Gypsum in Minoan architecture : exploitation, utilisation and weathering of a prestige stone
The present research examines the use of gypsum as a building and ornamental stone in Minoan palatial architecture during New Palace period. Survey, of the outcrops and the buildings, indicates a limited distribution of architectural gypsum that is exclusively used in the finest rooms of the most outstanding. Neopalatial buildings of central and east Crete, and assigns a prestige character and a symbolic significance to the material. Furthermore, the abundance of gypsum in the outcrops, in contrast to its limited systematic quarrying, suggests a controlled access to the outcrops, restricting its use to the elite of the society. A detailed examination of four thousands gypsum architectural members from Knossos, Phaistos, Agia Triada, Megaron Nirou and Pyrgos, provides insights into the provenance, the methods of production and supply, the variations and similarities in the range and popularity of forms between sites and allows the estimation of the total volume of gypsum per site and architectural function. Provenance was investigated by means of comparative petrographic study of the gypsum varieties that occur at both outcrops and archaeological sites. Examination of samples from Knossos, Phaistos, Agia Triada, Megaron Nirou, Pyrgos, Galatas, Zakros, Palaikastro, Pseira and the Neogene outcrops that are located in the region of each site indicated that the Knossian quarries supplied Megaron Nirou, Zakros, Palaikastro and Pseira, while Phaistos, Agia Triada, Galatas and Pyrgos exploited their own local sources. The predominant weathering forms that occur on Minoan gypsum were classified and described with respect to the crystallographic characteristics of the material and the factors and mechanisms of deterioration.