from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. A gneiss derived from an igneous rock.
from The Century Dictionary and Cyclopedia
- n. In petrography, a name given by Rosenbusch (1898) to gneiss derived from igneous rocks: opposed to paragneiss.
ortho- + gneiss (Wiktionary)
This hole ended in fresh, unaltered granodioritic orthogneiss at a drill core length of 406 metres.