slate


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slate,

fine-grained rockrock,
aggregation of solid matter composed of one or more of the minerals forming the earth's crust. The scientific study of rocks is called petrology. Rocks are commonly divided, according to their origin, into three major classes—igneous, sedimentary, and metamorphic.
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 formed when sedimentary rocks such as shaleshale,
sedimentary rock formed by the consolidation of mud or clay, having the property of splitting into thin layers parallel to its bedding planes. Shale tends to be fissile, i.e., it tends to split along planar surfaces between the layers of stratified rock.
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 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 schistsschist
, metamorphic rock having a foliated, or plated, structure called schistosity in which the component flaky minerals are visible to the naked eye. Schists are distinguished from the other foliated rocks, slates and gneisses, by the size of their mineral crystals; these are
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 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.

slate

A hard, brittle metamorphic rock characterized by good cleavage along parallel planes; used as cut stone in thin sheets for flooring, roofing, and panels, and in granular form as surfacing on composition roofing.
See also: Stone

Slate

 

a schistous, sedimentary rock used for roofing. It consists of argillaceous minerals (for the most part, various hydromicas and chlorite) whose particles are usually arranged in strictly parallel lines. This structure gives slate a sharply defined schistosity, that is, the capacity for cleavage into thin lamina. Slate does not fall apart in water and has the characteristics of geosynclinal sediments. It is formed by the compaction of clays and their partial recrystallization under pressure at considerable depths as well as by the effect of dynamic metamorphism. When it undergoes further change, it becomes a phyllte or a chlorite slate.

The largest known deposits of slate in the USSR are located in the Caucasus and the Urals. Slate is used as roofing material; in the production of low-voltage switchboards, knife switches, and other apparatus in the electrical industry; and in the production of certain structural components (panels for the interior facing of rooms). Slate is also used in a crushed, roasted, and aerated form as filler for certain types of concrete, large wall blocks, and for cladding ruberoid(roof-sheeting material).

V. P. PETROV

slate

[slāt]
(petrology)
A group name for various very-fine-grained rocks derived from mudstone, siltstone, and other clayey sediment as a result of low-degree regional metamorphism; characterized by perfect fissility or slaty cleavage which is a regular or perfect planar schistosity.

slate

A hard, brittle metamorphic rock consisting mainly of clay minerals, characterized by good cleavage along parallel planes; used extensively as dimension stone in thin sheets for flooring, roofing, panels (both decorative and electrical), and chalkboard, and in granular form as surfacing on composition roofing.

slate

1. 
a. a compact fine-grained metamorphic rock formed by the effects of heat and pressure on shale. It can be split into thin layers along natural cleavage planes and is used as a roofing and paving material
b. (as modifier): a slate tile
2. a dark grey colour, often with a purplish or bluish tinge
3. Chiefly US and Canadian a list of candidates in an election
4. Films
a. the reference information written on a clapperboard
b. Informal the clapperboard itself

slate

Another name for a tablet computer. In 2010, HP introduced tablets under the Slate brand. See Tablet PC and tablet computer.
References in periodicals archive ?
On January 2, 1,540 sheets of slate were delivered to Kok-Serek, Kosh-Bolot and Ak-Bashat villages of Jalal-Abad region.
com/movies/jon-hamm-jenny-slate-movie-date/) People that Hamm, 46, and Slate, 35, are just "friendly.
In an application to extend the removal operation, planning consultants SLR said: "Since the grant of the planning permission, only a limited amount of the slate waste has been removed and processed from the two tips identified in the original planning application.
Instead of using the local West Highland slate, Argyll and Bute Council are shelling out to have roof slates shipped from San Pedro De Trones in northern Spain for the centre on the Isle of Luing.
The use of slate for roofing dates back to thirteenth century Europe, where it was the material of choice for some of the world's most distinguished castles.
The building, which was placed on the National Register of Historic Places in 1980, was eventually converted into condominiums - Elizabeth Street Schoolhouse Condominiums - but its original, 119-year-old slate roof is in need of repair in portions of the building.
The Welsh Slate company has won the order to supply Heather Blue slate from the Penrhyn Quarry for the renovation project which will see the long disused, derelict, listed Grade II building brought back to life as a cultural, heritage and creative industries centre.
Made from Ffestiniog slate, the pillars are a geological slice through the mountains behind the town.
The betting money was that the slate of the United Front of Principleists would dominate.
Deputy chairman of the slate, MP Mohsen Al Sadoun, said in a joint news conference with members of his slate today "on the occasion of the starts of the second parliamentary round and the first legislative term, the Kurdish Alliance slate will carry out it work to meet the ambitious and goals of the Iraqi people and the quest for legislation of important laws in this phase, including oil and gas, political parties, the MOI salaries, and amendments of the retirement and the election laws.
The Slate Group will aim to "develop and manage a family of web-only magazines, new ventures and acquisitions," according to a Washington Post Company internal memo, described by paidcontent.
If you have a weak floor, it may cause the slate to crack.