ABSTRACT
Recent restoration accomplished on a Venetian style mirror conserved in the Virgen de la Encina Basílica at Ponferrada (León, Spain) raised the question if the mirror was produced in Venetian glass factories or in other place copying the well-known Venetian or façon de Venice style glasses. With the aim of answering this question a scientific and technical study of glass materials was accomplished. Selected glass samples, encompassing the variety of the mirror materials, were taken to undertake this study. Samples were characterized by low magnification binocular glass, X-ray fluorescence spectrometry (XRF), field emission scanning electron microscopy (FESEM) with energy dispersive X-ray microanalysis (EDS), and UV-Vis spectrophotometry. The results of chemical composition determined that all the samples were soda lime silicate glasses. However, three compositional groups were established. The first two groups resulted compatible with glasses produced in Venetian glass factories during 16th and 17th century: those so-called Venetian common and Venetian cristallo. The identification of a tin-mercury amalgam is also in agreement with this chronology. The presence of a notable content of arsenic oxide in the third group indicated that it could not be of Venetian origin and that it could have been produced later in time, probably at the end of 19th century or early 20th century.
