Raman identification of natural red to yellow pigments: ochre and iron‐containing ores
2008; Wiley; Volume: 39; Issue: 5 Linguagem: Inglês
10.1002/jrs.1858
ISSN1097-4555
AutoresFrançoise Froment, Aurélie Tournié, Philippe Colomban,
Tópico(s)Building materials and conservation
ResumoAbstract Red and yellow natural (roasted) pigments have been used for millennia. This paper reports on the Raman characterization of about 50 pigments of the Ôkhra ‘Mathériauthèque’ collection from different origins: violet, red, orange, apricot, yellow ochre, Umbrian and Siena earths from France (Puisaye, Ardennes, Vaucluse), Italy (Siena, Sardinia, Venice, etc.), Germany, Sweden, Cyprus and India (Madras). Comparison is made with ‘Bengara’ Japanese pigments. Goethite is the chromophore of yellow pigments, and haematite (sometimes with magnetite) that of red ochre and earths. Umbrian pigment (‘Terre d'Ombre’) contains additional manganese oxides. Color shades are related to the content of secondary phases: iron oxides (haematite, goethite, magnetite), quartz, gypsum and anhydrite, calcite, dolomite, alums (jarosites), and to the Fe/M substitution in the haematite structure. The set of secondary phases can be used to confirm a provenance signature (Supplementary Material available). Copyright © 2008 John Wiley & Sons, Ltd.
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