...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...

...William L. Griffin; Sarah E.M. Gain; Martin Saunders; Luca Bindi; Olivier Alard; Vered Toledo; Suzanne Y. O'Reilly Abstract Titanium diboride (TiB 2 ) is a minor but common phase in melt pockets trapped in the corundum aggregates that occur as xenoliths in Cretaceous basaltic volcanoes on Mt...

...Shreya Karmakar; Subham Mukherjee; Upama Dutta Abstract Growth of corundum in metamorphosed anorthosites and related basic-ultra-basic rocks is an exceptional feature, and its origin remains elusive. We describe the occurrence of and offer an explanation for the genesis of corundum in anorthositic...

... and silicate minerals form at temperatures similar to or lower than those of the observed carbon allotropes and carbides. Corundum and hibonite are the most refractory oxides, with formation temperatures estimated to exceed 1700 K ( Ebel 2006 and references therein). By contrast, Zega et al. (2014a...

...Barbara L. Dutrow; Darrell J. Henry; Ziyin Sun Infiltration of out-of-equilibrium fluids can lead to extensive fluid–rock interactions resulting in unusual and uncommon mineral assemblages that are petrologically and mineralogically important. The corundum (cor)–tourmaline (tur)–phlogopite rocks...

..., ilmenite, and apatite lamellae in garnet from the Brimfield Schist, Connecticut (≥1000 °C metamorphism; Central Maine Terrane, U.S.A.). We analyzed these data alongside published EBSD data for rutile, ilmenite, and corundum from metapegmatites metamorphosed in the eclogite facies from the Austrian Alps...

...J. Victor Owen; Jacob J. Hanley; Mitchell J. Kerr; Matthew Stimson; Brandon Boucher Abstract Frenchvale quarry, once mined for dolomitic marble, contains pink corundum-bearing, quartz-free/-poor, feldspathic gneiss that is unusually sodic (~7% wt.% Na 2 O) and iron-poor (~0.6 wt.% Fe 2 O 3...

...Victor V. Sharygin Abstract The intergrowths of Fe-rich corundum + Al-rich hematite + spinel + hibonite have been found as an assemblage in a plagioclase-clinopyroxene rock (paralava, former hornfels) at the Hatrurim Basin, Hatrurim combustion metamorphic Formation. Most spinels show oriented...

... of hopper/skeletal Ti-rich corundum, which have trapped melts that crystallized at f O 2 extending from 7 log units below the iron-wustite buffer (ΔIW = –7; SiC, Ti 2 O 3 , Fe-Ti silicide melts) to ΔIW ≤ –9 (native V, TiC, and TiN). The assemblage hibonite + grossite + spinel + TiN first crystallized late...

...Dmitry P. Krylov; Robert A. Evarestov Equilibrium oxygen isotope ( 18 O/ 16 O) fractionations ( β -factors) for corundum are predicted from first principles using the “frozen phonon” technique within the density functional theory (DFT). Calculations of the phonon frequencies and the isotopic...

... underutilized potential for pinpointing peak metamorphic conditions, particularly pressure, because of their resilience to melting and the variety of refractory minerals they contain. The typical silica-undersaturated mineral assemblage is garnet + spinel + corundum + plagioclase + K-feldspar + biotite...

..., and oxygen isotope ratios in blue to reddish-violet sapphires from Yogo Gulch, Montana, U.S.A., with rubies from the Chantaburi-Trat region of Thailand and the Pailin region of Cambodia. The similarities between Thai/Cambodian rubies and Yogo sapphires suggest a common origin for gem corundum from both...

...Jacqueline Wong; Charles Verdel; Charlotte M. Allen Abstract Significant uncertainty surrounds the processes involved in the formation of basalt-hosted corundum, particularly the role that the mantle plays in corundum generation. Some previous studies have suggested that trace-element ratios...

... needles with shape-preferred orientation included in gem corundum result from epitaxy of rutile on the corundum surface during growth of corundum in a magmatic environment. This is in contrast to the presently accepted view of oriented rutile needles in corundum being products of exsolution during cooling...

... in this issue of American Mineralogist , disagrees with our recent findings indicating that, in some gem corundum, oriented rutile needles grew by epitactic coprecipitation rather than the usual assumption of exsolution. Proyer's concerns are, in part, related to a misunderstanding of our model and, in places...

... materials in the ophiolites, are still enigmatic. Studies of a recently recognized SuR mineral system from Cretaceous volcanics on Mt Carmel, Israel, suggest an alternative genesis for the ophiolitic SuR phases. The Mt Carmel SuR mineral system (associated with Ti-rich corundum xenocrysts) appears...

..., are considered to be prospective for sapphire (corundum), lapis lazuli (lazurite), and spinel gem deposits. This research is an investigation of the hyperspectral signature of rocks from the Beluga sapphire occurrence near Kimmirut, Nunavut. Thirty-five rock and thin section offcut samples from the Beluga...

...-ultramafic hosted ruby deposits worldwide; (2) distinctive geochemical fingerprints for Paranesti; and (3) the likely P - T conditions of formation. Detailed petrographic and whole-rock analyses utilizing ICP-MS, XRF, and XRD have found the Paranesti corundum to be of a mafic/ultramafic protolith...