Gypsum-induced decay in granite monuments in Northwestern Spain


  • B. Silva Hermo Universidad de Santiago de Compostela
  • B. Prieto Lamas Universidad de Santiago de Compostela
  • T. Rivas Brea Universidad de Vigo
  • L. Pereira Pardo Universidad de Santiago de Compostela



monuments, granite, gypsum, plaque shedding, stone decay


One of the most common forms of decay in granite monuments is the detachment of the superficial layer of the stone (plaques, plaquettes and scales). Previous studies of granite monuments in the northwest Iberian Peninsula revealed a direct relation between this type of weathering and the presence of calcium sulphate, and a mechanism whereby the salt causes this type of decay was suggested. In the present study, various hypotheses as regards the origin of the gypsum found in granite monuments are proposed. The study involved analysis of the contents of ions soluble in water, the results of X-ray diffraction analyses and the ratios of CaO/SO3 in samples of stone, mortar and deposits collected from different monuments. It was concluded that in most cases the gypsum originated from old paintworks or/and from the joint mortars, although inputs from other sources cannot be discounted, as discussed


Download data is not yet available.


(1) Evans, I. S.: “Salt crystallisation and rock weathering: a review”. Revue de Geomorphologie Dynamique, 1er année, nº. 4 (1970), pp. 153-177.

(2) Arnold, A.; Zehnder, K.: “Salt weathering in monuments”. Proc. I. Int. Symp. Conservation of Monuments in the Mediterranean Basin., F. Zezza (ed.), Hari (1989), pp. 31-58.

(3) Charola, A. E.: “Salts in the deterioration of porous materials: an overview”. Journal of America Institute if Conservation 39 (2000), pp. 327-343.

(4) Doehne, E.; Selwitz, C. X.; Carson, D.; de Tagle A.: “Damage to monuments from the crystallization of mirabilite, thenardite and halite: mechanisms, environment and preventive possibilities”. 11th Annual V.M. Goldschmidt Conference (2001).

(5) Rodríguez-Navarro, C.; Doehne, E.; Sebastian, E.: “How does sodium sulfate crystallize? Implications for the decay and testing of building materials”. Cement and Concrete Research 30 (2000), 1527-1534. doi:10.1016/S0008-8846(00)00381-1

(6) Tsui, N.; Flatt, R.; Schere, G. W.: “Crystallization damage by sodium sulphate”. J. Cultural Heritage 4 (2003), 109-115. doi:10.1016/S1296-2074(03)00022-0

(7) Lazzarini, L.: “I graniti dei monumenti italiani ed il loro problemi di deterioramento”. Bolletino d’Arte del Ministerio per I Beni Culturali e Ambientali, nº 41/1987, 157-172.

(8) Esbert, R. M.: “Alteration of granite stone used in building construction”. Materiales de Construcción, vol. 57, 288 (2007), pp. 77-89.

(9) Casal, M.; Silva, B; Delgado, J.: “Agents and forms of weathering in granitic rocks used in monuments”. Proc. Europ. Symp. Science, Technology and European Cultural Heritage. N. S. Baer, C. Sabbioni and D. I. Sors (ed.), Bologna (1989), pp. 439-442.

(10) Alonso, F. J.; Vázquez, P.; Esbert, R. M.; Ordaz, J.: “Ornamental granite durability: evaluation of damage caused by salt cristalization”; Mater. Construcc., vol 58, nº 289-290 (2008), pp. 191-201.

(11) Silva, B.; Rivas, T.; Prieto, B.: “Soluble salts in granitic monuments: origin and decay effects”. Applied Study of Cultural Heritage and Clays. J. L. Pérez (ed.) (2003), pp. 113-130.

(12) Silva, B.; Rivas, T.; Prieto, B.; Delgado, J.: “A comparison of the mechanisms of plaque formation and sand disintegration in granite in historic buildings”, Degradation and Conservation of granitic rocks in monuments. M. A. Vicente, J. Delgado, J. Acevedo (ed.), European Commission DG XIII, Bruselas (1996), pp. 269-274.

(13) Silva, B.; Rivas, T.; Prieto, B.: “Relation between type of soluble salt and decay forms in granitic coastal churches in Galicia (NW Spain)”. European Commission Research Workshop Origin, Mechanisms and Effects of Salts on Degradation of Monuments in Marine and Continental Environments. Zezza (ed.). DGXII, Protection and Conservation of the European Cultural heritage, Bari (1996).Research report nº 4, pp. 181-190.

(14) Silva, B.; Rivas, T.; Prieto, B.; Casal, M.; Guitián, F.: “Forms and factors of weathering in the Cathedral of Santiago de Compostela”. Proceedings of VII International Congress on Deterioration and Conservation of Monuments in The Mediterranean Basin. Venecia (1994), pp. 743-748.

(15) Casal, M.; Delgado, J.; Silva, B.: “Construction materials and decay problems of Salome church in Santiago de Compostela”, Proceeding of the VII Int. Congress on Deterioration and Conservation of Stone, vol. 1 (1992), pp. 3-11.

(16) Rivas, T.; Prieto, B.; Silva, B.: “Plaque-shedding by granite in the Monastery of San Martín Pinario (Santiago de Compostela, NW Spain)”, Proceedings of the VII International Congress on Deterioration and Conservation of Monuments in the Mediterranean Basin, Venecia, Italia (1994), pp. 737-742.

(17) Sistema de Información Medioambiental de Galicia SIAM, Xunta de Galicia. Informe estadístico sobre calidad del aire, 2007. Accesible por Internet (

(18) Cabrera, J. M.: “Materiales de reparación: sus mecanismos de actuación y criterios de selección”, Actas de las jornadas sobre restauración y conservación de monumentos, Madrid (1989), pp. 89-100.

(19) Cabrera, J. M.: “Contaminación y patrimonio. Punto de vista del restaurador”, Actas del encuentro europeo sobre Patrimonio Histórico Artístico y contaminación, Madrid (1992), pp. 59-63.

(20) Prieto, B.; Aira, N.; Silva, B.: “Comparative study of dark patinas on outcrops and buildings”, Sci. Tot. Env. 381 (2007), pp. 280-289. doi:10.1016/j.scitotenv.2007.04.002 PMid:17499341

(21) O’Brien, P. F.; Bell, E.; Santamaría, S. P.; Boyland, P.; Cooper, T. P.: “Role of mortars in the decay of granite”. Sci. Tot. Env. 167 (1995), 103-110. doi:10.1016/0048-9697(95)04573-J

(22) Cooper, T. P.; Dowding, P.; Lewis, J. O.; Mulvin, L.; O’Brien, P.; Olley, J.; O’Daly, G.: “Contribution of calcium from limestone and mortar to the decay of granite walling”. Science, Technology and European Cultural Heritage. N.S. Baer, C. Sabbioni and A.I. Sors (eds.). Butterworth-Heineman, Oxford (1991), pp. 456-461.

(23) Wittenburg, C.; Dannecker, W.: “Salt enrichment in building stones by deposition of sulphur and nitrogen containing species from urban atmospheres”. In: Proc. 3rd Int. Symp. on the Conservation of Monuments in the Mediterranean Basin. IGCMM (1994), pp. 179-183.

(24) Furlan, V.; Girardet, F.: “Pollution atmospherique et reactivité des pierres”. Proc. VII Int. Cong. Deterioration and Conservation of Stone, Delgado, Henriques and Telmo (eds.). Lisboa (1992) vol. 1, pp. 153-161.

(25) Rivas, T.; Prieto, B.; Silva; B.: “Gypsum formation in granitic rocks by dry deposition of sulphur dioxide”. Proceedings of the IV Int. Symp. on the conservation of monuments in the Mediterranean Basin, Rhodes (1997), pp. 263-270.

(26) Rivas, T.; Prieto, B.; Silva, B.: “Artificial weathering tests of granitic rocks”. Mater. Construcc., vol. 58, nº 289-290 (2008), pp. 179-189.

(27) Schiavon, N.; Chiavari, G.; Fabbri, D.; Schiavon, G.: “Microscopical and chemical analysis of black patinas on granite”. Proceedings of the III Int. Symposium on the conservation of monuments in the Mediterranean Basin, Venice, Italy (1994), pp. 93-95.

(28) Prieto, B.; Seaward, M. R. D.; Edwards, H. G. M.; Rivas, T.; Silva, B.: “An FT-Ramman spectroscopic study of gypsum neoformation by lichens growing on granitic rocks”. Spectrochimic. Acta. A., vol. 55 (1999), pp. 211-217. doi:10.1016/S1386-1425(98)00245-5




How to Cite

Silva Hermo, B., Prieto Lamas, B., Rivas Brea, T., & Pereira Pardo, L. (2010). Gypsum-induced decay in granite monuments in Northwestern Spain. Materiales De Construcción, 60(297), 97–110.



Research Articles

Most read articles by the same author(s)