[nahys] 
| a metamorphic rock, generally made up of bands that differ in color and composition, some bands being rich in feldspar and quartz, others rich in hornblende or mica. |
| gneiss (nīs) n. A banded or foliated metamorphic rock, usually of the same composition as granite. [German Gneis, probably alteration of Middle High German ganeist, spark (from its appearance), from Old High German gneista.] gneiss'ic (nī'sĭk), gneiss'oid' (nī'soid'), gneiss'ose' (nī'sōs') adj. |
