Calcium hydroxide nanoparticles and hypogeum environment: test to understand the best way of application

For a long time the conservation of archaeological artefacts has been based on the principles of compatibility and minimal intervention. This involves a series of partially unsolved problems, concerning the products used for deteriorated structures consolidation. The choice of materials depends on several factors such as: microclimatic conditions, application methods, and reaction time of products. Recently the employment of nanolime in the consolidation treatments of decorative carbonate matrix surfaces had a great development, thanks to multifunctional use in calcium standard-sized particles treatments. However, while the use of the nanostructured materials is described in several specialized papers, the information about the best conditions of applicability of the nanolime and its related potentiality for the consolidation in hypogeum environment is rarely considered. The present work is devoted to represent a case study with the aim to give useful elements in order to evaluate the application of nanolime. The funerary inscriptions coming from St. Callixtus Catacombs have been the object of the research carried out in situ and in laboratory, checking indirectly in the short run and in the long run the porosity variation in the materials. The present study intends to indicate the best suspension concentration on consolidation in relationship with hypogeum environment

Tracing Provenance of Mesolithic and Neolithic Pottery Along the Nile River by Trace Elements and Sr Isotope Analysis

The aim of this research is to define the provenance of Mesolithic and Neolithic pottery found in some prehistoric sites in Central-Sudan. The study focuses on the analysis of both local raw materials (clay and temper) and ceramic artefacts. In particular, this research is orientated towards the application of Sr isotope analysis (87Sr/86Sr) to pottery characterised by similar pastes in terms of bulk chemical and petrographic composition. Moreover, the possibility of using Sr isotope analysis in provenance studies of pottery in Central Sudan is here investigated. The analysed samples have been found in several Mesolithic and Neolithic sites located along the Nile River across Central-Sudan and on an area located western of the river, in ancient times connected to the Nile by a tributary. The full set of samples includes both raw materials and pottery sherds. A total of 29 clays have been collected between 2013 and 2014 along the Nile system, covering a distance of nearly 1600 km, while during 2015 campaign six more samples have been added to the set of samples. Raw materials are described by a total of 35 geological samples, including clays, sands and rocks. As regards pottery, the initial selection criteria have been discussed with the archaeologist, Sandro Salvatori, and lead to the creation of a set of samples made by Mesolithic sherds found at Al Khiday (16-D-5) characterized by both quartz-tempered paste and decorative motifs that have a wide spatial-temporal distribution in Central Sudan (Rocker stamp dotted zigzag and Rocker stamp plain zigzag). Later, the set have been increased by adding Neolithic quartz-tempered pottery coming from both Al Khiday (16-D-5) and other regions where the same decorative motifs have been found, and in particular from: i) the Wadi Soba area, located along the Blue Nile and particularly the sites of Sheikh Mustafa and Al Mahalab supplied four sherds; ii) the Wadi Howar region lies in southern fringe of the Sudanese Eastern Sahara, and three samples from the site of Ennedi Erg have been studied. Lastly, the study was integrated with the analysis of K-feldspar-tempered pottery that has been found in several prehistoric archaeological sites of central Sudan, included Al Khiday. While raw materials and quartz-tempered pottery have been ground as is usual, pastes of K-feldspar-tempered pottery were micro-drilled in order to collect only the fine matrix and remove the K-feldspar inclusions. The issue regarding K-feldspar provenance is still under debate: it is usually found in combination with specific ceramic decorations (incised wavy line, rocker stamp dotted zigzag packed, alternating pivoted stamp) but its geological origin is attributable to outcrops of granite-like rocks (granite, syenite, and related ring complexes) that lies only in relatively small areas far away from Al Khiday sites (about 80-100 km), as the nearest location where they outcrop. Therefore, movement of raw materials or finite objects? The answer to this issue is very important to define social structure, relationships and exchange patterns within Mesolithic hunter-gatherer-fisher communities of central Sudan. As regards pottery studies, usually the localisation of the supply zone (the zone where people had direct access to the source of raw material/s) and therefore the definition of the provenance area are based on the presence of specific minero-petrographic markers if the ceramic production is committed to coarse pastes. If the pastes are of fine manufacture, the supply zone is identified by geochemical characteristics belonging to specific reference groups (e.g. production wastes). Nevertheless, in many cases the lack of specific traits of both lithological and geochemical nature prevents the resolution of important issues concerning pottery provenance. In the particular case study of Al Khiday, the presence of abundant quartz in the pastes causes a strong dilution effect also on trace elements potentially useful as markers of provenance. In cases where the coarse fraction of a ceramic is composed entirely of quartz (SiO2), which does not contains significant amounts of Rb or Sr, the Sr isotopic composition of the ceramic is derived almost entirely from the clay fraction. For this reason, the region of Central-Sudan is a suitable area where to apply this analytical method. The application of Sr isotopic analysis in ceramic provenance study rests on the premise that the geological origins of the minerals in ceramic pastes are not entirely obscured by processes associated with ceramic production. The comparison between the isotopic fingerprint of clays deposited by the Nile River across the central-Sudan and that of pottery coming from aforementioned prehistoric archaeological sites helped in the interpretation of provenance and production. Some supply zones have been excluded while others turned out to be more than plausible. Nevertheless, the study of pottery through Sr isotope analysis must face also the fact that the ceramic vessels were used in daily life and were subject to contamination by solid and liquid food. The comparison of Sr isotope signatures obtained from clay and pottery yielded information about the mixing processes of Nile sediments along the areas of interest and about some possible supply zones for raw materials used in pottery production. Because of the contamination of the sherds, which is evident analysing the bulk Sr contents, it is possible to make only some hypothesis about pottery provenance but all this information considerably contributed to the reconstruction of the material culture of Mesolithic and Neolithic populations of central Sudan.Scopo di questo progetto è lo studio di provenienza di ceramiche antiche rinvenute in alcuni siti archeologici del Sudan centrale, inteso come analisi sia delle materie prime locali che delle produzioni ceramiche. Nello specifico il lavoro è stato rivolto all’applicazione dell’analisi degli isotopi dello Stronzio (87Sr/86Sr) allo studio di manufatti ceramici che presentano impasti analoghi in termini di composizione petrografica e chimica di bulk, con la possibilità di utilizzare tale metodo per la determinazione della provenienza. I frammenti ceramici oggetto di studio provengono da diversi siti Mesolitici e Neolitici situati lungo il corso del Nilo che attraversa il Sudan centrale e in un’area posta ad ovest di questo, attraversata da uno dei suoi antichi affluenti. Il set di campioni analizzati include sia argille che ceramiche. Un totale di 29 argille è stato campionato tra il 2013 ed il 2014 coprendo una distanza di circa 1600 km, mentre nella campagna del 2015 ne sono state aggiunte sei, per un totale di 35 campioni geologici, tra argille, sabbie e rocce. Per quanto riguarda le ceramiche, dopo un confronto con l’archeologo Sandro Salvatori, per iniziare sono stati selezionati campioni provenienti dai siti di Al Khiday (16-D-5) appartenenti al periodo Mesolitico, decorati secondo uno stile ben distribuito nell’arco spazio-temporale relativo al Sudan Centrale (Rocker stamp dotted zigzag e Rocker stamp plain zigzag) e caratterizzati da impasto temperato a quarzo. Successivamente il set di campioni è stato ampliato aggiungendo ceramiche, sempre temperate a quarzo, appartenenti al periodo Neolitico provenienti sia dal medesimo sito di Al Khiday (16-D-5) che da altre zone in cui è stato rinvenuto lo stesso tipo di ceramica decorata con il medesimo motivo: la regione di Wadi Soba lungo il Nilo Blu, nello specifico i siti di Sheikh Mustafa e Al Mahalab; i siti della regione di Wadi Howar nel nord-ovest del Sudan, più precisamente dall’Ennedi Erg. Infine il quadro è stato completato con lo studio degli esemplari di ceramica temperata a feldspato potassico rinvenuta in numerosi siti archeologici, compreso quello di Al Khiday. Da questi impasti è stata meccanicamente prelevata unicamente la matrice fine e sono stati rimossi gli inclusi di feldspato potassico, la cui presenza determina delle importanti variazioni composizionali rispetto a quelle dell’argilla utilizzata. L’ipotesi della provenienza di questo smagrante è ancora dibattuta: si trova principalmente abbinato a specifici motivi decorativi (incised wavy line, rocker stamp dotted zigzag packed, alternating pivoted stamp) ma la sua origine geologica è imputabile ad affioramenti di rocce di tipo granitico che si trovano solo in determinate aree a molti chilometri di distanza (almeno 80-100 km) dai siti di Al Khiday. Questa parte del lavoro è stata rivolta alla risoluzione della questione se il feldspato venisse importato nei centri produttivi e mescolato con le argille locali di queste aree, o se i manufatti ceramici venissero prodotti in vicinanza delle zone di affioramento del feldspato e poi diffuse regionalmente. Pertanto, circolazione di una materia prima o di prodotti finiti? La risposta a questo quesito rappresenta un elemento importante nella definizione delle relazioni e della struttura sociale delle comunità di cacciatori-raccoglitori-pescatori Mesolitici. Per quel che riguarda i materiali ceramici, la presenza di markers minero-petrografici in produzioni ad impasto grossolano e specifici caratteri geochimici riferibili a gruppi di riferimento, cioè a produzioni di sicura origine locale (scarti di cottura, materiali di fornaci) o a materiali argillosi per le produzioni ad impasto fine, costituiscono il miglior vincolo nella definizione delle aree di approvvigionamento delle materie prime, e pertanto della provenienza. In molti casi però, l’assenza di elementi peculiari, siano essi litologici o geochimici, impedisce di risolvere importanti problematiche di provenienza delle ceramiche. Negli impasti presi in esame, inoltre, la predominanza di smagrante quarzoso determina anche un forte effetto di diluizione degli elementi in traccia, che quindi non consente di fornire indicazioni sulla provenienza delle argille. Per questo motivo il territorio del Sudan centrale preso in esame rappresenta una zona adatta per sperimentare questa indagine scientifica e, proprio in questo caso, l’analisi dei rapporti isotopici dello stronzio potrebbe rivelarsi decisiva; nei casi in cui viene utilizzato uno smagrante quarzoso, il quale non contiene quantità significative di Rb o Sr, la composizione isotopica dello stronzio nella ceramica è derivata per lo più dalla frazione argillosa/limosa. Il confronto tra l’impronta isotopica delle argille deposte dal Nilo lungo il suo corso attraverso il Sudan centrale e quella delle ceramiche provenienti dai siti sopracitati ha fornito una chiave di lettura per definire la provenienza di manufatti nei quali l’assenza di markers petrografici ne impedisce invece la collocazione. Alcune aree di approvvigionamento sono state escluse mentre altre sono risultate essere più plausibili. Tuttavia, lo studio del rapporto isotopico dello Sr in manufatti ceramici deve fare i conti con il fatto che questi oggetti erano parte integrante della vita quotidiana di queste popolazioni ed erano legati alla preparazione e alla consumazione del cibo, sia solido che liquido. Il confronto dei rapporti isotopici dello Sr di argille e ceramiche ha fornito informazioni sia riguardo ai processi di mescolamento dei sedimenti lungo il corso del Nilo nel Sudan centrale che ad alcune possibili zone di approvvigionamento di materie prime per la produzione delle ceramiche prese in esame. Ma, a causa della contaminazione dei frammenti ceramici, la quale si manifesta principalmente nell'analisi del contenuto in Sr, è possibile abbozzare solo alcune ipotesi sulla provenienza di queste ceramiche, sulla unica base isotopica. Tuttavia queste informazioni hanno contribuito in modo considerevole alla ricostruzione della cultura materiale delle popolazioni Mesolitiche e Neolitiche del Sudan centrale

Tracing Provenance of Mesolithic and Neolithic Pottery Along the Nile River by Trace Elements and Sr Isotope Analysis

The aim of this research is to define the provenance of Mesolithic and Neolithic pottery found in some prehistoric sites in Central-Sudan. The study focuses on the analysis of both local raw materials (clay and temper) and ceramic artefacts. In particular, this research is orientated towards the application of Sr isotope analysis (87Sr/86Sr) to pottery characterised by similar pastes in terms of bulk chemical and petrographic composition. Moreover, the possibility of using Sr isotope analysis in provenance studies of pottery in Central Sudan is here investigated. The analysed samples have been found in several Mesolithic and Neolithic sites located along the Nile River across Central-Sudan and on an area located western of the river, in ancient times connected to the Nile by a tributary. The full set of samples includes both raw materials and pottery sherds. A total of 29 clays have been collected between 2013 and 2014 along the Nile system, covering a distance of nearly 1600 km, while during 2015 campaign six more samples have been added to the set of samples. Raw materials are described by a total of 35 geological samples, including clays, sands and rocks. As regards pottery, the initial selection criteria have been discussed with the archaeologist, Sandro Salvatori, and lead to the creation of a set of samples made by Mesolithic sherds found at Al Khiday (16-D-5) characterized by both quartz-tempered paste and decorative motifs that have a wide spatial-temporal distribution in Central Sudan (Rocker stamp dotted zigzag and Rocker stamp plain zigzag). Later, the set have been increased by adding Neolithic quartz-tempered pottery coming from both Al Khiday (16-D-5) and other regions where the same decorative motifs have been found, and in particular from: i) the Wadi Soba area, located along the Blue Nile and particularly the sites of Sheikh Mustafa and Al Mahalab supplied four sherds; ii) the Wadi Howar region lies in southern fringe of the Sudanese Eastern Sahara, and three samples from the site of Ennedi Erg have been studied. Lastly, the study was integrated with the analysis of K-feldspar-tempered pottery that has been found in several prehistoric archaeological sites of central Sudan, included Al Khiday. While raw materials and quartz-tempered pottery have been ground as is usual, pastes of K-feldspar-tempered pottery were micro-drilled in order to collect only the fine matrix and remove the K-feldspar inclusions. The issue regarding K-feldspar provenance is still under debate: it is usually found in combination with specific ceramic decorations (incised wavy line, rocker stamp dotted zigzag packed, alternating pivoted stamp) but its geological origin is attributable to outcrops of granite-like rocks (granite, syenite, and related ring complexes) that lies only in relatively small areas far away from Al Khiday sites (about 80-100 km), as the nearest location where they outcrop. Therefore, movement of raw materials or finite objects? The answer to this issue is very important to define social structure, relationships and exchange patterns within Mesolithic hunter-gatherer-fisher communities of central Sudan. As regards pottery studies, usually the localisation of the supply zone (the zone where people had direct access to the source of raw material/s) and therefore the definition of the provenance area are based on the presence of specific minero-petrographic markers if the ceramic production is committed to coarse pastes. If the pastes are of fine manufacture, the supply zone is identified by geochemical characteristics belonging to specific reference groups (e.g. production wastes). Nevertheless, in many cases the lack of specific traits of both lithological and geochemical nature prevents the resolution of important issues concerning pottery provenance. In the particular case study of Al Khiday, the presence of abundant quartz in the pastes causes a strong dilution effect also on trace elements potentially useful as markers of provenance. In cases where the coarse fraction of a ceramic is composed entirely of quartz (SiO2), which does not contains significant amounts of Rb or Sr, the Sr isotopic composition of the ceramic is derived almost entirely from the clay fraction. For this reason, the region of Central-Sudan is a suitable area where to apply this analytical method. The application of Sr isotopic analysis in ceramic provenance study rests on the premise that the geological origins of the minerals in ceramic pastes are not entirely obscured by processes associated with ceramic production. The comparison between the isotopic fingerprint of clays deposited by the Nile River across the central-Sudan and that of pottery coming from aforementioned prehistoric archaeological sites helped in the interpretation of provenance and production. Some supply zones have been excluded while others turned out to be more than plausible. Nevertheless, the study of pottery through Sr isotope analysis must face also the fact that the ceramic vessels were used in daily life and were subject to contamination by solid and liquid food. The comparison of Sr isotope signatures obtained from clay and pottery yielded information about the mixing processes of Nile sediments along the areas of interest and about some possible supply zones for raw materials used in pottery production. Because of the contamination of the sherds, which is evident analysing the bulk Sr contents, it is possible to make only some hypothesis about pottery provenance but all this information considerably contributed to the reconstruction of the material culture of Mesolithic and Neolithic populations of central Sudan

Realgar and Light

Abstract Light, necessary for viewing a work of art, as it involves the transmission of energy, it can damage the artwork. Nowadays, the most common methods for controlling light are based on the control of the overall lighting intensity. In particular, museum lighting guidelines recommend to limit the time of illumination or to remove wavelengths of light to which human eyes are insensitive. This research aims at determining how lighting systems can be standardized and developed, by studying the interaction between light and the materials constituting cultural heritage. An interesting case-study was considered as starting point: the arsenic sulphides photo-oxidation induced by visible light. In particular, among arsenic sulphides, realgar photo-degradation was studied, as this pigment was used since antiquity. Light transforms realgar (red mineral, As4S4) in arsenolite (white as powder, As2O3) and pararealgar (yellow, As4S4). The process is not completely clarified so far. This study deepens the comprehension of the realgar degradation process and determines the ability of different halogen lamps and a LED lamp, used in museum exhibitions, to induce photodegradation of pigments The study was carried out by means of FT-IR, micro-Raman spectroscopy, XRD and spectra colorimeter analysis.Light, necessary for viewing a work of art, as it involves the transmission of energy, it can damage the artwork. Nowadays, the most common methods for controlling light are based on the control of the overall lighting intensity. In particular, museum lighting guidelines recommend to limit the time of illumination or to remove wavelengths of light to which human eyes are insensitive. This research aims at determining how lighting systems can be standardized and developed, by studying the interaction between light and the materials constituting cultural heritage. An interesting case-study was considered as starting point: the arsenic sulphides photo-oxidation induced by visible light. In particular, among arsenic sulphides, realgar photo-degradation was studied, as this pigment was used since antiquity. Light transforms realgar (red mineral, As4S4) in arsenolite (white as powder, As2O3) and pararealgar (yellow, As4S4)

Synchrotron tts-\ub5XRD identification of secondary phases in ancient ceramics

The study of the alteration process, and in particular of secondary phases precipitated in pottery after its production, can constrain the post-depositional environments or the type of use of the pottery. Detailed study of secondary phases can be done using different approaches, based on microscopic, microstructural and microchemical analyses, as well as mineralogical methods. In the present study are reported the results of the application of punctual mineralogical analysis by synchrotron through-the-substrate microdiffraction (tts-\u3bcXRD) to analyse secondary phases precipitated in ancient pottery (Bronze Age pottery form Frattesina in Italy and Mesolithic pottery form Al Khiday in Sudan). Although the chemical composition of these secondary phases in many cases almost matches with the stoichiometric composition of a known mineral, only some of them were actually true mineral phases (i.e. with crystallinity and therefore showing diffraction peaks), while others were amorphous. Some phases, the occurrence of which was previously attested only on the basis of their chemical composition (determined by scanning electron microscope or the electron microprobe analysis), were univocally identified as true vivianite (Fe3(PO4)2\u20228H2O) and crandallite (CaAl3(PO4)2(OH)5\u2022H2O) minerals. Part of the phases detected in studied pottery, the chemical composition of which was consistent with specific mineral phases, were instead amorphous. The synchrotron through-the-substrate microdiffraction (tts-\u3bcXRD), therefore, represents a valid method for properly determine the mineralogical nature of secondary phases in pottery, as well as other small-sized and rare mineral phases occurring in polycrystalline materials of archaeological interest, such as pottery, mortars, painting and glassy materials