Porphyritic Texture

the texture of a rock in which relatively large phenocrysts with regular crystal faces are set in a generally fine-grained groundmass. Rocks with porphyritic textures may be extrusive or intrusive. An extrusive rock with a porphyritic texture has a groundmass that contains an unequal number of phenocrysts and consists of either microlites or glass. An intrusive rock with a porphyritic texture has a finely crystalline and granitic groundmass; for this reason it is also called a granite porphyry.