Spectrochimica Acta Part A 75 (2010) 1398–1402 Contents lists available at ScienceDirect Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy journal homepage: www.elsevier.com/locate/saa Argentinean prehistoric pigments’ study by combined SEM/EDX and molecular spectroscopy L. Darchuk a,b,∗ , Z. Tsybrii b , A. Worobiec a , C. Vázquez d,e , O.M. Palacios f , E.A. Stefaniak a,c , G. Gatto Rotondo a , F. Sizov b , R. Van Grieken a a Department of Chemistry, University of Antwerp, BE 2610 Antwerp, Belgium b Department of IR Devices, Institute of Semiconductor Physics, NASU, Kyiv, Ukraine c Department of Chemistry, Catholic University of Lublin, Poland d Department of Chemistry, Buenos Aires University, Argentina e Department of Chemistry, Atomic Energy Commission, Buenos Aires, Argentina f CONICET-CIAFIC Group, Buenos Aires University, Argentina article info Article history: Received 22 October 2009 Received in revised form 12 January 2010 Accepted 27 January 2010 Keywords: Prehistoric pigments Red and yellow ochre Green earth Micro-Raman FTIR SEM/EDX abstract Composition of the prehistoric pigments’ (from Carriqueo rock shelter, Rio Negro province, Argentina) has been analysed by means of molecular spectroscopy (Fourier transform infrared (FTIR) and micro- Raman) and scanning electron microscopy (SEM) coupled to an energy-dispersive X-ray spectrometer (EDS). Red and yellow pigments were recognized as red and yellow ochre. The matrix of the pigments is composed of one or more substances. According to the matrix composition yellow and red pigments were also divided into two groups—i.e. those containing kaolinite or sulphates. Green pigment was detected as green earth, made up of celadonite as a chromophore. © 2010 Elsevier B.V. All rights reserved. 1. Introduction Natural earths have been used as pigments since prehistoric times. They have been found in artworks all over the world and in any historical period, probably due to their availability, high colour- ing capacities and stability to the light and to the different weather conditions. Ochre is natural earth pigment varying from yellow to red and brown shades. The colour shade of ochre depends on the type of the iron oxide chromophore. The red ochre contains mainly haematite (Fe 2 O 3 ), while the yellowish one is rich in hydrated iron oxide (goethite, FeO·OH) [1]. The presence of other minerals, such as clay minerals or some metal oxides, can also influence the colour of the ochre. The classification of ochre can be also made according to the matrix composition of kaolinite (Al 2 SiO 5 )(OH) 4 and/or gypsum (CaSO 4 ·2H 2 O), and/or sulphate [2]. Green earth is a clay pigment consisting of hydrated iron, magnesium, and alu- minium potassium silicates. Colour varies from a dark, greyish blue green to a dark, dull yellowish green. The colour of green ∗ Corresponding author at: Department of Chemistry, University of Antwerp, BE 2610 Antwerp, Belgium. Tel.: +32 32652345. E-mail address: larysa.darchuk@ua.ac.be (L. Darchuk). earth is derived from the presence of the minerals: glauconite or celadonite [2,3]. As the yellow and red ochre, the green earth or “terre verte” has been used as a pigment all over the world since ancient times. Studies on natural pigments play a very important role in the archaeological investigations in Argentina, but only a few attempts have been made to characterize pigments composition from the North Patagonia area. The literature investigations on this subject being limited to XRD, SEM and FTIR have shown that hematite, goethite, manganese dioxide and green earth were the main inor- ganic pigments used [4–10]. The samples investigated in this work are prehistoric powdered pigments, collected during an excavation in Argentina (the North Patagonia region) from different ground layers, corresponding to different historical periods up to 2600 ± 100 BP years. The pigment powders were found in the Carriqueo rock shelter archaeological site. The Carriqueo rock shelter (S 40 ◦ 37 ′ 27 ′′ ; W 70 ◦ 31 ′ 42 ′′ ) is located on the west side of La Oficina canyon, a tributary of the Limay river, Pilcaniyeu area, in the Río Negro province [11,12] (Fig. 1). From the archaeological point of view, Carriqueo town was a small specialized site with a doubtless both hunting activity and to a less extent, the sedentary living stile. From November to December 2006, the archaeological site Car- riqueo shelter was studied by Crivelli Monteroet al. [12]. 1386-1425/$ – see front matter © 2010 Elsevier B.V. All rights reserved. doi:10.1016/j.saa.2010.01.006