- 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
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018
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