ALTERATION PROCESSES OF HISTORICAL GRANITIC ROCK FOUND IN AVILA, SPAIN

Abstract

Granitic rock presenting varying alteration processes were sampled from three of five tombs unearthed in Ávila (Spain). The origin of these processes could be both biogenetic and climatic. The purpose of this study is to examine the alteration processes in granitic rocks from the tombs in the area around the Church of San Andrés (Ávila) and to compare these archaeological materials with similar raw materials that could have been employed in their construction. Samples of granitic rock used in the constructive elements of tombs were collected from the same location to compare their physicochemical properties with granite from local quarries. The physical properties of the samples were studied by Polarisation Microscopy and their porosity was determined by BET methodology. Their major and minor constituents were analysed by ICP-MS and their most relevant crystalline mineral compounds (quartz, opal, plagioclase, potassic feldspars, phyllosilicates and hematite) were quantified using X-Ray Diffraction Spectrometry