gneiss

[nahys]
noun
  1. 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

Borrowed into English from German around 1750–60
Related formsgneiss·ic, adjective
Can be confusedgneiss nice (see usage note at nice)
Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

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Historical Examples of gneiss


British Dictionary definitions for gneiss

gneiss

noun
  1. any coarse-grained metamorphic rock that is banded and foliated: represents the last stage in the metamorphism of rocks before melting
Derived Formsgneissic, gneissoid or gneissose, adjective

Word Origin for gneiss

C18: from German Gneis, probably from Middle High German ganeist spark; related to Old Norse gneista to give off sparks
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

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).

Online Etymology Dictionary, © 2010 Douglas Harper

gneiss in Science

gneiss

[nīs]
  1. 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.