- a rock resembling porphyry.
- a sedimentary rock that has been metamorphosed so as to leave some original crystals in a fine-textured, layered matrix.
Origin of porphyroid
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Examples from the Web for porphyroid
Pumice and trachyte are the most common rocks around this mountain, and these are augitic or porphyroid.The Andes and the Amazon
- (of metamorphic rocks) having a texture characterized by large crystals set in a finer groundmass
- a metamorphic rock having this texture
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012