Granites employed in Ávila-Spain. I. Chemical composition of the different types

The chemical composition of the different types of granite employed in the Cathedral and buildings of historic and artistic interest in Avila (Spain) is studied. The differences among the various fades studied (grey, ochre and bloodstone granites) are explained in terms of their different mineralogical composition, a result of the profound paleoweathering that occurred in the Iberian Hercynian Basement. The chemical differences between quarry stone and the samples taken from different parts of the buildings are due to weathering processes that occurred on the buildings. Among these, the precipitation of salts in humid zones and the effect of alkaline mortar on the varieties rich in opal are striking.