gneiss
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.
Origin of gneiss
1Other words from gneiss
- gneissic, adjective
Words that may be confused with gneiss
- gneiss , nice
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2024
How to use gneiss in a sentence
The commonest and most important types of gneiss are the mica-gneisses.
The gneisses appear to be due in many cases to the crushing and shearing of deep-seated igneous rocks, such as granite and gabbro.
The Elements of Geology | William Harmon NortonThe northern half of Guernsey is mainly dioritic, the southern half, below St Peter, is occupied by gneisses.
Epidote, often with enclosures of orthite, is by no means rare in gneisses from many different parts of the world.
Hornblende is green, rarely brownish; augite pale green or nearly colourless; enstatite appears in some granulite-gneisses.
British Dictionary definitions for gneiss
/ (naɪs) /
any coarse-grained metamorphic rock that is banded and foliated: represents the last stage in the metamorphism of rocks before melting
Origin of gneiss
1Derived forms of gneiss
- gneissic, gneissoid or gneissose, adjective
Collins English Dictionary - Complete & Unabridged 2012 Digital Edition © William Collins Sons & Co. Ltd. 1979, 1986 © HarperCollins Publishers 1998, 2000, 2003, 2005, 2006, 2007, 2009, 2012
Scientific definitions for 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.
The American Heritage® Science Dictionary Copyright © 2011. Published by Houghton Mifflin Harcourt Publishing Company. All rights reserved.
Browse