An infrared microspectroscopic study of plasters and pigments from the Neolithic site of Bestansur, Iraq

Abstract

Infrared (IR) Spectroscopy and microspectroscopy (μ-IR) supported by Environmental Scanning Electron Microscope-Energy Dispersive X-Ray analysis (ESEM-EDX) has been utilised to investigate the technology and use of multicoloured architectural plasters and pigments by Neolithic communities at the archaeological site of Bestansur, Iraq, c. 7,600 BC. Sub-samples of architectural materials and pigments were analysed using IR spectroscopy and fragile samples and thin sections were analysed using μ-IR and ESEM-EDX to determine the mineralogical and elemental composition of individual components and layers and the history of construction and use of three large rectilinear buildings. In addition, experimental investigations were undertaken into the application of IR to study of the firing of calcium carbonate and of clays to investigate if this technique was able to detect evidence of fired-lime materials and of reddening of building materials by fire. Whilst the IR analysis alone was not able to characterise the plasters and pigments, when combined with ESEM-EDX the minerals responsible for pigmentation in the samples were clearly identified. The green clay was determined to be local celadonite-bearing marine clays. The red pigment was found to contain iron, most likely in the form of hematite. The black pigment contained manganese and iron, likely to be present as manganese dioxide and magnetite. The investigations of firing indicate that a hard white exterior may come from fired-lime while a reddish silty clay wall surface had probably not been subject to high-temperature burning. Analysis of a series of wall plasters and pigments from Building 8 (pre-7,600 BC) revealed experiment and development in technologies and materials throughout the occupation of the building, which in the final sequence resemble those from significantly later level at the site of Çatalhöyük, Turkey (c. 7,000 BC).

Pre‐Pottery Clay Innovation in the Zagros Foothills

“…The clay‐rich deposits of the Mesopotamian plains and Zagros intermontane valleys are the result of orogenic activity, and the accompanying transgression and regression of the Tethys Sea (Khormali and Abtahi ; Abbaslou and Abtahi ; Godleman et al . ). Clays are the common denominator in the settlements of the Neolithic, used for constructing dwellings, lining pits and baskets, and for making tokens, figurines and, in the late Neolithic, vessels and trays.…”

“…At the Neolithic settlement of Bestansur, we see different clays used in the construction of buildings (Godleman et al . ). Similar patterns of selection may have been a feature of the process of planning for making smaller objects in clay.…”

“…Across south‐west Asia, people shared common practices of house construction, applying fired lime and pigments throughout living spaces (Godleman et al . ; W. Matthews ).…”

“…This malleable, adaptable material was transformed to serve a range of purposes, for cooking, constructing, roofing and plastering (Richardson ; Iversen ; Godleman et al . ; W. Matthews ). Lining the walls of cooking pits and the base of hearths, fire‐hardened clays provided infrastructure for the inhabitants of the Neolithic settlement at Bestansur.…”

“…The collision zone has exposed Mesozoic sediments, predominantly composed of limestone, with marble, alabaster and chert, as well as less commonly occurring gabbro, diorite and basalt (Karim et al 2009); nodules and cobbles of these materials have eroded from the rocky outcrops and can be gathered from the riverbeds (Jassim et al 1982;Al-Barzinjy 2008;Azizi et al 2013). The clay-rich deposits of the Mesopotamian plains and Zagros intermontane valleys are the result of orogenic activity, and the accompanying transgression and regression of the Tethys Sea (Khormali and Abtahi 2005;Abbaslou and Abtahi 2008;Godleman et al 2016). Clays are the common denominator in the settlements of the Neolithic, used for constructing dwellings, lining pits and baskets, and for making tokens, figurines and, in the late Neolithic, vessels and trays.…”