• Your continued donations keep Wikipedia running! •
• Learn more about using Wikipedia for research •
Slate
From Wikipedia, the free encyclopedia
Jump to: navigation, search
For other uses, see Slate (disambiguation).
Slate
Slate
Slate Macro (~ 6 cm long and ~ 4 cm high)
Slate Macro (~ 6 cm long and ~ 4 cm high)
Slate is a fine-grained, 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.
Contents
[hide]
* 1 Chemical composition
* 2 Uses of slate
* 3 Slate extraction
* 4 See also
* 5 External links
[edit] 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 nucelei, leaving a light green spotted texture - the spheres sometimes deformed by a subsequent applied stress field to ovoids, which appear as ellipses when viewed on a cleavage plane of the specimen.
[edit] Uses of slate
Slate roof
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 efflorence, 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.
[edit] Slate extraction
Exhibition Slate mine Fell
Exhibition Slate mine Fell
Historical Pit Vogelsberg 1 at 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. Granville, New York, of the Slate Valley claims to be the colored slate capital of the world.
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 rooved 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.
[edit] See also
* List of rocks
* Tile
* Welsh Slate Museum
* Exhibition slate mine fell
* Slate industry in Wales
[edit] 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
Retrieved from "http://en.wikipedia.org/wiki/Slate"
Categories: Metamorphic rocks | Materials | Stone | Dielectrics
Views
* Article
* Discussion
* Edit this page
* History
Personal tools
* Sign in / create account
Navigation
* Main page
* Contents
* Featured content
* Current events
* Random article
interaction
* About Wikipedia
* Community portal
* Recent changes
* Contact Wikipedia
* Donate to Wikipedia
* Help
Search
Toolbox
* What links here
* Related changes
* Upload file
* Special pages
* Printable version
* Permanent link
* Cite this article
In other languages
* Cymraeg
* Dansk
* Deutsch
* Eesti
* Esperanto
* Français
* עברית
* Italiano
* Nederlands
* 日本語
* Norsk (bokmål)
* Polski
* Português
* Suomi
* Svenska
Powered by MediaWiki
Wikimedia Foundation
* This page was last modified 09:16, 31 August 2007.
* All text is available under the terms of the GNU Free Documentation License. (See Copyrights for details.)
Wikipedia® is a registered trademark of the Wikimedia Foundation, Inc., a U.S. registered 501(c)(3) tax-deductible nonprofit charity.
* Privacy policy
* About Wikipedia
* Disclaimers
