FTIR – main clay peak (Si–O): 1030.1 cm⁻¹ (visible doublet 1079.6/1030.1 cm⁻¹); calcite: 876.4 cm⁻¹ (ν₂ sharp); 1490.2 cm⁻¹ peak likely nitrate contamination, not calcite ν₃; quartz: 796.1 cm⁻¹, 777.9 cm⁻¹; dolomite: Possible (713.1 cm⁻¹) (refs: B07)
