Micro‐Raman spectroscopy and complementary techniques (hXRF, VP‐SEM‐EDS, μ‐FTIR and Py‐GC/MS) applied to the study of beads from the Kongo Kingdom (Democratic Republic of the Congo). (10th February 2017)

• Record Type: Journal Article
• Authors: Coccato, Alessia; Costa, Mafalda; Rousaki, Anastasia; Clist, Bernard‐Olivier; Karklins, Karlis; Bostoen, Koen; Manhita, Ana; Cardoso, Ana; Barrocas Dias, Cristina; Candeias, António; Moens, Luc; Mirão, José; Vandenabeele, Peter
• Other Names: Korsakov Andrey V. guestEditor.; Marshall Craig Patrick guestEditor.
• Is Part Of: Journal of Raman spectroscopy. Volume 48:Number 11(2017)
• Page Start: 1468
• Page End: 1478
• Publication Date: 2017-02-10
• Subjects: micro‐Raman spectroscopy -- archaeometry -- Kongo Kingdom -- glass beads -- Japan wax; Raman spectroscopy -- Periodicals; 535.846
• DOI: 10.1002/jrs.5106
• Languages: English
• ISSNs: 0377-0486

Abstract

Abstract : In the framework of the inter‐disciplinary KongoKing project, a set of beads from archaeological excavations in the Democratic Republic of the Congo was analysed by means of a minimally invasive, multi‐analytical approach based on micro‐Raman spectroscopy. The full characterization of the materials, including glassy network, opacifiers and colorizers, was achieved thanks to the combination of data from handheld X‐ray fluorescence, variable pressure scanning electron microscopy coupled with energy‐dispersive X‐ray spectrometry, micro‐Fourier transform infrared spectroscopy and pyrolysis coupled to gas chromatography and mass spectrometry. The obtained chemical information was used to fill the existing gap in the chemical study of beads from Western Central Africa. The cobalt‐rich blue beads were found to be of Central European origin, while the copper‐rich turquoise beads were manufactured using distinct copper sources. Cadmium yellow and cadmium red are the colourants responsible for the bright colours of bead types 10 and 12, respectively. The type 12 beads were found to be composed of glass covered with a waxy layer tentatively identified as Japan wax. Prosser‐moulded bead type 9 was coloured by means of a chrome–tin pigment, while a combination of Mn and Fe is responsible for the black colour of the type 47 beads. Cuprite is most likely responsible for the red hue of glass layers from type 14. The dark palm green exterior of the type 17 bead was produced by using a combination of Cu and Fe compounds; iron was the only chromophore detected in the Indian red decoration. Copyright © 2017 John Wiley & Sons, Ltd. Abstract : This work focuses on the analysis of beads recovered between 2013 and 2015 from eight sites along the Inkisi River valley and one on the southern part of the Bangu range, in the current Democratic Republic of the Congo. Micro‐Raman spectroscopy was selected as a first‐choice technique for the material characterization of the glass, in terms of matrix (formers, stabilizers, flux, etc.) and colour/opacity, in combination with auxiliary techniques such as hXRF, VP‐SEM‐EDS, μ‐FTIR, and Py‐GC/MS, in order to fully characterize glass and non‐glass beads from a chemical point of view.