## 3 Results
### Oxide Pigments
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Pigment**} & \multicolumn{2}{c}{**ATR-FTIR**} & \multicolumn{2}{c}{**DRIFT**} \\ \cline{2-5}  & **Wavenumber (cm\({}^{-1}\))** & **Assignment 1** & **Wavenumber (cm\({}^{-1}\))** & **Assignment 1** \\ \hline \multirow{8}{*}{HE-N} & \(\sim\)3609 & v(–OH), aluminosilicate [42] & 3725 & v(–OH), aluminosilicate [35] \\ \cline{2-5}  & 3540–3045 & -OH [26], aluminosilicate (?) & 3650–3150 & –OH [26], aluminosilicate (?) \\ \cline{2-5}  & 1800 & v\({}_{8}\)+\(\delta\)(CO\({}_{3}\)\({}^{2-}\)), dolomite (?) & 1867 & v\({}_{8}\)+\(\delta\)(CO\({}_{3}\)\({}^{2-}\)) [14], dolomite \\ \cline{2-5}  & 1636 & –OH [26] & 1685 & –OH [26] \\ \cline{2-5}  & 1432, 875, 730 & CO\({}_{3}\)\({}^{2-}\), dolomite [63] & 1498, 1445 & CO\({}_{3}\)\({}^{2-}\) [26], dolomite (?) \\ \cline{2-5}  & 1165 & Si-O, quartz [44] & 1087, 1043, 745, 710 & Si–O, quartz [26] \\ \cline{2-5}  & 1021 & Si-O, kaolinite [44] & 935, 895, 820 & Al–OH, kaolinite [35] \\ \cline{2-5}  & 915 & Al-OH, kaolinite [44] & & \\ \cline{2-5}  & 800 & Al-Si-O, kaolinite [43] & & \\ \cline{2-5}  & 700 & Al-O [26], kaolinite (?) & 670 & Si–O, quartz [35] \\ \hline \multirow{2}{*}{HE-S} & \multirow{2}{*}{1186, 1144, 920} & \multirow{2}{*}{Si-O, quartz [26]} & 1690, 1560 & –OH [26] \\ \cline{2-5}  & & 1186, 1144, 920 & Si-O, quartz [26] & 1071, 927, 736, 710 & Si-O, quartz [26; 35] \\ \hline \multirow{8}{*}{RO-N} & \multirow{2}{*}{3700–3000} & v(–OH), aluminosilicate [26], & 3800–2900 & v(–OH), aluminosilicate [35; 64], lilite (?) \\ \cline{2-5}  & & & 2053 & v+\(\delta\)(Si-O) [14; 35], quartz (?) \\ \cline{2-5}  & & & 1925, 1839 & v\({}_{8}\)+\(\delta\)(CO\({}_{3}\)\({}^{2-}\)), calcite [26] \\ \cline{2-5}  & 1680, 1620 & –OH [26], gypsum (?) & 1720–1660 & –OH [26], gypsum (?) \\ \cline{2-5}  & & & 1269, 1186 & C–O [26], calcite (?) \\ \cline{2-5}  & 1080, 1023, 793 & Si–O, quartz [8; 34] & 1030–1060 & Si–O, silicate [26] \\ \cline{2-5}  & & & 828, 777, 749, 718 & Si–O, quartz [35] \\ \cline{2-5}  & 700, 670 & v(S–O) [26], gypsum (?) & & \\ \hline \multirow{8}{*}{YO-N} & \multirow{2}{*}{3650–3100} & \multirow{2}{*}{–OH [26], goethite (?)} & 3700–3150, 3072, 2960 & v(–OH), goethite [26; 65] \\ \cline{2-5}  & 1792 & C=O, calcite [8; 45] & 1845 & \(\delta\)(CO\({}_{3}\)\({}^{2-}\)), calcite [26] \\ \cline{2-5}  & 1640 & –OH [26], goethite (?) & 1680 & –OH [26], goethite (?) \\ \cline{2-5}  & 1395 & CO\({}_{3}\)\({}^{2-}\), calcite [8; 45] & 1481, 1430, 725 & CO\({}_{3}\)\({}^{2-}\), calcite [35] \\ \cline{2-5}  & & & 1266, 1187 & C-O [26], calcite (?) \\ \cline{2-5}  & 1090, 1014, 804 & Si–O, silicate [26] & 1090, 1035, 924 & Si–O, silicate [26] \\ \cline{2-5}  & 875 & v\({}_{8}\)(CO\({}_{3}\)\({}^{2-}\)), calcite [8; 45] & 890, 860, 815, 682 & \(\delta\)(CO\({}_{3}\)\({}^{2-}\)), calcite [26] \\ \cline{2-5}  & 715 & v\({}_{8}\)(CO\({}_{3}\)\({}^{2-}\)), calcite [8; 45] & & \\ \hline \multirow{2}{*}{CG-S} & \multirow{2}{*}{3570–3050} & \multirow{2}{*}{–OH [26]} & \multirow{2}{*}{1170, 1070, 880, 830,} & \multirow{2}{*}{Si–O, quartz [35]} \\ \cline{2-5}  & & & 802, 775, 760 & & \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Oxide-based pigments analysed by ATR-FTIR and DRIFT modalities. Bands (cm\({}^{-1}\)) and assignment (vibration mode and mineral associated) are included where possible. See Table 1 for the explanation of the pigment identification codes. As for natural ochre pigments, their colour depends on the nature of the iron oxide chromophore. As such, the reddish hue in RO-N is mainly due to anhydrous iron oxide (Fe\({}_{2}\)O\({}_{3}\)), whilst in YO-N, the yellow hue is due to hydrated iron oxides such as goethite (FeO-OH), as identified by XRD analysis. Their natural provenance implied the presence of impurities, as shown in Table 1: quartz, gypsum, diopside and illite in RO-N, and calcite in YO-N [66].