Study on the Mineralogical Properties of an Unknown Ti-Zr-U Oxide Using EPMA, SEM, Raman Spectroscopy and EBSD Techniques

Asub-micron uranium-bearing mineral in pomegranate amphibolite in the Altyn area was identified by Electron Microprobe(EPMA) and Scanning Electron Microscopy(SEM).Optical Microscope, Raman Spectroscopy and Electron Back Scattering Diffraction(EBSD) were used to study the chemical composition, occurrence state, physical and optical properties and crystal structure.Results show that this mineral is an opaque mineral closely associated with ilmenite and occurs at the edge of ilmenite.The mineral is composed of TiO₂, ZrO₂ and UO₂ and the crystallochemical formula is(Zr, U)Ti₂O₆ with isomorphous substitution of U and Zr.It has a unique Raman spectrum characteristic and possibly belongs to orthorhombic system with a fersmite structure.EPMA Th-U-Pb dating of Ti-Zr-U oxide mineral yields an isochron age of 451±49 Ma, which represents the retrograde age of the host rock.Compared to the crystals which have a similar chemical composition to Ti-Zr-U oxide, the crystal structure of Ti-Zr-U oxide was found to be different from that of Srilankite, but similar to a synthetic crystal(Zr₅Ti₇O₂₄) in chemical composition and crystal structure.Therefore, it is inferred that the Ti-Zr-U oxide is previously undiscovered mineral.