Mineralogical evolution of salt over nine years, after removal of efflorescence and saline crusts from Elche's Old Bridge (Spain)

The chemical composition of groundwater, with a high sodium chloride component and much lower concentrations of sulfate and bicarbonate, explained the presence of halite, while the presence of demolition waste of a gypsiferous nature near the bridge explained the presence of sulfate salts, thenardite, konyaite, aphthitalite, and arcanite. The dissolution of airborne particles in condensation water probably contributed to the genesis of nitrate-rich minerals such as nitratine, darapskite, and especially humberstonite.