Vibrational spectroscopy of synthetic archerite (K,NH4) and in comparison with the natural cave mineral

In order to mimic the formation of archerite in cave minerals, the mineral analogue has been synthesised. The cave mineral is formed by the reaction of the chemicals in bat guano with calcite substrates. X-ray diffraction proves that the synthesised archerite analogue was pure and more pure than the natural cave mineral. The vibrational spectra of the synthesised mineral are compared with that of the natural cave mineral from the Murra-el-elevyn Cave, Eucla, Western Australia. Raman and infrared bands are assigned to H 2 PO 4 - , OH and NH stretching and bending vibrations. The Raman band at 917 cm−1 is assigned to the HOP stretching vibration of H 2 PO 4 - units. Bands in the 1200–1800 cm−1 region are associated with NH 4 + bending modes. Vibrational spectroscopy enables the molecular structure of archerite analogue to be analysed.