shale


shale
shalelike, shaley, adj.
/shayl/, n.
a rock of fissile or laminated structure formed by the consolidation of clay or argillaceous material.
[1740-50; orig. uncert.; cf. obs. shale to split (said of stone), to shell, deriv. of shale shell, husk, OE scealu shell, husk; see SCALE2]

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I
Any of a group of fine-grained, laminated sedimentary rocks consisting of silt-and clay-sized particles.

Shale constitutes roughly 60% of the sedimentary rock in the Earth's crust. Shales are commercially important, particularly in the ceramics industry. They are a valuable raw material for tile, brick, and pottery and constitute a major source of alumina for portland cement. In addition, advances in recovery methods may one day make oil shale a practical source for liquid petroleum.
II
(as used in expressions)
kerogen shales

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rock
      any of a group of fine-grained, laminated sedimentary rocks consisting of silt- and clay-sized particles. Shale is the most abundant of the sedimentary rocks, accounting for roughly 70 percent of this rock type in the crust of the Earth.

      Shales are often found with layers of sandstone or limestone. They typically form in environments where muds, silts, and other sediments were deposited by gentle transporting currents and became compacted, as, for example, the deep-ocean floor, basins of shallow seas, river floodplains, and playas. Most shales occur in extensive sheets several metres thick, though some develop in lenticular formations.

      Shales characteristically consist of at least 30 percent clay minerals and substantial amounts of quartz. They also contain smaller quantities of carbonates, feldspars, iron oxides, fossils, and organic matter. Some organic-rich shales, called oil shales (oil shale), contain kerogen (a chemically complex mixture of solid hydrocarbons derived from plant and animal matter) in large enough quantities to yield oil when subjected to intense heat.

      Shales typically have a laminated structure and are fissile; i.e., they exhibit a tendency to split into thin layers that are usually parallel to the bedding-plane surface. Such physical properties as permeability and plasticity are largely dependent on the grain sizes of the constituent minerals. Shales' colour is determined primarily by composition. In general, the higher the organic content of a shale, the darker its colour. The presence of hematite and limonite (hydrated ferric oxide) gives rise to reddish and purple colouring, while mineral components rich in ferrous iron impart blue, green, and black hues. Calcareous shales (those having a large percentage of calcite), on the other hand, are light gray or yellowish.

      Shales are commercially important, having many applications in the ceramics industry in particular. They are a valuable raw material for tile, brick, and pottery and constitute a major source of alumina for Portland cement. In addition, advances in recovery methods may one day make oil shale a practical source for liquid petroleum.

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Universalium. 2010.

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Look at other dictionaries:

  • Shale — (also called mudstone) is a fine grained sedimentary rock whose original constituents were clay minerals or muds. It is characterized by thin laminae [cite encyclopedia title = shale encyclopedia = Chambers Dictionary of Science and Technology… …   Wikipedia

  • Shalë — Shalë …   Wikipedia Español

  • Shale — Shale, n. [AS. scealy, scalu. See {Scalme}, and cf. {Shell}.] 1. A shell or husk; a cod or pod. The green shales of a bean. Chapman. [1913 Webster] 2. [G. shale.] (Geol.) A fine grained sedimentary rock of a thin, laminated, and often friable,… …   The Collaborative International Dictionary of English

  • Shale — Shale, v. t. To take off the shell or coat of; to shell. [1913 Webster] Life, in its upper grades, was bursting its shell, or was shaling off its husk. I. Taylor. [1913 Webster] …   The Collaborative International Dictionary of English

  • shale — [ʃeıl] n [U] [: Old English; Origin: scealu shell, scale ] a smooth soft rock which breaks easily into thin flat pieces …   Dictionary of contemporary English

  • shale — [ ʃeıl ] noun uncount a type of smooth dark rock that breaks into thin layers …   Usage of the words and phrases in modern English

  • shale — (n.) 1747, possibly a specialized use of M.E. schale shell, husk, pod (late 14c.), also fish scale, from O.E. scealu (see SHELL (Cf. shell)) in its base sense of thing that divides or separate, in reference to the way the rock breaks apart in… …   Etymology dictionary

  • shale — ► NOUN ▪ soft stratified sedimentary rock formed from consolidated mud or clay. DERIVATIVES shaly (also shaley) adjective. ORIGIN probably from German Schale …   English terms dictionary

  • shale — [shāl] n. [< ME, lit., shell < OE scealu, SHELL] a kind of fine grained, thinly bedded sedimentary rock formed largely by the hardening of clay: it splits easily into thin layers: cf. MUDSTONE …   English World dictionary

  • Shale — A type of sedimentary rock found in the earth s crust composed chiefly of a combination of silt and clay. A great deal of the earth s usable fossil fuels are found in shale formations. There are many different types of shale, such as oil shale… …   Investment dictionary


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