...Helen V. Evans; George R. Rossman Abstract Single-crystal optical spectra of corundum (Al 2 O 3 ) and the Al 2 SiO 5 polymorphs andalusite, kyanite, and sillimanite, containing both Fe 2+ -Fe 3+ and Fe 2+ -Ti 4+ intervalence charge transfer (IVCT) absorption bands were measured at temperatures up...

...Eduardo O. Zappettini; João O.S. Santos Abstract Corundum xenocrysts from ouachititic dikes related to the ultrapotassic Puesto La Peña Complex, Mendoza, Argentina, contain inclusions of oxides, silicides, and silicates. Oxides identified are hibonite, carmeltazite, and as yet unnamed minerals...

...–muscovite–corundum–calcite domains in a calc-silicate rock. This uncommon oxy-dravite occurs as dark brown, equant to short-prismatic, idiomorphic crystals with vitreous lustre and up to ca. 4 × 3 cm in size. The oxy-dravite is optically uniaxial (–), with ω = 1.6453(5) and ɛ = 1.6074(18); its calculated...

...) and the generalized gradient approximation]. This approach was used to determine the effect of magnetic contributions to corundum-eskolaite and corundum-hematite phase equilibria from first principles. Two-component cluster expansions of the magnetic components of eskolaite and hematite were first performed showing...

... exploration company, there are images of ‘white breccia’ with Carmel sapphire or corundum grains with a white coating (Xiong et al. , 2017 ; Griffin et al. , 2021a ; Galuskin and Galuskina, 2023 , figure S9, supplementary materials). At this point, we can close the discussion with two brief...

...William L. Griffin; Vered Toledo; Suzanne Y. O'Reilly corundum + Liq → (low-REE) hibonite → grossite + spinel ± krotite → Ca 4 Al 6 F 2 O 12  + fluorite. The occurrence of grossite in meteorites cannot invalidate the existence of these samples; their disaggregation during eruption is responsible...

...Evgeny Galuskin; Irina Galuskina Abstract Corundum with inclusions of enigmatic super-reduced minerals was found in mineral separates received as a result of alluvial sediment exploration near Mt Carmel, Israel by the Shefa Yamim Company. This corundum, registered as ‘Carmel sapphire TM ’, has been...

...Philippe M. Belley Abstract A new, comprehensive approach to characterizing detrital corundum in sediments and placer deposits is outlined and applied to a sample of poorly sorted, mud-supported colluvium rich in rhyolite tuff clasts from the sapphire-producing layer at Gem Mountain Mine, Rock...

... in the ambient mantle, will partition some amount of Al, raising the question of how this will affect its crystal structure and properties. In this study, a series of samples along the MgSiO 3 -Al 2 O 3 (akimotoite-corundum) solid solution have been investigated by means of single-crystal X-ray diffraction...

... in a spheroid 20 μm across enclosed in corundum from the Cr-11 podiform chromitite orebody near the Kangjinla, Luobusa ophiolite, Tibet, China. In addition, wenjiite occurs with deltalumite, jingsuiite, osbornitekhambaraevite, and the K-bearing dmisteinbergite-like mineral in a lamellar intergrowth 100 μm long...

...Jianhua Liu; Shuyun Cao; Dingkui Zhou; Xiaowen Li; Yu Wu; Haobo Wang; Wenxuan Li Abstract Corundum is rarely found in situ within alkali syenites. A corundum-bearing syenite was found in the Yushishan rare metal deposits of the eastern section of the Altyn Tagh fault in the northeastern Tibetan...

... BaCO 3 cells. Third, we investigated the anorthite (CaAl 2 Si 2 O 8 ) + gehlenite (Ca 2 Al 2 SiO 7 ) + corundum (Al 2 O 3 ) = kushiroite (3CaAl 2 SiO 6 ) reaction ( Hays 1966a , 1966b ) at a constant pressure of ~1.3 GPa using talc cells to understand the role of pressure and assembly size (½″ vs...

...Michael C. Jollands; Etienne Balan Abstract The structure of corundum is not amenable to accommodating beryllium, yet Be is commonly added to corundum for purposes of colour modification. Where the main sites in corundum are octahedrally coordinated, Be is tetrahedrally coordinated in all known...

...William L. Griffin; Sarah E.M. Gain; Martin J. Saunders; Jin-Xiang Huang; Olivier Alard; Vered Toledo; Suzanne Y. O'Reilly Abstract Xenolithic corundum aggregates in Cretaceous mafic pyroclastics from Mount Carmel contain pockets of silicate melts with mineral assemblages [SiC (moissanite), TiC, Ti...

... by detailed petrography, Raman spectroscopy, microthermometry, and in situ titanite laser ablation-inductively coupled plasma-mass spectrometry dating. Some fluid inclusions in the corundum show an interesting morphology with a diaspore crystal fully separating the whole inclusion into two smaller inclusions...

... , constitute four inclusions up to 50 μm across in corundum recovered from the Cr-11 podiform chromitite orebody near Kangjinla, Luobusa ophiolite, Tibet, China. EELS, EDS, and 3D electron diffraction were applied to study the phases. In one inclusion, jingsuiite forms a rounded grain 40 μm across. Associated...

... stages of their evolution, recording a continuous decrease in oxygen fugacity ( f O 2 ) as crystallization proceeded. Corundum coexisting with Fe-Mg-Cr-Al spinels, other Fe-Mg-Al-Na oxides, and Fe-Ni alloys in apparent cumulates crystallized at f O 2 values near the iron-wüstite (IW) buffer ( f O 2 = IW...

...Xi-Sheng Xu; Xiao-Ming Chen; William L. Griffin; Suzanne Y. O'Reilly; Xi-Song Zhang; Li-Hui Chen Abstract Controversies on the origin of zircon, corundum, titanomagnetite, and quartz megacrysts in alkali basalts mostly reflect the lack of direct evidence of a “melt reservoir” required...

... of diamond and deltalumite from Koryaksky volcano; coexistence with super-reduced corundum and moissanite, Mn-Ni silicide inclusions, F-Cl enrichment and F/Cl ratios, and carbon and nitrogen isotopes in Tolbachik diamonds, as well as microtwinning, Mn-Ni silicides, and other inclusions in microcrystalline...

... basalt, gabbro, noritic orthopyroxenite, orthopyroxenite, dunite, harzburgite, and dacite. No other lithology has been reported up to date. In this study, we report a new occurrence of corundum in eucrite meteorite Northwest Africa (NWA) 8647. Three-dimensional petrographic observations reveal...