『Abstract
　Gypsum-rich coatings found on buildings constructed with granitic rock ashlars have been studied, from both an urban and a rural area of the NW of Spain. Previous works have attributed gypsum to rock weathering by atmospheric pollution. Mineralogical, chemical, and physical data of coatings have allowed us to distinguish six different types of coatings formed in several ways. In most cases, they are originated by the deterioration calcium-rich plaster building materials. Sulfation of Ca-rich coatings, in situ gypsum dissolution and precipitation, and deposition of air pollution particles are the most important agents related to genesis of coatings. In fact, remains of plasters practically intact were found in some studied buildings. Also, data from coatings and rock ashlars suggest that gypsum-rich coatings are not formed by environment-rock interaction. Coatings located on different parts and facades（cにセディーユが付く） of the buildings and submitted to different environmental conditions decay in a different way.

Keywords: Air pollution; Gypsum crusts; Granite rocks; Heritage; Rock decay』

1. Introduction
　1.1. Study area
　1.2. Features of the studied buildings
2. Methods
3. Results
　3.1. Type 1
　3.2. Type 2
　3.3. Type 3
　3.4. Type 4
　3.5. Type 5
　3.6. Type 6
4. Discussion
　4.1. Influence of the building characteristics
　4.2. Influence of environmental factors
　4.3. Coatings development
5. Conclusions
Acknowledgments
References