Definition of gneiss in English:

gneiss

Syllabification: gneiss
Pronunciation: /nīs
 
/

noun

A metamorphic rock with a banded or foliated structure, typically coarse-grained and consisting mainly of feldspar, quartz, and mica.
More example sentences
  • Corundum occurs as an accessory mineral in some metamorphic rocks, such as mica schist, gneiss, and crystalline limestone.
  • Between the Dharwas leucogranite and Kilar there is a simple planar structure of interspersed pelitic gneiss and leucogranite bands with a regional foliation dipping to the south or southeast.
  • The Borve Series is dominated by varieties of quartzo-feldspathic schist and gneiss, composed mainly of plagioclase, quartz, and biotite.

Origin

mid 18th century: from German, from Old High German gneisto 'spark' (because of the rock's sheen).

Derivatives

gneissic

adjective
More example sentences
  • Scattered throughout the Pena Negra migmatites there are small bodies of Upper Proterozoic gneissic granodiorite and granite.
  • The Cenozoic melanges, widely distributed in central and eastern Sabah, exclusively contain mixed mafic-ultramafic, chert, and Cenozoic sandstone blocks, and lack any granitic, gneissic, or otherwise ‘continental’ clasts.
  • The tonalite is gneissic, banded on a decimetre scale, and loaded with discrete mafic enclaves, metasedimentary xenoliths and garnet, feldspar and rutile xenocrysts, such that the body has a migmatitic appearance.

gneissoid

adjective
More example sentences
  • There are also gray and fine grained red granites, and in some places they have taken a gneissoid form.
  • The granodiorite deposits at Aswan are often gneissoid in texture, exhibiting parallel orientated feldspar phenocrysts.
  • In the inner sulfide zone gneissoid textures resulting from complete and vigorous replacement of the country rock have resulted.

Definition of gneiss in:

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Word of the day apposite
Pronunciation: ˈapəzit
adjective
apt in the circumstances or relation to something