1.
Photomicrograph
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A micrograph or photomicrograph is a photograph or digital image taken through a microscope or similar device to show a magnified image of an item. This is opposed to an image, which is at a scale that is visible to the naked eye. Micrography is the practice or art of using microscopes to make photographs, a micrograph contains extensive details that form the features of a microstructure. The neuropathologist Solomon C. Fuller designed and created the first photomicrograph in 1900, micrographs are widely used in all fields of microscopy. A light micrograph or photomicrograph is a micrograph prepared using an optical microscope, at a basic level, photomicroscopy may be performed simply by hooking up a regular camera to a microscope, thereby enabling the user to take photographs at reasonably high magnification. Roman Vishniac was a pioneer in the field of photomicroscopy, specializing in the photography of living creatures in full motion and he also made major developments in light-interruption photography and color photomicroscopy. An electron micrograph is a micrograph prepared using an electron microscope, however, the term electron micrograph is not used in electron microscopy. Digital micrography is a digital picture obtained either directly with a microscope or by scanning of a photomicrograph, digital micrographs are now commonly obtained using a USB microscope attached directly to a home computer or laptop. Today, an add-on three-in-one macro lens which has capability to take wide-angle, fish-eye and macro with 7x, 14x, micrographs usually have micron bars, or magnification ratios, or both. Magnification is a ratio between size of object on a picture and its real size, unfortunately, magnification is somewhat a misleading parameter. It depends on a size of a printed picture. Editors of journals and magazines routinely resize a figure to fit the page, a scale bar, or micron bar, is a bar of known length displayed on a picture. The bar can be used for measurements on a picture, when a picture is resized a bar is also resized. If a picture has a bar, the magnification can be easily calculated, ideally, all pictures destined for publication/presentation should be supplied with a scale bar, the magnification ratio is optional. All but one of the micrographs presented on this page do not have a bar, supplied magnification ratios are likely incorrect. The microscope has been used for scientific discovery. It has also linked to the arts since its invention in the 17th century. At first scientists used the microscope to view and draw objects not visible with the unaided eye, early adopters of the microscope, such as Robert Hooke and Antonie van Leeuwenhoek, were excellent illustrators
2.
Mafic
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Mafic is an adjective describing a silicate mineral or igneous rock that is rich in magnesium and iron, and is thus a portmanteau of magnesium and ferric. Most mafic minerals are dark in color, and common rock-forming mafic minerals include olivine, pyroxene, amphibole, common mafic rocks include basalt, dolerite and gabbro. Mafic rocks often also contain calcium-rich varieties of plagioclase feldspar, chemically, mafic rocks are on the other side of the rock spectrum from the felsic rocks. The term roughly corresponds to the basic rock class. Mafic lava, before cooling, has a low viscosity, in comparison to felsic lava, water and other volatiles can more easily and gradually escape from mafic lava. As a result, eruptions of volcanoes made of mafic lavas are less violent than felsic-lava eruptions. Most mafic-lava volcanoes are shield volcanoes, like those in Hawaii, QAPF diagram List of minerals List of rock types
3.
Intrusion
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Intrusive rock is formed when magma crystallizes and solidifies underground to form intrusions, for example plutons, batholiths, dikes, sills, laccoliths, and volcanic necks. Intrusive rock forms within Earths crust from the crystallization of magma, magma slowly pushes up from deep within the earth into any cracks or spaces it can find, sometimes pushing existing country rock out of the way, a process that can take millions of years. As the magma slowly cools into a solid, the different parts of the magma crystallize into rocks, many mountain ranges, such as the Sierra Nevada in California, are formed mostly from large granite intrusions, see Sierra Nevada Batholith. Intrusions are one of the two ways igneous rock can form, the other is extrusive rock, that is, an eruption or similar event. Technically speaking, an intrusion is any formation of igneous rock, rock formed from magma that cools. In contrast, an extrusion consists of rock, rock formed above the surface of the crust. Large bodies of magma that solidify underground before they reach the surface of the crust are called plutons, plutonic rocks form 7% of the Earths current land surface. Coarse-grained intrusive igneous rocks form at depth within the earth are called abyssal while those that form near the surface are called subvolcanic or hypabyssal. The term intrusive suite seems near synonymous, there is, however, a modest difference, An intrusive suite is a group of plutons related in time and space. Intrusions vary widely, from mountain-range-sized batholiths to thin veinlike fracture fillings of aplite or pegmatite, when exposed by erosion, such batholiths may occupy large areas. A well-known example of an intrusion is Devils Tower, another is Shiprock, New Mexico, USA. Be the pluton is large, it may be called a batholith or a stock, Intrusive rocks are characterized by large crystal sizes, and as the individual crystals are visible, the rock is called phaneritic. This is as the magma cools underground, and while cooling may be fast or slow, cooling is slower than on the surface, if it runs parallel to rock layers, it is called a sill. If an intrusion makes rocks above rise to form a dome, as heat dissipation is slow, and as the rock is under pressure, crystals form, and no vitreous rapidly chilled matter is present. The intrusions did not flow while solidifying, hence do not show lines, contained gases could not escape through the thick strata, thus form cavities, which can often be observed. Because their crystals are of the rough equal size, these rocks are said to be equigranular, there is typically no distinction between a first generation of large well-shaped crystals and a fine-grained ground-mass. Earlier crystals originated at a time when most of the rock was still liquid and are more or less perfect, later crystals are less regular in shape because they were compelled to occupy the spaces left between the already-formed crystals. The former case is said to be idiomorphic, the latter is xenomorphic, there are also many other characteristics that serve to distinguish the members of these two groups
4.
Igneous rock
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Igneous rock, or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma or lava, the magma can be derived from partial melts of existing rocks in either a planets mantle or crust. Typically, the melting is caused by one or more of three processes, an increase in temperature, a decrease in pressure, or a change in composition, solidification into rock occurs either below the surface as intrusive rocks or on the surface as extrusive rocks. Igneous rock may form with crystallization to form granular, crystalline rocks, Igneous and metamorphic rocks make up 90–95% of the top 16 km of the Earths crust by volume. Igneous rocks form about 15% of the Earths current land surface, most of the Earths oceanic crust is made of igneous rock. In terms of modes of occurrence, igneous rocks can be either intrusive or extrusive, the mineral grains in such rocks can generally be identified with the naked eye. Intrusive rocks can also be classified according to the shape and size of the intrusive body, typical intrusive formations are batholiths, stocks, laccoliths, sills and dikes. When the magma solidifies within the earths crust, it cools slowly forming coarse textured rocks, such as granite, gabbro, the central cores of major mountain ranges consist of intrusive igneous rocks, usually granite. When exposed by erosion, these cores may occupy huge areas of the Earths surface, intrusive igneous rocks that form at depth within the crust are termed plutonic rocks and are usually coarse-grained. Intrusive igneous rocks that form near the surface are termed subvolcanic or hypabyssal rocks, hypabyssal rocks are less common than plutonic or volcanic rocks and often form dikes, sills, laccoliths, lopoliths, or phacoliths. Extrusive igneous rocks, also known as rocks, are formed at the crusts surface as a result of the partial melting of rocks within the mantle. Extrusive igneous rocks cool and solidify quicker than intrusive igneous rocks and they are formed by the cooling of molten magma on the earths surface. The magma, which is brought to the surface through fissures or volcanic eruptions, hence such rocks are smooth, crystalline and fine-grained. Basalt is an extrusive igneous rock and forms lava flows, lava sheets. Some kinds of basalt solidify to form long polygonal columns, the Giants Causeway in Antrim, Northern Ireland is an example. The molten rock, with or without suspended crystals and gas bubbles, is called magma and it rises because it is less dense than the rock from which it was created. When magma reaches the surface from beneath water or air, it is called lava, eruptions of volcanoes into air are termed subaerial, whereas those occurring underneath the ocean are termed submarine. Black smokers and mid-ocean ridge basalt are examples of volcanic activity
5.
Basalt
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Basalt is a common extrusive igneous rock formed from the rapid cooling of basaltic lava exposed at or very near the surface of a planet or moon. Flood basalt describes the formation in a series of basalt flows. By definition, basalt is an igneous rock with generally 45-55% silica and less than 10% feldspathoid by volume. Basalt commonly features a very fine-grained or glassy matrix interspersed with visible mineral grains, the average density is 3.0 gm/cm3. Basalt is defined by its content and texture, and physical descriptions without mineralogical context may be unreliable in some circumstances. Basalt is usually grey to black in colour, but rapidly weathers to brown or rust-red due to oxidation of its mafic minerals into hematite, although usually characterized as dark, basaltic rocks exhibit a wide range of shading due to regional geochemical processes. Due to weathering or high concentrations of plagioclase, some basalts can be quite light-coloured and these phenocrysts usually are of olivine or a calcium-rich plagioclase, which have the highest melting temperatures of the typical minerals that can crystallize from the melt. Basalt with a texture is called vesicular basalt, when the bulk of the rock is mostly solid. Gabbro is often marketed commercially as black granite and these ultramafic volcanic rocks, with silica contents below 45% are usually classified as komatiites. Agricola applied basalt to the black rock of the Schloßberg at Stolpen. Tholeiitic basalt is relatively rich in silica and poor in sodium, included in this category are most basalts of the ocean floor, most large oceanic islands, and continental flood basalts such as the Columbia River Plateau. Basalt rocks are in some cases classified after their content in High-Ti and Low-Ti varieties. High-Ti and Low-Ti basalts have been distinguished in the Paraná and Etendeka traps and it has greater than 17% alumina and is intermediate in composition between tholeiite and alkali basalt, the relatively alumina-rich composition is based on rocks without phenocrysts of plagioclase. Alkali basalt is relatively poor in silica and rich in sodium and it is silica-undersaturated and may contain feldspathoids, alkali feldspar and phlogopite. Boninite is a form of basalt that is erupted generally in back-arc basins. Ocean island basalt Lunar basalt On Earth, most basalt magmas have formed by melting of the mantle. Basalt commonly erupts on Io, the third largest moon of Jupiter, and has formed on the Moon, Mars, Venus. The crustal portions of oceanic tectonic plates are composed predominantly of basalt, produced from upwelling mantle below, the mineralogy of basalt is characterized by a preponderance of calcic plagioclase feldspar and pyroxene
6.
Magma
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Besides molten rock, magma may also contain suspended crystals, dissolved gas and sometimes gas bubbles. Magma often collects in magma chambers that may feed a volcano or solidify underground to form an intrusion, magma is capable of intruding into adjacent rocks, extrusion onto the surface as lava, and explosive ejection as tephra to form pyroclastic rock. Magma is a complex high-temperature fluid substance, temperatures of most magmas are in the range 700 °C to 1300 °C, but very rare carbonatite magmas may be as cool as 600 °C, and komatiite magmas may have been as hot as 1600 °C. Environments of magma formation and compositions are commonly correlated, environments include subduction zones, continental rift zones, mid-ocean ridges and hotspots. Despite being found in such locales, the bulk of the Earths crust. Except for the outer core, most of the Earth takes the form of a rheid. Magma, as liquid, preferentially forms in high temperature, low pressure environments within several kilometers of the Earths surface, magma compositions may evolve after formation by fractional crystallization, contamination, and magma mixing. By definition rock formed of solidified magma is called igneous rock, melting of solid rocks to form magma is controlled by three physical parameters, temperature, pressure, and composition. Mechanisms are discussed in the entry for igneous rock, as a rock melts, its volume changes. When enough rock is melted, the small globules of melt link up, under pressure within the earth, as little as a fraction of a percent partial melting may be sufficient to cause melt to be squeezed from its source. The degree of melting is critical for determining what type of magma is produced. The degree of partial melting required to form a melt can be estimated by considering the relative enrichment of incompatible elements versus compatible elements, incompatible elements commonly include potassium, barium, cesium, and rubidium. Rock types produced by small degrees of melting in the Earths mantle are typically alkaline. Typically, primitive melts of this composition form lamprophyre, lamproite, kimberlite and sometimes nepheline-bearing mafic rocks such as alkali basalts, pegmatite may be produced by low degrees of partial melting of the crust. Some granite-composition magmas are eutectic melts, and they may be produced by low to high degrees of melting of the crust. At high degrees of melting of the crust, granitoids such as tonalite, granodiorite and monzonite can be produced. Being only the time in recorded history that magma had been reached, IDDP decided to invest in the hole. A cemented steel case was constructed in the hole with a perforation at the close to the magma
7.
Earth
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Earth, otherwise known as the World, or the Globe, is the third planet from the Sun and the only object in the Universe known to harbor life. It is the densest planet in the Solar System and the largest of the four terrestrial planets, according to radiometric dating and other sources of evidence, Earth formed about 4.54 billion years ago. Earths gravity interacts with objects in space, especially the Sun. During one orbit around the Sun, Earth rotates about its axis over 365 times, thus, Earths axis of rotation is tilted, producing seasonal variations on the planets surface. The gravitational interaction between the Earth and Moon causes ocean tides, stabilizes the Earths orientation on its axis, Earths lithosphere is divided into several rigid tectonic plates that migrate across the surface over periods of many millions of years. About 71% of Earths surface is covered with water, mostly by its oceans, the remaining 29% is land consisting of continents and islands that together have many lakes, rivers and other sources of water that contribute to the hydrosphere. The majority of Earths polar regions are covered in ice, including the Antarctic ice sheet, Earths interior remains active with a solid iron inner core, a liquid outer core that generates the Earths magnetic field, and a convecting mantle that drives plate tectonics. Within the first billion years of Earths history, life appeared in the oceans and began to affect the Earths atmosphere and surface, some geological evidence indicates that life may have arisen as much as 4.1 billion years ago. Since then, the combination of Earths distance from the Sun, physical properties, in the history of the Earth, biodiversity has gone through long periods of expansion, occasionally punctuated by mass extinction events. Over 99% of all species that lived on Earth are extinct. Estimates of the number of species on Earth today vary widely, over 7.4 billion humans live on Earth and depend on its biosphere and minerals for their survival. Humans have developed diverse societies and cultures, politically, the world has about 200 sovereign states, the modern English word Earth developed from a wide variety of Middle English forms, which derived from an Old English noun most often spelled eorðe. It has cognates in every Germanic language, and their proto-Germanic root has been reconstructed as *erþō, originally, earth was written in lowercase, and from early Middle English, its definite sense as the globe was expressed as the earth. By early Modern English, many nouns were capitalized, and the became the Earth. More recently, the name is simply given as Earth. House styles now vary, Oxford spelling recognizes the lowercase form as the most common, another convention capitalizes Earth when appearing as a name but writes it in lowercase when preceded by the. It almost always appears in lowercase in colloquial expressions such as what on earth are you doing, the oldest material found in the Solar System is dated to 4. 5672±0.0006 billion years ago. By 4. 54±0.04 Gya the primordial Earth had formed, the formation and evolution of Solar System bodies occurred along with the Sun
8.
Oceanic crust
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Oceanic crust is the uppermost layer of the oceanic portion of a tectonic plate. The crust overlies the solidified and uppermost layer of the mantle, the crust and the solid mantle layer together constitute oceanic lithosphere. Oceanic crust is the result of erupted mantle material originating from below the plate, cooled and in most instances and this occurs mostly at mid-ocean ridges, but also at scattered hotspots, and also in rare but powerful occurrences known as flood basalt eruptions. It is primarily composed of rocks, or sima, which is rich in iron. Although a complete section of oceanic crust has not yet been drilled, Oceanic crust is significantly simpler than continental crust and generally can be divided in three layers. Layer 1 is on an average 0.4 km thick and it consists of unconsolidated or semiconsolidated sediments, usually thin or even not present near the mid-ocean ridges but thickens farther away from the ridge. Layer 3 is formed by slow cooling of magma beneath the surface and consists of coarse grained gabbros and it constitutes over two-thirds of oceanic crust volume with almost 5 km thickness. The most voluminous volcanic rocks of the floor are the mid-oceanic ridge basalts. These rocks have low concentrations of large ion lithophile elements, light rare earth elements, volatile elements, there can be found basalts enriched with incompatible elements, but they are rare and associated with mid-ocean ridge hot spots such as surroundings of Galapagos Islands, the Azores and Iceland. Oceanic crust is continuously being created at mid-ocean ridges, as plates diverge at these ridges, magma rises into the upper mantle and crust. As it moves away from the ridge, the lithosphere becomes cooler and denser, the youngest oceanic lithosphere is at the oceanic ridges, and it gets progressively older away from the ridges. As the mantle rises it cools and melts, as the pressure decreases, the amount of melt produced depends only on the temperature of the mantle as it rises. Hence most oceanic crust is the same thickness, an example of this is the Gakkel Ridge under the Arctic Ocean. Thicker than average crust is found above plumes as the mantle is hotter and hence it crosses the solidus and melts at a depth, creating more melt. An example of this is Iceland which has crust of thickness ~20 km, the oceanic lithosphere subducts at what are known as convergent boundaries. These boundaries can exist between oceanic lithosphere on one plate and oceanic lithosphere on another, or between oceanic lithosphere on one plate and continental lithosphere on another, in the second situation, the oceanic lithosphere always subducts because the continental lithosphere is less dense. The subduction process consumes older oceanic lithosphere, so oceanic crust is more than 200 million years old. The process of super-continent formation and destruction via repeated cycles of creation and destruction of oceanic crust is known as the Wilson cycle, the oldest large scale oceanic crust is in the west Pacific and north-west Atlantic - both are about up to 180-200 million years old
9.
Mid-ocean ridge
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A mid-ocean ridge is an underwater mountain system formed by plate tectonics. It consists of various mountains linked in chains, typically having a known as a rift running along its spine. This type of mountain ridge is characteristic of what is known as an oceanic spreading center. The production of new results from mantle upwelling in response to plate spreading. The buoyant melt rises as magma at a linear weakness in the oceanic crust, a mid-ocean ridge demarcates the boundary between two tectonic plates, and consequently is termed a divergent plate boundary. Mid-ocean ridges are geologically active, with new magma constantly emerging onto the floor and into the crust at. The crystallized magma forms new crust of basalt and gabbro and they are formed by two oceanic plates moving away from each other. The rocks making up the crust below the seafloor are youngest along the axis of the ridge and age with increasing distance from that axis, new magma of basalt composition emerges at and near the axis because of decompression melting in the underlying Earths mantle. The oceanic crust is made up of much younger than the Earth itself. Most oceanic crust in the basins is less than 200 million years old. The crust is in a constant state of renewal at the ocean ridges, moving away from the mid-ocean ridge, ocean depth progressively increases, the greatest depths are in ocean trenches. As the oceanic crust moves away from the axis, the peridotite in the underlying mantle cools. The crust and the relatively rigid peridotite below it make up the oceanic lithosphere, by contrast, fast spreading ridges like the East Pacific Rise are narrow, sharp incisions surrounded by generally flat topography that slopes away from the ridge over many hundreds of miles. The overall shape of ridges results from Pratt isostacy, close to the ridge there is hot. As the oceanic plates cool, away from the axes, the oceanic mantle lithosphere thickens. Thus older seafloor is underlain by denser material and sits lower, there are two processes, ridge-push and slab pull, thought to be responsible for the spreading seen at mid-ocean ridges, and there is some uncertainty as to which is dominant. Ridge-push occurs when the bulk of the ridge pushes the rest of the tectonic plate away from the ridge. At the subduction zone, slab-pull comes into effect and this is simply the weight of the tectonic plate being subducted below the overlying plate dragging the rest of the plate along behind it
10.
Pluton
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For the Australian gold mine see Plutonic Gold Mine In geology, a pluton is a body of intrusive igneous rock that is crystallized from magma slowly cooling below the surface of the Earth. Plutons include batholiths, stocks, dikes, sills, laccoliths, lopoliths, in practice, pluton usually refers to a distinctive mass of igneous rock, typically several kilometers in dimension, without a tabular shape like those of dikes and sills. Batholiths commonly are aggregations of plutons, examples of plutons include Denali, Cuillin, Cardinal Peak, Mount Kinabalu and Stone Mountain. The most common types in plutons are granite, granodiorite, tonalite, monzonite. Generally light colored, coarse-grained plutons of these compositions are referred to as granitoids, the term originated from Pluto, the classical god of the underworld. Methods of pluton emplacement Subvolcanic rock Volcanic rock Glazner, A. F. Bartley, J. M. Coleman, D. S. Gray, W. and Taylor, are plutons assembled over millions of years by amalgamation from small magma chambers. Mind Over Magma, the Story of Igneous Petrology, best, Myron G. Igneous and Metamorphic Petrology. San Francisco, W. H. Freeman & Company
11.
Volcanism
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It includes all phenomena resulting from and causing magma within the crust or mantle of the body, to rise through the crust and form volcanic rocks on the surface. Magma from the mantle or lower crust rises through its crust towards the surface, if magma reaches the surface, its behavior depends on the viscosity of the molten constituent rock. Viscous magma produces volcanoes characterised by explosive eruptions, while non-viscous magma produce volcanoes characterised by effusive eruptions pouring large amounts of lava onto the surface, in some cases, rising magma can cool and solidify without reaching the surface. Instead, the cooled and solidified igneous mass crystallises within the crust to form an igneous intrusion, as magma cools the chemicals in the crystals formed are effectively removed from the main mix of the magma, so the chemical content of the remaining magma evolves as it solidifies slowly. Fresh unevolved magma injections can remobilise more evolved magmas, allowing eruptions from more viscous magmas, movement of molten rock in the mantle, caused by thermal convection currents, coupled with gravitational effects of changes on the earths surface drive plate tectonic motion and ultimately volcanism. Volcanoes are places where magma reaches the earths surface, the type of volcano depends on the location of the eruption and the consistency of the magma. These are formed where magma pushes between existing rock, intrusions can be in the form of batholiths, dikes, sills, earthquakes are generally associated with plate tectonic activity, but some earthquakes are generated as a result of volcanic activity. These are formed where water interacts with volcanism and these include geysers, fumaroles, hotsprings and mudpots, they are often used as a source of geothermal energy. The amount of gas and ash emitted by volcanic eruptions has a significant effect on the Earths climate, large eruptions correlate well with some significant climate change events. When the magma cools it solidifies and forms rocks, the type of rock formed depends on the composition of the magma. Magma that reaches the surface to become lava cools rapidly resulting in rocks with small crystals such as basalt, some of this magma may cool extremely rapidly and will form volcanic glass such as obsidian. Magma that remains trapped below ground in thin intrusions cools slower than magma exposed to the surface, magma that remains trapped in large quantities below ground cools most slowly resulting in rocks with larger crystals - such as granite and gabbro. Existing rocks that come into contact with magma may be melted and assimilated into the magma, other rocks adjacent to the magma may be altered by contact metamorphism or metasomatism as they are affected by the heat and escaping or externally circulating hydrothermal fluids. Volcanism is not confined only to Earth, but is thought to be found on any body having a solid crust, evidence of volcanism should still be found on any body that has had volcanism at some point in its history. It can be surmised that volcanism exists on planets and moons of this type in other systems as well. In 2014, scientists found 70 lava flows which formed on the Moon in the last 100 million years, bimodal volcanism Continental drift Hotspot Volcanic arc Glossary of Volcanic Terms. G. J. Hudak, University of Wisconsin Oshkosh,2001, crumpler, L. S. and Lucas, S. G. Volcanoes of New Mexico, An Abbreviated Guide For Non-Specialists. New Mexico Museum of Natural History and Science Bulletin, archived from the original on 2007-03-21
12.
Apennine Mountains
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The Apennines or Apennine Mountains are a mountain range consisting of parallel smaller chains extending c. 1,200 km along the length of peninsular Italy. In the northwest they join with the Ligurian Alps at Altare, in the southwest they end at Reggio di Calabria, the coastal city at the tip of the peninsula. The system forms an arc enclosing the east side of the Ligurian and Tyrrhenian Seas, the name originally applied to the north Apennines. However, historical linguists have never found a derivation with which they are universally comfortable, wilhelm Deecke said. its etymology is doubtful but some derive it from the Ligurian-Celtish Pen or Ben, which means mountain peak. The mountains lend their name to the Apennine peninsula, which forms the part of Italy. They are mostly verdant, although one side of the highest peak, Corno Grande is partially covered by Calderone glacier and it has been receding since 1794. The eastern slopes down to the Adriatic Sea are steep, while the western slopes form foothills on which most of peninsular Italys cities are located. The mountains tend to be named from the province or provinces in which they are located, for example, as the provincial borders have not always been stable, this practice has resulted in some confusion about exactly where the montane borders are. Often but not always a feature can be found that lends itself to being a border. The Apennines are divided into three sectors, northern, central, and southern, a number of long hiking trails wind through the Apennines. Of note is European walking route E1 coming from northern Europe and traversing the lengths of the northern, the Grand Italian Trail begins in Trieste and after winding through the Alpine arc traverses the entire Apennine system, Sicily and Sardinia. The northern Apennines consist of three sub-chains, the Ligurian, Tuscan-Emilian, and Umbrian Apennines, the Ligurian Apennines border the Ligurian Sea in the Gulf of Genoa, from about Savona below the upper Bormida River valley to about La Spezia below the upper Magra River valley. The range follows the Gulf of Genoa separating it from the upper Po Valley, the northwestern border follows the line of the Bormida River to Acqui Terme. There the river continues northeast to Alessandria in the Po Valley, the upper Bormida can be reached by a number of roads proceeding inland at a right angle to the coast southwest of Savona, the chief one being the Autostrada Torino-Savona. They ascend to the Bocchetta di Altare, sometimes called Colle di Cadibona,436 m, a bronze plaque fixed to a stone marks the top of the pass. In the vicinity are fragments of the old road and three ruins of former fortifications, at Carcare, the main roads connect with the upper Bormida valley before turning west. The Scrivia, the Trebbia and the Taro, tributaries of the Po River, the range contains dozens of peaks. Toward the southern end the Aveto Natural Regional Park includes Monte Penna, nearby is the highest point of Ligurian Apennines, Monte Maggiorasca at 1,780 m
13.
Christian Leopold von Buch
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His scientific interest was devoted to a broad spectrum of geological topics, volcanism, fossils, stratigraphy and more. His most remembered accomplishment is the definition of the Jurassic system. He was known as Leopold von Buch, Buch studied with Alexander von Humboldt under Abraham Gottlob Werner at the mining school in Freiberg, Saxony. He afterwards completed his education at the universities of Halle and Göttingen and he began writing on geological topics early in life. His Versuch einer mineralogischen Beschreibung von Landeck was translated into French, in 1802 he published Entwurf einer geognostischen Beschreibung von Schlesien, which became the first volume of his Geognostische Beobachtungen auf Reisen durch Deutschland und Italien. He was at time a zealous upholder of the Neptunian theory of Werner. In 1797, he met Humboldt at Salzburg, and with him explored the geological formations of Styria, in the spring of 1798, Buch extended his excursions into Italy, where his faith in the Neptunian theory was shaken. In his early works, he had advocated the aqueous origin of basaltic and other formations, but now he saw cause to abandon Werners theory and he saw Vesuvius for the first time in 1799. Later, in 1805, he had the opportunity, along with Humboldt and Gay Lussac and it was a remarkable eruption, and supplied Buch with data for refuting many erroneous ideas then entertained regarding volcanoes. In 1802 he examined the extinct volcanoes of the Auvergne in the south of France. The aspect of the Puy de Dôme, with its cone of trachyte and its strata of basaltic lava, the results of all these geological travels were given to the world in the two volumes of his Geognostische Beobachtungen. In 1806, Buch proceeded to Scandinavia and spent two years in examining its physical constitution and this furnished the materials for his work entitled Reise durch Norwegen und Lappland. He made many important observations on the geography of plants, on climatology and he showed that many of the erratic blocks on the North German plains must have come from Scandinavia. He also established the fact that the whole of Sweden is slowly but continuously rising above the level of the sea from Frederikshald to Abo, in 1815 Buch visited the Canary Islands in company with Christen Smith, a Norwegian botanist. These volcanic isles furnished the starting point from which Buch commenced a course of study on the production. This is attested by his work on the subject entitled Physical Description of the Canary Isles. During his time in the Canary Islands, he visited the Las Cañadas Caldera on Tenerife, when he published his memoirs and observations about his excursion, he introduced the Spanish word Caldera into the geological and scientific vocabulary. After his return from the Canaries he visited the group of the Hebrides
14.
Metamorphism
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Metamorphism is the change of minerals or geologic texture in pre-existing rocks, without the protolith melting into liquid magma. The change occurs primarily due to heat, pressure, and the introduction of chemically active fluids, the chemical components and crystal structures of the minerals making up the rock may change even though the rock remains a solid. Changes at or just beneath Earths surface due to weathering and/or diagenesis are not classified as metamorphism, Metamorphism typically occurs between diagenesis, and melting. Three types of metamorphism exist, contact, dynamic, and regional, Metamorphism produced with increasing pressure and temperature conditions is known as prograde metamorphism. Conversely, decreasing temperatures and pressure characterize retrograde metamorphism, Metamorphic rocks can change without melting. When pressure is applied, somewhat flattened grains that orient in the same direction have a stable configuration. The upper boundary of metamorphic conditions is related to the onset of melting processes in the rock, the maximum temperature for metamorphism is typically 700 –900 °C, depending on the pressure and on the composition of the rock. Migmatites are rocks formed at this limit, which contain pods. Since the 1980s it has recognized that rocks are rarely dry enough. Conditions producing widespread regionally metamorphosed rocks occur during an orogenic event, the collision of two continental plates or island arcs with continental plates produce the extreme compressional forces required for the metamorphic changes typical of regional metamorphism. These orogenic mountains are eroded, exposing the intensely deformed rocks typical of their cores. The conditions within the slab as it plunges toward the mantle in a subduction zone also produce regional metamorphic effects. The techniques of structural geology are used to unravel the collisional history, regional metamorphism can be described and classified into metamorphic facies or metamorphic zones of temperature/pressure conditions throughout the orogenic terrane. Contact metamorphism occurs typically around intrusive igneous rocks as a result of the increase caused by the intrusion of magma into cooler country rock. The area surrounding the intrusion where the contact metamorphism effects are present is called the metamorphic aureole, contact metamorphic rocks are usually known as hornfels. Rocks formed by contact metamorphism may not present signs of deformation and are often fine-grained. Contact metamorphism is greater adjacent to the intrusion and dissipates with distance from the contact, the size of the aureole depends on the heat of the intrusion, its size, and the temperature difference with the wall rocks. Dikes generally have small aureoles with minimal metamorphism whereas large ultramafic intrusions can have significantly thick, the metamorphic grade of an aureole is measured by the peak metamorphic mineral which forms in the aureole
15.
Rosignano Marittimo
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Rosignano Marittimo is a comune in the Province of Livorno in the Italian region Tuscany, located about 80 kilometres southwest of Florence and about 20 kilometres southeast of Livorno. Rosignano Marittimo borders the municipalities, Castellina Marittima, Cecina, Collesalvetti, Livorno, Orciano Pisano. During World War II a major United States Army Air Force base was located near Rosignano, after the war the airfield was closed and the land returned to agricultural use. Today there is little or no evidence of its existence, Rosignano Marittimo is twinned with, Champigny-sur-Marne, France. Musselburgh, United Kingdom Zug, Western Sahara Comune di Rosignano Maritimo
16.
Municipality
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It is to be distinguished from the county, which may encompass rural territory and/or numerous small communities such as towns, villages and hamlets. The term municipality may also mean the governing or ruling body of a given municipality, a municipality is a general-purpose administrative subdivision, as opposed to a special-purpose district. The term is derived from French municipalité and Latin municipalis, a municipality can be any political jurisdiction from a sovereign state, such as the Principality of Monaco, or a small village, such as West Hampton Dunes, New York. The power of municipalities range from virtual autonomy to complete subordination to the state, municipalities may have the right to tax individuals and corporations with income tax, property tax, and corporate income tax, but may also receive substantial funding from the state. Similar terms include Spanish ayuntamiento, also called municipalidad, Polish gmina, Dutch/Flemish Gemeente, in Australia, the term local government area is used in place of the generic municipality. Here, the LGA Structure covers only incorporated areas of Australia, incorporated areas are legally designated parts of states and territories over which incorporated local governing bodies have responsibility. In Canada, municipalities are local governments established through provincial and territorial legislation, the Province of Ontario has different tiers of municipalities, including lower, upper, and single tiers. Types of upper tier municipalities in Ontario include counties and regional municipalities, nova Scotia also has regional municipalities, which include cities, counties, districts, or towns as municipal units. In India, a Nagar Palika or Municipality is a local body that administers a city of population 100,000 or more. Under the Panchayati Raj system, it directly with the state government. Generally, smaller cities and bigger towns have a Nagar Palika. Nagar Palikas are also a form of local self-government entrusted with duties and responsibilities. Such a corporation in Great Britain consists of a head as a mayor or provost, since local government reorganisation, the unit in England, Northern Ireland and Wales is known as a district, and in Scotland as a council area. A district may be awarded borough or city status, or can retain its district title, in Jersey, a municipality refers to the honorary officials elected to run each of the 12 parishes into which it is subdivided. This is the highest level of government in this jurisdiction. In the United States, municipality is usually understood as a city, town, village, or other local government unit, in the Peoples Republic of China, a direct-controlled municipality is a city with equal status to a province, Beijing, Tianjin, Shanghai, and Chongqing. In Taiwan, a municipality is a city with equal status to a province, Kaohsiung, New Taipei, Taichung, Tainan, Taipei. In Portuguese language usage, there are two words to distinguish the territory and the administrative organ, when referring to the territory, the word concelho is used, when referring to the organ of State, the word município is used
17.
Tuscany
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Tuscany is a region in central Italy with an area of about 23,000 square kilometres and a population of about 3.8 million inhabitants. Tuscany is known for its landscapes, traditions, history, artistic legacy, Tuscany produces wines, including Chianti, Vino Nobile di Montepulciano, Morellino di Scansano and Brunello di Montalcino. Having a strong linguistic and cultural identity, it is considered a nation within a nation. Tuscany is traditionally a popular destination in Italy, and the main tourist destinations by number of tourist arrivals are Florence, Pisa, Montecatini Terme, Castiglione della Pescaia and Grosseto. The village of Castiglione della Pescaia is also the most visited destination in the region. Additionally, Siena, Lucca, the Chianti region, Versilia and Val dOrcia are also internationally renowned, Tuscany has over 120 protected nature reserves, making Tuscany and its capital Florence popular tourist destinations that attract millions of tourists every year. In 2012, the city of Florence was the worlds 89th most visited city, roughly triangular in shape, Tuscany borders the regions of Liguria to the northwest, Emilia-Romagna to the north and east, Umbria to the east and Lazio to the southeast. The comune of Badia Tedalda, in the Tuscan Province of Arezzo, has an exclave named Ca Raffaello within Emilia-Romagna, Tuscany has a western coastline on the Tyrrhenian Sea, containing the Tuscan Archipelago, of which the largest island is Elba. Tuscany has an area of approximately 22,993 square kilometres, surrounded and crossed by major mountain chains, and with few plains, the region has a relief that is dominated by hilly country used for agriculture. Hills make up nearly two-thirds of the total area, covering 15,292 square kilometres, and mountains. Plains occupy 8. 4% of the total area—1,930 square kilometres —mostly around the valley of the River Arno, many of Tuscanys largest cities lie on the banks of the Arno, including the capital Florence, Empoli and Pisa. The pre-Etruscan history of the area in the late Bronze and Iron Ages parallels that of the early Greeks, following this, the Villanovan culture saw Tuscany, and the rest of Etruria, taken over by chiefdoms. City-states developed in the late Villanovan before Orientalization occurred and the Etruscan civilization rose, the Etruscans created the first major civilization in this region, large enough to establish a transport infrastructure, to implement agriculture and mining and to produce vibrant art. The Etruscans lived in Etruria well into prehistory, throughout their existence, they lost territory to Magna Graecia, Carthage and Celts. Despite being seen as distinct in its manners and customs by contemporary Greeks, the cultures of Greece, one reason for its eventual demise was this increasing absorption by surrounding cultures, including the adoption of the Etruscan upper class by the Romans. Soon after absorbing Etruria, Rome established the cities of Lucca, Pisa, Siena, and Florence, endowed the area with new technologies and development, and ensured peace. These developments included extensions of existing roads, introduction of aqueducts and sewers, however, many of these structures have been destroyed by erosion due to weather. The Roman civilization in the West collapsed in the 5th century AD, in the years following 572, the Longobards arrived and designated Lucca the capital of their Duchy of Tuscia
18.
Cuillin
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The Cuillin is a range of rocky mountains located on the Isle of Skye in Scotland. The true Cuillin is also known as the Black Cuillin to distinguish it from the Red Cuilin across Glen Sligachan, the Red Cuilin hills are lower and, being less rocky, have fewer scrambles or climbs. The highest point of the Cuillin, and of the Isle of Skye, is Sgùrr Alasdair in the Black Cuillin at 992 m, the Cuillin is one of 40 National Scenic Areas in Scotland. The peaks of the Black Cuillin are mainly composed of gabbro, a rough black igneous rock which provides a superb grip for mountaineers, and basalt. The summits of the Cuillin are bare rock, jagged in outline and with steep cliffs, twelve Black Cuillin peaks are listed as Munros, though one of them, Blaven, is part of a group of outliers separated from the main ridge by Glen Sligachan. The scrambler can access most of the individual peaks by their easiest routes, only the Inaccessible Pinnacle is a graded rock climb by its simplest line but several of the other summits require scrambling skills. There are no sources of water on the ridge, all water must be carried by the visitor. In addition to climbing individual peaks, there is the challenge of a traverse of the ridge. The first recorded traverse in under 24 hours was in 1911 by L. Shadbolt, the record for the full traverse, set by Finlay Wild in October 2013, stands at 2 hours,59 minutes and 22 seconds. A longer traverse of the Black Cuillin, is the Greater Traverse, this involves continuing on to Clach Glas and Blaven. This traverse was first done independently by two parties, in the summer of 1939, with I Charleson and W Forde claiming precedence over W. H. Murray & R. G. Donaldon a few weeks later. Some believe the ultimate mountaineering experience of the UK is the full traverse of the Cuillin Ridge, the Isle of Skyes position in the warm Gulf Stream makes genuine winter conditions rare, and the very short winter days probably make a 24-hour traverse impractical. The first recorded, over two days, was in 1965 by D Crabbe, B Robertson, T Patey and H MacInnes. The Cuillin is perhaps the only range in the United Kingdom to approach in sheer jagged rawness the mountain experience of such ranges as the Alps or Rockies, the Red Hills are sometimes known as the Red Cuillin. They are mainly composed of granite which is paler than the gabbro and has weathered into more rounded hills with vegetation cover to summit level, the highest point of the hills is Glamaig, one of only two Corbetts on Skye. Here is a list of Munros, Corbetts and Grahams of the Cuillin and this listing excludes peaks such as Clach Glas which in hill walking/mountaineering terms are considered of significance. The Battle of Coire Na Creiche was fought on the slopes below Bruach na Frìthe in 1601 and it was the last Scottish clan battle fought on Skye, in which the Clan MacDonald of Sleat defeated the Clan MacLeod after a bitter feud. In 2000 the Cuillin were put on sale for £10 million by the Laird in a scheme of land in exchange for repairs to Dunvegan Castle, following a dispute over ownership, a deal was cut for the property to be gifted in return for repairs to the clan castle
19.
Isle of Skye
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Skye, or the Isle of Skye, is the largest and northernmost of the major islands in the Inner Hebrides of Scotland. The islands peninsulas radiate from a centre dominated by the Cuillins. Although it has suggested that the Gaelic Sgitheanach describes a winged shape there is no definitive agreement as to the names origins. The island has been occupied since the Mesolithic period, and its history includes a time of Norse rule, resident numbers declined from over 20,000 in the early 19th century to just under 9,000 by the closing decade of the 20th century. Skyes population increased by 4 per cent between 1991 and 2001, about a third of the residents were Gaelic speakers in 2001, and although their numbers are in decline, this aspect of island culture remains important. The main industries are tourism, agriculture, fishing and forestry, Skye is part of the Highland Council local government area. The islands largest settlement is Portree, known for its picturesque harbour, There are links to various nearby islands by ferry and, since 1995, to the mainland by a road bridge. The climate is mild, wet and windy, the abundant wildlife includes the golden eagle, red deer and Atlantic salmon. The local flora is dominated by heather moor, and there are nationally important invertebrate populations on the sea bed. Skye has provided the locations for various novels and feature films and is celebrated in poetry, the first written references to the island are Roman sources such as the Ravenna Cosmography, which refers to Scitis and Scetis, which can be found on a map by Ptolemy. One possible derivation comes from skitis, an early Celtic word for winged, subsequent Gaelic-, Norse- and English-speaking peoples have influenced the history of Skye, the relationships between their names for the island are not straightforward. Various etymologies have been proposed, such as the winged isle or the notched isle but no solution has been found to date. The island was referred to by the Norse as Skuy. The traditional Gaelic name is An t-Eilean Sgitheanach, An t-Eilean Sgiathanach being a more recent, but the meaning of this Gaelic name is unclear. Eilean a Cheò, which means island of the mist, is a poetic Gaelic name for the island, at 1,656 square kilometres, Skye is the second-largest island in Scotland after Lewis and Harris. The coastline of Skye is a series of peninsulas and bays radiating out from a centre dominated by the Cuillin hills, Martin Martin, a native of the island, reported on it at length in a 1703 publication. Resemble nutmegs, and many rivulets here afford variegated stones of all colours, stones of a purple colour flow down the rivulets here after great rains. The Black Cuillin, which are composed of basalt and gabbro, include twelve Munros and provide some of the most dramatic
20.
Scotland
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Scotland is a country that is part of the United Kingdom and covers the northern third of the island of Great Britain. It shares a border with England to the south, and is surrounded by the Atlantic Ocean, with the North Sea to the east. In addition to the mainland, the country is made up of more than 790 islands, including the Northern Isles, the Kingdom of Scotland emerged as an independent sovereign state in the Early Middle Ages and continued to exist until 1707. By inheritance in 1603, James VI, King of Scots, became King of England and King of Ireland, Scotland subsequently entered into a political union with the Kingdom of England on 1 May 1707 to create the new Kingdom of Great Britain. The union also created a new Parliament of Great Britain, which succeeded both the Parliament of Scotland and the Parliament of England. Within Scotland, the monarchy of the United Kingdom has continued to use a variety of styles, titles, the legal system within Scotland has also remained separate from those of England and Wales and Northern Ireland, Scotland constitutes a distinct jurisdiction in both public and private law. Glasgow, Scotlands largest city, was one of the worlds leading industrial cities. Other major urban areas are Aberdeen and Dundee, Scottish waters consist of a large sector of the North Atlantic and the North Sea, containing the largest oil reserves in the European Union. This has given Aberdeen, the third-largest city in Scotland, the title of Europes oil capital, following a referendum in 1997, a Scottish Parliament was re-established, in the form of a devolved unicameral legislature comprising 129 members, having authority over many areas of domestic policy. Scotland is represented in the UK Parliament by 59 MPs and in the European Parliament by 6 MEPs, Scotland is also a member nation of the British–Irish Council, and the British–Irish Parliamentary Assembly. Scotland comes from Scoti, the Latin name for the Gaels, the Late Latin word Scotia was initially used to refer to Ireland. By the 11th century at the latest, Scotia was being used to refer to Scotland north of the River Forth, alongside Albania or Albany, the use of the words Scots and Scotland to encompass all of what is now Scotland became common in the Late Middle Ages. Repeated glaciations, which covered the land mass of modern Scotland. It is believed the first post-glacial groups of hunter-gatherers arrived in Scotland around 12,800 years ago, the groups of settlers began building the first known permanent houses on Scottish soil around 9,500 years ago, and the first villages around 6,000 years ago. The well-preserved village of Skara Brae on the mainland of Orkney dates from this period and it contains the remains of an early Bronze Age ruler laid out on white quartz pebbles and birch bark. It was also discovered for the first time that early Bronze Age people placed flowers in their graves, in the winter of 1850, a severe storm hit Scotland, causing widespread damage and over 200 deaths. In the Bay of Skaill, the storm stripped the earth from a large irregular knoll, when the storm cleared, local villagers found the outline of a village, consisting of a number of small houses without roofs. William Watt of Skaill, the laird, began an amateur excavation of the site, but after uncovering four houses
21.
Pyroxene
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The pyroxenes are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes are silicon-aluminum oxides with Ca, Na, Fe, Mg, Zn, Mn, Li substituting for Si, although aluminium substitutes extensively for silicon in silicates such as feldspars and amphiboles, the substitution occurs only to a limited extent in most pyroxenes. They share a structure consisting of single chains of silica tetrahedra. The name pyroxene is derived from the Ancient Greek words for fire, however, they are simply early-forming minerals that crystallized before the lava erupted. The upper mantle of Earth is composed mainly of olivine and pyroxene, a piece of the mantle is shown at right and is dominated by olivine, typical for common peridotite. Pyroxene and feldspar are the minerals in basalt and gabbro. Pyroxene minerals are named according to the chemical species occupying the X site, the Y site, cations in Y site are closely bound to 6 oxygens in octahedral coordination. Cations in the X site can be coordinated with 6 to 8 oxygen atoms, twenty mineral names are recognised by the International Mineralogical Associations Commission on New Minerals and Mineral Names and 105 previously used names have been discarded. A typical pyroxene has mostly silicon in the site and predominately ions with a charge of +2 in both the X and Y sites, giving the approximate formula XYT2O6. The names of the common calcium – iron – magnesium pyroxenes are defined in the pyroxene quadrilateral shown in Figure 2, the enstatite-ferrosilite series contain up to 5 mol. % calcium and exists in three polymorphs, orthorhombic orthoenstatite and protoenstatite and monoclinic clinoenstatite. Increasing the calcium content prevents the formation of the orthorhombic phases, there is not complete solid solution in calcium content and Mg-Fe-Ca pyroxenes with calcium contents between about 15 and 25 mol. % are not stable with respect to a pair of exolved crystals. This leads to a miscibility gap between pigeonite and augite compositions, there is an arbitrary separation between augite and the diopside-hedenbergite solid solution. The divide is taken at >45 mol. % Ca, as the calcium ion cannot occupy the Y site, pyroxenes with more than 50 mol. % calcium are not possible. A related mineral wollastonite has the formula of the hypothetical calcium end member, magnesium, calcium and iron are by no means the only cations that can occupy the X and Y sites in the pyroxene structure. A second important series of minerals are the sodium-rich pyroxenes. The inclusion of sodium, which has a charge of +1, in jadeite and aegirine this is added by the inclusion of a +3 cation on the Y site. Table 1 shows the range of other cations that can be accommodated in the pyroxene structure. For example, Na and Al give the jadeite composition, coupled substitution of a 1+ ion on the X site and a mixture of equal numbers of 2+ and 4+ ions on the Y site
22.
Plagioclase
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Plagioclase is a series of tectosilicate minerals within the feldspar group. Rather than referring to a mineral with a specific chemical composition, plagioclase is a continuous solid solution series. This was first shown by the German mineralogist Johann Friedrich Christian Hessel in 1826, the series ranges from albite to anorthite endmembers, where sodium and calcium atoms can substitute for each other in the minerals crystal lattice structure. Plagioclase in hand samples is often identified by its polysynthetic crystal twinning or record-groove effect, plagioclase is a major constituent mineral in the Earths crust, and is consequently an important diagnostic tool in petrology for identifying the composition, origin and evolution of igneous rocks. Plagioclase is also a constituent of rock in the highlands of the Earths moon. Analysis of thermal emission spectra from the surface of Mars suggests that plagioclase is the most abundant mineral in the crust of Mars, the extinction angle is an optical characteristic and varies with the albite fraction. There are several named plagioclase feldspars that fall between albite and anorthite in the series, the following table shows their compositions in terms of constituent anorthite and albite percentages. Anorthite was named by Gustav Rose in 1823 from the Ancient Greek meaning oblique, anorthite is a comparatively rare mineral but occurs in the basic plutonic rocks of some orogenic calc-alkaline suites. Albite is named from the Latin albus, in reference to its pure white color. It is a common and important rock-making mineral associated with the more acid rock types and in pegmatite dikes, often with rarer minerals like tourmaline. The intermediate members of the group are very similar to each other. Bytownite, named after the name for Ottawa, Canada, is a rare mineral occasionally found in more basic rocks. Labradorite is the characteristic feldspar of the basic rock types such as diorite, gabbro, andesite. Labradorite frequently shows an iridescent display of colors due to light refracting within the lamellae of the crystal and it is named after Labrador, where it is a constituent of the intrusive igneous rock anorthosite which is composed almost entirely of plagioclase. A variety of known as spectrolite is found in Finland. Andesine is a mineral of rocks such as diorite which contain a moderate amount of silica. Oligoclase is common in granite, syenite, diorite, and gneiss and it is a frequent associate of orthoclase. The name oligoclase is derived from the Greek for little and fracture, sunstone is mainly oligoclase with flakes of hematite
23.
Amphibole
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Amphiboles can be green, black, colorless, white, yellow, blue, or brown. The International Mineralogical Association currently classifies amphiboles as a mineral supergroup, amphiboles crystallize into two crystal systems, monoclinic and orthorhombic. In chemical composition and general characteristics they are similar to the pyroxenes, the chief differences from pyroxenes are that amphiboles contain essential hydroxyl or halogen and the basic structure is a double chain of tetrahedra. Most apparent, in specimens, is that amphiboles form oblique cleavage planes. Amphiboles are also less dense than the corresponding pyroxenes. In optical characteristics, many amphiboles are distinguished by their stronger pleochroism, amphiboles are the primary constituent of amphibolites. Amphiboles are minerals of either igneous or metamorphic origin, in the former case occurring as constituents of rocks, such as granite, diorite, andesite. Calcium is sometimes a constituent of naturally occurring amphiboles and those of metamorphic origin include examples such as those developed in limestones by contact metamorphism and those formed by the alteration of other ferromagnesian minerals. Pseudomorphs of amphibole after pyroxene are known as uralite, the name amphibole was used by René Just Haüy to include tremolite, actinolite, tourmaline and hornblende. The group was so named by Haüy in allusion to the variety, in composition and appearance. This term has since applied to the whole group. Numerous sub-species and varieties are distinguished, the important of which are tabulated below in two series. The formulae of each will be seen to be built on the general double-chain silicate formula RSi4O11, four of the amphibole minerals are among the minerals commonly called asbestos. These are, anthophyllite, riebeckite, cummingtonite/grunerite series, and actinolite/tremolite series, the cummingtonite/grunerite series is often termed amosite or brown asbestos, riebeckite is known as crocidolite or blue asbestos. These are generally called amphibole asbestos, anthophyllite occurs as brownish, fibrous or lamellar masses with hornblende in mica-schist at Kongsberg in Norway and some other localities. An aluminous related species is known as gedrite and a deep green Russian variety containing little iron as kupfferite, hornblende is an important constituent of many igneous rocks. It is also an important constituent of amphibolites formed by metamorphism of basalt, actinolite is an important and common member of the monoclinic series, forming radiating groups of acicular crystals of a bright green or greyish-green color. It occurs frequently as a constituent of greenschists, the name is a translation of the old German word Strahlstein
24.
Olivine
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The mineral olivine is a magnesium iron silicate with the formula 2SiO4. Thus it is a type of nesosilicate or orthosilicate and it is a common mineral in the Earths subsurface but weathers quickly on the surface. The ratio of magnesium and iron varies between the two endmembers of the solid solution series, forsterite and fayalite, compositions of olivine are commonly expressed as molar percentages of forsterite and fayalite. Forsterite has a high melting temperature at atmospheric pressure, almost 1,900 °C. The melting temperature varies smoothly between the two endmembers, as do other properties, olivine incorporates only minor amounts of elements other than oxygen, silicon, magnesium and iron. Manganese and nickel commonly are the elements present in highest concentrations. Olivine gives its name to the group of minerals with a structure which includes tephroite, monticellite and kirschsteinite. It has a structure similar to magnetite but uses one quadravalent. Olivine gemstones are called peridot and chrysolite, olivine is named for its typically olive-green color, though it may alter to a reddish color from the oxidation of iron. Translucent olivine is sometimes used as a gemstone called peridot, some of the finest gem-quality olivine has been obtained from a body of mantle rocks on Zabargad island in the Red Sea. Olivine occurs in mafic and ultramafic igneous rocks and as a primary mineral in certain metamorphic rocks. Mg-rich olivine crystallizes from magma that is rich in magnesium and low in silica and that magma crystallizes to mafic rocks such as gabbro and basalt. Ultramafic rocks such as peridotite and dunite can be left after extraction of magmas. Olivine and high pressure structural variants constitute over 50% of the Earths upper mantle, the metamorphism of impure dolomite or other sedimentary rocks with high magnesium and low silica content also produces Mg-rich olivine, or forsterite. In contrast, Mg-rich olivine does not occur stably with silica minerals, Mg-rich olivine is stable to pressures equivalent to a depth of about 410 km within Earth. Mg-rich olivine has also discovered in meteorites, on the Moon and Mars, falling into infant stars. Such meteorites include chondrites, collections of debris from the early Solar System, the spectral signature of olivine has been seen in the dust disks around young stars. The tails of comets often have the signature of olivine
25.
Clinopyroxene
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The pyroxenes are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes are silicon-aluminum oxides with Ca, Na, Fe, Mg, Zn, Mn, Li substituting for Si, although aluminium substitutes extensively for silicon in silicates such as feldspars and amphiboles, the substitution occurs only to a limited extent in most pyroxenes. They share a structure consisting of single chains of silica tetrahedra. The name pyroxene is derived from the Ancient Greek words for fire, however, they are simply early-forming minerals that crystallized before the lava erupted. The upper mantle of Earth is composed mainly of olivine and pyroxene, a piece of the mantle is shown at right and is dominated by olivine, typical for common peridotite. Pyroxene and feldspar are the minerals in basalt and gabbro. Pyroxene minerals are named according to the chemical species occupying the X site, the Y site, cations in Y site are closely bound to 6 oxygens in octahedral coordination. Cations in the X site can be coordinated with 6 to 8 oxygen atoms, twenty mineral names are recognised by the International Mineralogical Associations Commission on New Minerals and Mineral Names and 105 previously used names have been discarded. A typical pyroxene has mostly silicon in the site and predominately ions with a charge of +2 in both the X and Y sites, giving the approximate formula XYT2O6. The names of the common calcium – iron – magnesium pyroxenes are defined in the pyroxene quadrilateral shown in Figure 2, the enstatite-ferrosilite series contain up to 5 mol. % calcium and exists in three polymorphs, orthorhombic orthoenstatite and protoenstatite and monoclinic clinoenstatite. Increasing the calcium content prevents the formation of the orthorhombic phases, there is not complete solid solution in calcium content and Mg-Fe-Ca pyroxenes with calcium contents between about 15 and 25 mol. % are not stable with respect to a pair of exolved crystals. This leads to a miscibility gap between pigeonite and augite compositions, there is an arbitrary separation between augite and the diopside-hedenbergite solid solution. The divide is taken at >45 mol. % Ca, as the calcium ion cannot occupy the Y site, pyroxenes with more than 50 mol. % calcium are not possible. A related mineral wollastonite has the formula of the hypothetical calcium end member, magnesium, calcium and iron are by no means the only cations that can occupy the X and Y sites in the pyroxene structure. A second important series of minerals are the sodium-rich pyroxenes. The inclusion of sodium, which has a charge of +1, in jadeite and aegirine this is added by the inclusion of a +3 cation on the Y site. Table 1 shows the range of other cations that can be accommodated in the pyroxene structure. For example, Na and Al give the jadeite composition, coupled substitution of a 1+ ion on the X site and a mixture of equal numbers of 2+ and 4+ ions on the Y site
26.
Augite
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Augite is a common rock-forming pyroxene mineral with formula 2O6. The crystals are monoclinic and prismatic, augite has two prominent cleavages, meeting at angles near 90 degrees. Augite is a solution in the pyroxene group. Diopside and hedenbergite are important endmembers in augite, but augite can also contain significant aluminium, titanium, with declining temperature, augite may exsolve lamellae of pigeonite and/or orthopyroxene. There is also a miscibility gap between augite and omphacite, but this gap occurs at higher temperatures, there are no industrial or economic uses for this mineral. Augite is a mineral in mafic igneous rocks, for example, gabbro and basalt. It also occurs in relatively high-temperature metamorphic rocks such as mafic granulite and it commonly occurs in association with orthoclase, sanidine, labradorite, olivine, leucite, amphiboles and other pyroxenes. Occasional specimens have an appearance that give rise to the minerals name. It was named by Abraham Gottlob Werner in 1792, transparent augites containing dendritic patterns are used as gems and ornamental stones known as shajar in parts of India. It is found near the Ken River, local jewelers export raw shajar stone and items to different parts of India. Banda is one city noted for trade of shazar stone, fassaite Deer, W. A. Howie, R. A. and Zussman, J. An introduction to the rock-forming minerals
27.
Orthopyroxene
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The pyroxenes are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. Pyroxenes are silicon-aluminum oxides with Ca, Na, Fe, Mg, Zn, Mn, Li substituting for Si, although aluminium substitutes extensively for silicon in silicates such as feldspars and amphiboles, the substitution occurs only to a limited extent in most pyroxenes. They share a structure consisting of single chains of silica tetrahedra. The name pyroxene is derived from the Ancient Greek words for fire, however, they are simply early-forming minerals that crystallized before the lava erupted. The upper mantle of Earth is composed mainly of olivine and pyroxene, a piece of the mantle is shown at right and is dominated by olivine, typical for common peridotite. Pyroxene and feldspar are the minerals in basalt and gabbro. Pyroxene minerals are named according to the chemical species occupying the X site, the Y site, cations in Y site are closely bound to 6 oxygens in octahedral coordination. Cations in the X site can be coordinated with 6 to 8 oxygen atoms, twenty mineral names are recognised by the International Mineralogical Associations Commission on New Minerals and Mineral Names and 105 previously used names have been discarded. A typical pyroxene has mostly silicon in the site and predominately ions with a charge of +2 in both the X and Y sites, giving the approximate formula XYT2O6. The names of the common calcium – iron – magnesium pyroxenes are defined in the pyroxene quadrilateral shown in Figure 2, the enstatite-ferrosilite series contain up to 5 mol. % calcium and exists in three polymorphs, orthorhombic orthoenstatite and protoenstatite and monoclinic clinoenstatite. Increasing the calcium content prevents the formation of the orthorhombic phases, there is not complete solid solution in calcium content and Mg-Fe-Ca pyroxenes with calcium contents between about 15 and 25 mol. % are not stable with respect to a pair of exolved crystals. This leads to a miscibility gap between pigeonite and augite compositions, there is an arbitrary separation between augite and the diopside-hedenbergite solid solution. The divide is taken at >45 mol. % Ca, as the calcium ion cannot occupy the Y site, pyroxenes with more than 50 mol. % calcium are not possible. A related mineral wollastonite has the formula of the hypothetical calcium end member, magnesium, calcium and iron are by no means the only cations that can occupy the X and Y sites in the pyroxene structure. A second important series of minerals are the sodium-rich pyroxenes. The inclusion of sodium, which has a charge of +1, in jadeite and aegirine this is added by the inclusion of a +3 cation on the Y site. Table 1 shows the range of other cations that can be accommodated in the pyroxene structure. For example, Na and Al give the jadeite composition, coupled substitution of a 1+ ion on the X site and a mixture of equal numbers of 2+ and 4+ ions on the Y site
28.
Monoclinic
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In crystallography, the monoclinic crystal system is one of the 7 crystal systems. A crystal system is described by three vectors, in the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic system. They form a rectangular prism with a parallelogram as its base, hence two vectors are perpendicular, while the third vector meets the other two at an angle other than 90°. There is only one monoclinic Bravais lattice in two dimensions, the oblique lattice, two monoclinic Bravais lattices exist, the primitive monoclinic and the centered monoclinic lattices. In this axis setting, the primitive and base-centered lattices interchange in centering type, sphenoidal is also monoclinic hemimorphic, Domatic is also monoclinic hemihedral, Prismatic is also monoclinic normal. Crystal structure Hurlbut, Cornelius S. Klein, Cornelis, hahn, Theo, ed. International Tables for Crystallography, Volume A, Space Group Symmetry
29.
Calcium
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Calcium is a chemical element with symbol Ca and atomic number 20. Calcium is a soft grayish-yellow alkaline earth metal, fifth-most-abundant element by mass in the Earths crust, the ion Ca2+ is also the fifth-most-abundant dissolved ion in seawater by both molarity and mass, after sodium, chloride, magnesium, and sulfate. Free calcium metal is too reactive to occur in nature, Calcium is produced in supernova nucleosynthesis. Calcium is a trace element in living organisms. It is the most abundant metal by mass in animals, and it is an important constituent of bone, teeth. In cell biology, the movement of the calcium ion into, Calcium carbonate and calcium citrate are often taken as dietary supplements. Calcium is on the World Health Organizations List of Essential Medicines, Calcium has a wide variety of applications, almost all of which are associated with calcium compounds and salts. Calcium metal is used as a deoxidizer, desulfurizer, and decarbonizer for production of ferrous and nonferrous alloys. In steelmaking and production of iron, Ca reacts with oxygen, Calcium carbonate is used in manufacturing cement and mortar, lime, limestone and aids in production in the glass industry. It also has chemical and optical uses as mineral specimens in toothpastes, Calcium hydroxide solution is used to detect the presence of carbon dioxide in a gas sample bubbled through a solution. The solution turns cloudy where CO2 is present, Calcium arsenate is used in insecticides. Calcium carbide is used to make acetylene gas and various plastics, Calcium chloride is used in ice removal and dust control on dirt roads, as a conditioner for concrete, as an additive in canned tomatoes, and to provide body for automobile tires. Calcium citrate is used as a food preservative, Calcium cyclamate is used as a sweetening agent in several countries. In the United States, it has been outlawed as a suspected carcinogen, Calcium gluconate is used as a food additive and in vitamin pills. Calcium hypochlorite is used as a swimming pool disinfectant, as an agent, as an ingredient in deodorant. Calcium permanganate is used in rocket propellant, textile production, as a water sterilizing agent. Calcium phosphate is used as a supplement for animal feed, fertilizer, in production for dough and yeast products, in the manufacture of glass. Calcium phosphide is used in fireworks, rodenticide, torpedoes, Calcium sulfate is used as common blackboard chalk, as well as, in its hemihydrate form, Plaster of Paris
30.
Plagioclase feldspar
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Plagioclase is a series of tectosilicate minerals within the feldspar group. Rather than referring to a mineral with a specific chemical composition, plagioclase is a continuous solid solution series. This was first shown by the German mineralogist Johann Friedrich Christian Hessel in 1826, the series ranges from albite to anorthite endmembers, where sodium and calcium atoms can substitute for each other in the minerals crystal lattice structure. Plagioclase in hand samples is often identified by its polysynthetic crystal twinning or record-groove effect, plagioclase is a major constituent mineral in the Earths crust, and is consequently an important diagnostic tool in petrology for identifying the composition, origin and evolution of igneous rocks. Plagioclase is also a constituent of rock in the highlands of the Earths moon. Analysis of thermal emission spectra from the surface of Mars suggests that plagioclase is the most abundant mineral in the crust of Mars, the extinction angle is an optical characteristic and varies with the albite fraction. There are several named plagioclase feldspars that fall between albite and anorthite in the series, the following table shows their compositions in terms of constituent anorthite and albite percentages. Anorthite was named by Gustav Rose in 1823 from the Ancient Greek meaning oblique, anorthite is a comparatively rare mineral but occurs in the basic plutonic rocks of some orogenic calc-alkaline suites. Albite is named from the Latin albus, in reference to its pure white color. It is a common and important rock-making mineral associated with the more acid rock types and in pegmatite dikes, often with rarer minerals like tourmaline. The intermediate members of the group are very similar to each other. Bytownite, named after the name for Ottawa, Canada, is a rare mineral occasionally found in more basic rocks. Labradorite is the characteristic feldspar of the basic rock types such as diorite, gabbro, andesite. Labradorite frequently shows an iridescent display of colors due to light refracting within the lamellae of the crystal and it is named after Labrador, where it is a constituent of the intrusive igneous rock anorthosite which is composed almost entirely of plagioclase. A variety of known as spectrolite is found in Finland. Andesine is a mineral of rocks such as diorite which contain a moderate amount of silica. Oligoclase is common in granite, syenite, diorite, and gneiss and it is a frequent associate of orthoclase. The name oligoclase is derived from the Greek for little and fracture, sunstone is mainly oligoclase with flakes of hematite
31.
Labradorite
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Labradorite, a feldspar mineral, is an intermediate to calcic member of the plagioclase series. It has a percentage of between 50 and 70. The specific gravity ranges from 2.68 to 2.72, the streak is white, like most silicates. The refractive index ranges from 1.559 to 1.573, as with all plagioclase members, the crystal system is triclinic, and three directions of cleavage are present, two of which form nearly right angle prisms. It occurs as clear, white to gray, blocky to lath shaped grains in common mafic igneous rocks such as basalt and gabbro, the geological type area for labradorite is Pauls Island near the town of Nain in Labrador, Canada. It has also reported in Norway and various other locations worldwide. Labradorite occurs in igneous rocks and is the feldspar variety most common in basalt. The uncommon anorthosite bodies are composed almost entirely of labradorite and it also is found in metamorphic amphibolites and as a detrital component of some sediments. Common mineral associates in igneous rocks include olivine, pyroxenes, amphiboles, Labradorite can display an iridescent optical effect known as labradorescence. The term labradoresence was coined by Ove Balthasar Bøggild, who defined it as follows, Contributions to the understanding of the origin and cause of the effect were made by Rayleigh, the cause of this optical phenomenon is phase exsolution lamellar structure, occurring in the Bøggild miscibility gap. The effect is visible when the separation is between 128 to 252 nm, the lamellae are not necessarily parallel, and the lamellar structure is found to lack long range order. Relationships between lamellar separation and chemical composition have been found for the An content of the mineral, some gemstone varieties of labradorite exhibiting a high degree of labradorescence are called spectrolite. Aventurescence Larvikite Chisholm, Hugh, ed. Labradorite
32.
Bytownite
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Bytownite is a calcium rich member of the plagioclase solid solution series of feldspar minerals. It is usually defined as having %An between 70 and 90, like others of the series, bytownite forms grey to white triclinic crystals commonly exhibiting the typical plagioclase twinning and associated fine striations. The specific gravity of bytownite varies between 2.74 and 2.75, the refractive indices ranges are nα=1.563 –1.572, nβ=1.568 –1.578, and nγ=1.573 –1.583. Precise determination of two properties with chemical, X-ray diffraction, or petrographic analysis are required for identification. Bytownite is a rock forming mineral occurring in mafic rocks such as gabbros. It also occurs as phenocrysts in volcanic rocks. It is rare in metamorphic rocks and it is typically associated with pyroxenes and olivine. The mineral was first described in 1835 and named for an occurrence at Bytown, other noted occurrences in Canada include the Shawmere anorthosite in Foleyet Township, Ontario, and on Yamaska Mountain, near Abbotsford, Quebec. It occurs on Rùm island, Scotland and Eycott Hill, near Keswick and it is reported from Naaraodal, Norway and in the Bushveld complex of South Africa. It is also found in Isa Valley, Western Australia, in the US it is found in the Stillwater igneous complex of Montana, from near Lakeview, Lake County, Oregon. It occurs in the Lucky Cuss mine, Tombstone, Arizona, in the eastern US it occurs at Cornwall, Lebanon County, Pennsylvania and Phoenixville, Chester County, Pennsylvania. Bytownite is occasionally used in jewelry, as a gemstone, bytownite is usually faceted with the transparent gems varying in color from a pale, straw yellow to a light brown. A variety from Mexico has been marketed under the trademarked name Golden Sunstone, hurlbut, Cornelius S. Klein, Cornelis,1985, Manual of Mineralogy, 20th ed. Wiley, ISBN 0-471-80580-7 Mineral galleries Chisholm, Hugh, ed. Bytownite
33.
Anorthosite
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Anorthosite is a phaneritic, intrusive igneous rock characterized by a predominance of plagioclase feldspar, and a minimal mafic component. Pyroxene, ilmenite, magnetite, and olivine are the minerals most commonly present. Anorthosite on Earth can be divided into two types, Proterozoic anorthosite and Archean anorthosite and these two types of anorthosite have different modes of occurrence, appear to be restricted to different periods in Earths history, and are thought to have had different origins. Lunar anorthosites constitute the areas of the Moons surface and have been the subject of much research. Proterozoic anorthosites were emplaced during the Proterozoic Eon, Anorthosite plutons occur in a wide range of sizes. Some smaller plutons, exemplified by many bodies in the U. S. and Harris in Scotland. Larger plutons, like the Mt. Lister Anorthosite, in northern Labrador, Canada, many Proterozoic anorthosites occur in spatial association with other highly distinctive, contemporaneous rock types. These rock types include iron-rich diorite, gabbro, and norite, leucocratic mafic rocks such as leucotroctolite and leuconorite, importantly, large volumes of ultramafic rocks are not found in association with Proterozoic anorthosites. Occurrences of Proterozoic anorthosites are commonly referred to as massifs, however, there is some question as to what name would best describe any occurrence of anorthosite together with the rock types mentioned above. Batholith is used to such occurrences for the remainder of this article. The areal extent of anorthosite batholiths ranges from small to nearly 20,000 km2, in the instance of the Nain Plutonic Suite in northern Labrador. Major occurrences of Proterozoic anorthosite are found in the southwest U. S. the Appalachian Mountains, eastern Canada, across southern Scandinavia and eastern Europe. Mapped onto the Pangaean continental configuration of that eon, these occurrences are all contained in a single straight belt, the conditions and constraints of this pattern of origin and distribution are not clear. However, see the Origins section below, Anorthosites are also common in layered intrusions. Anorthosite in these layered intrusions can form as cumulate layers in the parts of the intrusive complex or as later-stage intrusions into the layered intrusion complex. Since they are composed of plagioclase feldspar, most of Proterozoic anorthosites appear, in outcrop. Individual plagioclase crystals may be black, white, blue, or grey, the feldspar variety labradorite is commonly present in anorthosites. Mineralogically, labradorite is a term for any calcium-rich plagioclase feldspar containing 50–70 molecular percent anorthite
34.
Pyroxenite
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Pyroxenite is an ultramafic igneous rock consisting essentially of minerals of the pyroxene group, such as augite, diopside, hypersthene, bronzite or enstatite. Pyroxenites are classified into clinopyroxenites, orthopyroxenites, and the websterites which contain both types of pyroxenes, closely allied to this group are the hornblendites, consisting essentially of hornblende and other amphiboles. They are essentially of igneous origin, though some pyroxenites are included in the metamorphic Lewisian complex of Scotland and this connection is indicated also by their mode of occurrence, for they usually accompany masses of gabbro and peridotite and seldom are found by themselves. They are often very coarse-grained, containing individual crystals which may be several inches in length, the principal accessory minerals, in addition to olivine and feldspar, are chromite and other spinels, garnet, magnetite, rutile, and scapolite. Pyroxenites can be formed as cumulates in ultramafic intrusions by accumulation of crystals at the base of the magma chamber. Here they are associated with gabbro and anorthite cumulate layers and are typically high up in the intrusion. They may be accompanied by layers, ilmenite layers. Pyroxenites are also found as layers within masses of peridotite and these layers most commonly have been interpreted as products of reaction between ascending magmas and peridotite of the upper mantle. The layers typically are a few centimeters to a meter or so in thickness, pyroxenites that occur as xenoliths in basalt and in kimberlite have been interpreted as fragments of such layers. Although some mantle pyroxenites contain garnet, they are not eclogites, as clinopyroxene in them is less sodic than omphacite, purely pyroxene-bearing volcanic rocks are rare, restricted to spinifex-textured sills, lava tubes and thick flows in the Archaean greenstone belts. This is in similar to the formation of olivine spinifex textures in komatiite lava flows. They frequently occur in the form of dikes or segregations in gabbro and peridotite, in Shetland, Cortland on the Hudson River, North Carolina, Baltimore, New Zealand and they are also found in the Bushveld Igneous Complex in South Africa and Zimbabwe. The pyroxenites are often subject serpentinization under low temperature retrograde metamorphism, under pressure-metamorphism hornblende is developed and various types of amphibolite and hornblende-schist are produced. Sobolev, A. V. and others,2007, The amount of recycled crust in sources of mantle-derived melts, Science 316, media related to Pyroxenite at Wikimedia Commons Flett, John Smith
35.
Biotite
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Biotite is a common phyllosilicate mineral within the mica group, with the approximate chemical formula K 3AlSi 3O102. Hausmann in 1847 in honor of the French physicist Jean-Baptiste Biot, iron, magnesium, aluminium, silicon, oxygen, and hydrogen form sheets that are weakly bound together by potassium ions. It is sometimes called iron mica because it is more iron-rich than phlogopite and it is also sometimes called black mica as opposed to white mica – both form in some rocks, and in some instances side-by-side. Like other mica minerals, biotite has a perfect basal cleavage, and consists of flexible sheets, or lamellae. It has a crystal system, with tabular to prismatic crystals with an obvious pinacoid termination. It has four faces and two pinacoid faces to form a pseudohexagonal crystal. Although not easily seen because of the cleavage and sheets, fracture is uneven and it appears greenish to brown or black, and even yellow when weathered. It can be transparent to opaque, has a vitreous to pearly luster, when biotite is found in large chunks, they are called “books” because it resembles a book with pages of many sheets. The color of biotite is usually black and the mineral has a hardness of 2. 5-3 on the Mohs scale of mineral hardness, biotite dissolves in both acid and alkaline aqueous solutions, with the highest dissolution rates at low pH. However, biotite dissolution is highly anisotropic with crystal edge surfaces reacting 45 to 132 times faster than basal surfaces, under cross-polarized light biotite can generally be identified by the gnarled birds eye extinction. Biotite is found in a variety of igneous and metamorphic rocks. For instance, biotite occurs in the lava of Mount Vesuvius, biotite in granite tends to be poorer in magnesium than the biotite found in its volcanic equivalent, rhyolite. Biotite is an essential phenocryst in some varieties of lamprophyre, biotite is occasionally found in large cleavable crystals, especially in pegmatite veins, as in New England, Virginia and North Carolina. Other notable occurrences include Bancroft and Sudbury, Ontario and it is an essential constituent of many metamorphic schists, and it forms in suitable compositions over a wide range of pressure and temperature. It has been estimated that biotite comprises up to 7% of the continental crust. The largest documented single crystals of biotite were approximately 7 m2 sheets found in Iveland, biotite is used extensively to constrain ages of rocks, by either potassium-argon dating or argon-argon dating. Because argon escapes readily from the crystal structure at high temperatures. Biotite is also useful in assessing temperature histories of metamorphic rocks, because the partitioning of iron and magnesium between biotite and garnet is sensitive to temperature
36.
Quartz
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Quartz is the second most abundant mineral in Earths continental crust, behind feldspar. There are many different varieties of quartz, several of which are semi-precious gemstones, since antiquity, varieties of quartz have been the most commonly used minerals in the making of jewelry and hardstone carvings, especially in Eurasia. The word quartz is derived from the German word Quarz and its Middle High German ancestor twarc, the Ancient Greeks referred to quartz as κρύσταλλος derived from the Ancient Greek κρύος meaning icy cold, because some philosophers apparently believed the mineral to be a form of supercooled ice. Today, the rock crystal is sometimes used as an alternative name for the purest form of quartz. Quartz belongs to the crystal system. The ideal crystal shape is a six-sided prism terminating with six-sided pyramids at each end, well-formed crystals typically form in a bed that has unconstrained growth into a void, usually the crystals are attached at the other end to a matrix and only one termination pyramid is present. However, doubly terminated crystals do occur where they develop freely without attachment, a quartz geode is such a situation where the void is approximately spherical in shape, lined with a bed of crystals pointing inward. α-quartz crystallizes in the crystal system, space group P3121 and P3221 respectively. β-quartz belongs to the system, space group P6222 and P6422. These space groups are truly chiral, both α-quartz and β-quartz are examples of chiral crystal structures composed of achiral building blocks. The transformation between α- and β-quartz only involves a comparatively minor rotation of the tetrahedra with respect to one another, although many of the varietal names historically arose from the color of the mineral, current scientific naming schemes refer primarily to the microstructure of the mineral. Color is an identifier for the cryptocrystalline minerals, although it is a primary identifier for the macrocrystalline varieties. Pure quartz, traditionally called rock crystal or clear quartz, is colorless and transparent or translucent, common colored varieties include citrine, rose quartz, amethyst, smoky quartz, milky quartz, and others. The most important distinction between types of quartz is that of macrocrystalline and the microcrystalline or cryptocrystalline varieties, the cryptocrystalline varieties are either translucent or mostly opaque, while the transparent varieties tend to be macrocrystalline. Chalcedony is a form of silica consisting of fine intergrowths of both quartz, and its monoclinic polymorph moganite. Other opaque gemstone varieties of quartz, or mixed rocks including quartz, often including contrasting bands or patterns of color, are agate, carnelian or sard, onyx, heliotrope, amethyst is a form of quartz that ranges from a bright to dark or dull purple color. The worlds largest deposits of amethysts can be found in Brazil, Mexico, Uruguay, Russia, France, Namibia, sometimes amethyst and citrine are found growing in the same crystal. It is then referred to as ametrine, an amethyst is formed when there is iron in the area where it was formed
37.
Pohorje
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Pohorje, also known as the Pohorje Massif or the Pohorje Mountains, is a mostly wooded, medium-high mountain range south of the Drava River in northeastern Slovenia. According to the traditional AVE classification it belongs to the Southern Limestone Alps, geologically, it forms part of the Central Alps and features silicate metamorphic and igneous rock. Pohorje is sparsely populated with dispersed villages, there are also some ski resorts. Pohorje is an Alpine mountain ridge with domed summits south of the Drava and it roughly lies in the triangle formed by the towns of Maribor, Dravograd and Slovenske Konjice. To the northwest, it is bounded by the Mislinja River, to the south by the Vitanje Lowlands, to the east it descends to the Drava Plain and to the southeast it descends to the Pohorje Foothills. It measures about 50 km from east to west and 30 km from north to south and its highest elevations are Black Peak 1,543 m, the only slightly lower Big Kopa Peak, and Lake Peak, which rises to 1,537 m. Forests cover over 70% of its surface, Pohorje is a young mountain massif and represents the southeasternmost part of the Central Alps. It is the mountain chain in Slovenia made of silicate rock. Its peripheral parts consist of Paleozoic metamorphic rock, and its parts of igneous rock. Near the village of Cezlak lies the only deposit of cizlakite in the world. The southern parts of Pohorje are known for white marble, which were quarried Roman times, the following ski resorts stand at Pohorje, Rogla Ski Resort Kope–Ribnica Pohorje Ski Resort Maribor Pohorje Ski Resort Trije Kralji Ski Resort Media related to Pohorje at Wikimedia Commons Pohorje
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Nepheline
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Nepheline crystals are rare and belong to the hexagonal system, usually having the form of a short, six-sided prism terminated by the basal plane. It is found in compact, granular aggregates, and can be white, yellow, gray, green, the hardness is 5.5 -6, and the specific gravity 2.56 -2.66. It is often translucent with a greasy luster, an important determinative character of nepheline is the ease with which it is decomposed by hydrochloric acid, with separation of gelatinous silica and cubes of salt. For this reason, a crystal of nepheline becomes cloudy when immersed in acid. It has therefore been suggested that the formula, AlSiO4. The mineral is one liable to alteration, and in the laboratory various substitution products of nepheline have been prepared. In nature it is altered to zeolites, sodalite, kaolin. Two varieties of nepheline are distinguished, differing in their appearance and in their mode of occurrence, being analogous in these respects to sanidine. Glassy nepheline has the form of small, colorless, transparent crystals and it is characteristic of the later volcanic rocks rich in alkalis, such as phonolite, nepheline-basalt, leucite basalt, etc. and also of certain dike-rocks, such as tinguaite. The best crystals occur with mica, sanidine, garnet, etc. in the cavities of the ejected blocks of Monte Somma. It forms a constituent of certain alkaline plutonic rocks of the nepheline syenite series. The color and greasy luster of elaeolite are due to the presence of numerous microscopic enclosures of other minerals and this article incorporates text from a publication now in the public domain, Leonard James Spencer. Media related to Nepheline at Wikimedia Commons
39.
Cancrinite
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Cancrinite is a complex carbonate and silicate of sodium, calcium and aluminium with the formula Na6Ca2·2H2O. It is classed as a member of the group of minerals. Yellow, orange, pink, white or even blue, it has a vitreous or pearly luster, a hardness of 5-6 and it is unusual among the silicate minerals in that it will effervesce with hydrochloric acid due to the associated carbonate ions. Found originally in 1839 in the Ural Mountains, it is named after Georg von Cancrin, a Russian minister of finance
40.
Sodalite
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Sodalite is a rich royal blue tectosilicate mineral widely used as an ornamental gemstone. Although massive sodalite samples are opaque, crystals are transparent to translucent. Sodalite is a member of the group with hauyne, nosean. A light, relatively hard yet fragile mineral, sodalite is named after its sodium content, well known for its blue color, sodalite may also be grey, yellow, green, or pink and is often mottled with white veins or patches. The more uniformly blue material is used in jewellery, where it is fashioned into cabochons, lesser material is more often seen as facing or inlay in various applications. Although somewhat similar to lazurite and lapis lazuli, sodalite rarely contains pyrite and it is further distinguished from similar minerals by its white streak. Sodalites six directions of cleavage may be seen as incipient cracks running through the stone. It is sometimes referred to as poor mans lapis due to its similar color and its name comes from its high sodium content. Most sodalite will fluoresce orange under ultraviolet light, and hackmanite exhibits tenebrescence, hackmanite is an important variety of sodalite exhibiting tenebrescence. When hackmanite from Mont Saint-Hilaire or Ilímaussaq is freshly quarried, it is pale to deep violet. Conversely, hackmanite from Afghanistan and the Myanmar Republic starts off creamy white, if left in a dark environment for some time, the violet will fade again. Tenebrescence is accelerated by the use of longwave or, particularly, much sodalite will also fluoresce a patchy orange under UV light. Sodalite was first described in 1811 for the occurrence in its locality in the Ilimaussaq complex, Narsaq. Occurring typically in massive form, sodalite is found as fillings in plutonic igneous rocks such as nepheline syenites. It is associated with other minerals typical of undersaturated environments, namely leucite, cancrinite and natrolite, other associated minerals include nepheline, titanian andradite, aegirine, microcline, sanidine, albite, calcite, fluorite, ankerite and baryte. Significant deposits of material are restricted to but a few locales, Bancroft, Ontario, and Mont-Saint-Hilaire, Quebec, in Canada, and Litchfield, Maine. The Ice River complex, near Golden, British Columbia, contains sodalite, smaller deposits are found in South America, Portugal, Romania, Burma and Russia. Hackmanite is found principally in Mont-Saint-Hilaire and Greenland, euhedral, transparent crystals are found in northern Namibia and in the lavas of Vesuvius, Italy
41.
Magnetite
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Magnetite is a mineral and one of the main iron ores. With the chemical formula Fe3O4, it is one of the oxides of iron, Magnetite is ferrimagnetic, it is attracted to a magnet and can be magnetized to become a permanent magnet itself. It is the most magnetic of all the minerals on Earth. Naturally-magnetized pieces of magnetite, called lodestone, will attract small pieces of iron, today it is mined as iron ore. Small grains of magnetite occur in almost all igneous and metamorphic rocks, Magnetite is black or brownish-black with a metallic luster, has a Mohs hardness of 5–6 and leaves a black streak. The chemical IUPAC name is iron oxide and the chemical name is ferrous-ferric oxide. In addition to rocks, magnetite also occurs in sedimentary rocks, including banded iron formations and in lake. Magnetite nanoparticles are also thought to form in soils, where they probably oxidize rapidly to maghemite, Magnetite has an inverse spinel crystal structure. As a member of the group, it can form solid solutions with similarly structured minerals, including ulvospinel. Titanomagnetite, also known as titaniferous magnetite, is a solution between magnetite and ulvospinel that crystallizes in many mafic igneous rocks. Titanomagnetite may undergo oxyexsolution during cooling, resulting in ingrowths of magnetite and ilmenite, Magnetite has been important in understanding the conditions under which rocks form. Magnetite reacts with oxygen to produce hematite, and the pair forms a buffer that can control oxygen fugacity. Commonly, igneous rocks contain solid solutions of both titanomagnetite and hemoilmenite or titanohematite, Magnetite also is produced from peridotites and dunites by serpentinization. Lodestones were used as a form of magnetic compass. At low temperatures, magnetite undergoes a crystal structure phase transition from a structure to a cubic structure known as the Verwey transition. The Verwey transition occurs around 121 K and is dependent on size, domain state. An isotropic point also occurs near the Verwey transition around 130 K, the Curie temperature of magnetite is 858 K. Magnetite is sometimes found in large quantities in beach sand. Such black sands are found in places, such as Lung Kwu Tan of Hong Kong, California of the United States
42.
Ilmenite
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Ilmenite is the titanium-iron oxide mineral with the idealized formula FeTiO3. It is a weakly magnetic black or steel-gray solid, from the commercial perspective, ilmenite is the most important ore of titanium. Ilmenite is the source of titanium dioxide, which is used in paints, fabrics, plastics, paper, sunscreen, food. Ilmenite crystallizes in the trigonal system, containing high spin ferrous centers, ilmenite is paramagnetic. Ilmenite is commonly recognized in altered igneous rocks by the presence of an alteration product. Often ilmenites are rimmed with leucoxene, which allows ilmenite to be distinguished from magnetite, the example shown in the image at right is typical of leucoxene-rimmed ilmenite. In reflected light it may be distinguished from magnetite by more pronounced reflection pleochroism, samples of ilmenite exhibit a weak response to a hand magnet. Ilmenite most often contains appreciable quantities of magnesium and manganese and the chemical formula can be expressed as O3. Ilmenite forms a solution with geikielite and pyrophanite which are magnesian. At higher temperatures it has been demonstrated there is a solid solution between ilmenite and hematite. There is a miscibility gap at lower temperatures, resulting in a coexistence of two minerals in rocks but no solid solution. This coexistence may result in exsolution lamellae in cooled ilmenites with more iron in the system than can be accommodated in the crystal lattice. Altered ilmenite forms the mineral leucoxene, an important source of titanium in heavy mineral sands ore deposits, leucoxene is a typical component of altered gabbro and diorite and is generally indicative of ilmenite in the unaltered rock. Ilmenite is an accessory mineral found in metamorphic and igneous rocks. It is found in large concentrations in layered intrusions where it forms as part of a layer within the silicate stratigraphy of the intrusion. Ilmenite generally occurs within the portion of such intrusions. Magnesian ilmenite is indicative of kimberlitic paragenesis and forms part of the MARID association of minerals assemblage of glimmerite xenoliths, manganiferous ilmenite is found in granitic rocks and also in carbonatite intrusions where it may also contain anomalous niobium. Many mafic igneous rocks contain grains of magnetite and ilmenite
