Re-examining the chemical evaluation of diagenesis in human bone apatite

Isotopic analysis of human bone is becoming an increasingly important tool for the archaeologist in divining past life-ways. The isotopic ratios within bone are often assumed to be preserved as in life, but diagenetic change can alter the ratios, invalidating the results of isotopic analysis. Diagenesis can be evaluated in a number of ways, but most often spectroscopic techniques are utilised as the most efficient and easiest to understand methods for the archaeologist. Many isotopic studies do not report the possibility of diagenetic change, and if it is reported it has often been quantified using a single method of chemical analysis, FTIR spectroscopy. This study set out to test the value of FTIR analysis using human remains from the prehistoric site of Ban Non Wat, Northeast Thailand, and to compare the results with the non-destructive technique of FT-Raman spectroscopy. The study shows that FTIR spectroscopic analysis gives far less detail on the condition of bone than Raman spectroscopy, which does not merely indicate recrystallisation has occurred, but also shows clearly whether or not collagen is present, allows identification of ionic substitions which have occurred and identification of secondary minerals which have formed. Raman spectroscopy, combined with LA-ICP-MS analysis also revealed that soil composition and groundwater flow are the conditions which most affect diagenesis at Ban Non Wat.     

Natural preservation mechanisms at play in a Bronze Age wooden shovel found in the copper mines of Alderley Edge

A wooden shovel, dating from the Early Bronze Age, has survived in a remarkable state of preservation in the copper mines of Alderley Edge, Cheshire UK. Other historic timbers recovered from the mines, whilst still intact, have fared less well. An X-ray investigation into the distribution of minerals through the shovel using portable X-ray Fluorescence (PXRF) along with the use of synchrotron-based X-ray Absorption Spectroscopy (XAS) measurements of the copper and arsenic chemical speciations has provided clues to the methods by which metals from the mining environment have entered the wood of the shovel and ensured its survival. The distribution and nature of the minerals so determined suggest that the copper and arsenic, along with a significant lead content, entered the shovel during its original use in working mineral-rich deposits, rather than through the burial environment. The insights gained are expected to be applicable to other wooden artefacts recovered from ancient copper mines in other places.     

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.     

红外光谱法研究不同丝含量老化蚕丝蛋白

古代丝织品是否含有丝胶,不仅对丝织品保存状况有一定影响,而且是丝织品文物保护处理方法选择的重要依据之一.为了研究红外光谱作为有效的研究不同丝胶含量丝织品老化的一种检测分析手段的适用性,工作应用红外光谱分析对不同丝胶含量的人工老化蚕丝纤维进行了研究.研究结果表明,不同丝胶含量样品的红外谱图,一些特征峰的峰形、峰位、峰高均有明显差异,并且经不同老化方式老化的蚕丝蛋白的红外光谱图也有各自的特征,1445cm-1/1625cm-1比值可用于区分不同丝胶含量的样品.     

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.     

Lapis lazuli usage for blue decoration of polychrome painted glazed pottery: a recurrent technology during the Middle Ages in Apulia (Southern Italy)

Seven fragments of atypical proto-majolica from the archaeological site of Siponto (Manfredonia, Foggia) were analysed by chemical and physical methods. All fragments have blue, brown and yellow painted decorations. Raman microscopy and Scanning Electron Microscopy–Energy Dispersed Spectroscopy (SEM–EDS) investigations identified the blue pigment to lapis lazuli. We previously identified this mineral in the blue coloration of the tin–lead glaze of proto-majolica finds at other Medieval sites in Apulia (Castel Fiorentino and Lucera). The discovery of the fragments from Siponto, in spite of their peculiar technological-decorative features, proves that the use of lapis lazuli as a ceramic pigment was not an isolated occurrence, but was quite common in the Middle Ages in the production of typologically heterogeneous ceramics in Southern Italy.     

The rarest blue: An exceptional find of lapis lazuli in the polychromy of a funerary portrait from ancient Palmyra

The current interdisciplinary study of a funerary portrait has provided the first identification of a blue pigment on Palmyrene sculpture. The exceptional attestation of lapis lazuli on the examined portrait confirms the use of this highly valuable semiprecious stone in ancient polychromy, which was previously thought to be a later addition to the painter's palette. Considering that the archaeological record contains numerous minor objects carved from lapis lazuli, there are astonishingly few known instances of its use as a pigment. This Palmyrene discovery is only the third known example from Antiquity.     

Responses of South African Agate and Chalcedony When Heated Experimentally,and the Broader Implications for Heated Archaeological Minerals

Here we present a database of responses by South African agate and chalcedony to heat treatment. This will assist analyses of heated stone tools not only in South African archaeological sites, but wherever heated agate and chalcedony pieces were knapped. The minerals are abundant worldwide. To replicate potential heating methods during the Stone Age we placed some minerals in a wood fire, some under coals, and others were buried in sediments beneath fires. Thermal responses include lustrous flaked surfaces, pot lid fractures, semi-circular internal fractures, rough internal surfaces, and crazing. Aerobic heating is implied by pot lid fractures. To explain the thermal responses we analyzed the minerals using X-ray fluorescence, Raman spectroscopy, and carbon and sulfur analyses. Our chalcedony contains more water and impurities than agate, making it more vulnerable to thermal damage. Our method of combining field experiments with chemical analyses has global applications even though we expect that mineral components of agate and chalcedony will vary slightly in different parts of the world.     

唐张臣和墓彩绘陶质文物的拉曼光谱和X衍射分析

利用拉曼光谱和X衍射方法,对张臣和墓彩绘陶质文物颜料及胎体进行分析,结果表明各种颜料保存基本完好,为以后科学保护修复这批彩绘陶质文物提供了科学依据。同时也证明,在样品量极少的情况下,利用拉曼光谱和X衍射等方法可有效鉴别古代颜料的种类及文物胎体的成分。