slate

slate

slate / slāt/ • n. 1. a fine-grained gray, green, or bluish metamorphic rock easily split into smooth, flat pieces. ∎  a flat piece of such rock used as roofing material. 2. a flat piece of slate used for writing on, typically framed in wood, formerly used in schools. ∎  a list of candidates for election to a post or office, typically a group sharing a set of political views: another slate of candidates will be picked for the state convention. ∎  a range of something offered: the company has revealed details of a $60 million slate of film productions. ∎  a board showing the identifying details of a take of a motion picture, which is held in front of the camera at its beginning and end. 3. [usu. as adj.] a bluish-gray color: suits of slate gray. • v. [tr.] 1. cover (something, esp. a roof) with slates. 2. Brit., inf. criticize severely: his work was slated by the critics. 3. (usu. be slated) schedule; plan: renovations are slated for late June | [tr.] the former brickyard is slated to be renovated. ∎  (usu. be slated) nominate (someone) as a candidate for an office or post: I understand that I am being slated for promotion. 4. identify (a movie take) using a slate. PHRASES: wipe the slate cleansee wipe.DERIVATIVES: slat·y adj.

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"slate." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>.

"slate." The Oxford Pocket Dictionary of Current English. 2009. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O999-slate.html

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slate

slate In popular usage the word ‘slate’ refers to any sort of natural roofing material, including those composed of thin-bedded, flaggy, sandstones and limestones such as the Cotswold Slates of Jurassic age that cover so many buildings in Oxford. However, to a geologist these ‘slates’ are simply flagstones, unmetamorphosed sedimentary rocks that can be split into sheets thin enough to be used for roofing buildings.

True slates do not necessarily split along bedding planes. Instead, most of them split along planes that are inclined at an angle, sometimes a very high angle, to the bedding planes. These planes, referred to as slaty cleavage, are caused by the rearrangement of minerals such as mica, chlorite, and clay within the rock. It is along these planes that the rock splits into the characteristic roofing slates that we know from so many parts of Europe. These rocks were affected by the Caledonian orogeny, in which fine-grained shales composed of mud and volcanic ash were transformed by low-grade metamorphism and pressure into the variously coloured grey, purple, and green patterned slates. The colour banding indicates the original bedding of the rocks. As the intensity of metamorphism increases, so slates are transformed first into phyllites and then into schists.

Harold G. Reading

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PAUL HANCOCK and BRIAN J. SKINNER. "slate." The Oxford Companion to the Earth. 2000. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>.

PAUL HANCOCK and BRIAN J. SKINNER. "slate." The Oxford Companion to the Earth. 2000. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O112-slate.html

PAUL HANCOCK and BRIAN J. SKINNER. "slate." The Oxford Companion to the Earth. 2000. Retrieved May 27, 2012 from Encyclopedia.com: http://www.encyclopedia.com/doc/1O112-slate.html

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Slate

Slate

Slate is a hard, fine-grained metamorphic rock that forms when sedimentary rocks , such as shale and mudstone, are subjected to relatively low temperature and pressure. It occurs chiefly among older rocks. Millions of years of geological compression force the flaky minerals (mica, chlorite, quartz ) within clay sediments to shift perpendicular to the pressure. This pushing alters the material's fundamental structure and creates a new feature known as slaty cleavage. True slate splits easily along this plane into thin, but durable, sheets.

While slate's characteristic color is gray-blue, varieties range from dark gray to black. Organic materials present in the parent rock can create different tinges. Iron oxide creates a reddish purple tinge; chlorite turns slate green. The rock also varies greatly in surface texture and luster; some slates have a dull, matte finish while others can be as shiny as mica.

Better grades of the rock are widely used for roofing, flooring and sidewall cladding. Slate is also used to make blackboards and pool tables. Pennsylvania and Vermont serve as the principal slate producers for the United States, although slate mines can also be found in Maine, Georgia, Lake Superior, and the Rocky Mountains.

See also Bedding; Metamorphism; Sedimentation

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"Slate." World of Earth Science. 2003. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>.

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slate

slate fine-grained rock formed when sedimentary rocks such as shale are metamorphosed by great pressure. Slate splits into perfectly cleaved, broad thin layers; this characteristically regular and planar cleavage is called slaty cleavage. In the formation of slate, pressure causes the flaky minerals within the sedimentary rock, such as mica, clay, and chlorite, to be reoriented; the flat faces of the minerals lie at right angles to the source of the pressure, and the planes of easy cleavage are also at right angles to the source of the pressure. The rock is not necessarily compressed in the same direction as the sedimentary layers were originally laid down, and because the compression crumples and deforms the original sedimentary layers, the planes of slaty cleavage usually cut through the old bedding planes. Slate is intermediate in hardness between mica schists and shale; the better grades are used for roofing. Its characteristic color is gray-blue. Slate is mined in Maine, Vermont, Pennsylvania, Georgia, Lake Superior, and the Rocky Mts.

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"slate." The Columbia Encyclopedia, 6th ed.. 2011. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>.

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slate

slate Low-grade, regionally metamorphosed rock, which is highly fissile and fine grained. The fissility (slaty cleavage) results from the parallel alignment of numerous fine phyllosilicate minerals (e.g. muscovite and chlorite) induced by compressive tectonic deformation. The smooth, hard, impermeable surface produced when slate is split makes it commercially valuable for roofing, cladding of buildings, and for making such items as billiard-table tops, laboratory benches, and blackboards. Compare PHYLLITE; and SCHIST.

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AILSA ALLABY and MICHAEL ALLABY. "slate." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>.

AILSA ALLABY and MICHAEL ALLABY. "slate." A Dictionary of Earth Sciences. 1999. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O13-slate.html

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slate

slate Low-grade, regionally metamorphosed rock (see metamorphism and metamorphic rock), which is highly fissile and fine-grained. The fissility results from the parallel alignment of numerous fine minerals. The smooth, hard, impermeable surface produced when slate is split makes it commercially valuable for roofing, cladding buildings, and for making such items as billiard-table tops, laboratory benches, and blackboards.

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MICHAEL ALLABY. "slate." A Dictionary of Ecology. 2004. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>.

MICHAEL ALLABY. "slate." A Dictionary of Ecology. 2004. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O14-slate.html

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slate

slate Grey to blue, fine-grained, homogeneous metamorphic rock, which splits into smooth, thin layers. It forms by the metamorphosis of shale, and is valuable as a roofing material.

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slate

slate1 (tablet of) variety of stone that splits readily into plates. XIV (sclate, sklatestane). — OF. esclate, fem. corr. to m. esclat SLAT.

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T. F. HOAD. "slate." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>.

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Slate

Slate

a list of candidates prepared for nomination.

Examples : slate of candidatesLipton, 1970; of horses (in a race); of officers.

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"Slate." Dictionary of Collective Nouns and Group Terms. 1985. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>.

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slate

slate. Sedimentary stone readily divisible into thin plates or slabs used for cladding, roofing, paving, tomb-stones, etc.

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JAMES STEVENS CURL. "slate." A Dictionary of Architecture and Landscape Architecture. 2000. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>.

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slate

slate2 (sl.) ‘knock the hat over someone's eyes’; thrash; assail with abuse. XIX. app. f. prec.

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T. F. HOAD. "slate." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>.

T. F. HOAD. "slate." The Concise Oxford Dictionary of English Etymology. 1996. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O27-slate1.html

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slate

slateabate, ablate, aerate, ait, await, backdate, bait, bate, berate, castrate, collate, conflate, crate, create, cremate, date, deflate, dictate, dilate, distraite, donate, downstate, eight, elate, equate, estate, fate, fellate, fête, fixate, freight, frustrate, gait, gate, gestate, gradate, grate, great, gyrate, hate, hydrate, inflate, innate, interrelate, interstate, irate, Kate, Kuwait, lactate, late, locate, lustrate, mandate, mate, migrate, misdate, misstate, mistranslate, mutate, narrate, negate, notate, orate, ornate, Pate, placate, plate, prate, prorate, prostrate, pulsate, pupate, quadrate, rate, rotate, sate, sedate, serrate, short weight, skate, slate, spate, spectate, spruit, stagnate, state, straight, strait, Tate, tête-à-tête, Thwaite, translate, translocate, transmigrate, truncate, underrate, understate, underweight, update, uprate, upstate, up-to-date, vacate, vibrate, wait, weight

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"slate." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. 27 May. 2012 <http://www.encyclopedia.com>.

"slate." Oxford Dictionary of Rhymes. 2007. Encyclopedia.com. (May 27, 2012). http://www.encyclopedia.com/doc/1O233-slate.html

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Free newspaper and magazine articles

Repairing slate roofs: with simple spot repairs, a slate roof can last a...
Magazine article from: The Journal of Light Construction; 12/1/2003
Slate takes to the floor ...in style; (1) Lowri Turner's Home Improvements.
Newspaper article from: The Mail on Sunday (London, England); 5/13/2007
Slate of the art business takes off; PEMBROKESHIRE: Couple seek perfection as...
Newspaper article from: Western Mail (Cardiff, Wales); 1/16/2002

Facts and information from other sites

slate images
slate. Wikimedia Commons (Public Domain)