Characterization of the Stone Masonries and Evaluation of the Environmental Impact in Panam Viejo: A Contribution for the Conservation of the Monumental Complex

A fundamental step in the best preservation of heritage materials is investigating their chemical and physical characteristics, and understanding how they interact with the surrounding environment. For this reason, the stone masonry of the monumental UNESCO site of Panama Viejo was subjected to a thorough study to characterize the materials and evaluate their state of conservation. Additionally, potential outcrops were explored in order to identify sites for the supply of raw materials. The methodological approach encompassed mineralogical-petrographic investigations using stereomicroscopy, polarized light microscopy (PLM), X-ray powder diffraction (XRPD), scanning electron microscopy and energy dispersive X-ray spectrometry (ESEM-EDS) and X-ray fluorescence (XRF). The results revealed that the masonries primarily consists of polygenic breccia, basaltic andesite, rhyodacite, tuffite, and rhyolite. In addition, at the potential quarries, breccia and basaltic andesite were identified. The porous structure was studied using mercury intrusion porosimetry (MIP). Possible issues due to salt dissolution/crystallization cycles were considered. Consequently, ion chromatography (IC) was conducted on samples exhibiting alteration patinas to study the presence of soluble salts. In assessing the state of conservation, prevalent forms of deterioration included biological colonization, detachments, material loss, potential salt weathering, and chromatic alteration. In conclusion, the outcomes of this work provide a valuable resource for the current and future preservation of this site.