Vibrational spectroscopic analysis of the mineral crandallite CaAl3(PO4)2(OH)5·(H2O) from the Jenolan Caves, Australia

The mineral crandallite CaAl3(PO4)2(OH)5·(H2O) has been identified in deposits found in the Jenolan Caves, New South Wales, Australia by using a combination of X-ray diffraction and Raman spectroscopic techniques. A comparison is made between the vibrational spectra of crandallite found in the Jenolan Caves and a standard crandallite. Raman and infrared bands are assigned to PO43− and HPO42− stretching and bending modes. The predominant features are the internal vibrations of the PO43− and HPO42− groups. A mechanism for the formation of crandallite is presented and the conditions for the formation are elucidated.

Graphical abstractFigure optionsDownload full-size imageDownload as PowerPoint slideHighlights► The mineral crandallite CaAl3(PO4)2(OH)5·(H2O) has been identified in deposits found in the Jenolan Caves, using a combination of X-ray diffraction and Raman spectroscopy. ► A comparison is made between the vibrational spectra of crandallite found in the Jenolan cave and a standard crandallite. ► Raman and infrared bands are assigned to PO43− and HPO42− stretching and bending modes. ► The predominant features are the internal vibrations of the PO43 and HPO42− groups. ► A mechanism for the formation of crandallite is presented and the conditions for the formation are elucidated.