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

J García-Talegón,M Vargas,A C Íñigo,M A Vicente,E Molina

doi:10.3989/mc.1994.v44.i233.594

Abstract

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.

Highlights

In the construction and successive restoration of most buildings of historic and artistic interest in Avila different types of granite have been used
In de cathedral samples taken from weathered zones the decrease in the SiO^ contents of the red and white facies is due to the dissolution of opal, especially in the zones affected by alkaline mortar
- Among the five varieties of granite from quarries studied fresh granite, ''Avila Grey" (GG and gris fino (GF)), ochre (O), red (R) and white (B) facies, whose origin is linked to paleoweatherings of the Hercynian Basements, an increase in SiO^ contents is seen in the weatheredfacies, above all in the red and white facies, which have undergone a process of cementation by opal

Summary

Introduction

In the construction and successive restoration of most buildings of historic and artistic interest in Avila different types of granite have been used. Composición química (%) de los elementos mayores de las cinco variedades de rocas en cantera (C) y monumento (M): Granito gris fino (GF), Granito gris grueso (GG), Granito ocre (O), Granito blanco (B) y Granito rojo (R).

Results

Conclusion