Discovery of Panguite, a New Ultra-Refractory Titania Mineral in Allende

Abstract

During our nano-mineralogy investigation of the Allende meteorite, we identified a new titania mineral named "panguite" in an ultra-refractory inclusion within an amoeboid olivine aggregate (AOA). It has an orthorhombic Pbca structure related to the Ia3 bixbyite type and a formula unit (Ti^(4+),Al,Sc,Mg,Zr,Ca,□)_2O_3. We used electron probe microanalysis (EPMA), high-resolution scanning electron microscope (SEM), electron backscatter diffraction (EBSD), synchrotron micro-Laue diffraction with subsequent energy scans, and micro-Raman analyses to characterize the composition and structure. Panguite is not only a new mineral but also a new phase as synthetic Ia3 (Ti^(4+),Al,Sc,Mg,Zr,Ca,□)_2O_3 is not known. We report here the type occurrence of this new titania in nature and discuss implications of this phase for processes very early in the history of our solar system. The mineral and the mineral name (panguite) have been approved by the Commission on New Minerals, Nomenclature and Classification of the International Mineralogical Association (IMA 2010-057).

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