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A 100,000-year-old ochre-processing workshop at Blombos Cave, South Africa.

Early humans mixed and stored ochre pigments in shells 100,000 years ago, an indication of the emergence of higher planning. The conceptual ability to source, combine, and store substances that enhance technology or social practices represents a benchmark in the evolution of complex human cognition. Excavations in 2008 at Blombos Cave, South Africa, revealed a processing workshop where a liquefied ochre-rich mixture was produced and stored in two Haliotis midae (abalone) shells 100,000 years ago. Ochre, bone, charcoal, grindstones, and hammerstones form a composite part of this production toolkit. The application of the mixture is unknown, but possibilities include decoration and skin protection.

A Survey of Terahertz Applications in Cultural Heritage Conservation Science

The authors present a review of the advances that have been made to establish terahertz applications in the cultural heritage conservation sector over the last several years. This includes material spectroscopy, 2D and 3D imaging and tomographic studies, using a broad range of terahertz sources demonstrating the breadth and application of this burgeoning community.

Analysis of rock art painting and technology of Palaeolithic painters

Archaeologists have attempted the interpretation of rock art, but have often disregarded the technical aspects of paints. Analysing paint samples for preparation techniques and studying the various compounds used, allows us to determine the technology of early painters. Palaeolithic artists used two main colours: red (iron oxide: natural hematite or heated goethite) and black (charcoal or manganese oxides). These pigments could be prepared in different ways (grinding, mixing with extender and/or binder or by heating) in order to enhance the properties of the paints. Analyses attempt to determine the physicochemical nature of the matter and its preparation mode, and to get an idea of its geographic origin. This paper presents techniques and methods used in the C2RMF laboratory for manganese oxide pigments. Distinction between manganese oxides with or without other cations is made and heat treatment of manganese oxide minerals is described. Results obtained for black pigment in Lascaux and Ekain caves are presented and discussed. From paint analyses, several conclusions are drawn concerning the technical level of Palaeolithic artists.

A multi-analytical study of bone diagenesis: the Neolithic site of Bercy (Paris, France)

Bone remains play an important role in archaeology as a source of information about the past. However, they alter over time. Alteration occurs at all scales from the macroscopic to nanoscopic level. The evaluation of information extracted on palaeodiets, ages and palaeoclimates from their chemical and isotopic composition requires the study of diagenetic modifications by means of different complementary analytical methods. Diagenetic parameters that quantify the post-mortem alteration of bone are bone histology, porosity, protein content, crystallinity of bone apatite, carbonate content, enrichment and leaching of chemical species in general. The investigation of these features can be performed by a combination of complementary elemental and structural analyses (particle-induced x-ray emission, particle-induced γ-ray emission, scanning electron microscopy (SEM) coupled with energy dispersive x-ray (EDX), electron microprobe, x-ray diffraction, infrared spectroscopy, transmission electron microscopy (TEM) with EDX), microscopic observations (optical, SEM, TEM) and porosity measurements.The study of animal bones from the Neolithic site of Bercy, France (4000 BC) from the same archaeological layer within different local depositional, hydrological and redox environments illustrates the possible information that can be extracted from the diagenetic study on the processes affecting the state of bone preservation. The main characteristic of the bone buried in the waterlogged zone is a high level of preservation of the organic matter and a low level of porosity inhibiting major structural or chemical modifications. The bone sample from the zone with a fluctuating hydrological regime shows a low level of organic matter and high porosity. Knowledge of the diagenetic patterns enables an estimation of the reliability of information obtained from bone analyses.

TRACE ELEMENT COMPOSITION OF ARCHAEOLOGICAL BONES AND POST-MORTEM ALTERATION IN THE BURIAL ENVIRONMENT

Abstract We have performed Particle Induced X-ray Emission (PIXE) and Particle Induced Gamma-ray Emission (PIGE) analyses with an external proton millibeam on archaeological bones in order to determine possible alteration processes in their burial environment (dissolution, uptake and diffusion of foreign ions). The PIXE method enables us to quantify the post-mortem alteration by determining the concentration profile of several trace elements like Al, Si, S, Mn, Fe, Cu, Zn and Sr in transverse bone sections, while that of fluorine is inferred from PIGE analysis. Examples of concentration profiles of archaeological bone cross sections from the Seine river site in Paris, Bercy (4000 B.C.), are shown.

The crystallinity of ancient bone and dentine: new insights by transmission electron microscopy

We studied various archaeological and palaeontological bones and dentines from different burial environments by Fourier transform infrared spectroscopy (FT-IR), X-ray diffraction (XRD) and transmission electron microscopy (TEM), in the framework of a general study of diagenesis. FT-IR and XRD were used to evaluate the global preservation state of the bone and dentine mineral phase by determining a splitting factor (SF) or a crystallinity index (Cl), respectively. These data can be combined with studies on the nanometer scale made with TEM. This latter technique, coupled with electron microdiffraction, provides determination of dimensions and shapes of individual bone and dentine apatite nanocrystals as well as of secondary minerals formed during diagenesis. It enables us to distinguish between heat-induced recrystallization processes and crystal growth in solution occurring during diagenesis.

Degradation process of lead chromate in paintings by Vincent van Gogh studied by means of spectromicroscopic methods : 3 : synthesis, characterization, and detection of different crystal forms of the chrome yellow pigment

The painter, Vincent van Gogh, and some of his contemporaries frequently made use of the pigment chrome yellow that is known to show a tendency toward darkening. This pigment may correspond to various chemical compounds such as PbCrO(4) and PbCr(1-x)S(x)O(4), that may each be present in various crystallographic forms with different tendencies toward degradation. Investigations by X-ray diffraction (XRD), mid-Fourier Transform infrared (FTIR), and Raman instruments (benchtop and portable) and synchrotron radiation-based micro-XRD and X-ray absorption near edge structure spectroscopy performed on oil-paint models, prepared with in-house synthesized PbCrO(4) and PbCr(1-x)S(x)O(4), permitted us to characterize the spectroscopic features of the various forms. On the basis of these results, an extended study has been carried out on historic paint tubes and on embedded paint microsamples taken from yellow-orange/pale yellow areas of 12 Van Gogh paintings, demonstrating that Van Gogh effectively made use of different chrome yellow types. This conclusion was also confirmed by in situ mid-FTIR investigations on Van Goghs Portrait of Gauguin (Van Gogh Museum, Amsterdam).

Tem observations of goethite dehydration: application to archaeological samples

Abstract Red and black were the two colours around which Palaeolithic art was organised. Manganese oxides and charcoal were the black pigments and hematite (α-Fe 2 O 3 ) the red one. The latter mineral is naturally abundant, but archaeological observations nevertheless suggest that the well-known colour change accompanying the dehydration of yellow goethite (α-FeOOH) to red hematite may have been employed by Prehistoric artists to obtain red pigment. In order to confirm this assumption, a study was carried out on synthetic goethite samples using XRD and TEM. In particular, the goethite-to-hematite transformation was observed in situ and provided useful information about both dehydration and recrystallisation processes. The existence of water up to high heating temperatures was found to be coherent with the typical porous microstructure accompanying the phase transformation. Similar studies were carried out on archaeological hematites coming from Troubat, a French Pyrenean Palaeolithic site. Characteristic features of previous heating were identified, such as pores or small amounts of maghemite (α-Fe 2 O 3 ), which confirms that Prehistorics had acquired this technical know-how.

The dedicated accelerator-based IBA facility AGLAE at the Louvre

Abstract The 6 SDH-2 2 MV tandem Pelletron accelerator of NEC has been installed at the Louvre to characterize museum artifacts by using IBA analytical techniques: PIXE and PIGME, RBS, ERD, as well as NRA. The facility is fitted with an electrostatic energy scanning system for automatically carried out resonance depth profiling. The accelerator hall has been designed to facilitate all the possible developments of AGLAE during the next decade, including a microbeam and AMS. The hall is entirely surrounded by one meter of concrete for the protection against deuteron-induced neutrons from d-RBS, NRA and DIXE-DIGME experiments. The machine is remote-controlled and will be entirely automated. Seven ports are available on the switching magnet. Two ports are already set up, one for IBA using a multipurpose vacuum chamber and the other for extracted-beam experiments. All the beam lines have been modularly designed for well controlled, halo-free beam impacts and a clean vacuum. We shall describe the facility and discuss the VME system for the automation of the experiments, the electronic equipment, and the powerful computer system used for the fast processing of the spectra, control of the experiments, and data storage.

Experimental characterization of a random metallic rough surface by spectrophotometric measurements in the visible range

Abstract Back-reflected light from a random rough surface is studied with the purpose of characterising the surface statistical properties. A new goniospectrophotometer with optic fibres is presented and a random rough copper surface is analysed. The probability density of the surface normal and the h / l ratio (r.m.s. roughness/autocorrelation length) are so obtained. Optical results are compared with mechanical ones, performed with a profilometer. For the first time, Abels transform method is used to connect the two-dimensional statistical information deduced from optical measurements and the one-dimensional profiles.