porphyritic granite

1 definition found

porphyritic granite - 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]