Mineralogical decay processes in stones: the case of Lleida Cathedral

This paper describes the composition, decay patterns and degradation mechan isms of the building stones and mortars of the Cathedral of Lleida (Catalon ia, Spain). Various areas present considerable damage. Four forms of decay are apparent: grain disintegration, joint mortar loss, flaking and efflores cence. The type of stone, its composition and the orientation of the buildi ng determine the appearance of the decay forms. The paper analyses these al tered mineral forms in the monument, and discusses their possible origin at the level of mineral reactions and stability.