ADVANCED MATERIALS & PROCESSES | NOVEMBER/DECEMBER 2023 27 Ca2(Mn, Fe, Al)5Be4(PO4)6(OH)4·6H2O[30]. It is a multi-component mineral structure consisting of Ca-polyhedra with tetrahedra and octahedra. There is not much information available in literature about the physical and mechanical properties of these complex phosphates, thus this unique chemistry can act as an inspiration to materials engineers to coordinate more fundamental research with geological engineers to synthesize and characterize complex chemistry. Evaluation of 3D Optical Microscopy for Evaluating Phosphate Minerals. Figure 5 shows the 3D profile of three selected phosphate minerals: purpurite (Figs. 5a and 5b), churchite (Figs. 5c and 5d) and wavelite (Figs. 5e and 5f). Those profiles were performed with a Keyence VR-6000 3D optical profilometer. This 3D profile system captures full surface data across the target with a resolution of 0.1 µm, enabling measurement of features that can be measured without complicated sample preparation, cutting, or destroying the target. By using 3D optical microscopy, it was possible to delineate the rough topography of purpurite (Figs. 5a and 5b), acicular nature of the churchite (Figs. 5c and 5d), and 3D morphology of wavelite (Figs. 5e and 5f). This process also provides a powerful tool for mineralogy study and non-contact measurements. CONCLUSION As an essential element of life on Earth, phosphorus has been widely used in agriculture as well as in nonagricultural products. In this article, we reviewed the current and potential applications of phosphate materials. To better understand the basics of phosphate minerals for potential applications, this study examined five non-apatite phosphate minerals: purpurite, churchite, wavelite, variscite with crandallite, and eosphorite with roscherite by using SEM, EDS, and 3D optical profilometer. Based on this brief survey, it is also recommended that the chemistry of naturally occurring multi-component phosphates should be further explored for designing advanced materials for functional applications. ~AM&P Acknowledgments: We acknowledge the support of the Keyence Corp. of America for the 3D optical profile analysis. Materials Manufacturing Initiative (MMI) at the University of North Dakota is acknowledged for funding. The mineral samples are from the personal collection of one of the authors (SG). Fig. 4 – (a) Digital picture of eosphorite with roscherite: SEM micrographs of eosphorite with roscherite in (b) SE and (c) BSE images of the same region. Fig. 5 – 3D profile of purpurite: (a) overview of surface 3D profile and (b) surface 3D profile; churchite: (c) surface 3D profile and (d) local 3D profile; and wavellite: (e) surface 3D profile and (f) local 3D profile. (a) (b) (c) (d) (e) (f) (a) (b) (c)
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