Abstract
Reidite is a high-pressure polymorph of zircon with the scheelite structure. It has been found in an upper Eocene impact ejecta layer in marine sediments on the upper continental slope off New Jersey and on Barbados. Reidite occurs (epitaxially oriented) in shock-metamorphosed zircons. It is associated with impact glass (tektites), shocked quartz and feldspar with multiple sets of planar deformation features, coesite, and trace amounts of stishovite. This phase was first produced in high-pressure laboratory experiments in 1969 and has also been produced in shock recovery experiments. Reidite is brittle with an irregular fracture, a hardness of 7.5, a calculated density of 5.2 g/cm3, a white streak, adamantine luster, and it does not fluoresce. In index oil in transmitted light, shocked zircon grains consisting almost entirely of reidite are transparent. Pleochroism was not observed. Reidite appears to have parallel extinction and is length slow. The maximum birefringence is roughly 0.015. Reidite appears to be uniaxial positive. It is tetragonal, space group I41/a, a = 4.738 (1) Å, c = 10.506 (2) Å, V = 235.84(2) Å3. Previous shock-loading experiments on zircons indicate that the transition to reidite starts at about 30 GPa and is completed around 53 GPa. Reidite should be a useful indicator of peak pressure in shock metamorphosed rocks. Reidite is named after Alan Reid who first produced this phase in the laboratory.
© 2015 by Walter de Gruyter Berlin/Boston
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Artikel in diesem Heft
- Titanium in biotite from metapelitic rocks: Temperature effects, crystal-chemical controls, and petrologic applications
- Local equilibrium in polymetamorphic gneiss and the titanium substitution in biotite
- The enthalpy of formation and internally consistent thermodynamic data of Mg-staurolite
- Coexisting andalusite, kyanite, and sillimanite: Sequential formation of three Al2SiO5 polymorphs during progressive metamorphism near the triple point, Sivrihisar, Turkey
- Co-existing aluminum silicates in quartz veins: A quantitative approach for determining andalusite-sillimanite equilibrium in natural samples using oxygen isotopes
- Stability of corundum + quartz relative to kyanite and sillimanite at high temperature and pressure
- Andalusite-sillimanite replacement (Mazarrón, SE Spain): A microstructural and TEM study
- Hydroxyl-rich topaz in high-pressure and ultrahigh-pressure kyanite quartzites, with retrograde woodhouseite, from the Sulu terrane, eastern China
- Coesite exsolution from supersilicic titanite in UHP marble from the Kokchetav Massif, northern Kazakhstan
- Composition of synthetic tremolite-tschermakite solid solutions in amphibole + anorthiteand amphibole + zoisite-bearing assemblages
- Paragenesis and thermobarometry of Ca-amphiboles in the Barcroft granodioritic pluton, central White Mountains, eastern California
- B and Li in Proterozoic metapelites from the Black Hills, U.S.A.: Implications for the origin of leucogranitic magmas
- The role of Fe and cation order in the crystal chemistry of surinamite, (Mg,Fe2+)3(Al,Fe3+)3O[AlBeSi3O15]: A crystal structure, Mössbauer spectroscopic, and optical spectroscopic study
- Fe3+ and Fe2+ partitioning among silicates in metapelites: A synchrotron micro-XANES study
- Thermodynamic and structural behavior of analcime–leucite analogue systems
- In-situ synchrotron study of the kinetics, thermodynamics, and reaction mechanisms of the hydrothermal crystallization of gyrolite, Ca16Si24O60(OH)8·14H2O
- The crystal structures of grossular and spessartine between 100 and 600 K and the crystal chemistry of grossular-spessartine solid solutions
- The structures of becquerelite and Sr-exchanged becquerelite
- Elasticity and equation of state of orthoenstatite, MgSiO3
- Reidite: An impact-produced high-pressure polymorph of zircon found in marine sediments
- A new polymorph of eucryptite (LiAlSiO4), ε-eucryptite, and thermal expansion of α- and ε-eucryptite at high pressure
- Disordering during melting: An 17O NMR Study of crystalline and glassy CaTiSiO5 (titanite)
- Characterization of Mn oxides in cemented streambed crusts from Pinal Creek, Arizona, U.S.A., and in hot-spring deposits from Yuno-Taki Falls, Hokkaido, Japan