• journal_title：American Mineralogist
• Contributor：Chi Ma ; Oliver Tschauner ; John R. Beckett ; George R. Rossman ; Wenjun Liu
• Publisher：Mineralogical Society of America
• Date：2013-05-01
• Format：text/html
• Language：en
• Identifier：10.2138/am.2013.4290
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：98
• issue：5-6
• firstpage：870
• section：Articles

Kangite (IMA 2011-092), (Sc,Ti,Al,Zr,Mg,Ca,□)₂O₃, 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%) TiO₂ 36.6, Sc₂O₃ 26.4, ZrO₂ 11.3, Al₂O₃ 7.0, Y₂O₃ 5.4, CaO 3.9, MgO 3.14, Dy₂O₃ 1.8, SiO₂ 1.7, V₂O₃ 1.31, Er₂O₃ 0.92, FeO 0.8, Gd₂O₃ 0.60, Ho₂O₃ 0.40, Tb₂O₃ 0.18, Cr₂O₃ 0.09, ThO₂ 0.04, O −0.3, sum 101.28, which leads to an empirical formula calculated on the basis of 3 O atoms of [(Sc_0.54Al_0.16Y_0.07V_0.03Gd_0.01Dy_0.01Er_0.01)³⁺_∑0.83(Ti_0.66Zr_0.13)⁴⁺_∑0.79(Mg_0.11Ca_0.06 Fe_0.02)²⁺_∑0.19 □_0.19] _∑2.00O₃. 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 Ia3̄ bixbyite-type cubic structure. The cell parameters are a = 9.842(1) Å, V = 953.3(1) ų, Z = 16, which leads to a calculated density of 3.879 g/cm³. Kangite is a new ultra-refractory mineral, likely originating through low-temperature oxidation of a Sc-,Ti³⁺-enriched high-temperature condensate oxide dating to the birth of the Solar System.