http://popups.lib.uliege.be/3041-5527/index.php?id=631 Entrées d’index fr 0 http://popups.lib.uliege.be/3041-5527/index.php?id=1156 Red powdery and crusty concentrations from the fill-up and bottom of a female burial DV3 from the Dolní Věstonice I site, representing Pavlovian culture, as well as some red raw material from the site were examined. Burial floor and fill-up is composed of marly substrate mixed with bone powder, charcoal ash and red, rounded, relatively hard particles, composed of burnt iron bearing aluminosilicates. Red crusts, present on it (maybe also within it), applied probably as suspension, are composed of unburnt iron bearing aluminosilicates. The raw material for powders is assumed to come from the site hearths red ash. Red iron artifacts, macroscopically almost identical, occur on the site also as an assemblage of loose red lumps. They are petrographically inhomogeneous and their sources are localized up to 150 km from the site. Raw material similar to the one of some of red lumps may have been used for burial ceremony. Fri, 06 Dec 2024 09:15:59 +0100 Fri, 06 Dec 2024 09:16:17 +0100 http://popups.lib.uliege.be/3041-5527/index.php?id=1156 http://popups.lib.uliege.be/3041-5527/index.php?id=844 Les échantillons d’hématite kaolinitique ont été récoltés au centre sud de la région des montagnes de Aravalli (AMR), dans le district de Chittourgarh, Rajasthan, Inde. Des analyses de la microstructure, de la composition chimique et minéralogique ont été effectuées à l’aide de MLP, MEB/EDS, DRX, FRX. L’utilisation de techniques basées sur l’emploi du microscope et des techniques micro analytiques ont permis de faire la distinction entre une structure massive où des reliques de minéraux semblables aux plagioclases sont préservés et des microstructures semblables à des ooïdes (glaebules). Ces dernières ont été regroupées en quatre typologies en fonction de la distribution et de la concentration relative de Si, Al et Fe. En particulier, les microstructures sphériques montrent des noyaux riches en Fe entourés par une bordure fine, riche en Al (Type A), des noyaux riches en Al entourés par une bordure fine riche en Fe (Type B), Al associé à des noyaux riches en Al-Si avec une bordure en Al-Si (Type C) et des particules subarrondies riches en Al où l’Al est associé à des grains d’oxydes et à du Si (Type D). Le diamètre est compris entre 70 et 250 μm. Tous les échantillons contiennent de la kaolinite [Al2Si2O5(OH)4], de l’hématite (α-Fe2O3) et de l’anatase (TiO2). Sur la base du rapport ordre-désordre de la structure de la kaolinite il a été possible de rassembler les échantillons en un Type I, avec de la kaolinite ordonnée, et en un Type II où le désordre peut être mis en évidence grâce aux pics caractéristiques des diffractogrammes aux rayons X. Les pics de l’hématite et de l’anatase sont larges ce qui indique une cristallinité basse. La majorité des échantillons ont des pertes au feu >10 %, ce qui souligne leur état très altéré. Des contenus presque négligeables en alcalis confirment cette interprétation étant donné leur mobilité élevée dans tous les processus qui se déroulent dans la croûte terrestre. Les teneurs en TiO2 sont anormalement élevées et sont, en général, positivement corrélées avec les valeurs de Al2O3. Al et Ti sont tous les deux très résistants et peu mobiles pendant les processus d’hydratation et d’altération. Un rapport inversement proportionnel entre SiO2 et TiO2 confirme cette interprétation. Le SiO2 est corrélé positivement avec la perte au feu ce qui confirme ultérieurement que le SiO2 est le principal composant qui a été lessivé pendant le processus d’altération. Des valeurs élevées et variables de Fe2O3 indiquent soit que les roches étaient riches en Fe soit qu’il y a eu un enrichissement durant le processus d’altération. L’absence de corrélation systématique entre TiO2 et Fe2O3 suggère qu’il y a eu un enrichissement secondaire en fer durant le processus d’altération. La composition chimique totale (valeurs basses pour SiO2 et élevées pour Al2O3, TiO2, Fe2O3) indiquent que les roches à l’origine de ces argiles hématitiques étaient de nature basique (probablement des basaltes). Leur source potentielle pourrait être la large étendue des basaltes du Deccan (Crétacé final à base du Tertiaire) qui couvrent la région de Chittourgarh. Quelques échantillons très riches en silicium peuvent être attribués à des shales et à des grès protérozoïques appartenant au Super groupe Vindhyan qui sont sous les basaltes L’altération des roches hôtes en hématite kaolinique est donc un évènement post-Tertiaire. Ce travail représente un premier essai de caractérisation de l’hématite kaolinitique dans le but de disposer d’une banque de données ce qui est essentiel pour des études de provenance d’hématites utilisées dans d’objets archéologiques et historiques en hématite. Mineralogical, geochemical and microstructural characteristics of kaolinitic hematite samples from Chittourgarh in the south-central part of the Aravalli Mountain Region (AMR) in Rajasthan State, NW India, are presented and discussed. The analytical techniques used were PLM, SEM/EDS, XRD, XRF. Microscopic observations and microanalysis allowed to differentiate a massive microstructure where relics of plagioclase-like minerals are still preserved and ooid-like microstructures (glaebules) can be seen. Glaebules were grouped into four types according to relative concentrations of Si, Al, and Fe and their distribution. The rounded microstructures exhibit Fe-rich cores surrounded by a thin Al-rich rim (Type A), Al-rich cores surrounded by a thin Ferich rim (Type B), Al associated with Al-Si rich cores by a Al-Si rim (Type C) and Al-rich sub-rounded particles where Al is both related to oxide grains and to Si (Type D). The diameter ranges between 70 to 250 μm. All the samples contain kaolinite [Al2Si2O5(OH)4], hematite (α-Fe2O3) and anatase (TiO2). Based on the orderdisorder in kaolinite structure it was possible to group the samples in Type I where ordered kaolinite was detected and Type II where disorder is clearly displayed by characteristic XRD reflections. Hematite and anatase reflections are rather broad indicating poor-crystalline mineral phases. The majority of the samples have >10 % LOI (loss on ignition), underlining their heavily altered nature. Almost negligible alkali contents further substantiate this interpretation as these are highly mobile in any crustal process. TiO2 values are unusually high and also generally correlate positively with Al2O3. Both Al and Ti are extremely resistant and immobile during hydration and alteration processes. An inverse relationship between SiO2 and TiO2 also attests to this proposition. The SiO2 correlated positively with LOI, further confirming that the SiO2 was the major component that was lost during alteration. High and variable Fe2O3 values show both an iron rich rock as well as iron enrichment during alteration process. Lack of any systematic correlation between TiO2 and Fe2O3 suggests secondary iron enrichment during alteration. Overall geochemistry (low SiO2, high Al2O3, TiO2 and Fe2O3) indicate basic rocks (most likely, basalt) as the provenance for these iron rich clays. The potential source could be the vast expanse of Late Cretaceous – Early Tertiary Deccan basalts that are exposed in the Chittourgarh region. Some high silica samples may be attributed to shale and sandstones belonging the Proterozoic Vindhyan Supergroup that underlie the basalts. The alteration of host rocks into secondary kaolinitic hematite is therefore a post Tertiary event. This study is the first attempt to characterize kaolinitic hematite in order to develop a preliminary database essential for provenance studies of hematite used in archaeological and historical artefacts. Fri, 29 Nov 2024 15:24:50 +0100 Fri, 29 Nov 2024 15:25:00 +0100 http://popups.lib.uliege.be/3041-5527/index.php?id=844 http://popups.lib.uliege.be/3041-5527/index.php?id=828 Hematite is one of the most common red pigments used by hunter-gatherer societies. In Africa, the earliest and unambiguous evidence for the use of red ferruginous pigments dates to the early Middle Stone Age (MSA), more than 200 ky ago. Usually referred to as “ochre”, they were intensively exploited in Southern Africa from about 160 ky. Hundreds of ochre fragments have been found in MSA layers from dozens of South African sites. The powder extracted from these red rocks is assumed to have been involved in a variety of activities, for body painting, for medicinal or ritual purposes, in hide treatment or as a loading agent in adhesives. Direct evidence of its use by MSA populations is scarce and mostly inferred from powder residues staining archaeological artifacts, such as backed tools or shell beads. Although red pigment use by early modern humans has often been interpreted as reflecting symbolically mediated and complex behaviors, the way they were collected and selected before being used remains poorly documented. Provenance studies are among the most powerful approaches to reconstruct procurement strategies and to discuss selection criteria. In this paper we investigate the provenance of ochre pieces from the MSA units of Diepkloof Rock Shelter, South Africa, in order to discuss the complexity of ochre procurement. Samples were examined with a binocular microscope and a part of them was submitted to chemical analyses by SEM-EDS (micro-structure), XRD (mineralogical composition), ICP-OES and ICP-MS (composition in major and trace elements). They were compared with a geological database constituted of samples from 12 sources located around the site. Ochre pieces from Diepkloof were shown to belong to three main categories of rocks: clayish sedimentary rocks (shale) ; intensively ferruginized nodules (nodular ferricretes) ; partially ferruginized sedimentary rocks (shale/ferricrete). Petrological observations and mineralogical analyses suggest a local provenance for a majority of the shale pieces, probably from a shale bed located directly in the back of the shelter. A significant number is exogenous however, and several were shown to be non-local. Geochemical data interrogated by statistical methods confirm the presence of both local and exogenous shale pieces. In comparison to shale pieces, no ferricrete sources are encountered in the vicinity of the site. Ferricrete pieces are exogenous and some of them are probably non local according to their micro-structure. However the ferricrete sources do not show clear mineralogical or geochemical fingerprints as the shale sources do. Regarding the provenance of shale/ferricrete pieces, similar conclusions were reached. According to these results, raw materials containing high iron oxide amounts were preferentially collected although they required long distance movements. Most of the non-local ochre pieces (shale and ferricrete), come from formations located to the south-west, upstream of the valley where the site is located. They are all located in Howiesons Poort units. At least one shale piece could come from a more distant area located to the north-east, where deeper valleys are encountered (Cederberg area). Such connections between different valleys suggest long distance group mobility or group exchange. In conclusion, ochre procurement at Diepkloof followed complex patterns during the Howiesons Poort, involving local supply, day trips, and possibly long distance mobility or group exchange. Fri, 29 Nov 2024 15:12:28 +0100 Fri, 29 Nov 2024 15:12:34 +0100 http://popups.lib.uliege.be/3041-5527/index.php?id=828 http://popups.lib.uliege.be/3041-5527/index.php?id=623 L’exploitation de l’hématite durant le Néolithique ancien en Europe du Nord-Ouest (soit de la Linearbandkeramik à la fin du Blicquy/Villeneuve-Saint-Germain, 5200-4700 BC) est attestée sur des sites d’habitats et funéraires, en particulier à proximité des sources d’approvisionnement géologique. À partir d’une analyse technologique et fonctionnelle des fragments d’hématite et des outils macrolithiques portant des traces de colorants, il est possible de mieux appréhender l’usage des colorants dans le système technique. 496 fragments d’hématite issus de 22 sites dans trois régions différentes ont été analysés : la plaine de Caen (Normandie - 12 sites), le bassin de la Dendre (Hainaut - 3 sites), et la Hesbaye liégeoise (Liège - 7 sites). Les caractéristiques des fragments d’hématite utilisés sont comparables entre ces différentes régions et suggèrent une gamme commune d’usages. La combinaison de la morphologie et de la distribution des traces d’usure sur différents types d’objet permettent de proposer plusieurs interprétations fonctionnelles. Si la production de poudre et l’application de colorant sur différent types de matières semblent bien avoir été l’objectif principal de ces productions, les propriétés abrasives de l’hématite ont également été recherchées pour des opérations de façonnage d’objet ou d’assouplissement de matières semi-souples. Sur les sites d’habitat, les hématites ont été transformées et réduites en poudre à l’aide de meules, de percuteurs et de concasseurs. Les outils de percussion ont été employés pour le concassage d’hématite en fractions relativement grossières avec parfois une seconde étape de broyage plus fin. Les meules ont été réutilisées selon un geste circulaire (et non en va-et-vient) afin d’obtenir de la poudre. Il s’agit dans ce cas de réemplois de faible intensité et durée d’utilisation. Parallèlement, des outils opportunistes tels que des éclats façonnés ou retouchés ont été employés pour le broyage de colorants. L’usage de matières colorantes avec des polissoirs et de molettes à main est lié à leur utilisation respectivement pour le façonnage par abrasion de différents types d’objets et l’assouplissement de matières semi-souples. L’originalité du traitement de l’hématite durant le Néolithique ancien du nord-ouest de l’Europe réside ainsi dans l’importante variété de ses modes de transformation et de ses usages. The exploitation of hematite during the Early Neolithic of north-western Europe (from the Linearbandkeramik to the end of Blicquy/Villeneuse-Saint-Germain, 5200-4700 BC) is attested on settlements and funerary contexts, especially when located near geological sources. After the technological and use-wear analysis of fragments of hematite and macrolithic tools wearing traces of colorings, it is possible to better understand how the use of colouring materials is contributing to the technical system. 496 fragments of hematites from 22 sites in three different regions have been analyzed: the plain of Caen (Normandie – 12 sites), the Dendre basin (Hainaut – 3 sites), and Hesbaye (Liège - 7 sites). The characteristics of the fragments of hematites used is comparable between the different regions, suggesting a common range of uses. The combination of the morphology and of the distribution of the use-wear traces on the different types of objects allows the proposal of several functional hypotheses. If the production of powder and the application of color on different types of matters seems to have been one of the main goals of these productions, the abrasive properties of hematites have also been searched for some operations of shaping of objects and suppling of half hard matters. On settlements, hematites have been processed and reduced into powder with querns, hammerstones and crushing tools. Percussive tools have been employed for the crushing of hematites in quite coarse fractions, with sometimes a second stage of finer grinding. Querns have been reused in a circular motion (and not in a back-and-forth one) in order to obtain powder. In this case, it represents a reemployment of low intensity, and low duration. In parallel, opportunist tools such as shaping or resharpening flakes were used for the grinding of colorings. The use of colorings matters with polishers or handstones is linked to their use respectively for the shaping by abrasion of different kind of objects, and the suppling of half-rigid matters. The originality of hematite treatment in the early Neolithic of North-Western Europe is definitely linked to an important variety of the modes of transformation and uses of this matter. Fri, 29 Nov 2024 13:05:03 +0100 Fri, 29 Nov 2024 14:25:44 +0100 http://popups.lib.uliege.be/3041-5527/index.php?id=623