A Raman, IR and XRD analysis of the deterioration on historical monuments: case study from Mexico.

Raman, infrared and XRD analysis have been applied to the examination of deterioration on historical monuments (Morelia, Mexico). Forty-three samples pyroclastic volcanic rocks (ignimbrites) have been studied, all originating from two ex-convents San Francisco and San Agustin, which were the first architectonic complexes in the city of Morelia. Several new mineral neoformation such as sulfates, carbonates, halides, and phosphates were identified in these samples with spectrometric and XRD technique. The observed Raman and infrared spectra are reported and some mineral compound assignments in unaltered and deteriorated volcanic rocks have been made. This survey is the first Raman and infrared spectrometric examination of the environmental mineralogy in Mexico under conditions of urban weathering that are characterized mainly by one secondary alteration formations of low scale.