An electrochemical methodology for discriminating monetary emissions, a recurrent problem in much archaeological studies, is introduced. The method is based on the record of voltammetric signatures of cuprite and tenorite corrosion products in the patina using a minimally invasive nanosampling following the voltammetry of immobilized particles methodology. A model for the depth variation of voltammetric electrochemical parameters characterizing the composition of the corrosion patinas is presented. This model permits to rationalize electrochemical data and discriminate different monetary emissions. The application of this technique, corroborated by electrochemical impedance spectroscopy (EIS) and focusing ion beam-field emission scanning electron microscopy (FIB-FESEM-EDX), to a series of 10 cash copper coins produced around the Kuang Hsu and Hsüan T'ung last Chinese emperors permits to discern different provincial mints and reveals that the monetary unification developed in this period was not uniform.
A multi-technique strategy, including microscopy, spectroscopic and electrochemical techniques, is proposed to study thin corrosion layers that form on the surface of historic copper-based coins. An accurate characterisation of this external corrosion layer is important for selecting a suitable conservation and/or restoration treatment. For this purpose, a series of copper-based coins from different historical periods and provenances, which mainly exhibited atmospheric corrosion, was analysed. The morphology of the corrosion layer and the upper core of coins was studied in trenches done on coin surfaces with a focused ion beam gun, coupled to a field emission scanning electron microscope-X-ray microanalysis (FIB-FESEM-EDX). The X-ray microanalysis performed with FESEM-EDX on trenches allowed elemental composition profiles on the corrosion layer to be obtained. These results were complemented with the compositional data of the corrosion products provided by the voltammetry of immobilised microparticles (VIMP) and Fourier transform infrared spectroscopy (FTIR), and by studying visual appearance by optical microscopy and colorimetry. Cuprite and tenorite (the latter increased with coin age) were the main identified corrosion products, which were accompanied, to a lesser extent, by copper trihydroxychloride polymorphs. Interestingly, metal oxalates and metalcarboxylate complexes were identified on the corrosion layer of most coins. These unusual alteration products of copper-based coins were formed from the organic matter deposited on coin surfaces given their use when placed in circulation or by further manipulations of collectors.
The voltammetry of immobilized particles (VIMP) methodology was applied to the discrimination of Spanish maravedis produced in 10 different mints between 1661 and 1664 using characteristic signatures for the reduction of cuprite and tenorite in the patina of the coins and catalytic effects on the hydrogen evolution reaction (HER). The variation of the apparent tenorite/cuprite ratio with depth was fitted to potential laws differing from one mint to another for A Coruña, Burgos, Córdoba, Cuenca, Granada, Madrid, Trujillo, Segovia, Sevilla and Valladolid coins. Electrochemical data permitted to detect the changes in the composition (with lowering of the silver content) and manufacturing technique (from hammer to mill) occurring in this historical period.
The voltammetry of immobilized particles (VIMP) was applied for grouping a series of 86 Iberian coins nominally minted in the cities of Iltirta, Cástulo and Obulco in the 2th‐1th BCE period for which there are no chronological data. Using characteristic signatures for the reduction of cuprite, tenorite and lead corrosion products in the patina of the coins, voltammetric grouping of coins was proposed. Voltammetric data were found to be consistent with textural and compositional properties of the surface and subsurface of selected coins using FIB‐FESEM‐EDX. The obtained data confirmed a clear separation between the productions of Iltirta on one side, and those of Cástulo and Obulco on the other side, indicating the possibility to establish a rough chronology for these productions.
The cover image shows a Spanish maravedí produced in 1663 accompanied by SEM/EDX color map and a FIB‐FESEM trench and a voltammogram used for mint discrimination. More details are discussed in the article by Antonio Doménech‐Carbó et al., DOI: 10.1002/elan.201700326.
La incorporación de elementos lúdicos en el aula permite el aprendizaje de conceptos formales en un entorno favorable en el que los alumnos son incentivados en la consecución de desafíos potenciando la motivación y el desarrollo de competencias favoreciendo de esta manera el proceso cognitivo. Aprovechando las características que proporciona los juegos al aprendizaje, se diseña una actividad orientada a la resolución de problemáticas específicas en el ámbito de la Conservación y Restauración mediante la determinación de los instrumentos y métodos de examen necesarios para la documentación de los Bienes Culturales.
Coins extracted in mints ascribed to the archaeological sites of Iltirta (coin Ref. 8087), Cástulo (coin Ref. 42005), and Obulco (coin 42147) exhibited in the Museu de Prehistòria de València (Spain). As it can be seen in the map, the mints of Cástulo and Obulco are included into the group of Southern Iberian mints whereas the mint of Iltirta belongs to the Eastern group of mints. The coins studied were coined in an undefined period between the 2th and the 1th century BCE. The background image shows the trench performed with FIB‐FESEM‐EDX in the coin minted in Cástulo (Ref. 25654). Scale size of the coins 1 : 2. More Details can be found in the article by Antonio Doménech‐Carbó, María Teresa Doménech‐Carbó, Carla Álvarez‐Romero, Trinidad Pasíes, and Milagros Buendía. DOI: 10.1002/elan.201900090
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.