Compositional characteristics of late Islamic turquoise glazed stonepaste wares of Iran

Abstract

The turquoise glaze, with a broad spectrum of tones from yellowish green to bluish green, has been a prominent type of ceramic glazes for over two thousand years in West Asia. While ceramics with this glaze of the Sasanian and early Islamic periods has long been in the spotlight of ceramic scientists, those of the late Islamic period has been largely neglected. The authors, making use of 5 samples of Qajar period turquoise glazed stonepaste wares excavated from Tepe Naderi in North Khorasan Province, Iran, seek to investigate the compositional characteristics of such products of the late Islamic period. It appears that the bodies of these samples are characterized with high silicon and high alkali, a hallmark of the traditional Iranian stonepaste. They are coated with transparent alkali glazes with Na2O as main flux and painted with chromogenic elements of Cu, which is derived from Chalcocite, and Fe. The interaction of these and other elements produces Diopside (CaMg(SiO3)2) and Wollastonite (CaSiO3) in the glaze. The site of production for these samples cannot be located at present, however, due to the lack of study of late Islamic turquoise-glazed ceramics in West Asia.