AskDefine | Define slate

Dictionary Definition



1 (formerly) a writing tablet made of slate
2 thin layers of rock used for roofing [syn: slating]
3 a fine-grained metamorphic rock that can be split into thin layers
4 a list of candidates nominated by a political party to run for election to public offices [syn: ticket]


1 designate or schedule; "He slated his talk for 9 AM"; "She was slated to be his successor"
2 enter on a list or slate for an election; "He was slated for borough president"
3 cover with slate; "slate the roof"

User Contributed Dictionary



From esclate (French éclat).


  • /sleɪt/ /sleIt/
  • Rhymes with: -eɪt


  1. A fine-grained homogeneous sedimentary rock composed of clay or volcanic ash which has been metamorphosed so that it cleaves easily into thin layers.
  2. The bluish-grey colour of most slate.
    slate colour:   
  3. A sheet of slate for writing on with chalk.
  4. A tile made of slate.
  5. A record of money owed.
    Put it on my slate – I’ll pay you next week.
  6. A list of affiliated candidates for an election.
    Roy Disney led the alternative slate of directors for the stockholder vote.


sheet of slate for writing on
record of money owed
list of candidates for an election


  1. In the context of "colour": Having the bluish-grey/gray colour/color of slate.


bluish-grey/gray like slate


  1. In the context of "chiefly|UK": To criticise harshly.
    The play was slated by the critics.
  2. In the context of "mainly|US": To schedule.
    The election was slated for November 2nd.
  3. In the context of "mainly|US": To destine or strongly expect.
    The next version of our software is slated to be the best release ever.


criticise/criticize harshly
  • Dutch: afmaken, met de grond gelijk maken
  • German: verreissen
  • Dutch: plannen, vastleggen op/voor
  • German: ansetzen, planen
  • Dutch: voorzien, voorbestemmen
  • German: vorsehen, bestimmen

Extensive Definition

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. Slate is frequently grey in colour especially when seen en masse covering roofs. However, slate occurs in a variety of colours even from a single locality. For example slate from North Wales can be found in many shades of grey from pale to dark and may also be purple, green or cyan.

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 can be made into roofing slates, also called roofing shingles, installed by a slater in the USA. 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 is a good electrical insulator and fireproof, it was used to construct early 20th century electric switchboards and relay controls for large electric motors. British sculptor Stephen Kettle is notable 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 tiles were used in 19th century UK building construction (apart from roofs). They can be set into the walls to provide a rudimentary damp-proof membrane. Small offcuts are used as shims to level floor joists.
Slate is often used as a decor in freshwater aquariums. Slate will not alter the chemistry of water (except in the slate containing feldspar which may leach 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. Silicone 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

Slate-producing regions in Europe include Wales (see slate industry in Wales), Cornwall (famously the town of Delabole), and Cumbria (see Burlington Slate Quarries, Honister Slate Mine and Skiddaw Slate) in the United Kingdom; parts of France (Angers, Anjou and in the Maritime Alps); Belgium (formerly); 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's (Moselle River-region, Hunsrück, Eifel, Westerwald, Thuringia and north-Bavaria); Alta, Norway (actually schist not a true slate) and Galicia. In the Americas, slate is found in 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. The area around Granville, NY, is one place where colored slate (non-blue) is mined. Others include Wales (purple and formerly green) and Cumbria (green) in the UK; Brazil (green); China (many colors); and Newfoundland.
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.
slate in Catalan: Pissarra
slate in Welsh: Llechfaen
slate in Danish: Skifer
slate in German: Schiefer
slate in Estonian: Kilt
slate in Spanish: Pizarra
slate in Esperanto: Ardezo
slate in French: Ardoise
slate in Italian: Ardesia
slate in Hebrew: צפחה
slate in Dutch: Leisteen
slate in Japanese: 粘板岩
slate in Norwegian: Skifer
slate in Polish: Łupek
slate in Portuguese: Ardósia
slate in Finnish: Saviliuske
slate in Swedish: Skiffer

Synonyms, Antonyms and Related Words

Australian ballot, Indiana ballot, Massachusetts ballot, absentee ballot, agenda, ballot, batting order, bill, bill of fare, blanket ballot, blister, blueprint, board, book, brick, budget, calendar, card, carte du jour, castigate, clapboard, crawl, docket, excoriate, face, glass, glaze, lambaste, lath, line up, lineup, list of agenda, long ballot, menu, nonpartisan ballot, office-block ballot, paper, party emblem, party-column ballot, plank, playbill, program, program of operation, programma, prospectus, protocol, proxy, revet, roster, sample ballot, scarify, scathe, schedule, score, scourge, shake, sheathe, shingle, short ballot, split ticket, stone, straight ticket, thatch, ticket, tile, veneer, wall in, wall up, wallpaper, weatherboard
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