Characterization of stone from the Metropolitan Cathedral and from the facade of the National Museum at Tepotzotlan, Mexico

The deterioration of stone monuments in urban atmospheres mainly involves corrosion by acid solutions. Thus the characterization of the material is of great importance in the understanding of stone decay. In this work, samples were taken from the balcony of the Metropolitan Cathedral (Mexico City), from three different areas of the facade of the National Museum of Tepotzotlán (NW of Mexico City) and also, for comparison, new fresh stone from the quarries of Chiluca and Los Remedios. Mineralogical, petrographic, chemical and structural analyses were carried out on all the samples, and a relationship was established between the degree of decay and the stone characteristics, such as porosity, specific surface area and calcium content. The characterization of the type of stone also influences the selection of conservation treatments.