『Abstract
Under natural acid and wet conditions, one of the main weathering
processes affecting granitic rocks is the kaolinisation of Na,
Ca and K-feldspar minerals by H2O + CO2 attack. We here report the occurrence of authigenic
kaolinite on the surface of an eighteenth century granitic monument
covered with sulphate-rich weathering patinas. We suggest that,
in humid mesothermic climates, anthropogenically derived gaseous
SO2 from air pollution is responsible for
accelerated kaolinisation of feldspars in an urban environment;
SO2 from air pollution thus plays a dual
role in the weathering of silicate rocks being responsible for
the well known sulphation of Ca-bearing materials leading to the
formation of sulphate salts such as gypsum as well as the weathering
of feldspar minerals to kaolinite. the kaolinisation reaction
weakens the granite mirofabric leading to enhanced decay of the
building stone.
Keywords: Granite; Urban environment; sulphur dioxide; Feldspar;
Kaolinite; Weathering』
Introduction
Materials and methods
Results
Discussion
Conclusions
Acknowledgments
References