A multi-analytical approach was used to study the pictorial layers of a set of 17th century historic glazed tiles (azulejos) of Portuguese manufacture.
The pictorial layer was studied by -EDXRF, -Raman, SEM-EDS and OM. Although the established palette comprises few pigments, it was
found that the tiles were enhanced by the use of pigment mixtures, which were identified by -Raman and -EDXRF. As expected, the blue
colour derives from cobalt oxide, purple from manganese oxide and emerald-green from copper oxide. Regarding the yellow pigment, -Raman
results show it is consistent with the composition of a ternary oxide, whereas -EDXRF shows a high intensity of Zn in this colour, indicating a
composition close to a Pb–Sb–Zn ternary oxide. Some compounds from the original ores were also indentified: in two very dark blue samples,
cobalt and nickel olivines (-Co2SiO4, -Ni2SiO4), and in a dark brown sample, braunite (a manganese silicate).
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