Publication Date:
2013-05-11
Description:
Kangite (IMA 2011-092), (Sc,Ti,Al,Zr,Mg,Ca,) 2 O 3 , is a new scandia mineral, occurring as micrometer-sized crystals with REE-rich perovskite and spinel in a davisite-dominant ultra-refractory inclusion from the Allende CV3 carbonaceous chondrite. The phase was characterized by SEM, EBSD, synchrotron micro-Laue diffraction, micro-Raman, and EPMA. The mean chemical composition of the type kangite is (wt%) TiO 2 36.6, Sc 2 O 3 26.4, ZrO 2 11.3, Al 2 O 3 7.0, Y 2 O 3 5.4, CaO 3.9, MgO 3.14, Dy 2 O 3 1.8, SiO 2 1.7, V 2 O 3 1.31, Er 2 O 3 0.92, FeO 0.8, Gd 2 O 3 0.60, Ho 2 O 3 0.40, Tb 2 O 3 0.18, Cr 2 O 3 0.09, ThO 2 0.04, O –0.3, sum 101.28, which leads to an empirical formula calculated on the basis of 3 O atoms of [(Sc 0.54 Al 0.16 Y 0.07 V 0.03 Gd 0.01 Dy 0.01 Er 0.01 ) 3+ 0.83 (Ti 0.66 Zr 0.13 ) 4+ 0.79 (Mg 0.11 Ca 0.06 Fe 0.02 ) 2+ 0.19 0.19 ] 2.00 O 3 . Synchrotron micro-Laue diffraction (i.e., an energy scan by a high-flux X-ray monochromatic beam) on one type domain at submicrometer resolution revealed that kangite has a cation-deficient Ia bixbyite-type cubic structure. The cell parameters are a = 9.842(1) Å, V = 953.3(1) Å 3 , Z = 16, which leads to a calculated density of 3.879 g/cm 3 . Kangite is a new ultra-refractory mineral, likely originating through low-temperature oxidation of a Sc-,Ti 3+ -enriched high-temperature condensate oxide dating to the birth of the Solar System.
Print ISSN:
0003-004X
Electronic ISSN:
1945-3027
Topics:
Geosciences
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