porphyritic granite


From The Collaborative International Dictionary of English v.0.48:

Granite \Gran"ite\ (gr[a^]n"[i^]t), n. [It. granito granite,
   adj., grainy, p. p. of granire to make grainy, fr. L. granum
   grain; cf. F. granit. See Grain.] (Geol.)
   A crystalline, granular rock, consisting of quartz, feldspar,
   and mica, and usually of a whitish, grayish, or flesh-red
   color. It differs from gneiss in not having the mica in
   planes, and therefore in being destitute of a schistose
   structure.
   [1913 Webster]

   Note: Varieties containing hornblende are common. See also
         the Note under Mica.
         [1913 Webster]

   Gneissoid granite, granite in which the mica has traces of
      a regular arrangement.

   Graphic granite, granite consisting of quartz and feldspar
      without mica, and having the quartz crystals so arranged
      in the transverse section like oriental characters.

   Porphyritic granite, granite containing feldspar in
      distinct crystals.

   Hornblende granite, or

   Syenitic granite, granite containing hornblende as well as
      mica, or, according to some authorities hornblende
      replacing the mica.

   Granite ware.
   (a) A kind of stoneware.
   (b) A Kind of ironware, coated with an enamel resembling
       granite.
       [1913 Webster]
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