Laser-induced breakdown spectroscopy and optical microscopy investigations of crowns on the Pietà from the parish church in Skrzatusz, Poland

Abstract

Research into two crowns from the Pietà in the parish church in Skrzatusz, Poland, is presented. The aim was to authenticate the individual elements from these crowns and to investigate their composition. Laser-induced breakdown spectroscopy (LIBS), optical microscopy, and multivariate analysis were used. In the first half of the seventeenth century, open crowns were typical for the first Piastowski royal dynasty in Poland. In the following two centuries, specific flower-like bows, decorative finials, and precious stones in settings were added to the crowns. LIBS showed that the crowns were made of very thickly gilded silver. Stratigraphic distributions of alloy elements were determined for all structural components. Some differences between the concentrations of elements in distinct components were confirmed, while optical microscopy demonstrated the small craters caused by the LIBS measurements. Our results confirmed data obtained earlier by art historians, and helped to authenticate the crowns.