Results of long-term researches of mineralogy of a natural patina on a surface of bronze monuments of St.-Petersburg are generalized. It is shown that such patina doesn\'t possess sufficient resistance against aggressive influences of the air environment and doesn\'t provide safety of monuments. The insignificant centers of bronze illness are present on the majority of monuments. The contribution of internal factors (structure and homogeneity of an alloy, quality of a surface, a state of an internal reinforcement), and also of the presence and a state of protective coating for speed of corrosion is great and in many cases exceeds environment influence.
Keywords: a patina, atmospheric corrosion, copper minerals, brochantite, antlerite, malachite, cuprite, atakamite,nantakite, kalyumetite.