Contents lists available at ScienceDirect Journal of Archaeological Science: Reports journal homepage: www.elsevier.com/locate/jasrep Physicochemical investigation of prehistoric rock art pigments in Tewet Cave, Sangkulirang-Mangkalihat Site, East Kalimantan-Indonesia Nadya Nurdini a , Evi Maryanti a,b , Moh. Mualliful Ilmi a , Pindi Setiawan c , Chatree Saiyasombat d , Grandprix T.M. Kadja a,e,f, ⁎ , Ismunandar a, ⁎ a Division of Inorganic and Physical Chemistry, Institut Teknologi Bandung, Jl. Ganesha No. 10, Bandung 40132, Indonesia b Department of Chemistry, Universitas Bengkulu, Jl. W.R. Supratman, Bengkulu 38371, Indonesia c Division of Visual Communication and Multimedia, Institut Teknologi Bandung, Jl. Ganesha No. 10, Bandung 40132, Indonesia d Synchrotron Light Research Institute, 111 University Ave, Muang, Nakhon Ratchasima, Thailand e Research Center for Nanosciences and Nanotechnology, Institut Teknologi Bandung, Jl. Ganesha No. 10, Bandung 40132, Indonesia f Center for Catalysis and Reaction Engineering, Institut Teknologi Bandung, Jl. Ganesha No. 10, Bandung 40132, Indonesia ARTICLEINFO Keywords: Hematite Physicochemical characteristics Pigment Rock art Synchrotron ABSTRACT Three color samples (red, brick-red, and purple) hand stencils in Tewet Cave at the Sangkulirang-Mangkalihat site, East Kalimantan, Indonesia, were thoroughly investigated using several advanced characterizations to identify physicochemical characteristics present in the pigments. The XRD techniques investigated the minerals of the sample pigments, whereas the local geometries and electronic structure information were obtained using XANES. Synchrotron radiation was used to provide high-resolution data for both characterizations with a minimum sample. Further physicochemical characterizations were performed on XRF (the chemical composi- tions), FTIR (the bonding and functional groups), and SEM (morphology). The results showed that all three samples contained hematite, which serves as the pigments while gypsum and calcite are observed in the rock base of the paintings. Our analyses show that the tint discrepancy is due to the octahedral geometry distortion of Fe 2 O 3 . The distortion of Fe 3+ coordination in iron oxide causes an energy shift between t 2g and e g , therefore, produce diferent hues. Besides, the diferent crystallinity of the hematite within the samples give a role to color changes of iron oxide. The purple sample has the highest geometry distortion among other samples with the highest hematite content and highest crystallinity, followed by brick red and red samples. These diferences might be due to the discrepancies in the thermal treatment to, either deliberately or unintentionally, prepare the pigments. More distorted geometry and higher crystallinity are produced through the thermal treatment at higher temperatures or longer time. Our investigation may provide more in-depth insight into understanding the chemistry and engineering behind the pigment preparation. 1. Introduction Rock art or rock paintings are terms to refer to images made by prehistoric humans with various techniques on media such as rock surfaces and walls and ceilings of caves. This kind of arts has been re- garded as the source of knowledge and information from the prehistoric age. It has described within several interpretative ways, such as re- ligious-magical-functionalistic, structuralist, and post-structuralist ex- planatory (Bjeland and Helberg, 2007). As a graphic, rock art consists of three types of signs, i.e., pictograms, ideograms, and psychograms. Pictograms are identifed, such as human fgures (anthropomorphic) and animals’ fgures (zoomorphic). Ideograms are repetitive and syn- thetic signs which convey ideas from the writer to the reader (anatomic, conceptual, and numeric), including hand stencils and geometric shapes. Psychograms represent unrecognizable signs to express the imagination from the artist (Gomes et al., 2013; Tascon et al., 2016; Permana, 2015; Anati, 1994). Most of the rock paintings were created at the hunting and gatherer practices era (Upper Paleolithic) as a result of technology growth and cultural adaptations (Ferraro, 2012). Forty thousand years old rock paintings have been found in Western Europe and Indonesia (Pike et al., 2012; Aubert et al., 2014, 2018a). The oldest types of rock paintings are handprints and fgurative geometric shapes, whereas the oldest non- fgurative rock paintings have been discovered in Iberia, which are claimed to be 64,000 years old based on U-Th dating (Hofmann et al., 2018), but this claim is still in debate among scientist (White et al., https://doi.org/10.1016/j.jasrep.2020.102345 Received 15 November 2019; Received in revised form 20 March 2020; Accepted 28 March 2020 ⁎ Corresponding authors at: Division of Inorganic and Physical Chemistry, Institut Teknologi Bandung, Jl. Ganesha No. 10, Bandung 40132, Indonesia. E-mail addresses: kadja@chem.itb.ac.id (G.T.M. Kadja), ismu@chem.itb.ac.id (Ismunandar). Journal of Archaeological Science: Reports 31 (2020) 102345 2352-409X/ © 2020 Elsevier Ltd. All rights reserved. T