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[pley-jee-uh-kleys] /ˈpleɪ dʒi əˌkleɪs/

any of the feldspar minerals varying in composition from acidic albite, NaAlSi 3 O 8 , to basic anorthite, CaAl 2 Si 2 O 8 , found in most igneous rocks: shows twinning striations on good cleavage surfaces.
a series of feldspar minerals consisting of a mixture of sodium and calcium aluminium silicates in triclinic crystalline form: includes albite, oligoclase, and labradorite

“triclinic feldspar,” 1868, from German, coined 1847 by German mineralogist Johann Friedrich August Breithaupt (1791-1873) from plagio- + Greek klasis “fracture,” from stem of klan “to break” (see clastic). Related: Plagioclastic.
Any of a series of common feldspar minerals, consisting of differing mixtures of sodium and calcium aluminum silicates. Plagioclase is typically white, yellow, or reddish-gray, but it can also be blue to black. It occurs in igneous rocks. The minerals albite, oligoclase, andesine, labradorite, bytownite, and anorthite are all plagioclases. Chemical formula: (Na,Ca)Al(Si,Al)Si2O8.


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    [pley-jee-uh-hee-druh l] /ˌpleɪ dʒi əˈhi drəl/ adjective 1. (of a crystal) having faces arranged obliquely in a helix.

  • Plagiotropic

    [pley-jee-uh-trop-ik, -troh-pik] /ˌpleɪ dʒi əˈtrɒp ɪk, -ˈtroʊ pɪk/ adjective, Botany. 1. growing more or less divergent from the vertical.

  • Plagiotropism

    [pley-jee-o-truh-piz-uh m] /ˌpleɪ dʒiˈɒ trəˌpɪz əm/ noun, Botany. 1. tendency or growth. /ˌpleɪdʒɪəʊˈtrəʊˌpɪzəm/ noun 1. the growth of a plant at an angle to the vertical in response to a stimulus

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