Search

This paper presents the results of a fully non-invasive photographic and spectroscopic study on a masterpiece by the famous Venetian painter Jacopo Tintoretto (1518-1594): "The Wedding feast at Cana" (1561), located inside the sacristy of the Santa Maria della Salute Basilica in Venice. A restoration campaign was carried out on the painting between 2016 and 2017. Various techniques were chosen to characterize in detail the materials used by the painter, especially pigments: Near Infrared Reflectography (NIR) to identify preparatory sketch and also allowing formulating hypothesis on some pigments; Raman and Fiber Optics Reflectance Spectroscopy (FORS) applied directly to the surface of the object, avoiding sample collection, to identify the pigments palette applied by Tintoretto. Information about binders was also obtained in a totally non-invasive way by using NIR spectroscopy. All analysis points were precisely (±2 mm) registered on a painting virtual map in order to recover them in a future possible conservation project., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2019 Elsevier B.V. All rights reserved.)

During the last decades, Raman spectroscopy has grown to an established analytical technique in archaeometry, art analysis and conservation science. Mobile Raman instruments were designed to be used for in situ characterisation and identification of inorganic and organic materials in art and archaeometry. This research paper aims to point out several aspects that need to be considered when selecting a mobile Raman spectrometer for in situ archaeometrical studies. We describe an approach to evaluate these parameters and apply this to a dual laser portable Raman spectrometer. Twofold characterisation of mobile Raman instrumentation for art analysis: (i) investigation of spectroscopic characteristics such as (amongst others) spectral resolution, spectral window, signal to noise ratio and limit of detection; (ii) evaluation of specific properties that are useful for mobile studies in archaeometry. These include options for easy positioning and focussing, the ability to reduce laser power on the surface of the art object and the working distance between the probehead and the artefact. Finally, the research was completed with field tests by studying the pigments of a mediaeval wall painting., (Copyright © 2013 Elsevier B.V. All rights reserved.)

Raman spectroscopy represents a new way to obtain detailed comprehensive information on heavy-mineral assemblages. In this work are presented several examples from major Alpine (Po River) and Himalayan (Ganga and Brahmaputra Rivers) fluvio-deltaic sands. Our attention was focused on the chemical properties of garnet, which is a widespread mineral in orogenic sediments, easy to be identified, and relatively stable during both equatorial weathering and intrastratal dissolution. Garnet grains were studied in different samples representative of various depositional environments (fluvial bar, fluvial levee, shoreface, beach berm, eolian dune), in order to investigate specifically the hydraulic behaviour of grains with different density in different hydrodynamic conditions. Raman spectra and semi-quantitative analysis of Raman shifts allowed us to rapidly determine the distribution of garnet types in each sample in order to obtain chemical composition, to calculate the density of each garnet, and finally to infer their respective provenance. This manuscript presents one possible application of the "MIRAGEM" method described by Bersani et al. in this volume. References, data sets and details on the analytical routine are widely explained in the above mentioned work.

Green colored samples on wall paintings and green powder from a pigment pot found in Pompeii area are investigated by micro-Raman, FT-IR and, for one sample, SEM-EDX. To obtain the green color, green earths and malachite were used, together with mixture of Egyptian blue and yellow ochre. The mineralogical identification of the green earths has been attempted through the comparison of the vibrational features, discriminating between celadonite and glauconite spectra. Traces of a modern synthetic pigment containing copper phthalocyanine were found in a fresco fragment.

Fluid inclusions in the quartz crystals present in gold-rich veins from central Honduras have been studied by means of micro-thermometry and micro-Raman spectroscopy in order to provide information on the physico-chemical conditions and chemical composition of the mineralizing fluids. The use of a confocal micro-Raman apparatus allowed to obtain information on the fluid composition, in particular on the gas phase, minimizing the contributions of the host matrix to the Raman signal. The samples studied were collected from an area (Lepaguare mining district, Northern-Central Honduras) rich in ore deposits due to the Cenozoic magmatic activity, where the gold and sulphide mineralization is connected with a system of quartz veins (few decimetres thick) occurring in low-grade metamorphic rocks and produced by hydrothermal fluids. The quartz crystals present in the gold-rich veins often contain fluid inclusions. Four types of fluid inclusions have been observed, but their assemblage in the same clusters and fracture systems, as well as their comparable salinity and homogenization data, suggest that they have the same origin. Micro-thermometry and Raman spectroscopy provide a composition of the mineralizing fluids attributable to the system H(2)O-NaCl-KCl-CO(2)-CH(4), with temperature and pressure intervals of 210-413 degrees C and 1050-3850 bar, respectively. These data agree with an epigenetic origin of the gold deposit (depth < 6 km) related to granitoid or granodiorite intrusions associated to orogenic environments.

A rapid system to obtain molar compositions of minerals belonging to the garnet group by means of Raman spectroscopy is illustrated here. A series of standard garnets, whose composition was determined by means of Wavelength Dispersive System (WDS) electron microprobe measurements, was used to correlate the wavenumbers of the different Raman peaks with chemical composition. A simple software routine was then developed in order to obtain garnet molar composition starting from the Raman spectrum, based on the assumption that in a solid solution belonging to the garnet family the Raman wavenumbers are linear combinations of end member wavenumbers, weighted by their molar fraction. The choice of the Raman bands used for the calculations and their behaviour are also discussed. The method, called MIRAGEM (Micro-Raman Garnets Evaluation Method), was then tested on a second series of garnets with satisfactory results.

Micro-Raman spectroscopy, combined with gas chromatography and ultra-violet fluorescence photography, was used to study some wall paintings in the S. Giovanni Evangelista Abbey in Parma, Italy. The restoration of some painted chapels enabled a comparison between two painters of the 16th century: Parmigianino (Girolamo Francesco Maria Mazzola, 1503-1540) and Michelangelo Anselmi (1492?-1556?). Micro-Raman spectroscopy determined the palette used by the artists, leading to the identification of different white, yellow, red, brown, green, blue and black pigments. Some pigments are evidence of later restorations. Gas chromatography combined with mass spectroscopy revealed the presence of organic binding media and enabled to distinguish between fresco and secco paintings.