Environmental Earth Sciences

, Volume 69, Issue 4, pp 1085–1094 | Cite as

The Angera stone: a challenging conservation issue in the polluted environment of Milan (Italy)

  • D. Gulotta
  • M. Bertoldi
  • S. Bortolotto
  • P. Fermo
  • A. Piazzalunga
  • L. Toniolo
Special Issue


The Angera stone is a sedimentary Triassic dolostone mainly composed of dolomite, which was widely employed in the Lombard architecture. In the present work, the study of the Angera stone of the ‘Cortile del Richini’, a masterpiece of the Lombard baroque, is discussed as an example of a particularly challenging conservation issue. The courtyard suffered from a particularly troubled conservative history and the highly polluted urban environment of Milan provided very favourable conditions for the decay of such a delicate stone type. The last extensive conservative intervention was performed during the nineties due to massive black crust formation and granular disintegration of the stone. Almost 20 years later, a thorough study of the stone has been aimed at the definition of a long-term maintenance project. The Angera stone has been investigated in order to define an updated version of its state of conservation, as well as to track any changes in the degradation mechanisms due to the environmental variations of the Milan city centre. In particular, the soluble salts’ content of the stone substrate has been evaluated as an indicator of the damage level. The results highlighted that the stone is currently in critical condition: An extensive sulphation process is taking place, leading to the chemical transformation of the dolomitic substrate into gypsum. Moreover, the powder deposits affecting the stone surfaces have a similar composition to those generally found in the black crusts growing in urban environment. Therefore, they can be considered as precursor of this particularly dangerous decay mechanism.


Dolostone Atmospheric pollutants Sulphation Salt decay Magnesium sulphate Stone conservation 



This research has been developed thanks to the financial support of the Fondazione Cariplo, grant no. 2009-2819.


  1. AA.VV (1993) La Ca’ Granda di Milano. L’intervento conservativo sul cortile richiniano, Progetto Monumenti Snam, MilanoGoogle Scholar
  2. Alessandrini G (1993a) Le pietre del monumento. La Ca’ Granda di Milano. L’intervento conservativo sul cortile richiniano. Progetto Monumenti Snam, MilanoGoogle Scholar
  3. Alessandrini G (1993b) Lo stato di conservazione dei materiali lapidei: morfologia e cause di degrado. La Ca’ Granda di Milano. L’intervento conservativo sul cortile richiniano. Progetto Monumenti Snam, MilanoGoogle Scholar
  4. Alessandrini G, Bugini R, Peruzzi R (1987) I materiali lapidei impiegati nei monumenti lombardi ed i loro problemi di conservazione. Materiali lapidei: problemi relativi allo studio del degrado e della conservazione. Istituto Poligrafico dello Stato, RomeGoogle Scholar
  5. Beni Culturali—NorMaL (2003) Technical standard UNI 11087. Cultural heritage—Natural and artificial stones—Water soluble salts determinationGoogle Scholar
  6. Bernardoni V, Vecchi R, Valli G, Piazzalunga A, Fermo P (2011) PM10 source apportionment in Milan (Italy) using time-resolved data. Sci Total Environ 409:4788–4795CrossRefGoogle Scholar
  7. Bonazza A, Sabbioni C, Ghedini N (2005) Quantitative data on carbon fractions in interpretation of black crusts and soiling on European built heritage. Atmos Environ 39:2607–2618CrossRefGoogle Scholar
  8. Bonazza A, Messina P, Sabbioni C, Grossi CM, Brimblecombe P (2009) Mapping the impact of climate change on surface recession of carbonate buildings in Europe. Sci Total Environ 407:2039–2050CrossRefGoogle Scholar
  9. Brimblecombe P, Grossi CM (2008) Millennium-long recession of limestone facades in London. Environ Geol 56:463–471CrossRefGoogle Scholar
  10. Colombo C, Conti C, Realini M, Sansonetti A (2006) Diagnostic studies aimed to conservation works in S. Fedele church (Milan)Google Scholar
  11. El-Metwally A, Ramadan A (2005) The role of air pollutants and sewage waste in acceleration of degradation of the Islamic cultural heritage of Cairo. Comparative risk assessment and environmental decision making. In: Linkov I, Ramadan A (eds) NATO science series IV, earth and environmental sciences. Springer, Berlin, vol 38, part 3, pp 363–370Google Scholar
  12. Ghedini N, Gobbi G, Sabbioni C, Zappia G (2000) Determination of elemental and organic carbon on damaged stone monuments. Atmos Environ 34:4383–4391CrossRefGoogle Scholar
  13. Ghedini N, Sabbioni C, Bonazza A, Gobbi G (2005) Chemical–thermal quantitative methodology for carbon speciation in damage layers on building surfaces. Environ Sci Technol 40:939–944CrossRefGoogle Scholar
  14. Grassi L (1958) La Ca’ Granda. Storia e Restauro, MilanoGoogle Scholar
  15. Grossi CM, Brimblecombe P (2008) Past and future colouring patterns of historic stone buildings. Materiales De Construccion 58:143–160CrossRefGoogle Scholar
  16. Grossi CM, Brimblecombe P, Bonazza A, Sabbioni C, Zamagni J (2006) Sulfate and carbon compounds in black crusts from the Cathedral of Milan and Tower of London, London. Taylor & Francis Ltd, New YorkGoogle Scholar
  17. ICOMOS, ISCS (2008) Illustrated glossary on stone deterioration patternsGoogle Scholar
  18. Il Cortile del Richini (2011) Project website (online). Available: http://users.unimi.it/richini/wordpress
  19. Lopez-Arce P, Garcia-Guinea J, Benavente D, Tormo L, Doehne E (2009) Deterioration of dolostone by magnesium sulphate salt: an example of incompatible building materials at Bonaval Monastery, Spain. Constr Build Mater 23:846–855CrossRefGoogle Scholar
  20. Maravelaki-Kalaitzaki P (2005) Black crusts and patinas on Pentelic marble from the Parthenon and Erechtheum (Acropolis, Athens): characterization and origin. Anal Chim Acta 532:187–198CrossRefGoogle Scholar
  21. Riontino C, Sabbioni C, Ghedini N, Zappia G, Gobbi G, Favoni O (1998) Evaluation of atmospheric deposition on historic buildings by combined thermal analysis and combustion techniques. Thermochim Acta 321:215–222CrossRefGoogle Scholar
  22. Sabbioni C (1994) L’areosol atmosferico e il degrado dei monumenti in pietra. Conservazione del patrimonio culturale. Accademia dei Lincei, RomaGoogle Scholar
  23. Sabbioni C, Zappia G, Riontino C, Blanco-Varela MT, Aguilera J, Puertas F, Van Balen K, Toumbakari EE (2001) Atmospheric deterioration of ancient and modern hydraulic mortars. Atmos Environ 35:539–548CrossRefGoogle Scholar
  24. Sabbioni C, Ghedini N, Bonazza A (2003) Organic anions in damage layers on monuments and buildings. Atmos Environ 37:1261–1269CrossRefGoogle Scholar
  25. Siegesmund S, Snethlage R (eds) (2011) Stone in conservation. Properties, durability. Springer, BerlinGoogle Scholar
  26. Siegesmund S, Török A, Hüpers A, Müller C, Klemm W (2007) Mineralogical, geochemical and microfabric evidences of gypsum crusts: a case study from Budapest. Environ Geol 52:385–397CrossRefGoogle Scholar
  27. Tambe S, Gauri KL, Li S, Cobourn WG (1991) Kinetic study of sulfur dioxide reaction with dolomite. Environ Sci Technol 25:2071–2075CrossRefGoogle Scholar
  28. Toniolo L, Zerbi C, Bugini R (2009) Black layers on historical architecture. Environ Sci Pollut Res 16:218–226CrossRefGoogle Scholar
  29. Torok A, Licha T, Simon K, Siegesmund S (2011) Urban and rural limestone weathering; the contribution of dust to black crust formation. Environ Earth Sci 63:675–693CrossRefGoogle Scholar
  30. Vecchi R, Bernardoni V, Fermo P, Lucarelli F, Mazzei F, Nava S, Prati P, Piazzalunga A, Valli G (2009) 4-Hours resolution data to study PM10 in a “hot spot” area in Europe. Environ Monit Assess 154:283–300CrossRefGoogle Scholar
  31. Winkler E (1994) Stone in architecture. Properties, durability. Springer, BerlinGoogle Scholar
  32. Zappia G, Sabbioni C, Riontino C, Gobbi G, Favoni O (1998) Exposure tests of building materials in urban atmosphere. Sci Total Environ 224:235–244CrossRefGoogle Scholar
  33. Zehnder K (2007) Long-term monitoring of wall paintings affected by soluble salts. Environ Geol 52:353–367CrossRefGoogle Scholar

Copyright information

© Springer-Verlag Berlin Heidelberg 2012

Authors and Affiliations

  • D. Gulotta
    • 1
  • M. Bertoldi
    • 1
  • S. Bortolotto
    • 2
  • P. Fermo
    • 3
  • A. Piazzalunga
    • 3
    • 4
  • L. Toniolo
    • 1
  1. 1.Dipartimento di Chimica, Materiali e Ingegneria Chimica “Giulio Natta”Politecnico di MilanoMilanItaly
  2. 2.Dipartimento di Progettazione dell’ArchitetturaPolitecnico di MilanoMilanItaly
  3. 3.Dipartimento di ChimicaUniversità degli Studi di MilanoMilanItaly
  4. 4.Dipartimento Scienze Ambientali e del TerritorioUniversità di Milano-BicoccaMilanItaly

Personalised recommendations