Natural stones have represented one of the main building materials since ancient times.In recent decades, a worsening in degradation phenomena related mostly to environmental pollution was observed, threatening their conservation.The present work is focused on the minero-petrographic and geochemical characterization of black crust (BC) samples taken from the historical center of Naples, after selecting two pilot flexcon reverse osmosis water storage tank monumental areas.The latter were chosen based on their historical importance, type of material, state of preservation and position in the urban context (i.
e., high vehicular traffic area, limited traffic area, industrial area, etc.).The building materials used and their interaction with environmental pollutions were studied comparing the results obtained by means of different analytical techniques such as polarized light Optical Microscopy (OM), scanning electron microscopy with energy dispersion system (SEM-EDS), X-ray powder diffraction (XRPD) and laser ablation coupled whole wheat phyllo dough with inductive plasma mass spectrometry (LA-ICP-MS).