from The American Heritage® Dictionary of the English Language, 5th Edition.

  • noun Metamorphic rock having porphyritic texture.

from The Century Dictionary.

  • noun A sedimentary rock, originally (in some cases at least) a clay slate, or quartzite, which has been altered by dynamic metamorphism or by some other metamorphic agency so as to take on a slaty and more or less perfectly developed porphyritic structure.


Sorry, no etymologies found.



Log in or sign up to get involved in the conversation. It's quick and easy.