from Wiktionary, Creative Commons Attribution/Share-Alike License

  • adj. A textural term used in petrographic classification of volcanic rocks, referring to a volcanic rock groundmass, which is visible only under magnification with a petrographic microscope, that contains a mixture of very fine-grained mineral crystals either mixed with natural volcanic glass, or surrounded by thin bands of volcanic glass.

from The Century Dictionary and Cyclopedia

  • In petrography, noting the structure of some lavas in which microscopic prisms are crowded in a glass matrix.


Sorry, no etymologies found.


    Sorry, no example sentences found.


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