Surface orange patinas on the limestone of the Batalha Monastery (Portugal): characterization and decay patterns

Samples of orange patinas found on a limestone window tracery and an ornament of the Batalha Monastery have been investigated by X-ray micro-diffractometry (μ-XRD) and low-vacuum scanning electron microscopy coupled with energy dispersive spectrometry (LV-SEM + EDS). The aim of the study was to determine the composition of the layered patinas, assess whether they have been intentionally applied or naturally formed, and study their degradation patterns. Preliminary results revealed that the orange patinas on the window tracery and the ornament showed different compositions and appearance, suggesting distinct formation pathways. Orange patinas on the ornament, which are now showing decay and delamination patterns, mainly consisted of gypsum with hematite as a minor component, implying the possibility of an intentional application of a mixture of ochre and lime as tint plaster. Orange patinas on the window tracery show, instead, the presence of Ca-oxalates, abundant weddellite, and minor whewellite, with minor hematite suggesting the yellowish/orange color as being due to Ca-oxalate patinas imbedding soil dust airborne particles. Such patina was possibly formed naturally either by the chemical attack due to atmospheric air pollutants from traffic exhausts emissions or by bacterial activity. No delamination was observed on the window tracery sample with granular decohesion as the major decay phenomenon. A comparison was made between this patina and the so-called scialbatura, a surface yellowish coating often found by conservators on limestone and marble in ancient monuments in the Mediterranean region.European Commission , H2020-MSCA-ITN-EJD ED-ARCHMAT, GA 76631

Microbial communities analysis assessed by pyrosequencing - a new approach applied to conservation state studies of mural paintings

The knowledge about the microbial communities present in mural paintings is of utmost importance to develop effective conservation and mitigation strategies. The present paper describes a methodological approach for the detailed characterisation of microorganisms thriving in mural paintings by combining culture-dependent methods that allow the identification of microorganisms capable of growing in the laboratory conditions and to obtain high cell densities for further studies, and culture independent methods, such as denaturing gradient gel electrophoresis (DGGE) and pyrosequencing. The coupled use of culture-dependent methods and DGGE does not give enough information to investigate the diversity and abundance of microorganisms present in wall paintings. Pyrosequencing, a novel molecular technique, used here for the first time in this area of research, allowed the identification of a large number of microorganisms, confirming some already identified by the cultivation-dependent methods such as fungi of the genera Penicillium and Cladosporium, but also providing a great contribution in the identification of several genera and species, not previously identified in these artworks, giving also a detailed overview of contaminants which was not possible with the other approaches. The results obtained on several mural painting samples show a strong relationship between the most deteriorated areas of the paintings and higher microbial contamination

Oxalate biofilm formation in mural paintings due to microorganismse -A comprehensive study

Oxalate film formation is a pathology that often occurs in mural paintings and may result from the concomitant action of microorganisms and environmental conditions. Low Choir of the Convent of Nossa Senhora da Saudação (Portugal) has mural paintings with an extraordinary beauty, which over time have been suffered polychromy degradation and biofilm formation, presenting an ideal case study to investigate the role and impact of microorganisms in the biodeterioration process. Bacterial populations, filamentous fungi belonging to the genera Cladosporium, Penicillium, Nectria and yeast strain of the genera Rhodotorula were isolated from these wall paintings. The penetration of fungal hyphae in the microstructure of mortars, observed by scanning electron microscopy, seems to be responsible for cracking and detachments in some areas of the painting. The study revealed that the veils on the surface of the paintings are essentially oxalates and that these biofilms are caused by metabolic activity of bacterial communities. Furthermore, the colour alteration of green areas due to microorganisms was detected by Raman microscopy, in real samples and under in vitro conditions, being the result of the metabolic activity of microorganisms present on the paintings, which promote calcium oxalates formation over the malachite paint layers

The metallic artifacts of the prehistoric fortified settlement of Leceia (Oeiras) inventory and analytical study

This paper presents the results of a study carried on a collection of 144 metal artefacts from the Early (ca. 2800-2600/2500 a.C.) and the Middle/Final Chalcolithic (ca. 2600/2500-2000 a.C.), found at the site of Leceia (Oeiras, Central Portugal) during the excavations conducted between 1983 and 2000. A systematised analysis of the collection was provided in order to enumerate the different typologies found in the site and to determine their chemical composition. From a typological point of view, a great diversity of artifacts was found, namely, punches, fish-hooks, flat axes, chisels, saws, ingots and foundry remnants. Elemental analysis, by X-ray Fluorescence, shows that the artefacts were made of copper, with a variable occurence of arsenic, nickel, silver, antimony, bismuth, lead and iron. In this paper, data is exposed and discussed within the regional early metallurgy.info:eu-repo/semantics/publishedVersio

Pathway Weathering in Granitoid Rocks from Central Region of Angola: Geochemical and Mineralogical Data

The Central Region of Angola is characterized by the abundance of granitoid rocks, whose weathering “in situ” originated the so-called residual soils. The textural, geochemical and mineralogical properties of these soils depend not only on the chemical composition of parent rock, but mainly on the local climatic and geomorphological characteristics. In the study area, sampling sites were selected, which extend from the region of Kwanza- Norte (Kassenda, Dondo) through Kwanza-Sul (Cangulo, Quibala and Waco Kungo) until the plateau of Huambo, where samples of fresh rock, weathered rock and its residual soil were collected along each weathering profile. Chemical analytical data were determined using X-ray fluorescence (XRF) analysis of the major and minor elements, whereas mineralogical data were determined using X-ray diffraction (XRD), on the samples of rock and on the respective residual soil. The results obtained and their comparative analysis between the sampling sites, as well as along each weathering profile is presented. This paper allows contributing to the knowledge of the geochemical weathering in tropical areas, as is the case of Angola

Isótopos de estrôncio no estudo da proveniência do ligante em argamassas: crónica de um insucesso

A cidade Romana de Ammaia é um importante sítio arqueológico, localizado no distrito de Portalegre (Portugal), que se desenvolveu durante o Império Romano. Pensa-se que tenha sido abandonada de forma abrupta, apesar de algumas evidências de posterior apropriação durante a ocupação muçulmana. Este uso descontinuado provocou a não-ocupação da cidade em épocas mais recentes, o que terá contribuído para a preservação das estruturas e dos vestígios da organização da cidade. Integrado num projeto de estudo mais vasto, as argamassas de assentamento das alvenarias e rebocos foram estudadas. As argamassas podem revelar a capacidade tecnológica e construtiva das sociedades e da sua disponibilidade em empenharem recursos. No estudo prévio das argamassas da Ammaia, conclui-se que os agregados são locais e que em sucessivos períodos históricos (i.e. pré-romanos, romano e pós-romano) foram utilizados diferentes ligantes de terra, calcíticos e dolomíticos. A restrição do uso da matéria-prima dolomite a um determinado período de tempo não era esperado porque a Ammaia localiza-se a escassos 500m de importantes afloramentos deste material (Calcários Dolomíticos da Escusa). Sabendo que os carbonatos retêm estrôncio e que este elemento acarreia uma assinatura que é susceptível de definir uma proveniência [2], foi definida uma metodologia para analisar diversas amostras de argamassa, de calcários dolomíticos da Escusa e de mármores de Estremoz. Cada um dos espécimes foi parcialmente dissolvido em ácido fraco (acético) e posteriormente a solução resultante foi analisada para razões isotópicas 87Sr/86Sr por Espectrometria de Massa de Ionização Térmica (TIMS). Esperava-se que a assinatura isotópica das argamassas se aproximasse da razão dos calcários dolomíticos da Escusa ou dos mármores de Estremoz. No entanto, verificou-se que estas assinaturas isotópicas se sobrepõem, e que a contribuição dos silicatos é, em algumas amostras, suficiente para alterar os valores e aproximá-los do que seria expectável nas rochas ígneas regionais. Desta forma, sem menosprezar as potencialidades do uso dos isótopos na determinação de proveniência de ligantes em argamassas, os autores reconhecem que a metodologia de preparação de amostra deve ser melhorada e a aplicação do sistema isotópico Rb-Sr poderá não ser o mais adequado às rochas e problemática em questão

Recording of Weathering Profile Development by Uranyl-Phosphate Minerals

Recording of Weathering Profile Development by Uranyl-Phosphate Mineral

Os nanomateriais na conservação do Património Cultural: Nanocais para suportes de pinturas murais

Nas últimas décadas os nanomateriais têm sido vistos como uma boa alternativa de materiais para a preservação do Património Cultural [1], nomeadamente, como consolidantes de pedra e de argamassas de cal. Estes materiais apresentam propriedades distintas quando comparados com os tradicionais. O trabalho que tem vindo a ser desenvolvido no Laboratório HERCULES em parceria com o LNEC [2,3] compreende a preparação de nanomateriais consolidantes inovadores, à base de cal, compatíveis com as superfícies originais e eficazes a longo prazo, tendo sempre em consideração a minimização dos fatores de risco ambiental e humano. Nesta comunicação serão apresentadas e discutidas diferentes estratégias para a obtenção de nanopartículas de hidróxidos de metais alcalino-terrosos, nomeadamente, as condições experimentais de síntese. Adicionalmente serão apresentados e discutidos os resultados de estudos de eficiência das dispersões de nanocais preparadas quando aplicadas em provetes de argamassas de cal. [1] Piero Baglioni, Emiliano Carretti and David Chelazzi (2015) Nanomaterials in art conservation. Nature Nanotechnology, 10 APR, 287-29 [2] P.I. Girginova, C. Galacho, J. Mirão, R. Veiga, A.S. Silva, A. Candeias (2016) Estudos preliminares para consolidação de suportes com pintura mural: síntese e caracterização de nanocais. Conservar património, 23, 103-107. [3] G. Borsoi, B. Lubellia, R. van Hees, R. Veiga, A.S. Silva (2016) Understanding the transport of nanolime consolidants within Maastricht limestone. Journal of Cultural Heritage, 18, 242-249.SFRH/BPD/97692/2013 (FCT

Iron age pottery from Garvão votive deposit

The Iberian Peninsula was an attractive area in ancient times due to its abundance in geological resources. Hence, the Iberian Iron Age is a period of successive social and political transformations, sometimes resulting in conflicts [1]. In 1982, an impressive votive deposit was discovered in Garvão (SW Portugal) revealing an important Iron Age II holy site [2]. Beside some uncertainties, this region is marked by very strong Mediterranean cultural influence but the inhabitants are celtic. The materials recovered (mainly pottery) were intentionally deposited, carefully arranged in order to optimize the available space [2, 3]. The pottery recovered shows that during Iron Age this archeological site was a merging geostrategic point of the Iberian societies with strong influences of the Mediterranean world and the Iberia celtic influences. Pottery fragments are one of the most common signs of human occupation. Its aesthetic aspects are extensively studied as one of mankind’s earliest expressions of representational art. But the ceramic characteristics depend also on the technology accessibility, the relationship of the societies with their environment, especially with the availability of raw materials, and on the commercial and cultural connections with other societies [4, 5]. Raw materials used by these communities provide essential information to understand specific historical periods. The geological resources are particularly useful for this purpose because even processed they can figure out identifiable signatures of provenance or technology used. Moreover, their intermittent occurrence and human necessity justify the existence of trade routes. A detailed study of the pottery based on stylistic analysis was envisaged which allowed the classification into different clusters. Special emphasis will be given to the provenance of the pottery, the technological aspects and the relationship between populations and Garvão holy site. The study of geological raw materials applying and combining modern techniques of earth materials sciences and the principles of physical sciences (e.g. geology and chemistry) can provide answers and a better understanding of the Garvão importance in this area of the Iberian Peninsula. A multi-analytical methodology was setup using optical and electron microscopy, infrared spectroscopy, X-ray fluorescence and X-ray diffraction. The combination of these techniques applied to selected Garvão pottery materials allowed the recognition of the ceramic phase composition, firing temperature, kiln atmosphere, ceramic manufacturing processes and origin of raw materials. With this study, connections with Mediterranean areas and with local production areas were underlined revealing that Garvão was a multicultural area. References [1] Alfenin, R. & Pariera, R.: Taller Poliorcética, Conclusiones, in “Poliorcética, Fortificación y Patrimonio (Asalto y Defensa de Plazas Fuertes)”, Editorial Universidad Politécnica de Valencia, pp. 307-322, 2005. [2] Beirão, C. de M., Tavares, C., Soares, J., Varela, M. and Varela, R.: Depósito votivo da II Idade do Ferro de Garvão. Notícia da primeira campanha de escavações, O Arqueólogo Português, 3, 45-136, 1985. [3] Beirão, C. de M., Tavares, C., Soares, J., Gomes, M. and Varela, R.: Um depósito votivo da II Idade do Ferro, no sul de Portugal, e as suas relações com as culturas da Meseta, Veleia, 2-3, 2017-221, 1985-86. [4] Maggetti, M. & Galetti, G.: Late La Téne pottery from western Switzerland: one regional or several local workshops? in Maggetti, M. & Messiga, B. (eds) “Geomaterials in Cultural Heritage”. Geological Society, London, Special Publications, 257, 63-80, 2009. [5] Arnold, D.: Linking society with the compositional analyses of pottery: a model from comparative ethnography. in: Livingstone Smith, A., Bosquet, D. & Marttineau, R. (eds) “Pottery Manufacturing Process: Reconstitution and Interpretation”. British Archaeological Reports International Series. Archaeopress, Oxford, 1349, 1-12, 2001. Acknowledgments This work was financial supported by “Fundação para a Ciência e Tecnologia” (FCT) through the project PTDC/HIS-ARQ/108758/2008 and the PhD grant SFRH/BD/67093/2009

Abandoned mine slags analysis by EPMA WDS x-ray mapping

The mining activity on the Iberian pyritic Belt (Portugal and Spain) started before Phoenician times, became particularly intense during the Roman occupation of the Iberian Peninsula (for gold) and after the industrial revolution (for gold, copper, zinc, lead and sulphur). The commonest ore of this region is a massive polymetalic sulphide accumulation, where pyrite (FeS2) is the main mineral, with variable concentrations of chalcopyrite (CuFeS2), sphalerite (ZnS), galena (PbS), arsenopyrite (FeAsS2), other sulphides and sulfosalts which include minor elements like Mn, Co, Ni, Se, Cd, Sb, Te, Hg and Bi. Some of the main and minor elements of these ores are hazardous and the drainage basins of pollutant source areas often induce health concerns in the resident population. Electron microprobe study followed previous optical and XRD analysis of the slags. The study focused on the identification of phases how sulphide and meta11ic phases are distributed within the material and infer about leachable elements during weathering. Electron microprobe X-Ray maps show evidences of different behavior between the elements: Ca and Zn are completely leached; iron is retained in oxyhydroxides, lead and arsenic precipitate as sulphates. Electron microprobe studies are essential to understand complex materials as earth materials. Nevertheless, care is required to a correct interpretation of data and most quantitative compositional data are not trustworthy