Monitoring of Origin and Evolution of Building Stones through Their Major Components

The aim of this work is to establish the original quarries used to construct the Roman bridge in Salamanca (Spain). Nineteen granite-type samples from the bridge were obtained. For comparison, 12 samples were taken from eight different quarries, where the original stones were probably exploited. The study is based on element chemical analysis for major elements. The results have been statistically analyzed using an inertia method based on an HJ-biplot. This method permits the characterization of three different clusters of samples and relates them to the original quarries, from the chemical composition of the samples. We conclude that the following three types of granite were used in the Roman bridge of Salamanca: (1) granodioritic granites from the Los Santos quarry, in Salamanca; (2) leucogranites from quarries in Villaseco de los Gamitos, Ledesma, Trabanca, and Zorita (Los Arribes, Salamanca); and (3) vaugneritic granites, probably from the quarry in Ledesma (Salamanca). The chemical changes produced by weathering of the different types of granites through the different decay processes in different areas of the Roman bridge in Salamanca have also been observed.