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.
If you go down to see them, you will find some with the gneiss attached to the quartz.
gneiss resembles schist, except that the minerals are arranged into bands.
British Dictionary definitions for gneiss
gneiss
/naɪs/
noun
1.
any coarse-grained metamorphic rock that is banded and foliated: represents the last stage in the metamorphism of rocks before melting
Derived Forms
gneissic, gneissoid, gneissose, adjective
Word Origin
C18: from German Gneis, probably from Middle High German ganeist spark; related to Old Norse gneista to give off sparks
Word Origin and History for gneiss
n.
1757, from German Gneiss "type of metamorphic rock," probably from Middle High German gneist "spark" (so called because the rock glitters), from Old High German gneisto "spark" (cf. Old English gnast "spark," Old Norse gneisti).
gneiss in Science
gneiss
(nīs) A highly foliated, coarse-grained metamorphic rock consisting of light-colored layers, usually of quartz and feldspar, alternating with dark-colored layers of other minerals, usually hornblende and biotite. Individual grains are often visible between layers. Gneiss forms as the result of the regional metamorphism of igneous, sedimentary, or other metamorphic rocks.