The emerald and gold necklace from Oplontis,Vesuvian Area,Naples, Italy

The present study refers to the characterization of an emerald and gold necklace, dating from the first century AD, found in Oplontis (Torre Annunziata, Naples, Italy), using non-destructive methodologies such as EPMA and microFTIR. Reference samples, from mines known to be active in the Roman Imperial period, were collected and analyzed using the same techniques. Experimental data were also statistically treated in order to classify the emeralds' mines. The comparison of archaeological and reference data allowed to hypothesize, with high probability, an Egyptian origin for the Oplontis emeralds – even if the Habachtal mine cannot be definitively excluded.     

Fracture‐focused fluid flow in an acid and redox‐influenced system: diagenetic controls on cement mineralogy and geomorphology in the Navajo Sandstone

Differential cement mineralogy is influenced by depositional textures, structural deformation, pore fluid chemistry, and ultimately influences landscape evolution by introducing heterogeneities in erodibility. In Southern Utah, the region West of the Kaibab uplift known as Mollies Nipple (Mollies) in Grand Staircase‐Escalante National Monument exhibits a complex history of fluid–sediment interactions, which has resulted in a localized zone of anomalous diagenetic iron sulfate (jarosite) mineralogy in a well‐exposed dune–interdune deposit within the Navajo Sandstone. Mineralogy and geochemistry of cements within this region are examined using reflectance and imaging spectroscopy, field investigations, microscopy, and whole‐rock geochemical analyses. These data show that the in‐situ jarosite cement is localized to a plane along the highest ridge of the butte, providing an armor along with other secondary cements, which controls the butte's geomorphic evolution. The jarosite cement is associated with other mineralogies suggesting that the sulfate was one of the latest fluid‐related precipitates in the paragenetic sequence. It was preceded by a regional bleaching event, precipitation of clay cements, some localized concretionary iron oxide precipitation, and formation of deformation bands. At least one generation of dense iron oxide mineralization is associated with cataclastic brittle deformation predating the sulfate precipitation. Trace element geochemistry of cements shows certain metal oxide populations associated with extremely high (>2000 ppm) arsenic values. We interpret the combination of spatial mineral distribution, observed paragenetic sequence, and trace element geochemistry to suggest this region experienced acid sulfate diagenesis along fracture‐controlled fluid conduits related to weathering of proximal, unidentified, sulfides, or H₂S associated with deep source beds. Jarosite is highly soluble, and its presence suggests that abundant fluid flow has not occurred in this region since its formation. This terminal cement‐forming event must have occurred prior to sandstone exhumation and erosion to form the current extreme landscape at Mollies. This site exhibits the influence that fluid geochemistry, sedimentary mineralogy, and structural fabric have on geomorphic evolution.     

The Copper CHARM Set: A New Set of Certified Reference Materials for the Standardization of Quantitative X‐Ray Fluorescence Analysis of Heritage Copper Alloys*

This paper introduces a new set of certified reference materials designed to aid scientists and conservators working in cultural heritage fields with quantitative X‐ray fluorescence analysis of historical and prehistoric copper alloys. This set has been designated as the Copper CHARM Set (Cultural Heritage Alloy Reference Material Set). The Copper CHARM Set is designed to be used by a wide range of museum‐, art‐ and archaeology‐oriented scientists and conservators to help improve the accuracy and range of their calibrations for quantitative ED–XRF spectrometry of copper alloys, and also increase the number of elements that can routinely be quantified. In addition, the common use of a single core set of the reference materials is designed to significantly improve inter‐laboratory reproducibility, allowing greater data sharing between researchers and thus furthering possibilities for collaborative study.     

Early Opacifiers In The Glaze Industry Of First Millennium bc Persia: Persepolis And Tepe Rabat

This study characterizes the opacifiers and colouring agents used in the glazed bricks of Persepolis (mid‐first millennium bc ) and the Mannean site of Tepe Rabat in north‐western Iran (eighth to seventh centuries bc ). Various analytical studies show that lead antimonate and brizziite (NaSbO₃) were used as the yellow and white opacifiers in the glazes of Persepolis and Tepe Rabat. Brizziite is shown to be incorporated in the white, green and turquoise glazes, and is also associated with lead antimonate and CaSb₂O₆ in some yellow and white opacifiers. The simultaneous formation of these opacifiers in one glaze might have been accidental. A possible connection between the Achaemenid glaze industry and the Mannean glaze production at Tepe Rabat is discussed.     

A Multi‐Analytical Approach to the Study of the Mural Paintings in the Presbytery of Santa Maria Antiqua Al Foro Romano in Rome

This paper presents the results of analyses carried out on three decorative phases of the presbytery of the church of Santa Maria Antiqua al Foro Romano in Rome: the fourth‐century ad mosaics setting bed; the Adoration of the Cross, dated to the papacy of John VII (ad 705–7); and the paintings in the apse of the Pope Paul I (ad 757–68) phase. The research allowed the characterization of the painting techniques, pigments, organic compounds and degradation products by means of a video microscope, optical microscopy, and μ‐Raman and FT–IR spectroscopy, contributing to a better understanding of the changes in the techniques and materials used throughout the centuries in one of the most relevant medieval Christian monuments in Western Europe.     

Analysis of rock samples collected from rock hewn churches of Lalibela,Ethiopia using laser-induced breakdown spectroscopy

With the aim to study alteration processes of the rock hewn churches from Lalibela (Ethiopia), we applied Laser Induced Breakdown Spectroscopy (LIBS) technique to measure the elemental composition both of the bulk rock materials and their external layers, exposed to the environmental factors. The analytical plasma was generated by nanosecond pulses of an Nd: YAG laser emitting at 1064 nm. Different major and minor sample constituents were detected, including Ca, Mg, Na, Fe, Ti, Al and K. The detected O emission originates both from air surrounding and the sample, while the intensity of N lines, coming exclusively from air, was used for the LIBS signal normalization. By depth profiling of the weathered basalt rock, we observed a lower presence of K in the external layers, corresponding to the first 5 laser shots. The emission from this element is anti-correlated with the line intensities from O, and this was attributed to the variations in relative abundances of clay minerals and K-feldspar. The analogue measurements were performed on the tuff rock, and compared to the spectra from powder samples containing only the external soft material, scratched from the rocks. These analyses show an abundance of H in the weathered, wetted layers and suggest that cations are lost from the constituent primary minerals and replaced by H⁺; this process disrupts the lattice structure and causes a marked loss of strength. The studies presented here demonstrate that LIBS is a useful technique for studying the alteration processes in the rocks, caused by environmental factors.     

Prehistoric settlement chronology on Rapa Nui,Chile: obsidian hydration dating using infrared photoacoustic spectroscopy

The prehistoric Polynesian inhabitants of Rapa Nui (Easter Island) utilized obsidian for nearly 700 years in many activities connected with daily life. The near ubiquitous occurrence of the natural glass in both domestic residences and religious structures makes the application of obsidian hydration dating highly suitable for the investigation of cultural change. We have applied previously developed calibrations that estimate hydration rates for obsidian based upon the structural water content of the glass as determined by infrared spectroscopy. The archaeological ages estimated by this method were compared with accelerator mass spectrometry (AMS) dates using short-lived woody species endemic to the island. The convergence between the two dating methods is strong and we suggest that obsidian hydration dating may be used on Rapa Nui to reliably date contexts where suitable material for AMS dating may not be available.     

Identification of pigments used in rock art paintings in Gode Roriso-Ethiopia using Micro-Raman spectroscopy

In this paper we present results on the rock art painting materials from the Gode Roriso rock shelter, located in the eastern Hararghe region of Ethiopia. This analysis included X-microfluorescence, Micro-Raman spectroscopy and microstratigraphy. As far as the results of the analysis are concerned, a white natural wax (beeswax), carbon black and iron oxides (a mixture of haematite and magnetite) along with charcoal particles (forming as a red colourant) have been applied on a natural substrate constituted of granite containing feldspar crystalline forms. Although very much a science-based piece of research, the results have far-reaching outcomes for understanding the sequencing of pigment application.     

Characterization of prehispanic cosmetics found in a burial of the ancient city of Teotihuacan (Mexico)

The present paper reports the chemical data obtained on samples of pigmenting materials contained in 31 miniature vessels found in a burial found in Teopancazco, a multiethnic neighborhood center located in the southeastern sector of the archaeological site of Teotihuacan (Central Mexico) and the analytical protocol established for the complete characterization of these archaeological materials. For this purpose a multi-technique approach based on the combination of several non destructive and micro-destructive instrumental techniques, namely, light microscopy (LM), scanning electron microscopy-X-ray microanalysis (SEM-EDX), transmission electron microscopy (TEM), voltammetry of microparticles (VMP), X-ray microdiffraction (μXRD), X-ray diffraction (XRD), UV-Vis spectrophotometry, FTIR spectroscopy and gas chromatography-mass spectrometry (GC-MS) has been developed in an attempt to completely characterize these materials. These instrumental techniques provide reliable and complementary data including elemental and mineralogical composition, identification of functional groups as well as speciation studies of electroactive species. Among the most relevant findings, volcanic pyroclastic rocks and clayey soils, most probably, from the Teotihuacan valley as well as galena, jarosite and mica from other provenances in Mesoamerica, have been identified. Charcoal and Ocote resin have also been identified. The chemical composition of the samples is discussed with a view to the possible function as cosmetic materials and their use in funerary rites. The results have been critically compared with those others obtained in other ancient civilizations. The study carried out on the materials found in the burial 105 is especially relevant insofar it represents the first evidence, scientifically characterized, of the use of cosmetics in Mesoamerica at this early period (AD 200-550).     

化隆县纳卡遗址彩陶颜料的拉曼光谱分析

本文利用拉曼光谱(Raman)、X射线衍射(XRD)和X射线荧光光谱(XRF)等方法,分析了青海省化隆县纳卡遗址出土的马家窑文化及齐家文化彩陶。结果显示:马家窑文化黑彩在不同文化阶段其显色机理不同,半山阶段黑彩以磁铁矿及黑锰矿为主,且Fe/Mn比值较低,反射率最低,呈现浓翠的黑色;而马厂阶段黑彩则以赤铁矿及黑锰矿为主,Fe/Mn比值较高,反射率偏高,主波长为400~450nm,呈偏紫色的黑彩。表明马家窑文化陶工已认识到赤铁矿与黑锰矿的混合矿物颜料、含锰磁铁矿二者之间具有不同的呈色性能,并且熟练掌握了浓淡的变换规律,使之满足于彩绘的需求。齐家文化黑彩以磁铁矿为主,含有锐钛矿,主波长为650~700nm,呈偏红黄色的黑彩,表明这个阶段彩陶的烧制温度不高,彩陶文化已趋向衰落。