arkose

American  

[ahr-kohs] / ˈɑr koʊs /

noun

1. a granular sedimentary rock composed of quartz and feldspar or mica; a feldspathic sandstone.

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arkose British  

/ ˈɑːkəʊs /

noun

1. a sandstone consisting of grains of feldspar and quartz cemented by a mixture of quartz and clay minerals

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arkose Scientific  

/ är′kōs /

1. A usually pinkish or red sandstone consisting primarily of quartz and feldspar. Arkose usually forms as the result of the rapid disintegration of granite in areas of vigorous erosion. Its grains are usually angular and poorly sorted (mixed randomly in differing sizes).

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Other Word Forms

• arkosic adjective

Etymology

Origin of arkose

Borrowed into English from French around 1830–40

Example Sentences

Its heavy concentration of feldspar grains — known as arkose — means the rock is inevitably prone to chemical decay.

From Washington Post • Apr. 1, 2021

Dickinson, W. R. Interpreting detrital modes of graywacke and arkose.

From Textbooks • Jan. 1, 2017

The quartz arenite and arkose have relatively little silt-clay matrix, while the lithic wacke has abundant matrix.

From Textbooks • Jan. 1, 2015

The Triassic rocks are mainly red sandstones,—often feldspathic, or arkose, with some conglomerates and shales.

From The Elements of Geology by Norton, William Harmon

The Nieuwerust beds contain quartzite, arkose and shales.

From Encyclopaedia Britannica, 11th Edition, Volume 5, Slice 2 "Camorra" to "Cape Colony" by Various