Dictionary:

slate

  (slāt)

1. A fine-grained metamorphic rock that splits into thin, smooth-surfaced layers.
2. 1. A piece of this rock cut for use as roofing or surfacing material or as a writing surface.
   2. A writing tablet made of a similar material.
3. A record of past performance or activity: start over with a clean slate.
4. A list of the candidates of a political party running for various offices.
5. A dark or bluish gray to dark bluish or dark purplish gray.

1. Made of a fine-grained metamorphic rock: a slate roof.
2. Of the color slate.

1. To cover (a roof, for example) with slate.
2. To put on a list of candidates.
3. To schedule or designate: Our professor has slated the art history lecture for Thursday afternoon; was slated to direct the studio's next film.

[Middle English sclate, from Old French esclate, splinter, feminine of esclat. See slat.]

Any of the deformed fine-grained, mica-rich rocks that are derived primarily from mudstones and shales, containing a well-developed, penetrative foliation that is called slaty cleavage. Slaty cleavage is a secondary fabric element that forms under low-temperature conditions (less than 540°F or 300°C), and imparts to the rock a tendency to split along planes. It is a type of penetrative fabric; that is, the rock can be split into smaller and smaller pieces, down to the size of the individual grains. If there is an obvious spacing between fabric elements (practically, greater than 1 mm), the fabric is called spaced. Slates typically contain clay minerals (for example, smectite), muscovite/illite, chlorite, quartz, and a variety of accessory phases (such as epidote or iron oxides). Under increasing temperature conditions, slate grades into phyllite and schist. See also Argillaceous rocks; Clay minerals; Phyllite; Schist; Shale.

Slaty cleavage is defined by a strong dimensional preferred orientation of clay in a very clay rich, low-grade metamorphic rock, and the resulting rock is a slate. Slaty cleavage tends to be smooth and planar. Coupled with the penetrative nature of slaty cleavage, these characteristics enable slates to split into very thin sheets. This and the durability of the rock are reasons why slates are used in the roofing industry, in the tile industry, and in the construction of pool tables.

noun

A list of candidates proposed or endorsed by a political party: lineup, ticket. See politics.

verb

To enter on a schedule: program, schedule. See remember/forget.

Idioms beginning with slate:
slated for, be

In addition to the idiom beginning with slate, also see clean slate.

A weak sedimentary rock, easily split along thin layers of bedding, formed by the compression of shales by the overlying rocks.

For more information on slate, visit Britannica.com.

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.

For other uses, see Slate (disambiguation).

Slate

Slate Macro (~ 6 cm long and ~ 4 cm high)

Slate is a fine-grained, foliated, homogeneous, metamorphic rock derived from an original shale-type sedimentary rock composed of clay or volcanic ash through low grade regional metamorphism. The result is a foliated rock in which the foliation may not correspond to the original sedimentary layering.

Chemical composition

Slate is mainly composed of quartz and muscovite or illite, often along with biotite, chlorite, hematite, and pyrite along with, less frequently, apatite, graphite, kaolin, magnetite, tourmaline, or zircon as well as feldspar. Occasionally, as in the purple slates of North Wales, ferrous reduction spheres form around iron nuclei, leaving a light green spotted texture. These spheres are sometimes deformed by a subsequent applied stress field to ovoids, which appear as ellipses when viewed on a cleavage plane of the specimen.

Uses of slate

Slate roof

Slate can be made into roofing slates, also called roofing shingles, installed by a slater. Slate has two lines of breakability: cleavage and grain. This makes it possible to split slate into thin sheets. Fine slate can also be used as a whetstone to hone knives. Due to its thermal stability and chemical inertness, slate has been used for laboratory bench tops and for billiard table tops. In 18th and 19th century schools, slate was extensively used for blackboards and individual writing slates for which chalk pencils were used. Because it was a good electrical insulator and was fireproof, it was used to construct early 20th century electric switchboards and relay controls for large electric motors. Stephen Kettle is notable as a British sculptor for his use of slate to create statues housed in the Science Museum in London.

Slate tiles are often used for interior and exterior flooring or wall cladding. Tiles are installed and set on mortar and grouted along the edges. Chemical sealants are often used on tiles to improve durability and appearance, increase stain resistance, reduce efflorescence, and increase or reduce surface smoothness. Tiles are often sold gauged, meaning that the back surface is ground for ease of installation.

Slate is often used as a decor in freshwater aquariums. Slate will not alter the chemistry of water (except in the slate containing felspar which may leech silicates into the water resulting in excess diatom growth in marine aquaria). When broken, slate produces a natural appearance while remaining relatively flat and can be easily stacked. Silicon glue adheres to slate, creating a non-toxic bond to secure it. It is also used in stairs and pathways for the same reasons.

Traditional Japanese Go equipment uses slate for the black pieces.

Slate extraction

Exhibition Slate mine Fell

Historical Pit Vogelsberg 1 at Fell

Slate-producing regions include Cornwall (famously the town of Delabole), Wales and Cumbria (see Burlington Slate Quarries and Skiddaw Slate) in the United Kingdom (see slate industry in Wales), Liguria in northern Italy especially between the town of Lavagna (which means chalkboard in Italian) and Fontanabuona valley, Portugal especially around Valongo in the north of the country, Germany (Moselle River-region, Hunsrück, Eifel, Westerwald, Thuringia, north-Bavaria), Alta, Norway, Galicia, Brazil around Papagaio in Minas Gerais, the east coast of Newfoundland, the Slate Belt of Eastern Pennsylvania, and the Slate Valley of Vermont and New York.

There was also a major slating operation in Monson, Maine during the late 19th and early 20th centuries. The slate found in Monson is usually a dark purple to blackish color, and many local structures are still roofed with slate tiles. Of many operations there is only one business currently operating. The output was so great it formed a train route throughout the woods of Monson and as many as 18 quarries were made. St. Patricks's Cathedral in New York's roof was made from roofing slate from Monson, as well as the Headstone of John F. Kennedy.

Slate is also found in the Arctic and was used by the Inuit to make the blades for ulus. China has vast slate deposits; in recent years its export of finished and unfinished slate has increased.

See also

• List of rock types
• Tile
• Welsh Slate Museum
• Exhibition slate mine fell
• Slate industry in Wales

External links

• AditNow - Photographic database of mines
• History of the Welsh slate industry
• Slatesite — bilingual site focusing on Welsh slate
• Step-by-step guide to how Roofing Slate is produced at Greenstone Slate
• John T F Turner - A Familiar Description of the Old Delabole Slate Quarries, 1864
• History of the Scottish Slate Islands

This entry is from Wikipedia, the leading user-contributed encyclopedia. It may not have been reviewed by professional editors (see full disclaimer)

Dansk (Danish)
n. - skifer, skifertagsten, tavle, hinkesten
v. tr. - lægge skifertag på, sætte på liste, foreslå, beramme, forudbestemme
adj. - skifergrå, skifer-

idioms:

• slate PC    PC hvor man kan skrive data ind med en lyspen
• wipe the slate clean    begynde på en frisk

Nederlands (Dutch)
lei, leisteen, grijs, kandidatenlijst, kandideren, afkraken

Français (French)
n. - ardoise, (US) liste de candidature
v. tr. - couvrir (qch) d'ardoises, (GB) taper sur, blâmer, (US, Pol) mettre (qn) sur la liste, (US) avoir de fortes chances de
adj. - d'ardoise

idioms:

• slate PC    (Comput) ordinateur bloc-notes
• wipe the slate clean    faire table rase (du passé)

Deutsch (German)
n. - Schiefer, Schiefertafel, Schieferplatte, Kandidatenliste
v. - vorsehen, scharf kritisieren
adj. - schiefergrau

idioms:

• slate PC    Mobil-PC mit einer Oberfläche für Dateneingabe mit einem elektr. Kuli
• wipe the slate clean    einen Schlußstrich ziehen

Ελληνική (Greek)
n. - (μαθητική) πλάκα, αβάκιο, (γεωλ.) σχιστόλιθος, (ΗΠΑ) λίστα υποψηφίων για αξίωμα
v. - καλύπτω (στέγη κ.λπ.) με πλάκες σχιστόλιθου, (ΗΠΑ) προετοιμάζω εκδήλωση, (ΗΠΑ) προτείνω κάποιον ως υποψήφιο, (Βρετ., καθομ.) επικρίνω, κατσαδιάζω
adj. - από πλάκες σχιστόλιθου

idioms:

• slate PC    φορητός υπολογιστής με ηλεκτρονική γραφίδα
• wipe the slate clean    γυρίζω νέα σελίδα

Italiano (Italian)
stroncare, ardesia, lavagna, lista dei candidati

idioms:

• a clean slate    tabula rasa
• wipe the slate clean    fare tabula rasa, ricominciare daccapo

Português (Portuguese)
n. - ardósia (f), cinzento azulado (m), lousa (f)
v. - assentar, censurar, criticar
adj. - critico (m)

idioms:

• a clean slate    começar de novo
• wipe the slate clean    esquecer o passado e começar vida nova

Русский (Russian)
шиферная плитка, грифельная доска, шиферный сланец, список, программа (состязаний), аспидный цвет, разгромная рецензия, крыть шифером, заносить в список кандидатов, выдвигать для рассмотрения, назначать (на какое-то время), дать нагоняй, выпороть

idioms:

• a clean slate    безупречная репутация, полный порядок (в делах)
• wipe the slate clean    забыть старые ошибки и начать с чистого листа

Español (Spanish)
n. - pizarra, lista de candidatos
v. tr. - echar una bronca, vapulear, castigar
adj. - de pizarra, pizarreño, apizarrado

idioms:

• slate PC    (comp) notebook con superficie para ingresar datos con un lápiz electrónico
• wipe the slate clean    hacer borrón y cuenta nueva

Svenska (Swedish)
n. - skiffer, takplatta, takskiffer, griffeltavla, skiffergrått, preliminär kandidatlista för ett val
v. - täcka med skiffer, skiffertäcka, göra ner, läxa upp, tufsa till, föreslå som kandidat, tillkännage, planera in, avtala, utsätta, förutbestämma
adj. - skiffergrå

中文（简体） (Chinese (Simplified))
板岩, 石片, 石板, 铺石板, 痛打, 责骂, 暗蓝灰色的, 含板岩的

idioms:

• slate PC    板形计算机
• wipe the slate clean    把以往的过错或不和债务等一笔勾销

中文（繁體） (Chinese (Traditional))
n. - 板岩, 石片, 石板
v. tr. - 鋪石板, 痛打, 責罵
adj. - 暗藍灰色的, 含板岩的

idioms:

• slate PC    板形電腦
• wipe the slate clean    把以往的過錯或不和債務等一筆勾銷

한국어 (Korean)
n. - 슬레이트, 짙은 청회색, (지명) 후보자 명부
v. tr. - (지붕을) 슬레이트로 이다, 후보자 명단에 올리다, 예정하다
adj. - 석판질의, 석판색

日本語 (Japanese)
n. - スレート, 粘板岩, スレート色, 候補者名簿, 石板
v. - スレートでふく, 候補者名簿に載せる, 予定する, 予定させる, 酷評する

العربيه (Arabic)
‏(الاسم) صخر يسهل قطعه ألى ألواح تكسى بها ألسقوف, لوح أردوازي للكتابه, سجل أعمال أو أحداث (فعل) يسجل ألاسماء, يكسو بألواح أردوازيه (صفه) مكسو بألواح أردوازيه‏

עברית (Hebrew)
n. - ‮צפחה, רעף, לוח צפחה, רשימת מועמדים‬
v. tr. - ‮כיסה ברעפים, הציע מועמדות, הועיד, תכנן, גינה, תקף, קטל‬
adj. - ‮אפור-כחול, עשוי רעפים‬

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