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. Metamorphic rock is the result of the transformation of an existing rock type the protolith, in a process called Metamorphism, which means "change Shale (also called mudstone) is a fine-grained Sedimentary rock whose original constituents were Clay minerals or Muds It is characterized by Sedimentary rock is one of the three main rock types (the others being igneous and Metamorphic rock) Clay is a naturally occurring material composed primarily of fine-grained Minerals which show plasticity through a variable range of Water content, and Plate tectonics and hotspots Divergent plate boundaries At the Volcanic ash consists of small Tephra, which are bits of pulverized rock and glass created by volcanic eruptions less than in diameter Metamorphism can be defined as the solid state recrystallisation of pre-existing rocks due to changes in heat and/or pressure and/or introduction of fluids i The result is a foliated rock in which the foliation may not correspond to the original sedimentary layering. Foliation is any penetrative planar fabric present in rocks. Foliation is common to rocks affected by regional metamorphic compression typical of orogenic 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. Cyan (saɪæn from Greek κυανός / kyanos, meaning "blue" may be used as the name of any of a number of a range of colors in the blue/green part of

Contents 1 Chemical composition 2 Uses of slate 3 Slate extraction 4 See also 5 External links

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. Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in Muscovite (also known as Common Mica, Isinglass, or Potash mica) is a phyllosilicate Mineral of Aluminium Illite is a non-expanding Clay -sized micaceous mineral Illite is a phyllosilicate or layered alumino-silicate Biotite is a common phyllosilicate Mineral within the Mica group with the approximate chemical formula K(Mg Fe3AlSi3O10(F The chlorites are a group of phyllosilicate Minerals Chlorites can be described by the following four endmembers based on their chemistry via substitution Hematite, also spelt hæmatite, is the Mineral form of Iron(III oxide (Fe2O3 one of several Iron oxides The Mineral graphite, as with Diamond and Fullerene, is one of the Allotropes of carbon. Kaolinite is a Clay mineral with the chemical composition Al 2 Si 2 O 5( OH)4 Magnetite is not to be confused with Magnesite or Maghemite. Magnetite is a ferrimagnetic Mineral with chemical Tourmaline is a Crystal Silicate mineral compounded with elements such as Aluminium, Iron, Magnesium, Sodium, Lithium Zircon is a Mineral belonging to the group of nesosilicates. Its chemical name is Zirconium silicate and its corresponding chemical formula is Feldspar is the name of a group of rock-forming Minerals which make up as much as 60% of the Earth 's crust. Occasionally, as in the purple slates of North Wales, ferrous reduction spheres form around iron nuclei, leaving a light green spotted texture. The slate industry in Wales began during the Roman period when Slate was used to Roof the fort at Segontium, now Caernarfon. 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. Cleavage, in Mineralogy, is the tendency of crystalline materials to split along definite planes creating smooth surfaces of which there are several named types

Uses of slate

Slate can be made into roofing slates, also called roofing shingles, installed by a slater in the USA. Vietnam roofjpg|thumb|The roofs of Vietnam.]] A roof is the covering on the uppermost part of a Building. Roof shingles are a roof covering consisting of individual overlapping elements A slater, or slate mason is a Tradesman who covers buildings with Slate. 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. A billiard table or billiards table (or more specifically a pool table or snooker table) is a bounded table on which billiards-type games In 18th and 19th century schools, slate was extensively used for blackboards and individual writing slates for which chalk pencils were used. A chalkboard or blackboard is a reusable Writing surface on which text or drawings are made with sticks of Calcium sulfate, known when used for this A writing slate is a piece of flat material used as a medium for Writing. 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. An insulator, also called a Dielectric, is a material that resists the flow of Electric current. "Fireproof" redirects here For the album see Fireproof (album. An electric switchboard is a device that directs Electricity from one source to another A relay is an electrical Switch that opens and closes under the control of another Electrical circuit. An electric motor uses Electrical energy to produce Mechanical energy. British sculptor Stephen Kettle is notable for his use of slate to create statues housed in the Science Museum in London. Stephen Kettle (born 12 July, 1966, in Castle Bromwich, England) is a British Sculptor who works exclusively with Slate For science museums in general check out Science museum. The Science Museum on Exhibition Road, South Kensington, London is part

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. Effloresce redirects here for the album by Oceansize see Effloresce (album. 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. A damp-proof course (often abbreviated to DPC is a horizontal barrier in a Wall designed to prevent moisture rising through the structure by Capillary action 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. The Fell Exhibition Slate Mine is a former slate mine in Germany located about 20 km east from Trier ( Germany) and about 60 km east from Luxembourg The slate industry in Wales began during the Roman period when Slate was used to Roof the fort at Segontium, now Caernarfon. Cornwall ( Kernow ˈkɛɹnɔʊ is the most southwesterly county of England, on the Peninsula that lies to the west of the River Tamar Delabole is a village in North Cornwall, England. It is the third highest village in Cornwall the two highest are also in the North Cornwall district Burlington Slate Quarries are located near Kirkby in Furness in SW CumbriaEngland The Honister Slate Mine is a group of Slate mines and quarries located at the top of the Honister Pass. Skiddaw slate is an early Ordovician metamorphosed Sedimentary rock, as first identified on the slopes of Skiddaw in the English Lake District The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom, the UK or Britain,is a Sovereign state located Liguria is a coastal region of north-western Italy, the third smallest of the Italian regions Italy (Italia officially the Italian Republic, (Repubblica Italiana is located on the Italian Peninsula in Southern Europe, and on the two largest Portugal, officially the Portuguese Republic (República Portuguesa is a country on the Iberian Peninsula. Valongo ( pron vɐ'lõngu is a Portuguese municipality located in the District of Porto, the city Population is 16698 and Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. The Moselle (Moselle Mosel Musel is a River flowing through France, Luxembourg and Germany. The Hunsrück is a low Mountain range in Rhineland-Palatinate, Germany. The Eifel is a low mountain range in western Germany. It occupies parts of southwestern North Rhine-Westphalia and northwestern Rhineland-Palatinate The Westerwald (ˈvɛstɐvalt is a low Mountain range on the right bank of the river Rhine in the German federal states of Rhineland-Palatinate The Free State of Thuringia (Freistaat Thüringen is located in central Germany. Bavaria ( German:, with an area of 70553 Km² (27241 square miles and almost 12 ( Áltá or formerly Álaheadju in Northern Sami, Alattio or Alta in Finnish / Kven) is a municipality and town in the county Galicia (occasionally Galiza) is an autonomous community in northwest Spain. 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. Minas Gerais is one of the 26 states of Brazil, the second most populous and fourth largest by area in the federation Newfoundland — ˈn(jufənˌlænd (Terre-Neuve Talamh an Éisc — is a large island 15 km off the east coast of The Commonwealth of Pennsylvania ( often colloquially referred to as PA (its abbreviation by natives and Northeasterners is a state located in the Northeastern Vermont ( is a state in the New England region of the northeastern United States of America. New York ( is a state in the Mid-Atlantic and Northeastern regions of the United States and is the nation's third most populous The area around Granville, NY, is one place where colored slate (non-blue) is mined. Granville is a Town in Washington County, New York, United States. 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. Monson is a town in Piscataquis County, Maine, United States. 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. The Monson Railroad was a gauge narrow gauge railroad which operated between Monson Junction on the Bangor and Aroostook Railroad and Monson St. Patricks's Cathedral in New York's roof was made from roofing slate from Monson, as well as the Headstone of John F. St Patrick's Cathedral is a decorated Neo-Gothic -style Catholic Cathedral in North America Kennedy.

Slate is also found in the Arctic and was used by the Inuit to make the blades for ulus. The Arctic is the Region around the Earth 's North Pole, opposite the Antarctic region around the South Pole. Inuit (plural the singular Inuk, means "man" or "person" is a general term for a group of culturally similar Indigenous peoples inhabiting An ulu ( Inuktitut syllabics: ᐅᓗ, plural uluit) is an Inuit woman's all-purpose Knife. China has vast slate deposits; in recent years its export of finished and unfinished slate has increased.

See also

• List of rock types
• Tile
• National Slate Museum
• Fell Exhibition Slate Mine
• Slate industry in Wales

External links

• AditNow - Photographic database of mines
• History of the Welsh slate industry
• John T F Turner - A Familiar Description of the Old Delabole Slate Quarries, 1864
• History of the Scottish Slate Islands
• Granville Slate Museum [1]

This page is intended as a list of all rock types A Amphibolite Andesite Anorthosite Anthracite A tile is a manufactured piece of hard-wearing material such as Ceramic, stone, metal or even Glass. The National Slate Museum, (which was previously known as the Welsh Slate Museum) is located at Gilfach Ddu in the 19th century workshops of the now disused The Fell Exhibition Slate Mine is a former slate mine in Germany located about 20 km east from Trier ( Germany) and about 60 km east from Luxembourg The slate industry in Wales began during the Roman period when Slate was used to Roof the fort at Segontium, now Caernarfon.

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