Arkose (pronEng|ˈɑrkoʊz) is a detrital sedimentary rock, specifically a type of sandstone containing at least 25% feldspar.cite book
author = Folk, R.L.
year = 1974
title = Petrology of Sedimentary Rocks
publisher = Hemphill
isbn = 0-914696-14-9
url =
] ,cite book
author = Stow, D.A.V.
year = 2005
title = Sedimentary rocks in the field
publisher = Manson
isbn = 1-874545-69-3
] Arkosic sand is sand that is similarly rich in feldspar, and thus the potential precursor of arkose. The other mineral components may vary, but quartz is commonly dominant, and minor mica is often present. Apart from the mineral content, rock fragments may also be a significant component. Arkose usually contains small amounts of calcite cement, which causes it to effervesce slightly in dilute hydrochloric acid; sometimes the cement also contains iron oxide. Arkose is typically grey to reddish in colour. The sand grains making up an arkose may range from fine to very coarse, but tends toward the coarser end of the scale. Fossils are rare in arkose, due to the depositional processes that form it, although bedding is frequently visible.

Arkose is generally formed from the weathering of feldspar-rich igneous or metamorphic rocks, most commonly granitic rocks, which are primarily composed of quartz and feldspar. These sediments must be deposited rapidly and/or in a cold or arid environment such that the feldspar does not undergo significant chemical weathering and decomposition; therefore arkose is designated a "texturally immature" sedimentary rock. Arkose is often associated with conglomerate deposits sourced from granitic terrain and is often found above unconformities over such granitic terrain.

The famous central Australian monolith Uluru (Ayers Rock) is composed of late Neoproterozoic or Cambrian arkose, deposited in the Amadeus Basin.cite book
author = Sweet, I.P., Crick, I.H.
year = 1991
title = unicode|Uluṟu & Kata Tjuṯa: A Geological History
publisher = Australian Geological Survey Organization
isbn = 0-644-25681-8
url =


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  • arkose — ● arkose nom féminin Grès feldspathique, dérivant de l érosion de roches granitiques sédimentées et constitué de grains de quartz, feldspaths et micas. ⇒ARKOSE, subst. fém. GÉOL. Grès composé de quartz et de feldspath (contenant parfois du mica) …   Encyclopédie Universelle

  • Arkose — Ar*kose , n. [F] (Petrog) A sandstone derived from the disintegration of granite or gneiss, and characterized by feldspar fragments. {Ar*kos ic}, a. [Webster 1913 Suppl.] …   The Collaborative International Dictionary of English

  • Arkose — Arkose, ein im mittleren Frankreich, sowie im Rothliegenden Deutschlands vorkommender Sandstein, welcher neben Quarzkörnern viele Feldspathkörner u. Glimmerblättchen in einem thonigen Bindemittel enthält; häufig ist dieser A. dem Granit sehr… …   Pierer's Universal-Lexikon

  • Arkōse — Arkōse, feldspatreicher Sandstein, z. T. gebildet aus Granitgrus (regenerierter Granit), mit tonigem oder kieseligem Bindemittel, findet sich vielfach im Karbon, Rotliegenden, Buntsandstein etc …   Meyers Großes Konversations-Lexikon

  • arkose — [är′kōs΄, är kōs′] n. [Fr] a medium grained sandstone containing feldspar, derived from the erosion of igneous rock, esp. granite …   English World dictionary

  • Arkose — Exemple d utilisation d arkose pour la construction d une église en Auvergne. L arkose est une roche sédimentaire détritique terrigène composée de quartz (jusqu à 60 %), de feldspath (au moins 25 %), souvent de quelques micas et d un… …   Wikipédia en Français

  • arkose — arkosic, adj. /ahr kohs/, n. a granular sedimentary rock composed of quartz and feldspar or mica; a feldspathic sandstone. [1830 40; < F] * * * Coarse sandstone that has formed by the disintegration of granite without appreciable decomposition.… …   Universalium

  • Arkose — Relativ dunkle Arkose; Fundort: Bebertal in Sachsen Anhalt; Alter: Oberkarbon; Länge des Handstückes: ca. 6 cm Arkose bezeichnet eine Klasse von Sandsteinen, welche sich durch einen hohen Gehalt an Feldspat auszeichnet. Inhaltsverzeichnis …   Deutsch Wikipedia

  • Arkose — Ar|ko|se 〈f. 19; unz.; Geol.〉 Feldspat u. Glimmer enthaltendes Sedimentgestein * * * Arkose   [französisch] die, , Sandstein mit mehr als 25 % Feldspat; unter ariden Bedingungen aus feldspatreichen Gesteinen (Granit, Gneis) entstanden. * * *… …   Universal-Lexikon

  • Arkose, Arkosesandstein — Arkose, Arkosesandstein, s.v.w. Feldspatsandsteine, s. Sandstein …   Lexikon der gesamten Technik

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