Raman identification of natural red to yellow pigments: ochre and iron‐containing ores

Abstract

Red and yellow natural (roasted) pigments have been used for millennia. This paper reports on the Raman characterization of about 50 pigments of theÔkhra '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).

Renewable chitin from marine sponge as a thermostable biological template for hydrothermal synthesis of hematite nanospheres using principles of extreme biomimetics

“…The Raman spectrum of α- shows all the characteristic hematite bands which belong to the D 6 3d space group: A 1g mode (494 cm -1 ) and three E g modes (289 cm -1 , 407 cm -1 , 608 cm -1 ) [51][52][53]. As represented on Figure 7, the Raman spectra of chitin/Fe 2 O 3 composites obtained show the presence of the four most intense peaks typical for hematite (vertical lines).…”

The ceramics of Malpaís of Zacapu, Michoacán, Mexico, during the Early and Middle Postclassic periods (900–1450AD): Micro-chemical characterization of surface paintings

“…7) while amorphous carbon was identified by μ-Raman in samples 2 and 10. Magnetite large broad Raman band at 670 cm -1 [24] was also detected on sherd 2b.…”

On-site Raman analysis of 17th and 18th century Limoges enamels: Implications on the European cobalt sources and the technological relationship between Limoges and Chinese enamels

“…The red colour was found to be always achieved with the same pigment as hematite -Fe 2 O 3 ), easily detected with its strong resonance feature at ~1310 cm -1 and a series of peaks at 223, 290, 405, 493 and 605 cm -1 [46]. This pigment is also used for the flesh tones (carnation, Fig.…”