Application of X-ray fluorescence imaging to ceramics from the American Southwest

We have used synchrotron-based X-ray fluorescence imaging (XRFI) to examine sherds of painted ceramics from prehistoric cultures of the American Southwest. These sherds are very well suited to XRFI analysis. Paints can generally be detected and distinguished by the fluorescence intensities of their constituent elements. Spatial maps of element distributions yield the spatial distribution of pigments. Pigments can be distinguished that are (or have become) visually similar; layers that have been obscured by overpainting can be examined; and pigment residues can be distinguished from surface contaminants deposited after painting and firing. As a result, XRFI allows the painted motifs to be clarified and hidden features to be revealed. Furthermore, the very rapid scanning and high sensitivity elemental detection possible with synchrotron-based XRFI facilitate measurements on large collections of sherds, allowing an integrative rather than anecdotal analysis.     

Another (mud)brick in the wall: scientific analysis of Bronze Age earthen construction materials from East Crete

Mudbricks appear to have been one of the most common building materials used in domestic architecture in Bronze Age Crete. Well-preserved earthen construction materials from the sites of Vasiliki, Makrygialos and Mochlos in East Crete have been examined with regard to their macromorphological characteristics and their mineralogical and chemical composition in order to investigate the nature of the raw materials used, the technology of manufacture and the potential use of specific recipes. The methods applied include a combination of mineralogical and chemical analytical techniques, namely petrography, neutron activation (NAA), X-ray fluorescence (XRF), and X-ray diffraction (XRD) analysis. Finally, a range of raw materials from the immediate vicinity of each site were sampled and analyzed in order to compare with the archaeological data and identify potential sources. The analyses suggested that there is a degree of standardization in the recipes and the manufacturing process and that the selection of the raw materials depends on availability.     

Synchrotron radiation-based x-ray analysis of bronze artifacts from an Iron Age site in the Judean Hills

Seven bronze bangles from Tell en-Nasbeh, northern Judah, were investigated to understand the phase composition and manufacturing process of the artifacts, and possibly suggest a provenance for their origin. Synchrotron x-ray radiation diffraction (XRD) and fluorescence (XRF) were used in the analysis to avoid any destructive sampling and at the same time penetrate through the surface into the core metal. These techniques enabled us to determine that the bangles were not just tin bronze, but leaded tin bronze. Based on excavation reports, it is unlikely that the metal objects were manufactured locally at Tell en-Nasbeh; rather, preliminary XRD and XRF data point towards the neighboring region of Edom as their origin. Despite their political enmity during the Iron Age II, the data suggest that Judahite social demands for bronze may have fostered a strong economic relationship between these two polities.     

Energy dispersive X-ray fluorescence analysis of 1st millennium ad glass from Britain

A series of energy dispersive X-ray fluorescence analyses has been undertaken in response to archaeological problems relating to 1st millennium AD glass excavated in Britain. The aim of the work was to furnish a set of comparable analytical results to be used in assessing hypotheses concerning the general state and development of glass technology through this period. Within this framework, however, it has also been possible to attempt answers to specific archaeological questions relating to material from particular sites. The paper discusses the background to, and the interpretation of such results, particulars of the analytical technique used, a general overview of approximately 200 analyses and three examples of the use of this data in relation to specific archaeological problems.     

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.     

Investigating experimental knapping damage on an antler hammer: a pilot-study using high-resolution imaging and analytical techniques

Organic (bone, antler, wood) knapping tools were undoubtedly a component of early human tool kits since the Lower Palaeolithic. Previous studies have identified pitting and the occasional presence of embedded flint flakes as important features for recognizing archaeological bone and antler percussors. However, no systematic protocol of analysis has been suggested for the study of this rare archaeological material. Here we present qualitative and quantitative results of a preliminary analysis of an experimental knapping hammer, using a novel combination of microscopy (focus variation optical microscope and scanning electron microscope), micro-CT scanning and energy dispersive X-ray spectroscopy. These imaging and analytical techniques are used to characterize use-damage from the manufacture of handaxes. This paper highlights the strengths and weakness of each technique. Use-wear on the working area included attritional bone loss, micro-striations and compaction of the outer layer of the antler matrix from repeated hitting of the beam against the sharp edge of the handaxe during knapping. Embedded flint flakes were also identified in the pits and grooves. This combination of high-resolution imaging techniques is applicable to fragile archaeological specimens, including those encrusted by sediment or encased in matrix.     

Testing the accuracy of portable X-ray fluorescence to study Aztec and Colonial obsidian supply at Xaltocan,Mexico

This article demonstrates the accuracy of non-destructive portable X-ray fluorescence (pXRF) for the study of obsidian in central Mexico. Obsidian sources were identified for a sample of 103 artifacts from the site of Xaltocan, which spanned the rise and fall of the Aztec empire and the first centuries of Spanish colonial rule (AD 900–1700). Sources were assigned by comparing pXRF measurements with previously published source data and were verified using the standard techniques of laboratory XRF (lXRF) and instrumental neutron activation analysis (INAA). Additional tests of potentially confounding factors show that neither length of read time, presence of surface residue, nor incomplete detector coverage due to small artifact size compromised our ability to attribute sources to artifacts. Concave surfaces did decrease the accuracy of readings because of the greater distance between the artifact and the detector. Our results provide new insight into the stability of supply networks and markets well into the Colonial period as well as the homogenizing tendencies of the Aztec market system.     

An X-ray Diffraction (XRD) and X-ray Fluorescence (XRF) investigation in human and animal fossil bones from Holocene to Middle Triassic

We examined by Rietveld refinement of X-ray Diffraction patterns a series of 61 human and animal fossil bones in an age range from present time to Middle Triassic (around 245 Ma). This approach, supplemented by elemental analysis according to X-ray Fluorescence, has permitted to obtain a quantitative evaluation of the mineralogical phases in the specimens, thus allowing to reconstruct the mineralization process involved. Concerning the apatite phase, after adopting a monoclinic geometry for the unit cell, the method permits to determine with fair degree of precision the unit cell volume, which is found to decrease in relatively short geological times as a function of the fluorine substitution process for the hydroxyl group –OH. After excluding the role of a high-temperature fire treatment to the bones, it is found that a certain linear correlation may exist over the geological time scale involved between the age of the specimen and the average crystallite size. This observation permits to use the XRD pattern as an evaluation of the age of the fossil, although the stratigraphic observations, where available, remain as the main reliable source for dating such biomaterials. The uncertainty related to this age estimation may be hardly better than 15–20% in absolute, because of various assumptions involved in the XRD methodology used and in the variability of the burial environment that may be subjected to discontinuous changes over the very long time of deposition.     

A study by thermal treatment and X-ray powder diffraction on burnt fragmented bones from tombs II,IV and IX belonging to the hypogeic necropolis of “Sa Figu” near Ittiri,Sassari (Sardinia,Italy)

In the course of an anthropological investigation of three tombs of the hypogeic necropolis of “Sa Figu” (near the village of Ittiri in North Sardinia, Italy), numerous burnt bone fragments were collected. In particular, from the whole necropolis we selected a tenth of long bones from tomb IV, a small fragment of femur from tomb II and four fragments belonging to tomb IX. The aim of this work is to determine a temperature range to which the bone fragments were heated, in order to assess a funerary cremation which was presumably used at that time to quickly and hygienically eliminate the flashy parts of deceased people rather than a purification rite with fires inside the sepulchres. We attempted to evaluate the range of temperature to which the bones were likely subjected, making a joint use of thermal treatment and powder X-ray diffraction investigations. From our X-ray line broadening results carried out with a modern approach (Rietveld method), it emerged that a group of five fragmented burnt bones (one specimen belonging to tomb IV, the other four from tomb IX) were subjected to a heat treatment in a temperature range from 600 and 750 °C. Conversely another group of bones (belonging to tombs II and IV) turned out to be subjected to temperatures not higher than 250 °C.     

Microchemical and crystallographic analysis of human bones from Nasca,Peru. A possible method of direct dating of archaeological skeletal material

This paper provides two archaeometric equations obtained by crystal–chemical parameters for dating human bone samples from the archaeological site of Nasca, Peru. Based on radiocarbon dating, the burials span from 500 BC to AD 1000. Crystal–chemical modifications in bone hydroxylapatite over time were compared with a twentieth century skeleton from Italy. Chemical analysis was carried out by means of electron microprobe along a profile from the periosteal to the endosteal border of the midshaft of four human femurs. The results indicate that the Ca/P ratio is linearly correlated with time according to the equation t=7880.68Ca/P−12805.90 (r=0.97; r²=0.95). Bone apatite X-ray powder diffraction analysis showed a systematic increase in the (002) reflection intensity with time, according to the equation t=250.49h/a−1961.86 (r=0.98; r²=0.97). The two independent archaeometric equations permit good accuracy in dating osteoarchaeological remains from the south coast area of Peru. © 1998 John Wiley & Sons, Ltd.     

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.     

Patterning in procurement of obsidian in Chaco Canyon and in Chaco-era communities in New Mexico as revealed by X-ray fluorescence

X-ray fluorescence analysis of obsidian artifacts from sites located in Chaco Canyon and from three Chaco-era communities in New Mexico permits determination of their geological origin. These source data are used to describe patterning in obsidian procurement in sites located in Chaco Canyon dating from A.D. 500–1150, and in a three non-Canyon communities occupied during the period of Chaco Canyon's regional prominence (ca. A.D. 875–1150). These data demonstrate that the most proximate sources generally dominate the sourced obsidian assemblages from sites of all periods, but also suggest differences in procurement patterning both over time and across space. Within Chaco Canyon, there is a notable shift from Mount Taylor obsidian to use of Jemez Mountains sources over time. These data also suggest that earlier analyses of obsidian from sites in Chaco Canyon misidentified some obsidian artifact sources; these new data indicate the central areas of disagreement and provide a revision of procurement patterning. In the Chaco-era communities located outside Chaco Canyon, procurement patterning diverges. The Blue J community shows an increase in use of the nearby Mount Taylor source over time. Two communities located toward the southern extent of the Chaco great house distribution reveal a markedly distinct procurement pattern, obtaining nearly all of their obsidian from southern sources largely unrepresented at Chaco Canyon. Combined, these data provide new insights into raw material procurement and artifact production at sites in Chaco Canyon, and in communities occupied during the Chaco Phenomenon, the period of the Canyon's greatest regional influence.     

Decorated prehistoric pottery from Castello di Annone (Piedmont,Italy): archaeometric study and pilot comparison with coeval analogous finds

Prehistoric pottery decorated with incisions or impressions filled with white and seldom coloured inlays is well documented in the archaeological literature, but the related in-depth archaeometric studies are sporadic. 43 decorated ceramic shards, dating from the Neolithic to the Bronze Age, and an Iron Age fibula from the archaeological site of Castello di Annone (Piedmont, North-Western Italy) were analysed with FTIR, Raman and XRPD for characterization of the ornamental pigments forming these inlays. Few white components were used as fillers, namely talc and bone ash (hydroxyapatite – Bone White), often as a mixture and seldom accompanied by other pigments (i.e. kaolinite and presumably secondary calcite). Comparison with freshly-heated biogenic hydroxyapatite proved that ancient Bone White pigment was calcined at about 900 °C. Such a process was kept separate from pottery firing as these white mixtures show absence of talc degradation by-products and sporadic presence of kaolinite, implying these ceramics were decorated only after firing in furnace. Actual presence of fluorapatite in bone ash could allow dating with the Fluorine Method, but lack of fluorine detection with SEM-EDS causes such an attempt to be impracticable so far. A pilot comparative study with a restricted but representative group (11) of coeval finds from other sites of Piedmont suggests that while recurrence of talc prevails in Castello di Annone from the Neolithic throughout the Bronze age, massive use of bone ash (Bone White) becomes widespread in the close Iron Age settlements, possibly consequent to a more efficient handling of its production technology.     

Glass and metal analyses of gold leaf tesserae from 1st to 9th century mosaics. A contribution to technological and chronological knowledge

An archaeometric study was carried out on 40 gold leaf tesserae from mosaics in Italy dated 1st to the 9th century AD. Glass layers and gold leaf were both analysed by X-ray microanalysis. The main aim was the identification of the composition of the glass and of the gold leaf, in order to assess the variations in composition and nature of the tesserae in the examined period.     

X-ray fluorescence analysis of late Roman and Sassanian silver plate

About 200 analyses have been made on late Roman and Sassanian silver objects using energy-dispersive X-ray fluorescence. This has shown that the main feature of the composition of the silver throughout the period and across the geographical area studied was towards high fineness (average silver percentage about 95%). Compositional differences are found between Roman and Sassanian silversmiths' products for the elements copper and lead. Much of the material analysed came from hoards, and using a statistical technique on the analytical data (Discriminant Analysis) broad compositional differences between hoards were found to emerge. The use of different compositions of silver for different joined parts of a single object are discussed.     

A pilot study into the effects of X-ray and computed tomography exposure on the amplification of DNA from bone

This research investigates the intersection of radiography and aDNA, two commonly used methods in bioarchaeology. The goal of this project was to investigate the effects of radiation on the ability to amplify DNA from bone. Bones (n = 124) from domestic pig (Sus scrofa) feet were randomly sorted into a control group and four treatment groups: (1) single exposure X-ray; (2) single exposure CT; (3) multiple exposures X-ray; and (4) multiple exposures CT. Number of PCR cycles required to amplify DNA in 100 bp, 200 bp and 400 bp segments were used as a proxy for the amount of available DNA. In the 200 bp CT sample, distal phalanges required significantly more amplification cycles than did the other bones and were removed from analysis. Results suggest that in general radiation exposure fragments DNA thereby decreasing the amount that is amplifiable. While these results are suggestive, further research is required to elucidate the degree to which radiation fragments DNA in archaeological specimens.     

The multivariate statistical analysis and XRD analysis of pottery at Xigongqiao site

A series of pottery samples excavated from the Xigongqiao site in Tengzhou city of Shandong province was determined using inductively coupled plasma atomic emission spectrometry. Together with excavation data and archaeological analysis, the potential for provenance and technology of unearthed ancient pottery was studied by using multivariate statistical analysis and X-ray powder diffraction pattern (XRD) analysis. In order to characterize and classify these earthenware samples, the major and minor/trace element concentrations were studied with both cluster analysis and principal component analysis. The results showed that there were three different groups in cluster analysis dendrogram in good correlation with their colors. This indicated that the potteries were made from clays of different composition. These results were in agreement with the results of principal component analysis. XRD analysis further assessed the validity of multivariate statistical analysis.     

Degradation of mud brick houses in an arid environment: a geoarchaeological model

A common assumption in Near Eastern tell archaeology is that the majority of sediments originate from degraded mud bricks. Little is known about the mechanism of mud brick wall degradation. Here we present a detailed macro- and microscopic ethnoarchaeological study of the degradation of a mud brick house and propose a comprehensive mechanism for tell formation processes in arid environments. The study took place in southern Israel by trenching a ca. 60 year old abandoned mud brick house, followed by extensive sediment sampling. Macroscopic observations showed that mud brick walls degrade by collapse of single bricks and/or collapse of intact wall parts, either inwards or outwards. In addition, infill sediments within the house and outside it, in close proximity to its walls, form alternating sedimentary layers of various colors and textures. The degraded mud brick material lost its distinctive macroscopic structure, which makes it impossible to accurately identify this material by field observations alone. Mineralogical and elemental analyses established the sources of the house infill sediments, namely mud bricks and wind blown sediments. Alternating layers mostly originate from mixing between degraded mud brick material and wind blown sediments. Micromorphological observations revealed microscopic mechanisms of mud brick degradation and include processes of mud slurry gravity flows, sediment coatings and infillings, wind abrasion of walls, small-scale puddling, and bioturbation. This study provides a working scheme for site formation of abandoned mud brick structures in arid environments. It provides a set of criteria by which it is possible to differentiate floors from post-abandonment sedimentary features and thus improves the reliability of activity area research.     

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.