| Article ID | Journal | Published Year | Pages | File Type |
|---|---|---|---|---|
| 1234900 | Spectrochimica Acta Part A: Molecular and Biomolecular Spectroscopy | 2011 | 6 Pages |
In order to mimic the chemical reactions in cave systems, the analogue of the mineral stercorite H(NH4)Na(PO4)·4H2O has been synthesised. X-ray diffraction of the stercorite analogue matches the stercorite reference pattern. A comparison is made with the vibrational spectra of synthetic stercorite analogue and the natural Cave mineral. The mineral in nature is formed by the reaction of bat guano chemicals on calcite substrates.A single Raman band at 920 cm−1 (Cave) and 922 cm−1 (synthesised) defines the presence of hydrogen phosphate in the mineral. In the synthetic stercorite analogue, additional bands are observed and are attributed to the dihydrogen and phosphate anions. The vibrational spectra of synthetic stercorite only partly match that of the natural stercorite. It is suggested that natural stercorite is more pure than that of synthesised stercorite. Antisymmetric stretching bands are observed in the infrared spectrum at 1052, 1097, 1135 and 1173 cm−1. Raman spectroscopy shows the stercorite mineral is based upon the hydrogen phosphate anion and not the phosphate anion. Raman and infrared bands are found and assigned to PO43−, H2O, OH and NH stretching vibrations. Raman spectroscopy shows the synthetic analogue is similar to the natural mineral. A mechanism for the formation of stercorite is provided.
Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► We have synthesised the mineral stercorite to mimic the chemical reactions occurring in the Jenolan Caves. ► The mineral in nature is formed by the reaction of bat guano chemicals on calcite substrates. ► A single Raman band at 920 cm−1 defines the presence of hydrogen phosphate in the mineral.
