'Porphyritic granite' definitions:

Definition of 'Porphyritic granite'

From: GCIDE
  • 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]