Definition of "porphyritic" [por•phy•rit•ic]

• Of or containing porphyry. (adjective)
• Containing relatively large isolated crystals in a mass of fine texture. (adjective)

American Heritage(R) Dictionary of the English Language, Fifth Edition. Copyright (c) 2011 by Houghton Mifflin Harcourt Publishing Company. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.

• "The rock here is a porphyritic granite (porhyritic meaning that the stone has large-grained crystals, such as feldspar or quartz, dispersed in a fine-grained feldspathic matrix or groundmass)."
• "This nature reserve occupies the Scandola peninsula, an impressive porphyritic rock mass."
• "On the other side we pass over masses of porphyritic trap, in contact with the same mica schists, and these probably give to the soil the great fertility we observed."