THE DETERMINATION OF BRICK PROVENANCE AND TECHNOLOGY USING ANALYTICAL TECHNIQUES FROM THE PHYSICAL SCIENCES*†

This work applies established analytical techniques from the physical sciences to Irish brick, in order to gather evidence of ceramic technologies, provenance and sources of raw materials. Petrographic microscopy, X‐ray diffractometry and scanning electron microscopy with an energy‐dispersive X‐ray diffraction attachment were used to study the brick of Rathfarham Castle, Dublin, built c. 1618, where clay brick was introduced in 1771. Local clay was fired in the laboratory and analysed in a similar manner. The petrography of the pointing mortar was studied in order to gather evidence of ceramic provenance. This paper concludes that the brick was hand‐ moulded with a silica‐based, predominantly non‐calcareous clay of glacial origin, gathered locally, including fluxes and a high percentage of non‐plastic material. The mineralogy and petrography of the brick, together with the presence of pebbles and a coarse matrix, suggest that the raw clay was probably gathered from a glacial deposit. The presence of abundant pebbles and colour inhomogeneities suggests a lack of processing of the raw clay. The brick was probably fired in clamps at top firing temperatures ranging from 750°C to above 900°C. Transformation of limestone temper involving the breakdown of calcite and the generation of calcium silicates, and the new formation of plagioclase, high‐temperature quartz, hematite and spinel were revealed. The presence of spinel in ‘hot spots’ indicates that fuel was added to the raw clay in order to assist firing.     

ON THE USE OF COLOUR COORDINATES TO EVALUATE FIRING TEMPERATURES OF ANCIENT POTTERY*

Colour measurement was investigated as a means to evaluate equivalent firing temperatures of ancient pottery. Colour coordinates were determined on samples of six clays previously fired, and then refired, in the temperature range 600–1100°C. Under the adopted conditions, significant variations of colour hue and saturation were normally observed on refired samples only after the original firing temperature had been exceeded; less reliable information was provided by luminosity. Original firing temperatures of clay samples were correctly recognized in most cases by projecting the points representing samples’ colour on to the a*b* plane of the ClEL*a*b* colour space.     

Ancient Egyptian Pottery from the Subsurface Floodplain of the Saqqara–Memphis Area: Its Mineralogical and Geochemical Implications*

Potsherds recovered from the Saqqara–Memphis floodplain in Egypt, dated according to their typology and radiocarbon dating of the included sediments, are analysed geochemically and mineralogically to identify source materials and fabrication characteristics. Pottery layers were identified and potsherds were recovered from several settlement levels. Sherd typology was used to identify sherds from four periods (the Old and New Kingdoms, and from the Late Period to the Ptolemaic). The Pharaonic pieces were found at depths of between 8 and 12 m and the later material was between 6 and 3 m. Chemical analyses of the potsherds revealed three main source materials: local Nile silt, marl clay and mixed Nile silt–marl. Two marl clay types were recognized: marl clay from Upper Cretaceous marine sediment and another one from Late Pliocene deltaic sediments. The mineralogical composition of the pottery samples shows that the estimated firing temperature was about 850–900°C. No consistent differences in sherd mineralogy and geochemistry were found according to pottery types, so that the ancient Egyptian potters used essentially the same materials throughout the Pharaonic period. However, this initial study has revealed the existence of extensive pottery‐rich occupation sites buried within the Nile floodplain deposits between Memphis and Saqqara.     

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.     

IBERIAN CERAMIC PRODUCTION FROM BASTI (BAZA,SPAIN): FIRST GEOCHEMICAL,MINERALOGICAL AND TEXTURAL CHARACTERIZATION

Ceramic fragments from the archaeological excavation of the Iberian–Roman city of Basti (Spain) were studied from a geochemical point of view and by applying a statistical tool to X‐ray fluorescence data to discover similarities between ceramic materials. The analysis of these samples was completed by performing a mineralogical analysis, textural observation, and by characterizing the porous system and the colour of the pieces. Our results enabled us to identify the source area of the clayey raw material in the surroundings of Basti and to estimate the firing temperature of the ceramics. Differences in the chemistry were confirmed by characteristics of the pastes and the mineralogical composition of the pieces. Some samples show black cores, which would suggest the presence of organic matter in the raw material and fast firing of the ceramics. The main types of temper were quartz grains and gneiss fragments, although carbonate grains were also identified. Our evidence suggests that most of the samples were well fired. New silicate phases were found to be present in several samples. The mercury intrusion porosimetry verified and confirmed the firing temperature of non‐carbonated samples. Colorimetry showed that the colour of the ceramics varied according to the amount of CaO that they contained.     

The Making of Fired Clay Bricks in China Some 5000 Years Ago

Fired bricks are a hard and durable masonry material that has played a major role in the emergence of early human urban civilization. In China, fired clay bricks have been widely used as a building and flooring material since the Qin Dynasty (476?206 bc ), although a few lines of evidence show that fired clay bricks might have been invented as early as 5500 years ago in eastern central China. However, these burnt clumps of clay appear not to be bricks in the strict sense, and our knowledge about the origin of fired clay bricks in China still remains fragmentary. Archaeological excavations at a Middle Neolithic cultural site in northwestern China reveal that the making of fired clay bricks began some 5000 years ago. Our findings also open a window into the process of prehistoric brickmaking in East Asia.     

MINERALOGICAL INVESTIGATIONS OF MEDIEVAL BRICK SAMPLES FROM BÉKÉS COUNTY (SE HUNGARY)

Brick samples from nine archaeological sites representing seven contemporary medieval settlements in Békés County (SE Hungary) were analysed by quantitative X‐ray powder diffraction, optical microscopic, scanning electron microscopic and coupled thermal analytical – evolved gas analytical methods. The aims of this study were to give a mineralogical–petrographical characterization of the brick samples, to gain possible information on the raw clay and the admixed materials, and to determine the firing techniques applied in medieval southeastern Hungary. The mineralogical composition of the samples suggests that the locally extracted clay was mixed with fluvial sand and wheat (Triticum monococcum L.) chaff. The moulded bricks were fired in clamps. The different degrees of calcite consumption suggest that the firing temperature ranged from ～750°C to ～950°C. Moreover, the well‐developed reaction coronas on calcite grains indicate long firing times, lasting perhaps several days.     

Trace element fingerprinting of ceramic building material from Carpow and York Roman fortresses manufactured by the VI Legion

Trace element compositions of raw clay, fired clay and Roman ceramic building material (CBM) from Carpow Roman fortress, Newburgh, Scotland and the city of York, England have been determined through the use of inductively coupled plasma-mass spectrometry (ICPMS). It is confirmed that the firing of clay does not disturb any of the sample’s trace element composition and that trace element protolith identification is an applicable tool for fingerprinting the source of material used in CBM construction. It is also demonstrated through the particular proportions of LREE/HREE; Th/Co; La/Sc; La/Lu; Eu/Sm values on CBM from Carpow that these material were likely manufactured from clay used in the York Roman tile manufacturing industry, therefore suggesting importation. The transport of CBM from York to Carpow provides a useful addition to known examples of the long-distance shipping of CBM. It is postulated that similar analysis to that conducted here could be used to identify important trade networks within the Roman Empire.     

Raman Spectroscopic Analysis of Ancient Egyptian Pigments

The application of FT‐Raman spectroscopy and visible Raman microscopy to the non‐destructive analysis of pigment specimens excavated from Tell el Amarna by Flinders Petrie in the 1890s has provided information about the chemical composition of the materials used by XVIIIth Dynasty artists in the New Kingdom at the time of King Akhenaten, c. 1340 bc. Comparison of the Raman spectra of the samples labelled ‘red and yellow ochre’ with documented, archival material from geological collections provided a clear indication of the materials used in the iron(III) oxide/hydroxide system, including α‐hematite, goethite, maghemite, magnetite and lepidocrocite. The yellow–orange specimen labelled ‘realgar’ proved to be a mixture of realgar and pararealgar; since the specimen had been sheltered from light since its excavation, this could indicate that the ancient Egyptian artists recognized the colour variation and may have used this to effect in their decorations. A specimen of yellow ochre contained goethite, α‐FeO.OH, with particles of crystalline, highly ordered graphite; in contrast, the red ochre specimens contained amorphous carbon particles.     

A NOTE ON THE DIFFERENTIAL THERMAL ANALYSIS OF ARCHAEOLOGICAL CERAMICS

Evidence is presented that the clay in ancient ware fired at a temperature below 700–800°C becomes rehydrated over the millennia, such that it behaves somewhat like an unfired clay, rendering DTA a useful tool in identifying the clay minerals present. More recent samples can be artificially rehydrated by heating in a steam autoclave.     

Spectrochemical Characterization of Red Pigments Used in Classic Period Maya Funerary Practices

We studied the composition, colour chromaticity and form of application of red pigments in human bone samples from seven Classic period Lowland Maya sites. The samples were analysed by X‐ray diffraction, scanning electron microscopy (SEM) and X‐ray energy‐dispersive spectroscopy (EDS). Colour was measured using conventional colour identification standards (Munsell) and reflectance spectroscopy. Cinnabar and hematite were identified as the pigments used. We conclude that the reflectance method has advantages over conventional visual results, as it provides precise, objective and quantifiable optical data to distinguish the chromaticity, colour saturation and brightness of the pigments.     

The Characterization of Vegetable Tannins and Colouring Agents in Ancient Egyptian Leather from the Collection of the Metropolitan Museum of Art

This work characterizes both tanning and colouring materials found in ancient Egyptian leather objects from the Metropolitan Museum of Art. The analytical investigations focused on assessing the development of the technology of ancient tanners using high‐performance liquid chromatography (HPLC), surface‐enhanced Raman spectroscopy (SERS), X‐ray fluorescence (XRF), Fourier transform infrared spectroscopy (FT–IR), X‐ray radiography and a scanning electron microscope connected to an energy‐dispersive X‐ray detector (SEM–EDX). Reference leather samples and archaeological leather objects were investigated to identify the animal skin species and the early use of hydrolyzable vegetable tannins for leather tanning. Different methods were used to colour th leather, including madder dying and staining with hematite, or painting with Egyptian blue and Egyptian green.     

SCIENTIFIC INVESTIGATIONS OF THE SOPRON-KRAUT ACKER IRON AGE POTTERY WORKSHOP

Excavations at the Celtic settlement of Sopron-Krautacker (W. Hungary) make it possible to form an overall view on the local practice of pottery manufacture. Study of the soil conditions has established that the source of raw material is the nearly calcium carbonate-free upper layer of the local soil resulting from a leaching process. By the various analytical methods used (XRD, XRF spectroscopy, and thermal analysis) composition of the pottery has been determined, and it has been shown that the vessels were fired at 600–700 °C.     

河曲坪头遗址龙山时期陶器及其制陶原料的化学成分分析

为了对山西省忻州市河曲坪头遗址出土的龙山时期的陶器以及制陶原料中的粘土原料的种类和来源进行相关探讨,利用ICP-OES对出土的陶器、坯料,以及遗址附近采集的土样进行了化学成分测试,并使用SPSS软件对分析结果进行了降维处理和主成分分析。结果显示:坪头遗址不同质地的陶器陶土原料相同,只是在钙含量方面存在细微差异。制作陶器所用的粘土原料很可能取自附近的红色古土壤层。该遗址是古人在当地制作陶器的一个场所。     

指纹元素分析对南宋郊坛官窑的起源研究

选取30个南宋官瓷样品、2个效坛官窑的原料、紫金土和4个现代仿官瓷样品进行中子活化分析（NAA）,测定每个样品中36种微量元素的含量。从这36种元素中挑选出9种指纹元素的含量进行散布分析。结果表明：南宋官窑的釉料和胎料产地明显不同;南宋官窑有着长期稳定的釉料和胎料产地;遗址缸内的原料（35#）、练泥池内的原料（36#）、紫金土（37#）既不同于古官瓷的釉料,也不同于胎料。练泥地内的原料（36#）比较接近于胎料。现代官瓷的釉料和胎料与古官瓷的明显不同,说明它们的产地不同。     

苏家村遗址烧土样品的过火温度研究

烧土制品作为最早的人工建筑材料,使人类的居住环境得到了根本性的改善。然而,学界关于烧土建筑的成因存在人为烘烤处理、缘自火焚、废弃习俗等多种观点。通过科技手段研究烧土制品的过火温度,有助于科学分析烧土建筑的成因,探讨与之相关的建筑工艺,丰富史前建筑史研究。磁学研究表明,考古遗址中的土壤及其他沉积物在受热后新生成了磁铁矿、磁赤铁矿等强磁性矿物导致磁性显著增强,且矿物成分和磁性几乎不会再发生变化;但当重烧的温度接近或大于原始烧成温度时,样品中原始矿物的破坏或新矿物的生成,会引起矿物磁性的改变。基于这一原理,实验室内分析受热黏土的磁化率随再加热温度的变化特征,可反映烧土制品的过火温度。苏家村遗址是大汶口文化晚期至龙山文化中期早段一处重要的聚落遗址,遗址中第5层为厚约20～40 cm的红烧土层且覆盖整个遗址,推测为房屋倒塌造成的建筑垃圾堆积层或人为堆积层,出土大量烧土块。本研究利用X射线衍射分析法、X射线荧光光谱分析法和磁化率法等对苏家村遗址出土的烧土样品开展了组成及构造特征和样品的过火温度的综合分析。结果表明,苏家村遗址烧土样品中的白灰层中人为地添加了白色陶土原料,土层中有意地添加了植物残骸作...     

Ceremonial objects or household items? Non‐destructive μ‐XRD2 and μ‐XRF studies on three Neolithic hematite axes from Qatar

Three small stone axes were collected by the joint Qatari‐German South Qatar Survey Project (SQSP) at two places close to the eastern and western coast of Qatar in autumn 2012. Associated with settlement remains, flint artefacts and pieces of ?Ubaid pottery, the implements have been dated to the fifth millennium BCE. Non‐destructive μ‐XRD² and μ‐XRF analyses could, for the first time, prove the use of hematite as the raw material for the manufacture of these tools in Arabia. The absence of major hematite sources in the region and the special characteristics of hematite — a unique metallic shine of polished pieces and the blood‐red colour that appears during the manufacturing process — suggest the highly symbolic character of these objects.     

Dung-tempered Clay

Abstract

Cow manure was added to clay and fired in an electric kiln to examine its effect on the plasticity and firing ability of the clay. Two firing temperatures were tried. The experiment and the results are reported here. Dung was used. and continues to be used. as a tempering material and additive to increase plasticity in pottery around the world.     

Evaluation of Fe isotope values as a provenance tool for chert artefacts from the north-eastern United States

Iron (Fe) isotope compositions of prehistoric stone tools and geological sources were compared to evaluate the robustness of this isotopic fingerprinting technique. Artefacts and source materials were collected from the Hatch site in central Pennsylvania, United States, where both veined chert (Bald Eagle chert) and stone tools coexist within several metres. Yellow artefacts (δ⁵⁶Fe = 0.38 ± 0.1, n = 7) and source materials (δ⁵⁶Fe = 0.42 ± 0.1, n = 8) isotopically matched within error. The source values also overlap yellow chert samples from three other Bald Eagle chert locations in the area. These values are different from six other chert locations in the north-eastern United States. These data suggest that the Fe isotope composition of chert artefacts reflect distinct geological sources. To enhance the mechanical characteristics of the stone tools, the chert experienced heat treatment, which induced a phase shift of the Fe oxide mineral goethite to hematite. This phase shift changes the colour of the chert to red. The red chert artefacts and source material also have overlapping Fe isotope values, but are 0.2‰ higher than the initial yellow chert. Experimental work where cherts were heated with different clays shows that Fe exchange with site soils induces the +0.2 fractionation. These data demonstrate that predictable Fe isotope fractionation occurs during heating, resulting in isotopically distinct artefacts.     

Chemical and mineralogical characterization of Aguada Portezuelo pottery from Catamarca,north-western Argentina: PIXE,XRD and SEM-EDS studies applied to surface pre- and post-firing paints,slips and pastes

Particle-induced X-ray emission (PIXE), X-ray diffraction (XRD), electron microprobe analysis (EDS) and scanning electron microscopy (SEM) analytical techniques were used to characterize surface paints in pre- and post-fired Aguada Portezuelo decorated pottery. Surface paintings in black, white, red, brown, burgundy and ochre were analysed. Major, minor and trace elements were detected by PIXE, whereas XRD and SEM-EDS gave information on the main mineral phases and the characteristic morphology for each analysed pigment. The results obtained indicate that the main colour groups can be easily discriminated by PIXE, and they are characterized by only one pigment for each colour: hematite (red) and manganese mineral oxides (black), respectively, whereas white pigments are characterized by calcite, ghelenite and gypsum.