A Study of Geometric Ornaments of Plaster Mihrabs Made between 12th and the mid-14th Centuries in Iran

The geometric ornaments are considered as a kind of decorating that has been used mostly in the Islamic art, alone and sometimes in conjunction with other motifs or inscriptions. The plaster altars made between 12th and the mid-14th centuries towards the Seljuk and Ilkhanid dynasties, are also considered as the works that have been decorated using various plant decorations and inscriptions, as well as different geometric designs. The goal of this research is to introduce and compare different kinds of geometric ornaments used in the plaster altars of the mentioned centuries in terms of diversity, sustainability or repetition and place of application in different parts of the altars. Therefore, the main question of this research is arisen as follows: what are geometric ornaments of the plaster altars made between the 12th and the mid-14th centuries and what are their similarities and differences in terms of the type of designs and their place of application in different parts of the altars made during the Seljuks and Ilkhanids? The data was collected through field research, i.e. photography, and linear designing of the images, referring to the written resources and was analyzed through a comparative-historical method. The results, obtained from studying 40 plaster altars made during this period, show that in both periods, the majority of ornaments are composed of numerical knots on the basis of six, like “six and roundel”, “six and three rounding fairies”, etc. that are mostly seen on the half-columns and face or side walls of the plaster altars. The geometric, zigzag, chain and wicker-like designs have been repeated frequently along the narrow margins. The most significant differences of the altars made during Ilkhanids in terms of geometric ornaments are using more knots, simple geometric figures, more detailed and diverse geometric designs along narrow margins and combinations of knots with motifs (flower and leaf).