Identification of montgomeryite mineral [Ca4MgAl4(PO4)6·(OH)4·12H2O] found in the Jenolan Caves—Australia

In this paper, we report on many phosphate containing natural minerals found in the Jenolan Caves – Australia. Such minerals are formed by the reaction of bat guano and clays from the caves. Among these cave minerals is the montgomeryite mineral [Ca4MgAl4(PO4)6·(OH)4·12H2O]. The presence of montgomeryite in deposits of the Jenolan Caves – Australia has been identified by X-ray diffraction (XRD). Raman spectroscopy complimented with infrared spectroscopy has been used to characterise the crystal structure of montgomeryite. The Raman spectrum of a standard montgomeryite mineral is identical to that of the Jenolan Caves sample. Bands are assigned to H2PO4−, OH and NH stretching vibrations. By using a combination of XRD and Raman spectroscopy, the existence of montgomeryite in the Jenolan Caves – Australia has been proven. A mechanism for the formation of montgomeryite is proposed.

Graphical abstractRaman spectrum of montgomeryite from the Jenolan Caves.Figure optionsDownload full-size imageDownload as PowerPoint slideHighlights► Many phosphate containing minerals are found in the Jenolan Caves. ► Such minerals are formed by the reaction of bat guano and clays from the caves. ► Among these cave minerals is the mineral montgomeryite Ca4MgAl4(PO4)6·(OH)4·12H2O. ► By using a combination of XRD and Raman spectroscopy, the existence of montgomeryite in the Jenolan Caves has been proven.