A sample of granulite-facies metamorphic rock of felsic composition

Granulites are fine to medium–grained metamorphic rocks that have experienced high temperatures of metamorphism, composed mainly of feldspars sometimes associated with quartz and anhydrous ferromagnesian minerals, with granoblastic texture and gneissose to massive structure. Felsic is a term used in Geology to refer to Silicate minerals, Magma, and rocks which are enriched in the lighter elements such as Silicon Metamorphic rock is the result of the transformation of an existing rock type the protolith, in a process called Metamorphism, which means "change Temperature is a physical property of a system that underlies the common notions of hot and cold something that is hotter generally has the greater temperature Feldspar is the name of a group of rock-forming Minerals which make up as much as 60% of the Earth 's crust. Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in ^[1] They are of particular interest to geologists because many granulites represent samples of the deep continental crust. A geologist is a contributor to the Science of Geology, studying the physical structure and processes of the Earth and planets of the solar system The continental crust is the layer of granitic, Sedimentary, and Metamorphic rocks which form the Continents and the areas of shallow seabed Some granulites experienced decompression from deep in the Earth to shallower crustal levels at high temperature; others cooled while remaining at depth in the Earth. EARTH was a short-lived Japanese vocal trio which released 6 singles and 1 album between 2000 and 2001

The minerals present in a granulite will vary depending on the parent rock of the granulite and the temperature and pressure conditions experienced during metamorphism. Pressure (symbol 'p' is the force per unit Area applied to an object in a direction perpendicular to the surface A common type of granulite found in high-grade metamorphic rocks of the continents contains pyroxene, plagioclase feldspar and accessory garnet, oxides and possibly amphibole. A continent is one of several large Landmasses on Earth. They are generally identified by Convention rather than any strict criteria with seven regions The pyroxenes are a group of important rock-forming Silicate minerals found in many Igneous and metamorphic rocks. Plagioclase is a very important series of tectosilicate Minerals within the Feldspar family The garnet group includes a group of minerals that have been used since the Bronze Age as gemstones and abrasives An oxide is a Chemical compound containing at least one Oxygen atom as well as at least one other element Amphibole (pronounced amfi-bowl defines an important group of generally dark-colored rock-forming inosilicate Minerals composed of double chain SiO4 Both clinopyroxene and orthopyroxene may be present, and in fact, the coexistence of clino- and orthopyroxene in a metamorphosed basalt defines the Granulite facies. Basalt (bəˈsɔːlt ˈbeisɔːlt ˈbæsɔːlt is a common Extrusive Volcanic rock.

Formation

Granulites form at high temperature conditions at a range of pressure conditions, typically during regional metamorphism. In some cases, the high temperatures are difficult to account for at the inferred depths at typical geothermal gradients. In extreme cases, granulites may form at temperatures in excess of 1000 degrees Celsius. The Celsius Temperature scale was previously known as the centigrade scale. Some granulites may represent the residues of partial melting, and in other cases represent rocks that never melted, despite extremely high temperatures, because the minerals are anhydrous and therefore do not melt even at high temperature conditions. In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere

In continental crustal rocks, biotite may break down at high temperatures to form orthopyroxene + potassium feldspar + water, producing a granulite. Biotite is a common phyllosilicate Mineral within the Mica group with the approximate chemical formula K(Mg Fe3AlSi3O10(F Physical properties Orthoclase crystallizes in the Monoclinic crystal system Water is a common Chemical substance that is essential for the survival of all known forms of Life. Other possible minerals formed at dry conditions include sapphirine, spinel, sillimanite, and osumilite. Sapphirine is a rare Mineral, a Silicate of Magnesium and Aluminium with the Chemical formula ( Mg, Al)8(Al The spinels are any of a class of Minerals of general formulation XY2 O 4 which Crystallize in the cubic (isometric Sillimanite also called Bucholzite is an alumino-silicate Mineral with the Chemical formula Al2SiO5 Osumilite a very rare Hydrate potassium-sodium-iron-magnesium-aluminum Silicate mineral. Some assemblages such as sapphirine + quartz indicate very high temperatures. Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in

1911 Definition

Granulite (Latin granulum, "a little grain") is a name used by petrographers to designate two distinct classes of rocks. Latin ( lingua Latīna, laˈtiːna is an Italic language, historically spoken in Latium and Ancient Rome. In Geology, rock is a naturally occurring aggregate of Minerals and/or Mineraloids The Earth's outer solid layer the ‘ Lithosphere According to the terminology of the French school it signifies a granite in which both kinds of mica (muscovite and biotite) occur, and corresponds to the German Granit, or to the English muscovite biotite granite. This article is about the country For a topic outline on this subject see List of basic France topics. Granite (ˈɡrænɪt is a common and widely occurring type of intrusive, Felsic, igneous rock. 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 German language (de ''Deutsch'') is a West Germanic language and one of the world's major languages. English is a West Germanic language originating in England and is the First language for most people in the United Kingdom, the United States This application has not been accepted generally. To the German petrologists granulite means a more or less banded fine-grained metamorphic rock, consisting mainly of quartz and feldspar in very small irregular crystals and usually also containing a fair number of minute, rounded, pale-red garnets. Metamorphic rock is the result of the transformation of an existing rock type the protolith, in a process called Metamorphism, which means "change Quartz (from German) is the most abundant Mineral in the Earth 's Continental crust (although Feldspar is more common in Feldspar is the name of a group of rock-forming Minerals which make up as much as 60% of the Earth 's crust. In Materials science, a crystal is a Solid in which the constituent Atoms Molecules or Ions are packed in a regularly ordered repeating The garnet group includes a group of minerals that have been used since the Bronze Age as gemstones and abrasives Among English and American geologists the term is generally employed in this sense. A geologist is a contributor to the Science of Geology, studying the physical structure and processes of the Earth and planets of the solar system

The granulites are very closely allied to the gneisses, as they consist of nearly the same minerals, but they are finer-grained, have usually less perfect foliation, are more frequently garnetiferous, and have some special features of microscopic structure. Gneiss (ˈnaɪs is a common and widely distributed type of rock formed by high-grade regional metamorphic processes from preexisting formations that were originally A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition a highly ordered atomic structure and specific In the rocks of this group the minerals, as seen in a microscopic slide, occur as small rounded grains forming a closely-fitted mosaic. The individual crystals never have perfect form, and indeed traces of it area rare. In some granulites they interlock, with irregular borders; in others they have been drawn out and flattened into tapering lenticles by crushing. In most cases they are somewhat rounded with smaller grains between the larger. This is especially true of the quartz and feldspar which are the predominant minerals; mica always appears as flat scales (irregular or rounded but not hexagonal). Both muscovite and biotite may be present and vary considerably in abundance; very commonly they have their flat sides parallel and give the rock a rudimentary schistosity, and they may be aggregated into bands in which case the granulites are indistinguishable from certain varieties of gneiss. The schists form a group of medium-grade Metamorphic rocks chiefly notable for the preponderance of lamellar Minerals such as Micas chlorite The garnets are very generally larger than the above-mentioned ingredients, and easily visible with the eye as pink spots on the broken surfaces of the rock. They usually are filled with enclosed grains of the other minerals.

The feldspar of the granulites is mostly orthoclase or cryptoperthite; microcline, oligoclase and albite are also common. Physical properties Orthoclase crystallizes in the Monoclinic crystal system Albite is a plagioclase Feldspar Mineral. It is the sodium endmember of the Plagioclase Solid solution series Basic feldspars occur only rarely. Among accessory minerals, in addition to apatite, zircon, and iron oxides, the following may be mentioned: hornblende (not common), riebeckite (rare), epidote and zoisite, calcite, sphene, andalusite, sillimanite, kyanite, hercynite (a green spinel), rutile, orthite and tourmaline. Zircon is a Mineral belonging to the group of nesosilicates. Its chemical name is Zirconium silicate and its corresponding chemical formula is Altogether there are sixteen known Iron Oxides and oxyhydroxides 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 Riebeckite is a Sodium -rich member of the Amphibole group of Minerals chemical formula Na 2( Fe, Mg)5 Epidote is a Calcium Aluminium Iron sorosilicate Mineral, Ca2Al2(Fe3+Al(SiO4(Si2O7O(OH This article is about the mineral named zoisite For the Sailor Moon character see Shitennou. Calcite is a carbonate mineral and the most stable polymorph of Calcium carbonate ( Ca[[carbon C]] O 3 Titanite or sphene is a Calcium Titanium nesosilicate Mineral, Ca[[titanium Ti]] Si[[oxygen O]]5 Andalusite is an Aluminium nesosilicate Mineral with the chemical formula Al2SiO5 Sillimanite also called Bucholzite is an alumino-silicate Mineral with the Chemical formula Al2SiO5 Kyanite, whose name derives from the Greek word kyanos, meaning blue is a typically blue Silicate Mineral, commonly found in Aluminium -rich Emery is a very hard rock type used to make abrasive powder It largely consists of the mineral Corundum ( Aluminum oxide) mixed with other species such as the iron-bearing Rutile is a Mineral composed primarily of Titanium dioxide, Ti[[oxygen O]]2 Allanite is a sorosilicate group of minerals within the broader Epidote group that contain a significant amount of Rare earth elements It has the general Tourmaline is a Crystal Silicate mineral compounded with elements such as Aluminium, Iron, Magnesium, Sodium, Lithium Though occasionally we may find larger grains of feldspar, quartz or epidote, it is more characteristic of these rocks that all the minerals are in small, nearly uniform, imperfectly shaped individuals.

On account of the minuteness with which it has been described and the important controversies on points of theoretical geology which have arisen regarding it, the granulite district of Saxony (in the area of Rosswein and Penig) in Germany may be considered the typical region for rocks of this group. The Free State of Saxony (Freistaat Sachsen ˈzaksən Swobodny Stat Sakska is the easternmost federal state of Germany. Germany, officially the Federal Republic of Germany ( ˈbʊndəsʁepuˌbliːk ˈdɔʏtʃlant is a Country in Central Europe. It should be remembered that though granulites are probably the commonest rocks of this country, they are mingled with granites, gneisses, gabbros, amphibolites, mica schists and many other petrographical types. Gabbro (ˈɡæbrəʊ is a dark coarse-grained intrusive Igneous rock chemically equivalent to Basalt. Amphibolite (æmˈfɪbəlaɪt is the name given to a rock consisting mainly of hornblende Amphibole, the use of the term being restricted however to Metamorphic All of these rocks show more-or-less metamorphism either of a thermal character or due to pressure and crushing. 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 granites pass into gneiss and granulite; the gabbros into flaser gabbro and amphibolite; the slates often contain andalusite or chiastolite, and show transitions to mica schists. Slate is a fine-grained foliated homogeneous, Metamorphic rock derived from an original Shale -type Sedimentary rock composed of Clay The Mineral chiastolite is a variety of Andalusite with the chemical composition Al2SiO5 At one time these rocks were regarded as Archean gneisses of a special type. Johannes Georg Lehmann propounded the hypothesis that their present state was due principally to crushing acting on them in a solid condition, grinding them down and breaking up their minerals, while the pressure to which they were subjected welded them together into coherent rock. It is now believed, however, that they are comparatively recent and include sedimentary rocks, partly of Palaeozoic age, and intrusive masses which may be nearly massive or may have gneissose, flaser or granulitic structures. Sedimentary rock is one of the three main rock types (the others being igneous and Metamorphic rock) The Paleozoic or Palaeozoic Era (from the Greek palaio (παλαιο "old" and zoe (ζωη "life" meaning "ancient life" In Geology, an intrusion is a body of Igneous rock that has Crystallized from molten Magma below the surface of the Earth. These have been developed largely by the injection of semi-consolidated highly viscous intrusions, and the varieties of texture are original or were produced very shortly after the crystallization of the rocks. Viscosity is a measure of the resistance of a Fluid which is being deformed by either Shear stress or Extensional stress. Meanwhile, however, Lehmanns advocacy of post-consolidation crushing as a factor in the development of granulites has been so successful that the terms granulitization and granulitic structures are widely employed to indicate the results of dynamometamorphism acting on rocks at a period long after their solidification.

The Saxon granulites are apparently for the most part igneous and correspond in composition to granites and porphyries. Porphyry is a variety of Igneous rock consisting of large-grained Crystals such as Feldspar or Quartz, dispersed in a fine-grained There are, however, many granulites which undoubtedly were originally sediments (arkoses, grits and sandstones). Sediment is any particulate matter that can be transported by fluid flow and which eventually is deposited as a layer of solid particles on the bed or bottom of a body of Arkose (ˈɑrkoʊz is a Detrital Sedimentary rock, specifically a type of Sandstone containing at least 25% Feldspar. Sandstone is a Sedimentary rock composed mainly of Sand -size Mineral or rock grains. A large part of the highlands of Scotland consists of paragranulites of this kind, which have received the group name of Moine gneisses. Scotland ( Gaelic: Alba) is a Country in northwest Europethat occupies the northern third of the island of Great Britain.

Along with the typical acid granulites above described, in Saxony, India, Scotland and other countries there occur dark-colored basic granulites (trap granulites). In Computer science, ACID ( Atomicity Consistency Isolation Durability) is a set of properties that guarantee that Database transactions are India, officially the Republic of India (भारत गणराज्य inc-Latn Bhārat Gaṇarājya; see also other Indian languages) is a country These are fine-grained rocks, not usually banded, nearly black in color with small red spots of garnet. Their essential minerals are pyroxene, plagioclase and garnet: chemically they resemble the gabbros. Green augite and hypersthene form a considerable part of these rocks, they may contain also biotite, hornblende and quartz. Hypersthene is a common rock-forming inosilicate Mineral belonging to the group of Orthorhombic Pyroxenes Many references have formally abandoned Around the garnets there is often a radial grouping of small grains of pyroxene and hornblende in a clear matrix of feldspar: these centric structures are frequent in granulites. The rocks of this group accompany gabbro and serpentine, but the exact conditions under which they are formed and the significance of their structures is not very clearly understood. The serpentine group describes a group of common rock-forming hydrous Magnesium Iron phyllosilicate (()3 Minerals they

Granulite facies

Granulite facies is determined by lower temperature boundary of 700 +/- 50 °C and pressure range 5-15 kb. The most common mineral assemblage of granulite facies consists of antiperthitic plagioclase, alkali feldspar containing up to 50% albite and Al₂O₃-rich pyroxenes. Plagioclase is a very important series of tectosilicate Minerals within the Feldspar family Feldspar is the name of a group of rock-forming Minerals which make up as much as 60% of the Earth 's crust. Albite is a plagioclase Feldspar Mineral. It is the sodium endmember of the Plagioclase Solid solution series The pyroxenes are a group of important rock-forming Silicate minerals found in many Igneous and metamorphic rocks.

Transition between amphibolite and granulite facies is defined by these reaction isograds:

amphibole -> pyroxene + H₂O

biotite -> K-feldspar + garnet + orthopyroxene + H₂O. Amphibolite (æmˈfɪbəlaɪt is the name given to a rock consisting mainly of hornblende Amphibole, the use of the term being restricted however to Metamorphic In geology an isograd is a line in the field of constant metamorphic grade it also separates zones of different metamorphic grades

Hornblende granulite subfacies is transitional coexistence region of anhydrous and hydrated ferromagnesian minerals, so above mentioned isograds mark the boundary with pyroxene granulite subfacies – facies with completely anhydrous mineral assemblages. ^[2]

See also

• Migmatite and granite origin
• Metamorphic rocks
• Metamorphic facies
• Ultrahigh-temperature metamorphism

References

1. ^ D. Migmatite is a rock at the frontier between igneous and Metamorphic rocks They can also be known as diatexite. Granite (ˈɡrænɪt is a common and widely occurring type of intrusive, Felsic, igneous rock. 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 R. Bowes (1989), The Encyclopedia of Igneous and Metamorphic Petrology; Van Nostrand Reinhold ISBN: 0-442-20623-2
2. ^ D. R. Bowes (1989), The Encyclopedia of Igneous and Metamorphic Petrology; Van Nostrand Reinhold ISBN: 0-442-20623-2

• This article incorporates text from the Encyclopædia Britannica Eleventh Edition, a publication now in the public domain. 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