便携式X射线荧光现场分析壁画颜料适用性研究——以西藏拉萨大昭寺壁画为例

便携式X射线荧光光谱仪作为快捷的无损分析技术,广泛应用于壁画文物的现场分析中.本文利用便携式X射线荧光光谱仪分析了西藏拉萨大昭寺转经廊壁画,选取部分样品,利用实验室X射线荧光分析,发现所分析颜料的主要显色元素具有一致性,并利用拉曼光谱确定了壁画颜料的成分.通过比较研究,发现便携式X射线荧光光谱仪可确定大部分色彩较为纯正的颜料的成分,同时,由于西藏拉萨大昭寺壁画颜料的杂多性,对于含砷的橙色颜料、含砷或含铅与含铁的黄色颜料、含铜砷的绿色颜料、含钙硫的白色颜料、群青与孔雀石的混合颜料则需结合拉曼光谱确定之.本研究工作显示,利用便携式X射线荧光光谱仪开展现场检测,可极大地减少实验室分析样品的取样数量,有利于壁画颜料的无损分析与微损分析.     

U/Th-rich bitumen in Archean granites and Palaeoproterozoic metasediments, Rum Jungle Mineral Field, Australia: implications for mineralizing fluids

Uranium/thorium (U/Th)‐rich bitumen has been discovered within both Palaeoproterozoic black pelites and the Archean granitic basement of the Rum Jungle Mineral Field, Northern Territory, Australia. Granite‐hosted bitumen occurs as small (up to 400‐µm diameter) discrete individual nodules, which exhibit many morphological similarities to those observed in Phanerozoic siliciclastic rocks. Thorium, the dominant radioelement, occurs primarily as a hydrated Th–Y–Si–P phase. Uranium‐rich inclusions are rare, and correspond to a hydrated U–Th–Y–Si–P phase, identified as coffinite–thorogummite. Metasediment‐hosted bitumen is more variable in morphology, occurring as massive (<2 cm in width) veins that cross‐cut all foliations, as discrete individual nodules or as elongate seams (up to 500 µm in length), interpreted to represent a series of coalesced individual nodules. In all examples, uranium, the dominant radioelement in the metasediment‐hosted bitumen, is present as Th‐poor uraninite, with variable Y₂O₃ contents (up to 3.21 wt.%). Raman investigation of all types of bitumen indicates that it is a poorly organized carbonaceous matter, which has not been subjected to metamorphism. Consequently, a post‐metamorphic timing for hydrocarbon emplacement can be inferred and a magmatic origin can be precluded. Potential source rocks for the bitumen are black shales of the Whites Formation (up to 8 wt.% total organic carbon (TOC)) and the Koolpin Formation (approximately 13 wt.% TOC). Post‐metamorphic sericitization of rocks within the Whites Formation is accompanied by a near‐complete removal of organic matter. Alteration was possibly the catalyst for hydrocarbon generation. The Th–Y–Si–P phase within the granite‐hosted nodules is interpreted to be the result of the alteration of antecedent monazite. During this alteration, U, LREE and P were fractionated and removed, while Th, Y and Si remained immobile, and recombined to form a hydrated Th–Y–Si phase. This pervasive alteration within the basement U/Th‐rich granites is proposed as a genetic model for the formation of uranium deposits in the Rum Jungle Mineral Field and possibly unconformity associated uranium deposits on a global scale.     

Portuguese Blue‐on‐Blue 16th–17th Century Pottery

Blue‐on‐blue (‘berettino’) sherds have appeared in numerous production and consumption archaeological excavations in Lisbon and other archaeological sites in Portugal (dated from the mid‐16th century to the beginning of the 17th century). The abundance of this interesting faience led us to compare it with similar pottery from other well‐known production centres in Italy, namely Liguria (Savona and Albisola), Spain (the Triana kilns) and the Low Countries. Differences in the diffraction patterns of the sherds' pastes from the four countries were observed. In most samples, cobalt blue silicate (cobalt olivine) was identified in the dark blue or light blue glazes through the use of micro‐Raman spectroscopy and diffuse reflectance spectra. A remarkable difference in the calcite contents of the Lisbon and Seville pottery sherds was observed, in accordance with previous observations of high calcite contents of Seville ceramics. A comparison was also made for all of the blue‐on‐blue sherds studied here with many other 16th–17th century sherds from Lisbon using bivariate plots of K/Si versus Ca/Si. Lisbon and Seville pottery behave very differently, whereas sherds from Italy and the Low Countries occupy intermediate positions.     

Identification of colourants in icons of the Cretan School of iconography using Raman spectroscopy and liquid chromatography

The stratigraphies of twenty five (25) samples removed from twenty (20) icons of the Cretan School of iconography are studied using Optical Microscopy and micro-Raman spectroscopy. The objects are dated in 15th–17th c. and belong to the collection of the Benaki Museum, Athens, Greece. Cinnabar, red ochre, minium, yellow ochre, azurite, malachite, lapis lazuli, lead white, carbon black, and indigo are identified in the cross-sections of the icon samples using Raman spectroscopy.     

In search of the optimum Raman/IR signatures of potential ingredients used in San/Bushman rock art paint

Vibrational spectroscopy (Raman and FTIR) has played an important role in identifying pigments, substrata and deterioration products in rock art studies worldwide: in the laboratory and on-site. However, the detection of organic binders and carrying agents has so far been scarce and the quality of many spectra recorded on-site inadequate. In this study, possible pigments (charcoal, ochre, raptor faeces, thermally treated ostrich egg shell, etc.), binders (fat, egg, blood) and carrying agents (saliva, gall, egg, water) were selected based on artistic considerations and analysed with FTIR and Raman (514.6 and 785 nm excitation, both available in mobile instruments) spectroscopy in order to determine usable marker bands for each ingredient. The resultant marker bands were then used to analyse five ten year old San replica paints. It was found that FTIR spectroscopy is very efficient to identify organic compounds as there is no fluorescence but the broadness of the bands inhibits the exact assignment of many ingredients. A high fluorescence background experienced for many natural products prevented the recording of Raman spectra for all ingredients, in many instances though the sharp peaks usually associated with Raman spectra make identification easier than with FTIR spectroscopy. Most of the ingredients in the paints could be identified, but it is clear that better results are obtained when more that one technique is used.     

The Resinous Cargo of the Java Sea Wreck

A number of blocks of resinous materials were found in the cargo of a 12th‐ to 13th‐century shipwreck, discovered in the late 1980s in the Java Sea near the Indonesian islands of Sumatra and Java and excavated in 1996. These well‐preserved blocks presumably were trade materials used for religious, medicinal, cosmetic, decorative or practical purposes. Such materials, derived from plants and termed exudates, generally include frankincense, myrrh, ‘gum benjamin’, liquidambar, dragon's blood, dammar, copal and amber. The source of the cargo resin could not be determined from the site. Investigation by nuclear magnetic resonance (NMR) spectroscopy has revealed that the molecular structure corresponds to that of modern resin from the plant family Dipterocarpaceae, known in trade as dammar and closely resembling Group B copal and amber. Other molecular classes of exudates are excluded. Such materials are not present in the Middle East, which then cannot be their source. The NMR spectra differ from those of Group B samples from Australia, Papua New Guinea and Indonesia, but resemble those from India or Japan. The spectra indicate that the saline environment had a similar effect on the molecular structure to heating and aging.     

The origins of two purportedly pre-Columbian Mexican crystal skulls

The well-known life-size rock crystal skull in the British Museum was purchased in 1897 as an example of genuine pre-Columbian workmanship, but its authenticity has been the subject of increasing speculation since the 1930s. This paper is concerned with the history, technology and material of the skull and another larger white quartz skull, donated recently to the Smithsonian Institution. Manufacturing techniques were investigated, using scanning electron microscopy to examine tool marks on the artefacts, and compared with Mesoamerican material from secure contexts. A Mixtec rock crystal goblet and a group of Aztec/Mixtec rock crystal beads show no evidence of lapidary wheels. They were probably worked with stone and wood tools charged with abrasives, some of which may have been as hard as corundum. Textual evidence for Mexican lapidary techniques during the early colonial period, supported by limited archaeological evidence, also indicates a technology without the wheel, probably based on natural tool materials. In contrast, the two skulls under consideration were carved with rotary wheels. The British Museum skull was worked with hard abrasives such as corundum or diamond, whereas X-ray diffraction revealed traces of carborundum (SiC), a hard modern synthetic abrasive, on the Smithsonian skull. Investigation of fluid and solid inclusions in the quartz of the British Museum skull, using microscopy and Raman spectroscopy, shows that the material formed in a mesothermal metamorphic environment equivalent to greenschist facies. This suggests that the quartz was obtained from Brazil or Madagascar, areas far outside pre-Columbian trade networks. Recent archival research revealed that the British Museum skull was rejected as a modern artefact by the Museo Nacional de Mexico in 1885, when offered for sale by the collector and dealer, Eugène Boban. These findings led to the conclusion that the British Museum skull was worked in Europe during the nineteenth century. The Smithsonian Institution skull was probably manufactured shortly before it was bought in Mexico City in 1960; large blocks of white quartz would have been available from deposits in Mexico and the USA.     

Archaeometric Investigation of Medieval Pottery from Excavations at Novo Brdo,Serbia

Medieval pottery from excavations at Novo Brdo, Serbia, an important mining and trading centre during the 14th and 15th centuries, was investigated by a combination of optical microscopy, inductively coupled plasma – optical emission spectrometry, Fourier transform infrared, micro‐Raman and energy‐dispersive X‐ray fluorescence spectroscopy and X‐ray powder diffraction methods in order to determine its composition and firing temperature. The samples investigated were made of medium‐ to coarse‐grained, non‐calcareous clay, by a relatively well‐controlled firing procedure in an oxidizing atmosphere. The firing temperature was estimated to be 850–950°C. The similarity between the chemical composition of the investigated pottery and the local raw clay, combined with the outward appearance and the archaeological findings, indicate domestic production. The pottery is covered with the transparent lead‐rich glaze. Iron and copper were used as colourants.     

藤花落遗址出土石镞岩性的反射光谱图型分类研究

江苏连云港藤花落遗址出土了大量的石镞,多以泥板岩为主要的加工材料,其器型非常地多样化,可以看出当时的石镞工艺技术是有非常专业的生产体系。按其岩性的目测鉴定,全都是变质岩中的板岩,合计80件。透过反射光谱学反映石镞岩石总体的反射率大小以及光谱曲线斜率变化,用以辅助区分石镞的主要岩类,以达到分类的目的及定量统计分析。此次测试是藉由南京大学成矿作用国家重点实验室的Lambda900 UV/Vis/NIR光谱仪于密闭黑暗环境中所测试完成的。     

重庆忠县洞天堡墓地出土西汉青铜钫的腐蚀研究

为了解重庆洞天堡墓地出土青铜器的保存状况、腐蚀产物种类和埋藏环境特征等,并探索其锈蚀成因,为即将进行的保护修复工作提供科学的依据,利用三维视频显微镜、激光共聚焦拉曼光谱仪和扫描电子显微镜等对重庆忠县洞天堡墓地出土青铜钫残片进行微观形貌观察和锈蚀物结构成分分析,并利用X射线荧光和微生物分析技术对青铜钫附着土壤进行成分和微生物分析。结果表明:该青铜钫锈蚀物含孔雀石、白铅矿、铅钒、磷氯铅矿、砷铅矿和赤铜矿等;外层锈蚀存在磷和氯元素富集现象;土壤中的磷、硫和氯等元素向青铜器迁移,青铜器中铜、锡和铅元素因腐蚀向土壤中流失;附着土富含多种真菌类微生物,促进了磷氯铅矿和砷铅矿的形成。