Weathering steel, and particularly CorTen steel, is a very used material for modern artworks exhibited outdoors. One of the characteristic that makes this material so attractive to artists is the property to develop a protective rust layer composed by iron oxides which preserves its metallic core from atmospheric corrosion. This study was conducted to evaluate the conservation state of four CorTen sculptures by Eduardo Chillida, located in different places of Bilbao city (north of Spain) and affected by different factors (environmental among others) by using Raman spectroscopy. Measurements were performed in situ with a handheld Raman spectrometer mounted on a tripod with x–y–z axes motorization at the micron level. The most common oxyhydroxides detected were lepidocrocite (γ‐FeO(OH)), goethite (α‐FeO(OH)), hematite ( ‐Fe2O3) and magnetite (Fe3O4), being goethite the most stable phase. All the iron oxyhydroxides were identified in all of the studied sculptures but their relative amounts were different for each sculpture. The consequences of the marine aerosols exposure in the steel surface were also studied, detecting limonite (FeO(OH)·nH2O) and akaganeite (β‐FeO(OH)). The results confirmed that the evolution of the rust layer present on the analyzed weathering steels is different, depending both on the exposure and the particular type of the steel. Copyright © 2012 John Wiley & Sons, Ltd.

Weathering steel was designed to resist against the atmospheric impact due to the development of a characteristic rust layer that protects the metal by reducing the corrosion rate. This rust layer is formed by different iron (oxy‐hydr)oxides that acts as a barrier and provides the protective ability. In order to check the conservation state trough the protective capability, it is necessary to calculate the so‐called protective ability index (PAI). It mainly takes into account the ratio (α/γ) between the mass of goethite (α‐FeOOH) and lepidocrocite (γ‐FeOOH), present in the rust layer of weathering steel. Raman spectroscopy, apart from a qualitative technique, is recently becoming a semi quantitative approach. Therefore, it is a valuable tool for the calculation of the mentioned index. This paper is a widening of a previous work in which it was uncovered a problem in different weathering steel sculptures which are exposed to a Cl− and SO2‐rich urban atmosphere because they present different esthetical problems on their surfaces, such as detachments of steel chips, discolorations and irregularities. In order to relate these problems on the surface and the rust layer composition, PAI calculations were performed from the phase identification obtained from Raman imaging and using spectra decomposition to quantify each compounds. Although goethite and lepidocrocite were the most commonly detected compounds, hematite, akaganeite and magnetite were also identified. Hematite is a sub product formed in rich SO2 atmospheres; therefore, a PAI with its content is proposed. Protective indexes obtained for the different artworks exposed in different places provide quantitative clues for the conservation diagnosis of weathering steel structures. Copyright © 2014 John Wiley & Sons, Ltd.

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Darwin impact glass appeared in Tasmania (Australia) around 800 000 years ago by meteorite impact. To further study the formation process, several specimens of Darwin glass from the meteorites collection of the University of the Basque Country were analysed. Raman spectroscopy was considered the most suitable technique to determine the differences in composition between the surface layer and the inner matrix. These analyses were complemented by other techniques such as Scanning Electron Microscopy Energy Dispersive X-Ray Spectroscopy, Electron Micro Probe Analysis and Energy Dispersive X-Ray Fluorescence. The major elements found were Si, Al, Fe, K and Ca, together with a range of minor elements Ti, Cl, Zr, Ba, S, Cr, Mn, Ni and Sr. On the micrometre scale, highly heterogeneous elemental composition was found in the glassy matrixes, in particular a gradient in the concentration of iron and aluminium. Raman spectroscopy identified the characteristic silica vitreous matrix of impacted glasses with small inclusions of α-cristobalite (a mineral phase that indicates high temperature formation) and vesicles with iron or iron and nickel oxides filling the pores. Finally, malachite [Cu 2 CO 3 (OH) 2 ], ponsjankite [Cu 4 SO 4 (OH) 6 · H 2 O] and covellite (CuS) were identified by Raman spectroscopy formed after impact as secondary minerals due to the weathering of copper ore deposits incorporated to the matrix.

Meteorites and impact glasses have been largely analysed using different techniques, but most studies have been focused on their geologicalemineralogical characterization and isotopic ratios, mainly of a destructive nature. However, much more information can be gained by applying novel non-destructive analytical procedures and techniques that have been scarcely used to analyse these materials. This overview presents some new methodologies to study these materials and compares these new approaches with the commonly used ones. Techniques such as X-Ray Fluorescence (XRF) and Laser Induced Breakdown Spectroscopy (LIBS), for elemental characterization, the hyphenated Raman spectroscopy-SEM/EDS and the combination of them, allow extracting simultaneous information from elemental, molecular and structural data of the studied sample; furthermore, the spectroscopic image capabilities of such techniques allow a better understanding of the mineralogical distribution.