Chauffage de minéraux au Paléolithique pour en changer la couleur. Apport de la microscopie électronique en transmission

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De 20 000 à 18 000 BP en Quercy : apports de la séquence du Cuzoul de Vers à la compréhension de l'évolution des comportements socio-économiques entre Solutréen récent et Badegoulien

Essai de synthèse des travaux menés autour du gisement du Cuzoul de Vers (Lot)

Le groupe des « bisons adossés » de Lascaux : étude de la technique de l’artiste par analyse de pigments

http://dx.doi.org/10.1016/j.anthro.2006.07.008International audienceLa scène naturaliste des « bisons adossés » de Lascaux, déjà étudiée par les archéologues, pose la question de la conception d'une telle figure par les artistes magdaléniens. Afin de déterminer les différents modes d'application, la nature des matières picturales employées et leur mode de préparation, plusieurs prélèvements ont été étudiés par microscopie électronique. Six prélèvements, provenant de zones caractéristiques de ces deux bisons, nous permettent de reconstruire les gestes et de comprendre les intentions de ces hommes

Analysis of rock art painting and technology of Palaeolithic painters

International audienceArchaeologists 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

Selection and heating of colouring materials in Mousterian level of es-Skhul (ca. 100 000 years B.P., Mount Carmel, Israel)

The transformation of yellow goethite into red hematite by heating has long been assumed for Palaeolithic red artefacts excavated close to fireplaces. However, this transformation is extremely rare. Using SEM–FEG–EDX, PIXE–PIGE, TEM and mXRD, we characterized the mineralogical and chemical compositions of four microsamples of colouring materials from the Mousterian layer B in the es-Skhul rock-shelter, from about 100 kya ago. For some colouring materials, the Mousterian people of es-Skhul chose to gather remote yellow lumps for heating. Their significant transport distance provides evidence of the possible high cultural value of these colouring materials for transformation into red pigments.CNRS–OMLL programme; Programme ORIGINE II of the Aquitaine Region; Programme PROTEA; FP7/2007/2013)/ERC Grant TRACSYMBOLS n# 249587; ULg (Liège University) programme for post-doctoral fellowshi

Heating effect on manganese oxides used as black Paleolithic pigment

International audienceManganese oxihydroxide behaviour has been studied under heat treatment to understand the transformation mechanisms and subsequently to gain insights into the preparation procedures of black painting materials during the Palaeolithic period. These manganese oxihydroxides have been studied as a function of heat treatment by TEM, XRD, DTA and FTIR and XANES (Mn K-edge) spectroscopies. These materials have been used as black pigments during the Palaeolithic period to realise rock art paintings such as in Lascaux (Dordogne, France) and Gargas (Midi-Pyre´ne´ es, France). Specific morphological, chemical and structural criteria were determined to distinguish between natural and heat-treated pigments

Solutrean and Magdalenian ferruginous rocks heat-treatment: accidental and/or deliberate action?

Heating of prehistoric coloring materials can induce radical changes in color indicative of structural matter transformation. For instance, the structure of the yellow iron oxide-rich mineral, goethite, changes into the red iron oxide-rich mineral, hematite, when it is heated to around 250-300°C. For a long time, heating has been thought to be the reason for the high frequencies of red rocks used in camp sites and the red pigments in rock art paintings. However, records of heat-treatment of coloring materials are usually not well documented; the contextual information is not clear enough to confirm intentional heating. Two Solutrean camp sites (the flint workshop Les Maîtreaux and the hunting site Combe Saunière I) and one middle Magdalenian cave with rock art (Grotte Blanchard, La Garenne) allow us to study the heating process of ferruginous rocks. All three sites, which have been excavated relatively recently, have well-defined archaeological records and strong associations between the ferruginous rocks and other artifacts. With the use of X-ray diffraction and electron µ-diffraction for identifying structural modification and SEM-FEG and TEM-FEG for detecting dehydration nano-pores, we have strong evidence for intentional heat-treatment of yellow goethite-rich materials in two archaeological contexts and one site for unintentional heating, where rocks were only partially transformed. Intentional heating to obtain red hematite from primary goethite would have required ingenious methods of temperature control in fireplace settings and purpose-built ground ovens

Pigments from the Middle Palaeolithic levels of Es-Skhul (Mount Carmel, Israel)

Discovery of pigments at Middle Palaeolithic sites is of interest in the context of the ongoing debate about the tempo and mode of the emergence of modern human behaviour. Here we analyse four previously undescribed fragments of pigmental material from Es-Skhul shelter, layer B, Israel, McCown excavations, identified at the Department of Palaeontology, Natural History Museum, London. One of them is still partially embedded in the hard breccia characteristic of this layer. Inspection of breccia fragments from layer B has led to the identification of small pieces of red and orange pigmental material still enclosed in large clasts, further corroborating the attribution of the larger pieces analysed in this study to layer B. The four objects are studied using optical microscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), Energy Dispersive X-ray (EDX), X-ray micro-diffraction (m-XRD), Particle-Induced X-Ray Emission Spectrometry (PIXE), and Proton-Induced Gamma-ray Emission (PIGE). The specimens display various hues of yellow, orange, red, and one of them presents a gradual variation of shade from yellow to dark orange. SEM/EDX analysis identifies two specimens (Skhul 1 and 2) as being composed of iron-rich calcium phosphate, the third (Skhul 3) of potassium-rich clay with titanium-rich iron oxide inclusions, and the fourth (Skhul 4) of pure iron oxide crystals. TEM/ EDX and m-XRD analysis demonstrate that three pieces (Skhul 1, 2 and 4) were heated to at least 300 C, a process that has partially or completely dehydrated goethite into haematite and changed their pristine yellow colour into orange or red. Skhul 3 shows no sign of heating, suggesting that its haematite content has a geological origin. The different mineral composition of the pieces suggests that they must come from a variety of sources. This implies that the associated collection strategies included the selection of materials that differed not only with respect to colour but also with respect to other physical and chemical properties. Although no formal proof exists that these lumps of pigmental material were deliberately heated, results obtained are consistent with this explanation

La couleur à la grande grotte d'Arcy-sur-Cure (Yonne)

Depuis la découverte des peintures préhistoriques, les recherches se sont développées pour comprendre l'organisation archéologique de la Grotte Grande d'Arcy-sur-Cure : étude des parois, sondages, amincissement de la calcite pour révéler les oeuvres... L 'analyse de la couleur s'inscrit dans cette perspective, afin de préciser l'aspect technique de la réalisation des peintures

Préparation des pigments rouges préhistoriques par chauffage.

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