gneiss

noun

: a foliated metamorphic rock corresponding in composition to a feldspathic plutonic rock (such as granite)
gneissic adjective
gneissoid adjective
gneissose adjective

Examples of gneiss in a Sentence

Recent Examples on the Web
These examples are automatically compiled from online sources to illustrate current usage. Opinions expressed in the examples do not represent those of Merriam-Webster or its editors. Send us feedback about these examples.
Feldspar and mica, the main minerals in plutonic rocks like granite and metamorphic rocks like gneiss and schist, react with water and oxygen, decaying to clay minerals. David Bressan, Forbes, 31 Oct. 2024 The West Kootenay bouldering scene is arguably the fastest growing in Canada, with tons of high-quality gneiss and granite coupled with talented, motivated locals establishing new routes faster than anyone can document. Jayme Moye, Outside Online, 4 Oct. 2024 Fordham gneiss, one of the three main New York City rock types (Inwood marble and Manhattan schist are the others), had been the road builders’ big obstacle here. Ian Frazier, The New Yorker, 15 July 2024 Be sure to visit this Blue Ridge Parkway town and its namesake geological formation — an ancient gneiss outcrop whose rocky bulk causes the wind to blow vertically, making objects appear to float skyward. Anne Olivia Bauso, Travel + Leisure, 11 Apr. 2024 Back then, her great-great-great-uncle, the Viscount of Bom Retiro, expropriated private lands on behalf of the Brazilian state to reforest Rio’s peaks of granite and gneiss, which had been denuded by the growing coffee industry. Michael Snyder Pedro Kok, New York Times, 22 Mar. 2024 One billion years ago, following millennia of uplift and erosion, the gneiss breached the surface with its psychedelic ripples and baroque bands—the gray and pink of quartz, feldspar, and granite; the dark green and black of hornblende and biotite mica. Hugh Raffles, The New York Review of Books, 9 Oct. 2020 Outcrop of banded gneiss in the Canadian shield. Gemma Tarlach, Discover Magazine, 15 May 2013 But its two-billion-year-old vertical black gneiss walls have been almost inaccessible for millennia, even to the Ute, the first inhabitants of this region. Stephanie Pearson, Outside Online, 2 Nov. 2022

Word History

Etymology

German Gneis, alteration of Middle High German gneiste spark, from Old High German gneisto; akin to Old English fȳrgnāst spark

First Known Use

1757, in the meaning defined above

Time Traveler
The first known use of gneiss was in 1757

Dictionary Entries Near gneiss

Cite this Entry

“Gneiss.” Merriam-Webster.com Dictionary, Merriam-Webster, https://www.merriam-webster.com/dictionary/gneiss. Accessed 16 Nov. 2024.

Kids Definition

gneiss

noun
: a rock in layers that is similar in composition to granite

More from Merriam-Webster on gneiss

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