Terra Sigillata Research Articles

Application of artificial neural networks for the rapid classification of archaeological ceramics by means of laser induced breakdown spectroscopy (LIBS)

The aim of this work is to analyze the feasibility of artificial neural networks (ANN) for the classification, in function of the provenance, of archaeological ceramics Terra Sigillata analyzed by means of laser-induced breakdown spectroscopy (LIBS). In order to automate and facilitate the task of comparison of LIBS spectra, two ANN algorithms are proposed: One is fed with the whole LIBS spectra and the other with the areas of the most intense peaks of the spectra. In both cases, an analysis of the network architecture as a function of the number of hidden neurons and number of epochs of training was carried out in order to optimize the performance of the network. Following both procedures, the correct classification (higher than the 95% of success) of Terra Sigillata pieces from their LIBS spectra can be achieved in a systematic and objective way.

Book Review of Katalog der Punzenmotive in der Arretinischen Reliefkeramik, by Francesca Paola Porten Palange

This is the first installment of a work that has been long awaited, in two senses. In the first, the study of the decorated terra sigillata of Arezzo has hitherto lacked the kind of basic dictionary of motifs that was created for Gaulish sigillata by Joseph Déchelette (Les vases céramiques ornés de la Gaule romaine [Paris 1904]) and Felix Oswald (Index of Figure-Types on Terra Sigillata [“Samian Ware”] [Liverpool 1936–1937]), and which is an early prerequisite for further progress.

Grafitos cerámicos de Segobriga (1997-2006)

Este trabajo incluye 243 fragmentos cerámicos con grafitos latinos, griegos e ibéricos, descubiertos en Segobriga en las excavaciones oficiales de la ciudad romana y sus alrededores. Muchos de ellos son incompletos, pero algunos presentan el nombre del recipiente (panna) y cuentas de control de alfar. Casi todos están grabados en terra sigillata.

Synchrotron X-ray diffraction study of phase transformations in illitic clays to extract information on sigillata manufacturing processes

The phase transformations as a function of the temperature of two natural illitic clays were investigated through XRD measurements, ex situ at room temperature with conventional set up and in situ with synchrotron radiation, in order to understand the origin of the corundum phase, which is one of the main characteristics of the red glaze (slip) of Terra Sigillata from south Gaul. These clays were chosen on the basis of their chemical composition and for the quality of vitrification in the firing temperature range of sigillata (1030–1080 °C). Results show that corundum can be formed above 1000 °C if the amount of Mg is not too high. The corundum formation does not result directly from the total decomposition of illite ( 3–4 wt. %, this intermediate phase is not observed and only a spinel phase is formed.

Micro scanning XRF, XANES and XRD studies of the decorated surface of Roman Terra Sigillata ceramics

Micro scanning XRF, XANES and XRD studies of the decorated surface of Roman Terra Sigillata ceramics

D-79 Micro Scanning XRF, Xanes and XRD Studies of the Decorated Surface of Roman Terra Sigillata Ceramics

D-79 Micro Scanning XRF, Xanes and XRD Studies of the Decorated Surface of Roman Terra Sigillata Ceramics

Health Benefits of Geologic Materials and Geologic Processes

The reemerging field of Medical Geology is concerned with the impacts of geologic materials and geologic processes on animal and human health. Most medical geology research has been focused on health problems caused by excess or deficiency of trace elements, exposure to ambient dust, and on other geologically related health problems or health problems for which geoscience tools, techniques, or databases could be applied. Little, if any, attention has been focused on the beneficial health effects of rocks, minerals, and geologic processes. These beneficial effects may have been recognized as long as two million years ago and include emotional, mental, and physical health benefits. Some of the earliest known medicines were derived from rocks and minerals. For thousands of years various clays have been used as an antidote for poisons. "Terra sigillata," still in use today, may have been the first patented medicine. Many trace elements, rocks, and minerals are used today in a wide variety of pharmaceuticals and health care products. There is also a segment of society that believes in the curative and preventative properties of crystals (talismans and amulets). Metals and trace elements are being used in some of today's most sophisticated medical applications. Other recent examples of beneficial effects of geologic materials and processes include epidemiological studies in Japan that have identified a wide range of health problems (such as muscle and joint pain, hemorrhoids, burns, gout, etc.) that may be treated by one or more of nine chemically distinct types of hot springs, and a study in China indicating that residential coal combustion may be mobilizing sufficient iodine to prevent iodine deficiency disease.

Un taller de terra sigillata en Segobriga (Saelices, Cuenca)

Las excavaciones arqueológicas en Segobriga han proporcionado las primeras evidencias de un taller de producción de terra sigillata en esta ciudad. Los fragmentos de moldes recuperados permiten suponer que el taller comenzó a producir en época de Domiciano y que se mantuvo activo durante todo el siglo II.

Long-lived Samian?

ABSTRACTIn order to study the possibility that some samian (terra sigillata) vessels remained available and/or in circulation for quite some time, a review has been made of closed groups (especially grave-assemblages), as a useful starting point. This paper argues that it is reasonable to expect some complete first-century samian vessels to have survived into the second century; also that some second-century vessels had survived into the fourth century at least throughout Roman Britain.

Raw Material Sources for the Roman Bracarense Ceramics (NW Iberian Peninsula)

AbstractThe Bracarense ceramics are characterized by a fine, pale yellow paste covered with a brownish yellow slip. The name is derived from Bracara Augusta, the Roman town located in the north of Portugal, where this type of ceramic paste was first found and identified. Various forms with the same type of paste occur, such as imitations of sigillata, terra sigillata and thin walls from the Augustus-Tiberius period, and common ware. Later, similar ceramics were also found in other archeological sites, e.g. Aquis Querquennis (Galiza, Spain), which question the location of the production center of this type of ceramic paste.Mineralogical and chemical analyses showed that the majority of the Bracarense shards studied differ from the common ware of the Braga region. Despite minor differences, the Bracarense shards collected in Aquis Querquennis have the same geochemical pattern as those found in Bracara Augusta, i.e. they appear to have been manufactured with the same clay type. The firing products found indicate a kaolin character of the source clay, and point to firing temperatures near 900°C. The Aquis Querquennis shards have greater Br contents, which can be explained by use-wear and/or post-depositional processes, as this site is located in a thermal-water region.

Provenance Characterization of Archaeological Ceramics by Laser Induced Plasma Spectroscopy

Archaeological ceramics Terra Sigillata manufactured in different production centres have been studied by “laser induced plasma spectroscopy” (LIPS). The aim of this work is to demonstrate the capability of LIPS for the classification of pottery shreds in function of their provenance. Characteristic emission spectra of different pottery groups were obtained and simple linear correlation methods were used for grouping samples. In addition, complementary scanning electron microscopy coupled with energy-dispersive X-ray spectrometry (SEM-EDX) analysis were performed to obtain morphological features and to confirm chemical results

LIPS and linear correlation analysis applied to the classification of Roman pottery Terra Sigillata

Archaeological ceramics Terra Sigillata manufactured in different production centres have been studied by laser-induced plasma spectroscopy (LIPS). The aim of this work was to establish a procedure for the rapid classification of these archaeological ceramics in function of their provenance through combination of LIPS and statistical methodologies. Representative emission spectra of the Hispanic, Gaulish and African groups of pottery were selected as references. The use of linear correlation allowed one to cluster the samples by quantitative comparison of LIP spectra, leading to a reliable assignment of Terra Sigillata pieces to origin centres.

Micro scanning X-ray diffraction study of Gallo-Roman Terra Sigillata ceramics

The red glaze (slip) that characterizes the Terra Sigillata potteries, greatly contributed to their success during the Roman period. This feature can in fact be partially explained by the microstructure (crystalline phases and grain sizes) and the physico-chemistry (compositions) of the ceramics. In this paper, we describe how the technique of synchrotron micro scanning X-raydiffraction could contribute to the understanding of the elaboration process and origins of these ceramics. The small (micron) size of the X-raybeam coupled with the use of a sample scanning stage allows one to spatially resolve the distribution and other characteristics of the constitutive mineral phases.

Microstructural and Microchemical Characterization of Roman Period Terra Sigillate Slips from Archeological Sites in Southern France

Terra Sigillata is a fine ware produced during the Roman period. Its great success was because of its remarkable gloss (or slip), which provides a bright deep red color. Transmission electron microscopy and X‐ray powder diffraction techniques were used to characterize the microstructure and microcomposition of Roman period Terra Sigillata slip from two sites in southern France. Investigations on eight samples are presented. The slip coatings have similar structures and compositions, consisting of sub‐micrometric hematite (≤μm) and nanometric corundum (few tens nm) crystals in a glass matrix with inclusions of spinel and quartz crystals of varying size depending on the extent of preparation by eleutriation. The firing temperature, determined in previous studies, was in the range of 1020°–1080°C. The matrix does not contain iron or other metallic ions. Hematite and corundum crystals are homogeneously dispersed in the matrix and, together, confer the specific red‐orange color to the sigillata.

Analysis of roman pottery Terra Sigillata by laser induced plasma spectroscopy (LIPS)

Laser induced plasma spectroscopy (LIPS) has been applied for the elemental analysis of roman pottery Terra Sigillata from different ceramic production centers. For each sample, representative LIP spectra of slip and body were obtained in addition of compositional depth profiles. In all the cases investigated, calcium and iron are the elements which best define the transition between slip and body in these ceramic samples. Compositional gradient of other elements like silicon and aluminum depends on the samples. Moreover, complementary scanning electron microscopy coupled with energy dispersive X-ray spectroscopy (SEM - EDX) examinations were carried out to analyze morphological differences and to obtain verification of chemical results.

Peter, Paul and a Consul: Recent Discoveries in African Red Slip Ware

Abstract 1. The objects In the fourth and fifth centuries a wealth of figurative imagery appears on fine earthenware produced in North Africa. These plates, bowls and lamps were named after the material from which they were made – African Red Slip Ware in the English language (abbreviated as ARS) and Terra Sigillata Chiara in Italian. ARS tableware was very popular in late antiquity and, though produced in North Africa, was exported all over the Empire, finding its way to places as far away as the shores of the North Sea and the Crimea. Some of the images on this tableware are Christian, while others are clearly pagan or not definable in religious terms. In spite of a long tradition of collecting and studying ARS, starting with the French in the nineteenth century, new objects and unknown figurative images continue to turn up both in excavations, in archaeological surveys and on the art market.

Naked clay: ceramics without glaze

This book deals with ceramic work that does not have a glaze, but instead is finished by other methods such as Burnishing, terra sigillata, engobes, oxide washes, laminating, smoke firing and other methods. The book will look briefly at the historical uses of alternative methods of decorating/finishing work, but essentially will give a chapter to each method, looking at techniques and more importantly the work of specific artists in each field. It will be well-illustrated and a much needed manual on this subject.

Compositional analysis of Hispanic Terra Sigillata by laser-induced breakdown spectroscopy

Laser induced breakdown spectroscopy (LIBS) has been applied for the analysis of Roman pottery Hispanic Terra Sigillata dating back to the 1st–5th century A.C. from two important ceramic production centers in Spain. For each sample, several examinations were performed on slip and body providing data necessary to draw depth profiles of the contents of various elements. In all the cases investigated, the amount of some elements such as calcium and iron and the presence of other ones such as silicon and aluminum showed the differences existing between slip and body in these ancient ceramics in relation with their region and period of production. In addition, complementary analyses were carried out with scanning electron microscopy linked with energy dispersive X-ray microanalysis (SEM/EDX) to measure the thickness of slip and to obtain verification of chemical results.

The Raman Spectrum of Hematite: Possible Indicator for a Compositional or Firing Distinction among Terra Sigillata Wares

The Raman spectrum of hematite (alpha-Fe2O3) is here discussed as a distinctive feature for Terra Sigillata sample wares. The broadening of the Raman lines and the appearance and increasing of the disorder band at 660 cm(-1), while moving from the external slip to the inner body, are proposed as valuation parameters for the study of the mineralogical composition and firing process of pottery productions.

Samian Pottery, a Resource for the Study of Roman Britain and Beyond: the results of the English Heritage funded Samian Project. An e-monograph

Samian: the resource Samian pottery (terra sigillata) is one of the best-quality data sources available for research in the Roman period. Its wide distribution, standardised typology and comparatively close dating combine to make this artefact class particularly amenable to analytical approaches. Examination of its archaeological occurrence reveals dimensions of patterning that provide a unique and exciting window upon the character of society and cultural practice during the Roman era. Earlier phases of the project conducted in the late 1990s, funded by English Heritage, included a pilot survey which had verified the reliability and utility of the project methodologies, and a research synthesis which brought new light to bear on this familiar material type of the Roman era. The findings arising from these stages have been published previously (Willis 1997; 1998). The results of this project, as presented here, demonstrate how study of this material resource can contribute, and in a number of areas transform, our knowledge of the period. The project has had a strong synthesising and analytical imperative, with the intention of bringing together existing knowledge of samian to ensure fuller use of this valuable asset. The potential has hitherto been somewhat 'hidden', being compartmentalised within site reports and other publications, there having been only limited opportunities in the past for the distillation of the archaeology of samian beyond dating. (Samian is a key indicator of chronology in the early and mid Roman period in North-West Europe and will remain so. A developing archaeological awareness of the era, however, will be strongly enhanced through examination of other facets of samian data). Samian distribution and group composition is here shown to be a source of valuable information, which may be effectively harnessed to shed light upon a series of aspects of Roman Britain, with resonance beyond the province of Britannia. Project aims and results This study was directed towards making the best use of samian evidence as a key resource for exploring a range of questions in Roman archaeology. The study collates a large body of data and applies hitherto under-utilised methods in an endeavour to extract archaeological information from this material, particularly in the key areas of dating, the social distribution of samian and cultural practice. One avenue in respect of dating has been to explore the extent to which trends in the composition of groups of samian, in terms of forms present, may be used as a guide towards establishing the date of a group without having to depend heavily upon the dating of stamps and diagnostic decorated sherds, which may be comparatively rare. It is intended that the resulting guide, presented here, proves to be an accessible and straightforward tool for the non-specialist user. The project, moreover, aimed to move beyond the essential role of samian in providing 'dates', to exploit its evident high potential for elucidating aspects of cultural and economic life during the Roman era. Findings from analyses undertaken in a series of such areas are published here. The research, indeed, sheds light on a wide variety of aspects of Roman Britain. The nature, for instance, of samian supply to Britain is examined. It was intended that the project dataset would provide a flexible tool which readers themselves were able to access so that they may pursue their own questions (view database online), and/or with which they may compare their own samian groups, by reference to a corpus of data collected from a range of sites across Britain covering all appropriate periods (go to the ADS archive to download spreadsheets). In one highly significant finding, the collected data demonstrate how the character of site samian assemblages is strongly related to site type, status, function, exchange connections and identity. Previous work for the project has indicated that the incidence of samian is often patterned. The present study further defines the extent to which there are 'normal patterns' (or parameters) of samian occurrence by time, region and site type. A framework guide to the 'normal patterns' identified by the project and with which specific site assemblages and stratified groups can be compared is presented as a summary in section 13.1.2 of the article. While focusing on samian, the project has aimed to locate samian within its broader context. Hence project objectives and discussion of findings are integrated with the present general research aims in the study of the Roman era in western Europe. Throughout the study it was intended that the work be directed and relevant to themes in the archaeological investigation of the period, rather than be just specific to samian studies: this is appropriate since samian is part of a wider nuanced record of life in Roman Britain. Samian is here considered in a wide range of fields; it is striking how richly patterned and illuminating this evidence proves to be.