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Tridymite

About: Tridymite is a research topic. Over the lifetime, 840 publications have been published within this topic receiving 14831 citations.


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Journal ArticleDOI
TL;DR: Twinning on the unit cell level of the idealized cristobalite structure, using a mirror plane as the twin and composition plane, provides a simple relationship between 14 tetrahedral frameworks as discussed by the authors.

13 citations

Journal ArticleDOI
TL;DR: In this article, a pseudohexagonal twinning about the [-201] row of the true monoclinic lattice satisfactorily accounts for these unusual structural extinctions, and a possible mechanism of twin formation is proposed, based on the recently determined low tridymite structure.
Abstract: Tridymite from the Steinbach meteorite is monoclinic with cell dimensions: a 18.54, b 5.00, c 23.83 A, β 105.70° and space group C2⁄c or Cc. Its diffraction pattern shows an extremely large number of structural absences, leading to pseudo-orthorhombic superlattice with cell dimensions A 51.86, B 30.00, C 49.20 A. The method of twin analysis (Ito and Sadanaga, 1970) was applied uniquely to derive a crystal lattice from the twin pattern. Pseudohexagonal twinning about the [-201] row of the true monoclinic lattice satisfactorily accounts for these unusual structural extinctions. The symmetry of the twin is represented by the six-color symmetry symbolism. A possible mechanism of twin formation is proposed, based on the recently determined low tridymite structure.

13 citations

Journal Article
TL;DR: Quartz pseudomorphic after tridymite has recently been recognized in the micropegmatite member of the Nickel Irruptive of the Sudbury Basin, Ontario.
Abstract: Quartz pseudomorphic after tridymite has recently been recognized in the micropegmatite member of the Nickel Irruptive of the Sudbury Basin, Ontario. The "tridymite" occurs as blades radiating from quartz xenocrysts or adjacent to quartzite xenoliths, where the micropegmatite has brecciated and assimilated the overlying quartzite. A plume-like, almost spherulitic intergrowth of quartz and orthoclase is commonly associated with the "tridymite." These features indicate a high intrusion temperature in the 800 degrees C. to 900 degrees C. range, and rapid cooling of the upper phase of the micropegmatite.

13 citations

Journal ArticleDOI
TL;DR: In this article, the crystal structure of spherical particles of Sr 0.88M Eu 0.12 Al 2 O 4 synthesized by the spray method has been investigated by powder X-ray diffraction measurements.
Abstract: The crystal structure of spherical particles of Sr 0.88M Eu 0.12 Al 2 O 4 synthesized by the spray method has been investigated by powder X-ray diffraction measurements. After annealing at 1300°C for 2 h, the spheres of Sr 0.88 Eu 0.12 Al 2 O 4 crystallize in the hexagonal form with a = 5.1160(2) A, c = 8.3722(3)A, V = 189.77(1) A 3 Z = 2, and space group P6 3 22, which is distinct from the structure (monoclinic P2 l ) reported so far. This stable crystal structure was refined by the Rietveld method, and it was found that it consists of a nondistorted stuffed tridymite structure, and the doped Eu 2- ion is located at the same 2h site as the Sr 2+ ion. Furthermore, it is suggested that such an abnormal stabilization of the hexagonal form at ambient temperature is associated with defects of the oxygen ion at the 2d site based on the electron density map from Fourier synthesis.

13 citations

Journal ArticleDOI
TL;DR: Columnar jointing occurs in metamorphosed Triassic sandstones (buchites) adjacent to a Tertiary basalt neck as discussed by the authors, which contain cordierite, spinel, mullite, tridymite, corundum, and up to 65 per cent glass.
Abstract: Columnar jointing occurs in metamorphosed Triassic sandstones (buchites) adjacent to a Tertiary basalt neck. The buchites contain cordierite, spinel, mullite, tridymite, corundum, and up to 65 per cent glass. The temperature of metamorphism reached approximately 1000° c at a pressure of probably about 50 kg/cm 2 . Repacking of the grains in the sandstones, made possible by shrinkage of clays and development of a liquid phase, caused the contraction that gave rise to columnar jointing. A complex isotherm pattern and other factors resulted in considerable variation in the size and orientation of the columns.

13 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
202315
202231
202125
202027
201920
201826