pXRF: a study of inter-instrument performance

Integrating portable X-ray fluorescence (pXRF) instrumentation into archaeological investigations has generated as much interest as skepticism because several characteristics of the technique limit analytical accuracy and precision. This paper seeks to explore inter-instrument performance in order to assess the potential pXRF instrumentation has in examining the elemental composition of lithic raw materials. Two pXRF instruments, Delta and Omega models both manufactured by Olympus Innov-X Systems, were utilized to obtain the trace element signatures of five fine-grained volcanic sources and four obsidian sources in the Great Basin. We compared the two portable instruments to a wavelength-dispersive instrument extensively calibrated with geologic standards and to a commercial benchtop energy-dispersive system. Our results suggest that the relationships between the data produced by these different instruments are complex, and as we look to the future of pXRF use in archaeological analysis we argue that that the same strict protocols applied in laboratory-based XRF analyses, involving instrument calibration, evaluation of inter-instrument performance, and comparison to accepted geologic standards, need to be applied in pXRF analysis.     

XRF analysis of glass beads from the Mycenaean palace of Nestor at Pylos,Peloponnesus, Greece: new insight into the LBA glass trade

In recent years there has been a growing interest in Mycenaean glass among archaeologists and scientists. Scholars have traditionally thought that all Mycenaean glass was imported either in finished form or as ingots and simply shaped or worked at the Mycenaean sites. Chemical studies of other Mycenaean glass (50 and 43) support the hypothesis that glass was imported into Mycenaean Greece, but there is also indication for glass production in mainland Greece at the palace of Thebes (Nikita and Henderson, 2006). There is no evidence for glass making or working at the Palace of Pylos, yet there is an abundance of glass beads there. The aim of this paper is to identify the technology and source for the glass of these beads and thus to ascertain how Pylos was connected to the broader Mycenaean and Mediterranean economies. The composition of the glasses was determined by means of portable XRF analysis and compared to that of other Late Bronze Age glasses from Egypt, Mesopotamia and mainland Greece. Four blue beads coloured with cobalt and one blue bead coloured with copper have Ti and Zr compositions consistent with an Egyptian origin of manufacture while five other beads show Ti and Zr concentrations consistent with a Mesopotamian origin (Shortland et al., 2007). Based on the dearth of Egyptian and Mesopotamian imports in Pylos, the presented data support the hypothesis that Pylos was receiving via internal Greek trade routes foreign-produced glass, which may have been worked abroad or in Greece.     

明代“金花银”银锭元素组成的无损检测分析

目前对"金花银"银锭的专门研究比较缺乏,本研究利用X射线荧光能谱仪对上海博物馆所藏表面具有"金花银"三字戳记的6枚银锭和6枚普通银锭进行了无损元素组成分析,以此充实"金花银"银锭的研究。检测和分析结果表明:"金花银"银锭中的银含量较高,各表面都测得铁、铅、铜、金元素,其金的含量也较非"金花银"银锭明显偏高,表面可能有粉末形态的腐蚀产物,部分"金花银"银锭表面有结合紧密的汞元素;而非"金花银"银锭中的银含量具有个体差异,并且含金量均比"金花银"银锭的含金量低;此外,"金花银"银锭在形制上与同期的其他非"金花银"银锭有一定相似之处。分析结果为了解明代"金花银"银锭成分组成和制作方式提供了科学依据。     

中华民国三十四年中央银行纸币印刷颜料无损研究

法币在中国货币史特别是近代货币史上有着重要地位。1935年11月至1948年8月间,先后发行了15种从"壹分"到"壹萬圆"不同面额的法币,由中外十六家不同印刷公司承印,版别多达百余种。本研究利用超景深三维视频显微镜、激光显微共聚焦拉曼光谱仪和便携式X射线荧光光谱仪,对11枚1945年(中华民国三十四年)中央银行发行的壹仟圆法币的印刷颜料进行了无损研究。结果表明,红色部分(印章、冠字号、纹饰等)普遍使用了有机合成染料系列颜料红PR,而蓝色、绿色、棕色部分普遍使用了普鲁士蓝、铅铬黄和炭黑等颜料进行调配呈色。这些信息能够为纸币类文物的鉴别、保护修复以及相关研究提供依据。     

Determining the Provenance of native copper artifacts from Northeastern North America: evidence from instrumental neutron activation analysis

The emergence of archaeological interest in native copper in the mid-1800s developed in concert with explanations that privileged the Lake Superior area over other potential sources of copper. Most scholars have thus assumed that when copper artifacts first appeared in Northeastern North America, they arrived as finished implements or were locally made from Lake Superior raw materials. Procurement models that point to Lake Superior as the sole source of native copper have been widely accepted in the absence of systematic large-scale testing. This article evaluates the dominant model for native copper procurement and presents trace element data derived from instrumental neutron activation analysis (INAA) to determine whether hunter-gatherers in the Northeast utilized one dominant source of copper or in fact exploited a number of geological deposits. I specifically report on the chemical characterization of copper from 13 discrete geological deposits and 18 archaeological sites dating to the Late Archaic (ca. 5000–3000 B.P.) and Early Woodland (ca. 3000–2000 B.P.) periods to suggest that the dominant model for native copper procurement is oversimplified.     

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.     

Evaluating effects of chemical weathering and surface contamination on the in situ provenance analysis of building stones in the Cuzco region of Peru with portable XRF

As the only type of instrument capable of determining artifact geochemistry in a wide variety of settings, portable X-Ray Fluorescence (PXRF) may be frequently utilized as probably the best option for collecting data when removal of objects in part or in whole is unfeasible. However, using PXRF in circumstances where sample selection and preparation diverge from standards developed for lab-based instrumentation requires assessing the impact of new and potentially limiting factors to establish the validity of the method in these new contexts. Here we examine the effects of surface contamination and chemical weathering on the ability to assess provenance of igneous building stones used in the Cuzco region of Peru. Surface contamination was assessed through comparing low-impact cleaning methods on diorite and andesite blocks, and weathering was examined by comparing weathered vs. fresh surfaces of samples from two andesite quarries. In general, the lightest elements were most impacted by contamination and weathering while measurements of many of the heavier elements commonly used in provenance studies were relatively unaffected. Concentrations of Pb and Zn were problematic in the urban context of Cuzco because of pollution. Ability to determine provenance of building stones within those limitations (i.e., the validity of this application of PXRF) was demonstrated in a preliminary study by comparing measurements from uncleaned, exposed building stones in the region to fresh quarry samples.     

Geochemical and mineralogical analysis of stone anchors from west coast of India: provenance study using thin sections,XRF and SEM-EDS

Stone anchors have been recovered along the Indian coast as a part of the maritime archaeological studies at the National Institute of Oceanography (NIO), Goa. Study of stone anchors provides clues to understand the ancient maritime trade contacts of India with other countries. These anchors resemble those found in the Mediterranean Sea, Persian Gulf and Red Sea Coast. Underwater explorations at Bet Dwarka, Dwarka, Goa, Visawada and Somnath have yielded stone anchors of widely varying shapes, sizes and weights ranging between 16 and 410 kg. Sixteen (10 Indo-Arabian, 4 Ringstone and 2 Single hole type) of the total of 269 stone anchors have been studied to determine provenance of rock through petrographic analysis using thin section studies, X-ray Fluorescence (XRF), and Scanning Electron Microscope – Energy Dispersive Spectrometer (SEM-EDS).     

Non-destructive PXRF analysis of museum-curated obsidian from the Near East

Non-destructive pXRF has the potential to expand sample populations of archaeological provenancing studies by facilitating access to museum collections of artefacts. In this study, we use museum-curated obsidian for the sites of Tell Brak, Mersin-Yümüktepe and Tell Arpachiyah and geological obsidian samples from central Turkey to demonstrate that non-destructive pXRF is comparable to other techniques in differentiating between Near Eastern obsidian sources. Secondly, we use multivariate analysis to evaluate whether non-destructive pXRF is sufficiently accurate and precise to enable comparison with legacy datasets from previous analysis using PIXE and ICP-MS. Multivariate analyses show that instrumental offsets between the results from pXRF and other analytic techniques are less than source-to-source variation typical for most Anatolian obsidian outcrops and pXRF-identified geochemical groups are directly comparable to legacy datasets. Non-destructive pXRF analysis indicates that during the Chalcolithic, East Göllü da? and Nenezi da? continued to be the major sources of obsidian to communities in central Anatolia and the Bingöl range and mountains surrounding Lake Van supplied sites east of the Levant. Variations in the analysed assemblages suggest a number of obsidian exchange networks existed during this period.     

Application of electron microprobe analysis to identify the origin of ancient pottery production from the Castillo de Huarmey,Peru

A vast amount of ceramics (among other grave goods) were recovered from Castillo de Huarmey, a Wari culture (650–1050 ce ) archaeological site on the north coast of Peru. In order to assess ceramic production area(s) and possible trade, political or cultural interactions with other regions, and to complement earlier petrographic analysis, electron microprobe analysis (EMPA) was conducted following a rarely used methodology in archaeology. The chemical composition of individual minerals in ceramics and sediments samples from the Huarmey Valley was obtained, focusing mainly on amphiboles, feldspars and pyroxenes. The results of the analyses clearly indicate that the majority of the ceramic analysed was made of raw material of local origin.     

Chronological discrimination of silver coins based on inter‐elemental ratios using laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS)

This paper details the application of a statistical method for the chronological discrimination of silver coins using counts per second trace elemental, inter‐elemental ratios. The statistical method described is based on a method that has been applied to similar archaeological materials to determine their provenance. The method makes use of the inter‐element association patterns of multi‐element analytical data determined using laser ablation‐inductively coupled plasma‐mass spectrometry (LA‐ICP‐MS). The majority of the 266 coins analysed for this study have already been successfully identified by their mint markings. The data from LA‐ICP‐MS analyses, together with what is known about the coins through visual identification, were used to discriminate the reigning sovereign, and in the case of Mexico, the year of minting, of individual coins within the elemental fingerprint of different mints. Subsequently, unidentified coins can be placed in the confusion matrix, and their trace element information used to identify their year of minting when compared with other, identified coins from the same mint. The interpretational statistical technique linear discriminant analysis (LDA) was used to explore an identification of year of minting of coins that have previously not been identified by other means based on a statistical comparison against a database of compositional analysis of silver coins of known year of minting.     

青海都兰吐蕃唐墓包金银饰的科学分析

青海都兰位于古丝绸之路南道上,都兰吐蕃墓葬群出土了为数不少的隋唐时期金银器及饰物,其中一件"粟特银包金神袛人物连珠牌饰银丝腰带"牌饰上的人物具有典型的粟特特征,这对于研究中西方文化交流,有着极为重要的价值。但很多包金银饰片出土时腐蚀严重需要进行保护处理和相关的科学研究。为此,通过电子扫描电镜、X-射线衍射等分析方法,对工艺类似腰带牌饰的样品进行科学分析。结果表明,样品为包金银器饰物,包金层为金银合金,而银本体腐蚀严重,腐蚀产物主要是氯化银,这与环境的高含盐量有关,分析结果可为吐蕃墓出土文物的研究和保护提供理论依据。     

Age and exploitation of obsidian from the Medicine Lake Highland,California

The relationship between major and minor elements, trace element composition, and age of obsidian sources within a volcanic field, is of considerable interest for obsidian source and artifact research in the New and Old World. The present study investigates this relationship in the Medicine Lake Highland of western North America. Geological evidence had indicated a very young age for all obsidian sources in the Highland, yet archaeological evidence suggested that obsidian was utilized for several thousand years. X-ray fluorescence analysis distinguished the latest flow (Glass Mountain) from the Cougar Butte, Grasshopper Flat, and Lost Iron Wells sources. Data obtained from two nearby archaeological sites showed that obsidian from the latter two sources was used by c. 7500 bc, while Glass Mountain material was not used (or available) until after 1360± 240 bp. These findings indicate that inferences of an extremely recent age for all obsidian sources in the volcanic field were unwarranted. Further analysis of major and minor elements indicated different hydration rates for these sources. The results argue that significant geochemical variability, as well as age differences, can exist between obsidian sources within the same volcanic field.     

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.     

Sherds on the Edge: Characterization of 16th Century Colonial Spanish Pottery Recovered from the Solomon Islands

We present the results of instrumental neutron activation analysis of ceramics recovered from the Solomon Islands, associated with Alvaro de Mendaña y Neira's 16th century colonizing expedition to the region (c.1595–6). Based on the chemical and typological data and previously published petrological and geochronological research, this study assigns the provenance of the ceramics variously to Peru, Panama, Spain, China and Thailand. A comparison of the provenance results with historical records related to Mendaña's voyage also shows the value of the archaeological assemblage in providing a detailed picture of provisioned ceramic types and their provenance.     

Characterisation of archaeological mortars from Pompeii (Campania,Italy) and identification of construction phases by compositional data analysis

This work describes the compositional characterisation of coccciopesto and natural pozzolanic mortars sampled in the Regio VI area of the archaeological site of Pompeii, with particular reference to the Casa di Pansa in Insula 6 and Casa 17 in Insula 2. Samples were studied by optical microscopy and analysed by XRF, SEM-EDS, LA-ICP-MS and XRPD. The XRF and SEM-EDS data, subjected to multivariate analysis (cluster analysis), identified the three main construction phases involved in building the Casa di Pansa. In addition, mineralogical and petrographic characteristics of the aggregate were determined and found to be compatible with pyroclastic deposits from the volcano Vesuvius. Study revealed C–S–H phases in the binder, due to pozzolanic hydration phemomena of hydrated lime with cocciopesto and natural pozzalana.     

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.     

Structural Identification of a Masonry Tower Based on Operational Modal Analysis

A wide program of structural assessment has been carried out by Politecnico di Milano on the historic bell tower of the church Chiesa Collegiata in Arcisate (Varese, northern Italy). Within this context, the first part of the article summarizes the results obtained from the application of the stochastic subspace identification method to ambient response data collected in two dynamic tests, carried out in June 2007 and June 2008. Next presented is the vibration-based methodology developed for the calibration of a three-dimensional finite element model of the tower, consisting in the successive application of systematic manual tuning, sensitivity analysis, and simple system identification algorithm.     

Study on Response Spectral Acceleration from the Great Wenchuan,China Earthquake of May 12, 2008

The M _w7.9 Wenchuan earthquake produced a rich set of over 1,400 accelerograms, which helped us to better understand strong ground motions from such a large event. Using the abundant data, we investigated the characteristics of response spectral accelerations from this event. This study includes: the spatial distribution of spectral amplitudes at three periods selected to represent ground motions at short, short-middle, and middle-long period ranges; attenuations of response spectral accelerations at periods between 0.05 and 10 s; comparison between the observed ground motions and predicted motions from empirically based equations [Abrahamson and Silva,1997 Abrahamson, N. N. and Silva, W. J. 1997. Empirical response spectral attenuation relations for shallow crustal earthquakes. Seismological Ressearch Letters, 68: 9–23. [Crossref] , [Google Scholar]; Boore et al., 1997 Boore, D. M., Joyner, W. B. and Fumal, T. E. 1997. Equations for estimating horizontal response spectra and peak acceleration from Western North America earthquakes: a summary of recent work. Seismological Ressearch Letters, 68: 128–153. [Crossref] , [Google Scholar]; Campbell, 1997 Campbell, K. W. 1997. Empirical near-source attenuation relationships for horizontal and vertical components of peak ground acceleration, peak ground velocity, and pseudo-absolute acceleration response spectra. Seismological Ressearch Letters, 68: 154–179. [Crossref] , [Google Scholar]; Huo, 1989 Huo, J. R. Ph.D. 1989. Study on the attenuation laws of strong earthquake ground motion near the source, Dissertation, Institute of Engineering Mechanics, China Earthquake Administration. (In Chinese) [Google Scholar]] commonly used in America and China; comparison between the average response spectra at three distance bins and the Chinese seismic design spectra under major earthquake (with the recurrent interval of over 2,000 years);, the vertical-to-horizontal ratio of response spectra and its dependence on the rupture distance, period, and local site condition; and comparison between the fault-normal and fault-parallel component spectral accelerations within the rupture distance of 60 km. Based on these analyses, we finally drew some conclusions regarding the engineering characteristics of spectral accelerations from large earthquakes, such as Wenchuan of M _w 7.9.     

再谈义县奉国寺大雄殿大木尺度设计方法——从最新发布资料得到的启示

2008年,中国文化遗产研究院、天津大学等单位结合2004年以来实测工作,公布了辽宁义县奉国寺大雄殿的测量数据和研究成果;2011年,文物保护界又将1988年大雄殿大修过程中详细测量所得的构造图纸、数据和病害全面公布;2010年,中国文化遗产研究院、清华大学等单位使用三维激光扫描技术开展了补充测量工作。对比三份实测数据,通过结构几何解析结构的认识,本文尝试回顾关于斗拱设计、屋架结构设计和材分o与营造尺配合等方面假说,尝试证实、修正、调整先前假说,进一步厘清原始设计。