Assessing the applicability of portable X-ray fluorescence spectrometry for obsidian provenance research in the Maya lowlands

Recent innovations in portable energy-dispersive X-ray fluorescence (PXRF) spectrometry have increased its utility for the geochemical characterization of obsidian artifacts for archaeological provenance research. However, concerns over the utility of PXRF instrumental analyses have been raised, focused on the validity and reliability of the geochemical data produced. Here we adopt the framework of Richard Hughes (On Reliability, Validity, and Scale in Obsidian Sourcing Research, 1998), whereby reliability addresses instrument stability and issues of measurement while validity pertains to an instrument’s ability to discern geochemical source provenance. This is done in order to test the utility of PXRF instruments for archaeological provenance research. k-Means cluster analysis was used to test the accuracy of PXRF through statistical comparison of data acquired via laboratory and portable energy-dispersive XRF instruments. Multivariate analysis was employed to demonstrate obsidian source representation at two Classic Maya archaeological sites in southern Belize – Uxbenká and Ek Xux – and to test the validity of data obtained from a PXRF instrument in answering archaeological research questions pertaining to regional interactions between lowland Maya polities. Results suggest that portable XRF instruments produce internally consistent results. However, data acquired from a PXRF instrument are not statistically equivalent to other XRF instruments. This is to say that while PXRF is not a reliable technique, it is valid for questions pertaining to geochemical source representation.     

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.     

Sourcing of sanukite implements by X-ray fluorescence analysis II

Non-destructive analysis of sanukite stones of known source and sanukite implements was carried out by means of energy-dispersive X-ray fluorescence spectrometry. Attention was focussed on areas in middle-western Japan. Stone taken from four source districts was classified into nine different groups. More than a hundred implements obtained from thirty-six archaeological sites were allocated to their sources by means of Hotelling's T² test.     

Precision in the X-ray fluorescence analysis of sixty-one Augustan quadrantes

Sixty-one Augustan quadrantes were analysed for calcium, iron, nickel, copper, silver, tin, antimony, and lead by X-ray fluorescence. Most coins contained about 99·7% copper with the other seven elements present as trace impurities. Significant differences in composition were found for the three different issues of quadrantes minted in c. 9 BC indicating that these issues were not minted exactly contemporaneously. Quadrantes minted in c. 4 BC have trace element concentrations in ranges that differ from those of the 9 BC quadrantes. The precision is very good for all trace elements (the precision of calcium was not calculated): average standard deviations are 0·0021% for Fe, 0·0026% for Ni, 0·0038% for Ag, 0·0014% for Sn, 0·0031% for Sb, and 0·015 for Pb.     

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.     

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.     

秦子姬簋盖初探

珍秦斋藏秦子姬簋盖是新发现的春秋早期秦铭文材料。本文解释了铭文词句,又根据《史记·秦本纪》的有关记载,并参考宝鸡太公庙出土秦武公及王姬钟铭文的研究,认为铭文中的“秦子”是指秦出子,“秦子姬”乃是其生母“鲁姬子”。这对于讨论青铜器铭文研究中的“秦子”问题以及秦国早期历史的探索,有一定的参考价值。     

Non-destructive provenance study of cuneiform tablets using portable X-ray fluorescence (pXRF)

Portable X-Ray Fluorescence (pXRF) apparatus of the last generation was tested to determine its potential for routine provenance determination of clay cuneiform tablets, which cannot be analyzed by “classical” intrusive methods. A group of tablets from Hattuša (Bo?azköy) and from el Amarna, which were previously provenanced using optical mineralogy (OM) and instrumental neutron activation analysis (INAA), was analyzed by pXRF and the results were used to establish the grouping according to their elemental concentrations. These groups were compared with the previous results retrieved by OM and INAA in order to confirm their validity. The results corroborate the high potential of the pXRF for non-destructive study of well-defined, ‘closed’ assemblages of clay-derived, delicate artifacts, such as cuneiform tablets, bullae, and fine-ware pottery. Consequently, a group of previously unexamined tablets from Hattuša was analyzed by pXRF and the results are discussed with implications on future research.     

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.     

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.     

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.     

X-ray and spectrographic analyses of terracotta figurines from myrina: an attempt to characterize workshops

Physico-chemical techniques of analysis have been applied to a series of Hellenistic terracotta figurines found at Myrina on the coast of Asia Minor to explore the feasibility of using chemical and mineralogical composition as parameters in the identification of figurine workshops. The results suggest that there is a tentative basis for the correlation between composition and stylistic criteria among the figurines. The difficulties associated with this approach are discussed, and account is taken of an earlier enquiry that was carried out on similar lines.     

Sourcing of sanukite stone implements by X-ray fluorescence analysis

Both powder analysis and non-destructive analysis of original sanukite stones and sanukite implements were carried out by means of X-ray fluorescence spectrometry of a non-dispersive type. Fluorescence peaks of eight minor elements (K, Ca, Ti, Fe, Rb, Zr, Y and Sr) were obtained and ratios of peaks were used as indices of characteristics of the samples. Original stones taken from eight different sources in Western Japan showed large inter-source deviations of these ratios compared with intra-source standard deviations. Non-destructive analysis was carried out by a similar procedure and the effect of different shapes of the samples on these ratios was sufficiently small for the allocation. Sanukite implements excavated in seven archaeological sites were analysed without destruction and all but one sample were allocated to their sources.     

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.     

EDXRF analysis of pigment used for the decoration of Mleiha pottery

Energy dispersive X-ray fluorescence spectroscopy was utilized for the analysis of the elemental composition of pigment used to decorate pottery artifacts belonging to the Mleiha period (3rd c. B.C–3rd c. A.D).     

X-ray microtomographic imaging of charcoal

We assess the potential of X-ray microtomography as a tool for the non-destructive, three-dimensional examination of the internal structure of charcoal. Microtomographic analysis of a series of charcoals produced by the experimental pyrolysis of pine wood at temperatures from 300 and 600 °C in nitrogen only and in nitrogen mixed with 2% oxygen indicates that, despite substantial shrinkage, observed porosity, pore size and pore connectivity are all increased by pyrolysis and also by chemical oxidation. Analysis of a number of altered and unaltered archaeological and geological charcoals has demonstrated the capacity of the technique to identify and map the distribution of authigenic mineral contamination within charcoal fragments. The results are of significance to radiocarbon dating in that they provide insights into the mechanisms by which charcoal can be contaminated by extraneous carbon in the natural environment.     

Croatian Appoxiomenos alloy composition and lead provenance study

An ancient bronze statue of an athlete with a strigil (known as Apoxiomenos) – was raised from the north Adriatic Sea in 1999. In order to help to determine its place and date of manufacture various scientific techniques were used. ¹⁴C dating performed by the Accelerator Mass Spectrometry (AMS) on the organic material found inside the statue gave calibrated dates between 100 B.C. and 250 A.D. Non-destructive analysis performed by portable X-Ray Fluorescence (XRF) system and external beam Particle Induced X-Ray Emission (PIXE) spectroscopy could not provide representative results for metal alloy composition due to the electrochemical deterioration of the surface of bronze in seawater. This was observed by the analysis of alloy cross-sections performed by the proton microprobe. The analysis showed much higher lead concentrations on the surface of the bronze than inside, confirming that realistic alloy composition can be only performed on samples taken from at least 0.6 mm below the surface. Subsequent micro-PIXE analysis on metal cross-section showed inhomogeneous lead concentrations between 1 and 12%. Lead isotope analysis for provenance investigation has been done on 15 samples using Multi Collector Inductively Coupled Plasma Mass Spectrometry (MC-ICP-MS). Analysis showed that lead isotope composition is consistent with some of the lead ores originating either from the Eastern Alps or from Sardinia. Altogether, the results lead to the conclusion that the statue is not of a Greek origin, but most probable it is a Roman copy of the Greek original.     

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.     

殷墟车子遗迹及甲骨金文中的车字

商代甲骨文、金文中“车”字的几种字形及有关的记载,对我们发掘、研究殷墟出土的车子遗迹很有帮助,如曲衡马车的发现、车试及不同形式车厢的清理、车辙的研究等,都是受到甲骨文、金文中“车”字资料的启发,而使发掘与研究工作取得了更好的效果。