slate

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Related to slates: Slaters

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 classic literature ?
That slate tower bang over the porch, with the dormer windows and the iron railing and flagstaff atop makes us a present of the period.
Alec was evidently already won, for Rose had described the old slate and brown paper copy-book with pathetic effect, and the excellent man had not only decided to send Phebe to school long before the story was done, but reproached himself for forgetting his duty to one little girl in his love for another.
Anne had brought her slate down on Gilbert's head and cracked it--slate not head--clear across.
Her teachers complained that instead of doing her sums she covered her slate with animals, the blank pages of her atlas were used to copy maps on, and caricatures of the most ludicrous description came fluttering out of all her books at unlucky moments.
Now Tom began to scrawl something on the slate, hiding the words from the girl.
To this end, I had sat well back on the form, and while seeming to be busy with my sum, had held my slate in such a manner as to conceal my face: I might have escaped notice, had not my treacherous slate somehow happened to slip from my hand, and falling with an obtrusive crash, directly drawn every eye upon me; I knew it was all over now, and, as I stooped to pick up the two fragments of slate, I rallied my forces for the worst.
I should like to be," said I, glancing at the slate as he held it: with a misgiving that the writing was rather hilly.
exclaimed the stranger; "it is our nature to desire a monument, be it slate or marble, or a pillar of granite, or a glorious memory in the universal heart of man.
A slate gravestone would suit me as well as a marble one -- with just my name and age, and a verse of a hymn, and something to let people know that I lived an honest man and died a Christian.
But on the other side, on the flat Essex side, a shapeless and desolate red edifice, a vast pile of bricks with many windows and a slate roof more inaccessible than an Alpine slope, towers over the bend in monstrous ugliness, the tallest, heaviest building for miles around, a thing like an hotel, like a mansion of flats (all to let), exiled into these fields out of a street in West Kensington.
Why, it’s all down, squire,” said Benjamin, pointing to a slate that lay on the table, by the side of a mug of toddy, a short pipe in which the tobacco was yet burning, and a prayer-book.
At once the cap changed to a slate, on which was written in big, white chalk marks: