The schists form a group of medium-grade metamorphic rocks, chiefly notable for the preponderance of lamellar minerals such as micas, chlorite, talc, hornblende, graphite, and others. Metamorphic rock is the result of the transformation of an existing rock type the protolith, in a process called Metamorphism, which means "change A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific The word "mica" is thought to be derived from the Latin word la micare, "glitteren" in reference to the brilliant appearance of this mineral (especially The chlorites are a group of phyllosilicate Minerals Chlorites can be described by the following four endmembers based on their chemistry via substitution Talc (derived from the Persian via Arabic talq) is a Mineral composed of Hydrated Magnesium Silicate with Hornblende is a complex inosilicate series of Minerals Hornblende is not a recognized mineral in its own right but the name is used as a general or field term to The Mineral graphite, as with Diamond and Fullerene, is one of the Allotropes of carbon. Quartz often occurs in drawn-out grains to such an extent that a particular form called quartz schist is produced. Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in By definition, schist contains more than 50% platy and elongated minerals, often finely interleaved with quartz and feldspar. Feldspar is the name of a group of rock-forming Minerals which make up as much as 60% of the Earth 's crust. Schist is often garnetiferous. The garnet group includes a group of minerals that have been used since the Bronze Age as gemstones and abrasives

The individual mineral grains in schist, drawn out into flaky scales by heat and pressure, can be seen by the naked eye. A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific Schist is characteristically foliated, meaning the individual mineral grains split off easily into flakes or slabs. Foliation is any penetrative planar fabric present in rocks. Foliation is common to rocks affected by regional metamorphic compression typical of orogenic The word schist is derived from the Greek word σχίζειν meaning "to split", which is a reference to the ease with which schists can be split along the plane in which the platy minerals lie. Greek (el ελληνική γλώσσα or simply el ελληνικά — "Hellenic" is an Indo-European language, spoken today by 15-22 million people mainly

Most schists have been derived from clays and muds which have passed through a series of metamorphic processes involving the production of shales, slates and phyllites as intermediate steps. The Manhattan schist is a formation of Mica Schist rock that underlies much of the island of Manhattan in New York City. Clay is a naturally occurring material composed primarily of fine-grained Minerals which show plasticity through a variable range of Water content, and In computer gaming, a MUD ( Multi-User Dungeon, Domain or Dimension) is a multi-player computer game that combines elements of Shale (also called mudstone) is a fine-grained Sedimentary rock whose original constituents were Clay minerals or Muds It is characterized by Slate is a fine-grained foliated homogeneous, Metamorphic rock derived from an original Shale -type Sedimentary rock composed of Clay Phyllite is a type of foliated Metamorphic rock primarily composed of Quartz, Sericite Mica, and chlorite; the rock represents Certain schists have been derived from fine-grained igneous rocks such as basalts and tuffs. Igneous rocks (etymology from Latin ignis, fire are rocks formed by solidification of cooled Magma (molten rock Basalt (bəˈsɔːlt ˈbeisɔːlt ˈbæsɔːlt is a common Extrusive Volcanic rock. Tuff (from the Italian "tufo" is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption Most schists are mica schists, but graphite and chlorite schists are also common. The Mineral graphite, as with Diamond and Fullerene, is one of the Allotropes of carbon. The chlorites are a group of phyllosilicate Minerals Chlorites can be described by the following four endmembers based on their chemistry via substitution

Schists are named for their prominent or perhaps unusual mineral constituents, such as garnet schist, tourmaline schist, glaucophane schist, etc. The garnet group includes a group of minerals that have been used since the Bronze Age as gemstones and abrasives Tourmaline is a Crystal Silicate mineral compounded with elements such as Aluminium, Iron, Magnesium, Sodium, Lithium Glaucophane is a Mineral belonging to the Amphibole group chemical formula Na 2( Mg, Fe)3 Al 2

Schists are frequently used in building houses, as many are quite durable and strong. However, it should be noted that many foundation problems with buildings both large and small are due to the schist decaying or even the failure of the mortar. This in turn lets water into the joints thus weakening the schist further.

Formation

During metamorphism, rocks which were originally sedimentary or igneous are converted into schists and gneisses. Gneiss (ˈnaɪs is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from preexisting formations that were originally If the composition of the rocks was originally similar, they may be very difficult to distinguish from one another if the metamorphism has been great. A quartz-porphyry, for example, and a fine grained feldspathic sandstone, may both be converted into a grey or pink mica-schist. Quartz-porphyry, in Petrology, is the name given to a group of hemi- Crystalline Acid rocks containing Porphyritic crystals of Usually, however, it is possible to distinguish between sedimentary and igneous schists and gneisses. If the whole district, for example, occupied by these rocks have traces of bedding, clastic structure, or unconformability then it may be a sign that the original rock was sedimentary. Clastic rocks are composed of fragments or clasts, of pre-existing rock. An unconformity is a buried Erosion surface separating two rock masses or strata of different ages indicating that Sediment deposition was not In other cases intrusive junctions, chilled edges, contact alteration or porphyritic structure may prove that in its original condition a metamorphic gneiss was an igneous rock. In Geology, an intrusion is a body of Igneous rock that has Crystallized from molten Magma below the surface of the Earth. The last appeal is often to the chemistry, for there are certain rock types which occur only as sediments, while others are found only among igneous masses, and however advanced the metamorphism may be, it rarely modifies the chemical composition of the mass very greatly. Such rocks, for example, as limestones, dolomites, quartzites and aluminous shales have very definite chemical characters which distinguish them even when completely recrystallized. Limestone is a Sedimentary rock composed largely of the Mineral Calcite ( Calcium carbonate: CaCO3 Dolomite (ˈdɒləmaɪt is the name of a Sedimentary Carbonate rock and a Mineral, both composed Quartzite (from German Quarzit) not to be confused with the Mineral Quartz, is a hard Metamorphic rock which was originally

The schists are classified principally according to the minerals they consist of and on their chemical composition. For example, many metamorphic limestones, marbles, and calc-schists, with crystalline dolomites, contain silicate minerals such as mica, tremolite, diopside, scapolite, quartz and feldspar. Tremolite is a member of the Amphibole group of Silicate minerals with composition Ca 2 Mg 5 Si 8 Diopside is a Monoclinic Pyroxene Mineral with composition MgCaSi2O6 Scapolite (Gr asairos, rod stone is a group of rock-forming Silicate minerals composed of Aluminium, Calcium and Sodium Silicate Feldspar is the name of a group of rock-forming Minerals which make up as much as 60% of the Earth 's crust. They are derived from calcareous sediments of different degrees of purity. Another group is rich in quartz (quartzites, quartz schists and quartzose gneisses), with variable amounts of white and black mica, garnet, feldspar, zoisite and hornblende. The garnet group includes a group of minerals that have been used since the Bronze Age as gemstones and abrasives This article is about the mineral named zoisite For the Sailor Moon character see Shitennou. Hornblende is a complex inosilicate series of Minerals Hornblende is not a recognized mineral in its own right but the name is used as a general or field term to These were once sandstones and arenaceous rocks. The graphitic schists may readily be believed to represent sediments once containing coal or plant remains; there are also schistose ironstones (hematite-schists), but metamorphic beds of salt or gypsum are exceedingly uncommon. Ironstone is a fine-grained heavy and compact Sedimentary rock. Hematite, also spelt hæmatite, is the Mineral form of Iron(III oxide (Fe2O3 one of several Iron oxides Gypsum is a very soft Mineral composed of Calcium sulfate dihydrate with the Chemical formula Ca[[sulfur S]] O 4·2 Among schists of igneous origin there are the silky calc-schists, the foliated serpentines (once ultramafic masses rich in olivine), and the white mica-schists, porphyroids and banded halleflintas, which have been derived from rhyolites, quartz-porphyries and felsic tuffs. The serpentine group describes a group of common rock-forming hydrous Magnesium Iron phyllosilicate (()3 Minerals they Ultramafic (also referred to as ultrabasic) rocks are igneous and meta -igneous rocks with very low Silica content (less than 45% generally The Mineral olivine (when gem-quality also called Peridot) is a Magnesium Iron silicate with the formula ( Mg Hälleflinta (a Swedish word meaning rock-flint a white grey yellow greenish or pink fine-grained rock consisting of an intimate mixture of Quartz and Feldspar This page is about a volcanic rock For the ghost town see Rhyolite Nevada, and for the satellite system see Rhyolite/Aquacade. Tuff (from the Italian "tufo" is a type of rock consisting of consolidated volcanic ash ejected from vents during a volcanic eruption The majority of mica-schists, however, are altered claystones and shales, and pass into the normal sedimentary rocks through various types of phyllite and mica-slates. Claystone (ˈkleɪstoʊn is a geological term used to describe a Sedimentary rock that is composed primarily of Clay -sized particles (less than 1/256 Millimetre Phyllite is a type of foliated Metamorphic rock primarily composed of Quartz, Sericite Mica, and chlorite; the rock represents They are among the most common metamorphic rocks; some of them are graphitic and others calcareous. The Mineral graphite, as with Diamond and Fullerene, is one of the Allotropes of carbon. The diversity in appearance and composition is very great, but they form a well-defined group not difficult to recognize, from the abundance of black and white micas and their thin, foliated, schistose character. As a special subgroup we have the andalusite, staurolite, kyanite and sillimanite-schists which usually make their appearance in the vicinity of gneissose granites, and have presumably been affected by contact metamorphism. Andalusite is an Aluminium nesosilicate Mineral with the chemical formula Al2SiO5 Staurolite is a red brown to black mostly opaque nesosilicate Mineral with a white streak Kyanite, whose name derives from the Greek word kyanos, meaning blue is a typically blue Silicate Mineral, commonly found in Aluminium -rich Sillimanite also called Bucholzite is an alumino-silicate Mineral with the Chemical formula Al2SiO5 ^[1]

See also

• List of minerals
• List of rock textures

References

1. ^ This article incorporates text from the Encyclopædia Britannica Eleventh Edition article "Petrology", a publication now in the public domain. This is a List of Minerals for which there are Wikipedia articles This page is intended to be a list of rock textural and morphological terms The Encyclopædia Britannica Eleventh Edition (1910–1911 is a 29-volume reference work that marked the beginning of the Encyclopædia Britannica The public domain is a range of abstract materials &ndash commonly referred to as Intellectual property &ndash which are not owned or controlled by anyone

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