graywacke

or grey·wacke

[ grey-wak, -wak-uh ]

/ ˈgreɪˌwæk, -ˌwæk ə /

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noun

Geology. a dark-gray coarse-grained wacke.

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Origin of graywacke

1805–15; partly translation, partly adapted from German Grauwache;see wacke

Words nearby graywacke

Grayson, Grays Peak, gray squirrel, gray trout, gray urn, graywacke, gray water, graywether, gray whale, gray wolf, Graz

How to use graywacke in a sentence

Appropriately pronounced a "secondary graywacke slate," by Mr. Eaton.
Summary Narrative of an Exploratory Expedition to the Sources of the Mississippi River, in 1820|Henry Rowe Schoolcraft
In the transition graywacke of the south of Scotland, the galena mines of Leadhills occur.
A Dictionary of Arts, Manufactures and Mines|Andrew Ure
Their material, however, is not flint, but either graywacke or a kind of tough slate.
North American Stone Implements|Charles Rau
Is it primitive, or is it graywacke like Catskill Mountains?
Personal Memoirs Of A Residence Of Thirty Years With The Indian Tribes On The American Frontiers|Henry Rowe Schoolcraft

I received a specimen of slaty graywacke from Lake Superior.
Personal Memoirs Of A Residence Of Thirty Years With The Indian Tribes On The American Frontiers|Henry Rowe Schoolcraft

Scientific definitions for graywacke

graywacke

[ grā′wăk′, -wăk′ə ]

Any of various dark gray, coarse-grained sandstones that contain abundant feldspar and rock fragments and often have a clay-rich matrix. Graywackes are thought to originate in environments where erosion, transportation, and deposition happen so quickly that minerals and rock fragments do not have sufficient time to break down into finer constituents.