title: Discovery of the Fe-analogue of akimotoite in the shocked Suizhou L6 chondrite.
abstract: We report the first natural occurrence of the Fe-analogue of akimotoite, ilmenite-structured MgSiO3, a missing phase among the predicted high-pressure polymorphs of Fe-pyroxene, with the composition (Fe2+0.48Mg0.37Ca0.04Na0.04Mn2+0.03Al0.03Cr3+0.01)Σ=1.00Si1.00O3. The new mineral was approved by the International Mineralogical Association (IMA 2016-085) and named hemleyite in honour of Russell J. Hemley. It was discovered in an unmelted portion of the heavily shocked L6 Suizhou chondrite closely associated to olivine, clinoenstatite and Fe-bearing pyroxene with a composition nearly identical to that of hemleyite. We also report the first single-crystal X-ray diffraction study of a Si-bearing, ilmenite-structured phase. The fact that hemleyite formed in a meteorite exposed to high pressures (<20 GPa) and temperatures (<2000 °C) during impact-induced shocks indicates that it could play a crucial role at the bottom of the Earth's mantle transition zone and within the uppermost lower mantle.
authors.affiliation: Dipartimento di Scienze della Terra, Università di Firenze, Via La Pira 4, I-50121 Florence, Italy.|CNR-Istituto di Geoscienze e Georisorse, Via La Pira 4, I-50121 Florence, Italy.
authors.forename: Luca
authors.initials: L
authors.lastname: Bindi
authors.affiliation: State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.|Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou 510640, China.
authors.forename: Ming
authors.initials: M
authors.lastname: Chen
authors.affiliation: Guangdong Provincial Key Laboratory of Mineral Physics and Materials, Guangzhou 510640, China.|Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China.
authors.forename: Xiande
authors.initials: X
authors.lastname: Xie