Schist in the context of "Shale"

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⭐ Core Definition: Schist

Schist (/ˈʃɪst/ SHIST) is a medium-grained metamorphic rock generally derived from fine-grained sedimentary rock, like shale. It shows pronounced schistosity (named for the rock). This means that the rock is composed of mineral grains easily seen with a low-power hand lens, oriented in such a way that the rock is easily split into thin flakes or plates. This texture reflects a high content of platy minerals, such as mica, talc, chlorite, or graphite. These are often interleaved with more granular minerals, such as feldspar or quartz.

Schist typically forms during regional metamorphism accompanying the process of mountain building (orogeny) and usually reflects a medium grade of metamorphism. Schist can form from many different kinds of rocks, including sedimentary rocks such as mudstones and igneous rocks such as tuffs. Schist metamorphosed from mudstone is particularly common and is often very rich in mica (a mica schist). Where the type of the original rock (the protolith) is discernible, the schist is usually given a name reflecting its protolith, such as schistose metasandstone. Otherwise, the names of the constituent minerals will be included in the rock name, such as quartz-felspar-biotite schist.

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Schist in the context of Saana

Saana (Northern Sami: Sána) is a fell in Enontekiö, Finland. Saana's summit lies 1,029 metres (3,376 ft) above sea level and 556 m (1,824 ft) above the adjacent Kilpisjärvi lake. Geologically it is part of the Scandinavian Mountains, and is made of the same kinds of schist and gneiss rock. The peak is a popular destination for hikers and backpackers because of the sweeping views offered at the summit.

In December 2017, in celebration of the 100th anniversary of Finland's independence, Saana was lit with blue light. The area illuminated covered roughly 2.5 million square meters, making it the largest art illumination in the world.

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Schist in the context of Slate

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. It is the finest-grained foliated metamorphic rock. Foliation may not correspond to the original sedimentary layering, but instead is in planes perpendicular to the direction of metamorphic compression.

The foliation in slate, called "slaty cleavage", is caused by strong compression in which fine-grained clay forms flakes to regrow in planes perpendicular to the compression. When expertly "cut" by striking parallel to the foliation with a specialized tool in the quarry, many slates display a property called fissility, forming smooth, flat sheets of stone which have long been used for roofing, floor tiles, and billiard tables. Slate is frequently grey in color, especially when seen en masse covering roofs. However, slate occurs in a variety of colors 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. Slate is not to be confused with shale, from which it may be formed, or schist.

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Schist in the context of Aspromonte

The Aspromonte is a mountain massif in the Metropolitan City of Reggio Calabria (Calabria, southern Italy). In Italian aspro means "rough" whereas in Greek it means "white" (Άσπρος), therefore the name literally translates to either "rough mountain" or "white mountain". It overlooks the Strait of Messina, being limited by the Ionian and Tyrrhenian Seas and by the Pietrace river. The highest peak is Montalto (1,955 m (6,414 ft)). The constituting rocks are mostly gneiss, and mica schists, which form characteristic overlapping terraces. The massif is part of the Aspromonte National Park.

In the short coastal strip citrus fruits, vine and olives are grown, while at high elevations the vegetation is composed mostly by oak and holm oak under 1,000 m (3,300 ft), and by pine, Sicilian fir and beech over it. Olive trees grow in abundance. Also, the rare bergamot, the lemony-yellow fruit used in perfumes and flavouring for Earl Grey tea, only grows in the southern Aspromonte.

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Schist in the context of Mica

Micas (/ˈmkəz/ MY-kəz) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into fragile elastic plates. This characteristic is described as perfect basal cleavage. Mica is common in igneous and metamorphic rock and is occasionally found as small flakes in sedimentary rock. It is particularly prominent in many granites, pegmatites, and schists, and "books" (large individual crystals) of mica several feet across have been found in some pegmatites.

Micas are used in products such as drywalls, paints, and fillers, especially in parts for automobiles, roofing, and in electronics. The mineral is used in cosmetics and food to add "shimmer" or "frost".

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Schist in the context of Steatite

Soapstone (also known as steatite or soaprock) is a talc-schist, which is a type of metamorphic rock. It is composed largely of the magnesium-rich mineral talc. It is produced by dynamothermal metamorphism and metasomatism, which occur in subduction zones, changing rocks by heat and pressure, with influx of fluids but without melting. It has been a carving medium for thousands of years.

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Schist in the context of Foliation (geology)

Foliation in geology refers to repetitive layering in metamorphic rocks. Each layer can be as thin as a sheet of paper, or over a meter in thickness. The word comes from the Latin folium, meaning "leaf", and refers to the sheet-like planar structure. It is caused by shearing forces (pressures pushing different sections of the rock in different directions), or differential pressure (higher pressure from one direction than in others). The layers form parallel to the direction of the shear, or perpendicular to the direction of higher pressure. Nonfoliated metamorphic rocks are typically formed in the absence of significant differential pressure or shear. Foliation is common in rocks affected by the regional metamorphic compression typical of areas of mountain belt formation (orogenic belts).

More technically, foliation is any penetrative planar fabric present in metamorphic rocks. Rocks exhibiting foliation include the standard sequence formed by the prograde metamorphism of mudrocks; slate, phyllite, schist and gneiss. The slatey cleavage typical of slate is due to the preferred orientation of microscopic phyllosilicate crystals. In gneiss, the foliation is more typically represented by compositional banding due to segregation of mineral phases. Foliated rock is also known as S-tectonite in sheared rock masses.

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Schist in the context of Metamorphism

Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of 150 °C (300 °F), and often also at elevated pressure or in the presence of chemically active fluids, but the rock remains mostly solid during the transformation. Metamorphism is distinct from weathering or diagenesis, which are changes that take place at or just beneath Earth's surface.

Various forms of metamorphism exist, including regional, contact, hydrothermal, shock, and dynamic metamorphism. These differ in the characteristic temperatures, pressures, and rate at which they take place and in the extent to which reactive fluids are involved. Metamorphism occurring at increasing pressure and temperature conditions is known as prograde metamorphism, while decreasing temperature and pressure characterize retrograde metamorphism.

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Schist in the context of Wicklow Mountains

The Wicklow Mountains (Irish: Sléibhte Chill Mhantáin, archaic: Cualu) form the largest continuous upland area in Ireland. They occupy the whole centre of County Wicklow and stretch outside its borders into the counties of Dublin, Wexford and Carlow. Where the mountains extend into County Dublin, they are known locally as the Dublin Mountains (Sléibhte Bhaile Átha Cliath). The highest peak is Lugnaquilla at 925 metres (3,035 feet).

The mountains are primarily composed of granite surrounded by an envelope of mica-schist and much older rocks such as quartzite. They were pushed up during the Caledonian orogeny at the start of the Devonian period and form part of the Leinster Chain, the largest continuous area of granite in Ireland and Britain. The mountains owe much of their present topography to the effects of the last ice age, which deepened the glens and created corrie and ribbon lakes. Copper and lead have been the main metals mined in the mountains and a brief gold rush occurred in the 18th century.Several major river systems have their source in the mountains, such as the Liffey, Dargle, Slaney and Avoca rivers. Powerscourt Waterfall is the second tallest in Ireland at 121 metres (397 feet). A number of these rivers have been harnessed to create reservoirs for drinking water for Dublin and its surroundings.

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