from Wiktionary, Creative Commons Attribution/Share-Alike License

  • n. Plural form of tetrahedron.


Sorry, no etymologies found.


  • Lowell Gilbert @ 13, kid bitzer @ 15 -- Remember that the tetrahedral shape is that of the four bonds of the carbon atom; the implied tetrahedra are connected tip-to-tip, not solidly packed.

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  • Five points form the vertices of two regular tetrahedra, joined on a common face situated in the horizontal plane.

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  • “Clay” as a mineral refers to a “cousin” of micas; that is, a silicate mineral containing structural sheets of silica tetrahedra tetrahedral arrangements of one Si and 4 Oxygen atoms, with the Oxygen atoms at the 4 corners.

    Open thread: questions and explanations - The Panda's Thumb

  • Each of the 3 corners “shares” an oxygen atom with other tetrahedra, giving a ratio in the formula of 1 Si to 2.5 O, or Si2O5.

    Open thread: questions and explanations - The Panda's Thumb

  • In sheet silicates, each silicate tetrahedron is joined at 3 corners to other tetrahedra in sheet form.

    Open thread: questions and explanations - The Panda's Thumb

  • As with all silicate minerals, the basic building blocks of asbestos fibers are the silicate tetrahedra which may occur as double chains (Si4O11) -6, as in the amphiboles, or in sheets (Si4O10) -4, as in chrysotile.

    Geology of asbestos

  • The crystalline structure common to amphibole minerals consists of two ribbons of silicate tetrahedra placed back to back.

    Geology of asbestos

  • In the case of chrysotile, an octahedral brucite layer having the formula (Mg6O4 (OH) 4) -4 is intercalated between each silicate tetrahedra sheet.

    Geology of asbestos

  • Between craters the basalt was strewn in small tetrahedra, with angles rubbed and rounded, stone tight to stone like tesseract upon

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  • There were even stranger shapes, exploiting almost every possibility of geometry - bizarre, translucent kites, tetrahedra, spheres, polyhedra, tangles of twisted ribbons ...

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