Contents lists available at ScienceDirect Applied Clay Science journal homepage: www.elsevier.com/locate/clay Research paper Mineralogical and thermal analyses of the Hellenistic ceramics from Laodicea Temple, Iran Maria Daghmehchi a, ⁎ , Christina Rathossi b , Hadi Omrani c , Mohammadamin Emami d , Mehdi Rahbar e a University of Tehran, Department of Archaeology, Tehran 6619-14155, Iran b University of Patras, Section of Earth Raw Materials, Department of Geology, 26504 Rio Patra, Greece c Golestan University, Department of Geology, Gorgan 49138-15759, Iran d Art University of Isfahan, Department of Conservation, Isfahan 1744, Iran e Research Institute of Cultural Heritage and Tourism (RICHT), Iran ARTICLE INFO Keywords: Hellenistic ceramics TGA-DTA FTIR XRD Laodicea temple ABSTRACT In this study, thermal behavior of the Hellenistic ceramics from Laodicea Temple (Seleucid period), Iran, was investigated through spectroscopic, thermogravimetric, mineralogical and chemical analyses. The results in- dicate the same calcareous raw material was used for the ceramic production. On the basis of X-ray diffraction (XRD), four firing temperature ranges can be established: T < 750 °C, 850–900 °C, 950–1000 °C and 1000–1050 °C. These ceramics were differentiated based on different mineralogical phases resulting from the different firing temperatures. For low temperature fired ceramics, the main crystalline phases were calcite and quartz. Gehlenite is the predominant new mineral at 850 °C. CaO reacts with gehlenite and forms anorthite at around 950 °C. Diopside grows with increasing firing temperature up to 1050 °C in the Ca and Mg-rich clayey compositions and an oxidizing atmosphere, corroborated by trace hematite. The contemporaneous presence of secondary calcite and newly formed crystalline phases (diopside, gehlenite) at high temperatures indicates fast heating rate and/or short soaking time as well as coarse-grained primary calcite. Fourier Transform-Infrared (FT- IR) spectrometry indicates a considerable change in phase structures and a progressive decrease and broadening in calcite bands as a function of firing temperature. 1. Introduction Thermal transformation, dehydration, and dehydroxylation of mi- nerals contribute considerably to determination of firing temperatures of the Hellenistic ceramics (Ravisankar et al., 2014). The reaction-dif- fusion processes of high T new phases clearly reveal the firing tech- nology and raw material sources of the ceramics (Cultrone et al., 2001). The clay composition, firing temperature and atmosphere during the firing of ceramics contribute to the final color of the ceramics (Felicissimo et al., 2010). Therefore, the thermal behavior and the chemical-mineralogical composition of the ceramics can be the actual parameters for the ceramic classification. Firing technology and raw materials source also document the presence of new manufacturing techniques in comparison with Chilinky ceramics in Hellenistic period in western Iran (Noghani and Emami, 2014). XRD was used to identify of the mineralogical composition and determine the firing ranges of the ceramics. The investigation of Maritan et al. (2015) proves that XRD data provide a powerful means for assessing mineral transformation during firing processes. The results were also confirmed by TGA-DTA and FTIR techniques. Thermogravi- metric analysis (TGA) and differential thermal analyses (DTA) of the fired ceramic bodies determine different thermal effects with increasing firing temperature, thus are useful to identify maximum firing tem- perature of the ceramics. FTIR indicates the transition of phase struc- ture during firing of the ceramics which were produced with calcareous clay, and consequently provides further information for assessing the firing temperature and firing conditions of the ceramics (Akyuz et al., 2008; Barone et al., 2011; Medeghini et al., 2016). FTIR spectra also differentiate ceramic provenance due to the heterogeneous nature of ceramic materials (Medeghini et al., 2016). SEM observations, and chemical analyses were further conducted to investigate their micro- structural and chemical characterizations at different firing tempera- tures. SEM analysis documents the textural features of the ground mass and the degree of vitrification (Andaloro et al., 2001). https://doi.org/10.1016/j.clay.2018.06.007 Received 14 April 2018; Received in revised form 7 June 2018; Accepted 9 June 2018 ⁎ Corresponding author. E-mail address: Maria.daghmehchi@yahoo.com (M. Daghmehchi). Applied Clay Science 162 (2018) 146–154 0169-1317/ © 2018 Elsevier B.V. All rights reserved. T