Table 1 Summary of characteristic signatures from FTIR spectroscopy, SEM-EDX, SQWV and XRD for the minerals identified in samples 1 and 2 of funerary pigments found in the Rio Azul tomb
Mineral (Ideal Chemistry) | SEM-EDX Main emission lines identified | VMP Main Cathodic and anodic peaks (mV) | FTIR spectroscopy Wave numbers (cm−1) | XRD d-spacing (Å) |
|---|---|---|---|---|
Calcite CaCO3 | Calcium: Kα (Ca), Kβ (Ca) | – | 1394, 870, 710 | 3.033, 2.285, 2.095, 1.913 |
Gaylussite Na2Ca (CO3)2 | Calcium: Kα (Ca), Kβ (Ca) Sodium: Kα (Na) | – | 1403, 870, 710 | – |
Cinnabar HgS | Sulphur: Kα (S) Mercury: Mα (Hg), LαHg), Lβ (Hg) | Cathodic peak: +30; Anodic peak: − 450 | – | 3.359, 2.865, 2.027, 1.980, |
Galena PbS | Sulphur: Kα (S) Lead: Mα (Pb), Lα (Pb), Lβ (Pb) | – | – | – |
Goethite FeO (OH) | Iron: Kα (Fe), Kβ (Fe) | Cathodic peaks: +150 and − 200 | – | – |
Haematite Fe2O3 | Iron: Kα (Fe), Kβ (Fe) | Cathodic peak: − 400 | 570, 550 | 2.702, 2.519, 1.842, 1.696 |
Halloysite/kaolinite Al2Si2O5 (OH)4 | Aluminum: Kα (Al) Silicon: Kα (Si) | – | 3693, 3671, 3653, 3623, 3410, 1640, 1163, 1113, 1029, 1006, 937, 910, 795, 779, 753, 687, 533 | Halloysite: 7.522, 4.451, 3.633, 2.568 Kaolinite: 7.179, 3.576, 2.341, 1.486 |
Hydroxylapatite Ca5 (PO4)3 (OH) | Phosphor: Kα (P) Calcium: Kα (Ca), Kβ (Ca) | – | 1021, 638, 593 | – |
Quartz SiO2 | Silicon: Kα (Si), Kβ (Si) | – | 1163, 1150, 1085, 798, 780, 695, 514 | 4.259, 3.343, 1.817, 1.541 |
Whewellite Ca2C2O4∙H2O | – | – | 1617, 1315, 779 | – |