate heating up to 1400°C and can consequently be identified in ceramics fired at lower temperatures. Several diatom analyses have been made in Finnish Sub-Neolithic comb ware pottery in order to determinate the origin of their clay materials. According to the results of these studies, prehistoric potteries used clays deposited during the Yoldia and the Ancylus stages. The criteria used in selecting raw materials were identical to those of modern ceramic industries. Further details as to provenance of clay materials have been illustrated in connection with research on pottery from the Aland Islands. In the example from Kymi, South-eastern Finland, changes in the composition of the diatom flora have been found to correlate with changes in pottery decoration styles.     

The Terracotta Industry: its Distribution,Manufacturing Processes and Products

Abstract

This article considers the industrial aspects of the revival of terracotta and faience as architectural materials during the last two hundred years. It demonstrates how the distribution and development of the industry, and the nature of the terracotta produced, relates closely to clay geology. The transition from using younger clays found in the south-west of England through to exploiting clays from the Coal Measures explains the emergence of new firms able to mass-produce large, brightly coloured blocks on an extensive scale. In examining the technology of manufacture it is apparent that the basic processes changed little during the course of the revival, but that skills in making models and moulds in plaster and in applying glazes were fundamental to the decorative qualities of terracotta and faience architecture.     

Tracing the clay source of Nasca polychrome pottery: results from a preliminary raw material survey

This paper describes the results of the first season of a survey in which clays suitable for the production of Nasca polychrome pottery were collected in an effort to (1) determine the geological variability of clay sources in the Nasca region and (2) match clays compositionally to paste groups from previous provenance analyses. Clays were collected, processed, fired, and analyzed using neutron activation. The results demonstrate that clays in the region were compositionally heterogeneous, and that the clay source for the majority of Nasca polychrome pottery sampled thus far can be traced to lower valleys in the region near the ancient ceremonial center Cahuachi. The results have implications for understanding the nature of polychrome pottery production in the Nasca region, and suggest centralized production near the ceremonial center of the majority of painted ceramics consumed in the Southern Nasca Region.     

Using provenance data to assess archaeological landscapes: an example from Calabria, Italy

Ceramic provenance studies have helped archaeologists examine trade and exchange in multiple scales, the organization of production, and even vessel function. Yet, they may go even further, to provide a venue for the examination of past people’s perception of their landscape. To do so, a methodology is needed that links the choices prehistoric potters made, as reflected in their ceramics, with the choices their landscape could afford them, as reflected in the extent and distribution of local clays, and the physical, chemical and mineralogical characteristics of these clays. Using the region of Bova Marina in southwestern Calabria as a case study, we have combined a raw materials survey with field and laboratory experiments, along with chemical and mineralogical analyses of the collected sediments to understand the distribution and the physical, chemical and mineralogical variability of locally available clays and provide baseline data against which prehistoric ceramic materials from the region may be compared. We show that the local sediments can be divided into three major units, based on their macroscopic, mineralogical and chemical characteristics, that correspond well with the major geological units outcropping in the study area. While two of these units have internally consistent properties, the third is variable.     

Geomorphological setting and Native American acquisition of buff-firing ceramic clays in the Lower and Middle Gila River Valley, Arizona

This study addresses buff-firing clay sources in dynamic alluvial settings along Arizona’s Gila River in the U.S. Southwest. We establish clay resource distribution relative to the geomorphic histories of the Lower and Middle Gila River based on 38 clay samples and ethnographic data from two US Bureau of Reclamation (BOR) projects. Buff-firing clayey alluvium, deposited in the Gila River floodplain 800 to 1,500 or more years ago, was a surficial ceramic raw material source for prehistoric Hohokam and lowland Patayan potters. This geomorphic unit was later removed in some places and buried by up to 3-4 m of sediment in others, reducing the availability of buff-firing clays in the Hohokam Classic period and requiring historic Pee Posh and Akimel O’odham potters to dig pits to access it. Sources were further destroyed in catastrophic floods in the late 19th and early 20th century, affecting ceramic manufacture patterns and ultimately contributing to the decline of pottery production by the O’odham living in the Gila River Valley. Our results contribute to regional ceramic ecology and should also be of interest to others investigating alluvial clay use in general or buff-firing alluvial clays in particular. The study also illustrates the value of combining geomorphic and ethnographic data to examine major changes in resource distribution and use.     

PIGMENTS AND PLASTERS FROM THE ROMAN SETTLEMENT OF THAMUSIDA (RABAT,MOROCCO)

A total of 22 samples were taken both from plasters still in situ and from collapsed material recovered by French, Italian and Moroccan teams at the Roman settlement of Thamusida (Rabat, Morocco). The sample characterization was obtained using optical microscopy, scanning electron microscopy, image analysis and Raman micro‐spectroscopy. Plaster aggregate was made using a mixture of sands and clays that outcrop nearby, while lime was probably produced using the local limestone crust, as was further verified for the mortars. The plasters from the bath complexes (public buildings) and the Temple à trois cellae (sacred building) were very poorly made, while those from areas VII and XX (private buildings) indicated the involvement of more expert masons. The pigments used were cinnabar, red ochre, yellow ochre, Egyptian blue, green earth, chalk white and carbon black. The overall manufacture was of low quality, and hence perfectly comparable to that observed in other Roman Provinces. With respect to Italy and to other Mediterranean Roman sites, Thamusida fits well within an aesthetic and technical koinè that differentiates sites of the Italian peninsula from those in the Provinces.     

The forest or the trees? Behavioral and methodological considerations for geochemical characterization of heavily-tempered ceramic pastes using NAA and LA-ICP-MS

In this paper, the utility of LA-ICP-MS for instrumentally separating clay and temper within pottery samples is examined through a well-known case study that has been previously characterized through NAA and petrography. Coarse Orange pottery is composed of kaolinitic clays heavily tempered within volcanic ash from the basalt-rich Tuxtla Mountains of southern Veracruz, Mexico. We attempt to address the following topics with analyses on this pottery: 1) can LA-ICP-MS replicate the same groups previously identified by NAA and petrography; 2) can instrumental isolation of the clay fraction within the pottery replicate known patterns in raw clay source geochemistry in the Tuxtla Mountains; 3) can data for both the clay and volcanic ash fractions of each pottery sherd be combined to simulate the bulk INAA data? The results demonstrate that the clay fraction of the pottery sherds can be isolated. Furthermore, the LA-ICP-MS data for the clay fractions display nearly identical chemistry to available NAA data for raw clay samples collected from geological contexts in the region. Instrumentally isolating the clay fraction in this case eliminates the homogenizing effects of adding a common temper and increases the chemical separation among groups making it easier to identify clay procurement strategies for each specimen. However, focusing only on the clay fraction ignores significant tempering variation. Attempts to simulate the bulk NAA by combining LA-ICP-MS data for clays and temper was reasonably successful in reestablishing the tempering variation lost by exclusive focus on clays, but such an approach could not replace the more precise data generated from NAA and petrography.     

X-ray powder diffraction analysis of Late Holocene reservoir sediments

X-ray powder diffraction (XRD) analysis of clays from anthropogenic Late Holocene reservoir sediments can provide a paleoclimatic proxy. Illite and smectite are climate sensitive clay minerals and their relative amounts correlate with climatic episodes. Relative percent composition of clays in Late Holocene reservoir sediment is diagnostic of different mineral source areas and their hydraulic transport processes, which are climate controlled. Climosequences of clay minerals from Late Holocene reservoir sediments are correlative with magnetic susceptibility records and provide a relatively simple and cost-effective tool for gaining insight into paleoclimate.