gneiss

American

[nahys] / naɪs /

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.

gneiss British

/ naɪs /

noun

any coarse-grained metamorphic rock that is banded and foliated: represents the last stage in the metamorphism of rocks before melting

"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

gneiss Scientific

/ 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.

Other Word Forms

Derived Forms

gneissic

adjective

Etymology

Origin of gneiss

Borrowed into English from German around 1750–60

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Vocabulary lists containing gneiss

Rocks and Minerals - Middle School and High School

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Definitions and idiom definitions from Dictionary.com Unabridged, based on the Random House Unabridged Dictionary, © Random House, Inc. 2023