gneiss

[nahys]

noun

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

Examples from the Web for gneiss

Historical Examples of gneiss

Everywhere granite, gneiss, or other primitive rocks, show themselves.
The Young Voyageurs
Mayne Reid
Here and there are mixtures of schist, gneiss, and porphyry.
The Rocky Mountain Wonderland
Enos A. Mills
The southern parts of this range of mountains are composed of gneiss and granite.
The Central Eskimo
Franz Boas
My ground was on the gneiss side of the geological division.
The Mystery of the Sea
Bram Stoker
Come,” I said, “let us go back till we find the joining of the gneiss and granite.
The Mystery of the Sea
Bram Stoker

British Dictionary definitions for gneiss

gneiss

noun

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

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.