Discovery of Kangite, (Sc,Ti,Al,Zr,Mg,Ca)_2O_3, A New Ultra-Refractory Mineral in Allende

摘要

During a nano-mineralogy investigation of the Allende CV3 carbonaceous chondrite, we identified a new scandiaudmineral named "kangite" in an irregular ultra-refractory inclusion. It has a cubic Ia3 bixbyite-type structure and a formula unit (Sc,Ti,Al,Zr,Mg,Ca,)_2P_3. Field-emission SEM with EDS and electron back-scatter diffraction, electron microprobe and synchrotron micro-Laue diffraction were used to characterize the composition and structure. We report here the first occurrence of kangite in nature, as a new ultra-refractory oxide among the earliest solids formed in the solar nebula, and discuss its origin and significance for nebular processes. The mineral and the mineral name (kangite) have been approved by the Commission on NewudMinerals, Nomenclature and Classification of the International Mineralogical Association (IMA 2011-092).