New insight into the vaults of the kings in the Alhambra (Granada, Spain) by combination of portable XRD and XRF

Abstract

In the Hall of the Kings, along the east side of the Courtyard of Lions in the Alhambra (Granada), the vaulted ceilings are clad in painted leather depicting various Kings or Lords on their seats, the fountain of youth, and a Lady playing chess. These artworks are unique masterpieces because of the unusual medium used (leather) and the presence of human representation in 14th century Muslim art. The colour palette of the paints used was assessed without taking samples, using a prototype apparatus that simultaneously performs X-ray diffraction (XRD) and X-ray fluorescence (XRF), providing an elemental chemical and mineralogical characterization of the areas studied. The curvature of the vaulted ceiling and the size of device restricted analysis to the flattest parts and the most accessible areas. The results show that the red hues are made from cinnabar and/or hematite. The flesh colour is a mixture of cinnabar and hydrocerussite, while malachite was used for the greens. Blues were achieved using lazurite and azurite, and the ochre tones using clays. Furthermore, XRD detected the presence of red lead in the red-ochre and orange tones, while gold is present together with tin and iron. Moreover, strontium is associated with the plaster preparation, and a compound made with arsenic and sulphur was observed in the green areas.