An International Journal of MINERALOGY, CRYSTALLOGRAPHY, GEOCHEMISTRY, ORE DEPOSITS, PETROLOGY, VOLCANOLOGY and applied topics on Environment, Archaeometry and Cultural Heritage DOI: 10.2451/2014PM0017 Periodico di Mineralogia (2014), 83, 3, 313-327 PERIODICO di MINERALOGIA established in 1930 An International Journal of MINERALOGY, CRYSTALLOGRAPHY, GEOCHEMISTRY, ORE DEPOSITS, PETROLOGY, VOLCANOLOGY and applied topics on Environment, Archaeometry and Cultural Heritage Chemical and physical characterization of the stucco mihrab of the mausoleum of Muhammad Al-Hasawati, Fatimid period, Cairo, Egypt Abdullah M.A. Kamel 1, * , Hassan A.H. Marie 2 , Mona F. Ali 1 and Hala A. Mahmoud 1 1 Department of conservation, Faculty of Archaeology, Cairo University, 12613 Giza, Egypt. 2 Prof. of Building Materials at National Center for Housing and Building Research, Giza, Egypt * Corresponding author: dandarawy_241@cu.edu.eg Abstract Stucco mihrabs in Islamic buildings in Egypt are suffering from many causes of deterioration, mainly groundwater and salt weathering, which have caused the complete loss of the decorations of some of these mihrabs. Some other mihrabs need restoration and conservation, so a solution for this problem has become urgent. A physiochemical study using analytical techniques such as X-ray diffraction, X-ray fluorescence, Fourier transform infrared and scanning electron microscopy was done. This characterization study, on one hand made reproduction of the original material possible; on the other hand, the deterioration factors of the stucco were determined. All analytical methods indicated that the Al-Hasawaty stucco mihrab contains lime, gypsum, dolomite, quartz, anhydrite and bassanite; they also proved that sodium chloride (halite) is the principal salt causing deterioration. Key words: stucco; mihrab; gypsum; lime; deterioration; conservation. Introduction The mausoleum of Muhammad Al-Hasawati (519-550 A.H. / 1125-1150 A.D.), is a small mausoleum that lies about 60 yards south-west of the mausoleum of Imam ash-Shafi. It is constructed of brick and coated with stucco, (Figure1). The stucco mihrab of the mausoleum bears the closest possible relationship to that of Sayyida Ruqayya, and is only very slightly exceeded by the latter in size and richness of decoration. It has the same fluted conch with a