Lammerite as a Degradation Product of Emerald Green: Scientific Studies on a Rural Persian Wall Painting |
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| Authors: | Parviz Holakooei Amir-Hossein Karimy Golriz Nafisi |
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| Institution: | 1. Department of Objects Conservation, The Metropolitan Museum of Art, New?York, NY, USA;2. Department of Scientific Research, The Metropolitan Museum of Art, New?York, NY, USA;3. Department of Archaeometry, Art University of Isfahan, Isfahan, Iranparviz.holakooei@unife.it parvizholakooei@gmail.com;5. Department of Art Conservation, Art University of Isfahan, Isfahan, Iran |
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| Abstract: | Pigments on a figurative wall painting in Poudeh village, central Iran, were analysed by micro X-ray fluorescence spectrometry, micro Raman spectroscopy, scanning electron microscopy coupled with energy dispersive X-ray spectrometry, micro Fourier transform infrared spectroscopy, X-ray diffractometry, and polarised light microscopy. Red lead, ultramarine blue, chrome yellow, brass powder, white huntite, and lammerite (Cu3(AsO4)2) were identified as red, blue, yellow, golden, white, and green pigments, respectively, while gypsum and barite were used as extender. In addition, glushinskite (MgC2O4·2H2O) was identified as a deterioration product of white huntite. Moreover, several analytical studies suggested that lammerite was a degradation product of emerald green (Cu(CH3COO)2·3Cu(AsO2)2) originally used as green pigment in the painting. The formation of lammerite is suggested to be due to the migration of arsenic throughout the paint layer. Based on the pigments identified, the wall painting is dated from the mid-nineteenth century to the mid-twentieth century. |
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| Keywords: | Emerald green lammerite huntite glushinskite arsenic migration |
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