Leicestershire is a landlocked county in the English Midlands. The border with most of Warwickshire is Watling Street, the county has a population of just under 1 million with over half the population living in Leicesters built-up area. Leicestershire was recorded in the Domesday Book in four wapentakes, Framland and these became hundreds, with the division of Goscote into West Goscote and East Goscote, and the addition of Sparkenhoe hundred. In 1087, the first recorded use of the name was as Laegrecastrescir, Leicestershires external boundaries have changed little since the Domesday Survey. These actions were reversed on 1 April 1997, when Rutland, Rutland became a distinct Ceremonial County once again, although it continues to be policed by Leicestershire Constabulary. The symbol of the county council, Leicestershire County Cricket Club, Leicestershire is considered to be the birthplace of fox hunting as it is known today. Hugo Meynell, who lived in Quorn, is known as the father of fox hunting, Melton Mowbray and Market Harborough have associations with fox hunting, as has neighbouring Rutland.
A large part of the north-west of the county, around Coalville, the highest point of the county is Bardon Hill at 278 metres, which is a Marilyn. The lowest point is about 24. 8m, north of Bottesford where the River Devon leaves Leicestershire, the population of Leicestershire is 609,578 people. The county covers an area of 2,084 km2 and its largest population centre is the city of Leicester, followed by the town of Loughborough. Other large towns include Ashby-de-la-Zouch, Hinckley, Market Harborough, Melton Mowbray, Wigston, some of the larger of villages are, Burbage Birstall, Broughton Astley, Castle Donington, Kibworth Beauchamp, Great Glen, Ibstock and Kegworth. One of the most rapidly expanding villages is Anstey, which has seen a large number of development schemes. The United Kingdom Census 2001 showed a resident population for Leicester of 279,921. Approximately 62,000 were aged under 16,199,000 were aged 16–74,76. 9% of Leicesters population claim they have been born in the UK, according to the 2001 UK Census.
Mid-year estimates for 2006 indicate that the population of the City of Leicester stood at 289,700 making Leicester the most populous city in East Midlands, the population density is 3, 814/km2 and for every 100 females, there were 92.9 males. Of those aged 16–74 in Leicester,38. 5% had no academic qualifications,23. 0% of Leicesters residents were born outside of the United Kingdom, more than double than the English average of 9. 2%. Engineering has long been an important part of the economy of Leicestershire, John Taylor Bellfounders continues a history of bellfounding in Loughborough since the 14th century. In 1881 John Taylors cast the largest bell in Britain, Great Paul, snibston Discovery Park is built on one of three coal mines that operated in Coalville from the 1820s until 1986
Titanite, or sphene, is a calcium titanium nesosilicate mineral, CaTiSiO5. Trace impurities of iron and aluminium are typically present, commonly present are rare earth metals including cerium and yttrium, calcium may be partly replaced by thorium. Sphene was the most commonly used name until the IMA decision, the name sphene continues to be publishable in peer-reviewed scientific literature, e. g. a paper by Hayden et al. was published in early 2008 in the journal Contributions to Mineralogy and Petrology. Sphene persists as the name for titanite gemstones. Titanite, which is named for its content, occurs as translucent to transparent, reddish brown, yellow, green. These crystals are typically sphenoid in habit and are often twinned, possessing a subadamantine tending to slightly resinous luster, titanite has a hardness of 5.5 and a weak cleavage. Its specific gravity varies between 3.52 and 3.54, transparent specimens are noted for their strong trichroism, the three colours presented being dependent on body colour.
Owing to the effect of iron, sphene exhibits no fluorescence under ultraviolet light. Some titanite has been found to be metamict, in consequence of damage due to radioactive decomposition of the often significant thorium content. When viewed in section with a petrographic microscope, pleochroic halos can be observed in minerals surrounding a titanite crystal. Titanite occurs as an accessory mineral in intermediate and felsic igneous rocks. It occurs in rocks such as gneiss and schists. Titanite is a source of titanium dioxide, TiO2, used in pigments, as a gemstone, titanite is usually some shade of chartreuse, but can be brown or black. Hue depends on Fe content, with low Fe content causing green and yellow colours and it is prized for its exceptional dispersive power which exceeds that of diamond. Jewelry use of titanite is limited, both because the stone is uncommon in gem quality and is relatively soft, titanite can be used as a U-Pb geochronometer, specifically in metamorphic terranes
A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. Earths volcanoes occur because its crust is broken into 17 major, therefore, on Earth, volcanoes are generally found where tectonic plates are diverging or converging. This type of volcanism falls under the umbrella of plate hypothesis volcanism, Volcanism away from plate boundaries has been explained as mantle plumes. These so-called hotspots, for example Hawaii, are postulated to arise from upwelling diapirs with magma from the boundary,3,000 km deep in the Earth. Volcanoes are usually not created where two plates slide past one another. Erupting volcanoes can pose hazards, not only in the immediate vicinity of the eruption. Historically, so-called volcanic winters have caused catastrophic famines, the word volcano is derived from the name of Vulcano, a volcanic island in the Aeolian Islands of Italy whose name in turn comes from Vulcan, the god of fire in Roman mythology.
The study of volcanoes is called volcanology, sometimes spelled vulcanology, at the mid-oceanic ridges, two tectonic plates diverge from one another as new oceanic crust is formed by the cooling and solidifying of hot molten rock. Most divergent plate boundaries are at the bottom of the oceans, most volcanic activity is submarine, black smokers are evidence of this kind of volcanic activity. Where the mid-oceanic ridge is above sea-level, volcanic islands are formed, for example, subduction zones are places where two plates, usually an oceanic plate and a continental plate, collide. In this case, the plate subducts, or submerges under the continental plate forming a deep ocean trench just offshore. In a process called flux melting, water released from the subducting plate lowers the temperature of the overlying mantle wedge. This magma tends to be very viscous due to its high content, so it often does not reach the surface. When it does reach the surface, a volcano is formed, typical examples of this kind of volcano are Mount Etna and the volcanoes in the Pacific Ring of Fire.
Because tectonic plates move across them, each volcano becomes dormant and is eventually re-formed as the plate advances over the postulated plume and this theory is currently under criticism, however. The most common perception of a volcano is of a mountain, spewing lava and poisonous gases from a crater at its summit, however. The features of volcanoes are more complicated and their structure. Some volcanoes have rugged peaks formed by lava domes rather than a summit crater while others have features such as massive plateaus
Italy, officially the Italian Republic, is a unitary parliamentary republic in Europe. Located in the heart of the Mediterranean Sea, Italy shares open land borders with France, Austria, San Marino, Italy covers an area of 301,338 km2 and has a largely temperate seasonal climate and Mediterranean climate. Due to its shape, it is referred to in Italy as lo Stivale. With 61 million inhabitants, it is the fourth most populous EU member state, the Italic tribe known as the Latins formed the Roman Kingdom, which eventually became a republic that conquered and assimilated other nearby civilisations. The legacy of the Roman Empire is widespread and can be observed in the distribution of civilian law, republican governments, Christianity. The Renaissance began in Italy and spread to the rest of Europe, bringing a renewed interest in humanism, exploration, Italian culture flourished at this time, producing famous scholars and polymaths such as Leonardo da Vinci, Galileo and Machiavelli. The weakened sovereigns soon fell victim to conquest by European powers such as France and Austria.
Despite being one of the victors in World War I, Italy entered a period of economic crisis and social turmoil. The subsequent participation in World War II on the Axis side ended in defeat, economic destruction. Today, Italy has the third largest economy in the Eurozone and it has a very high level of human development and is ranked sixth in the world for life expectancy. The country plays a prominent role in regional and global economic, military and diplomatic affairs, as a reflection of its cultural wealth, Italy is home to 51 World Heritage Sites, the most in the world, and is the fifth most visited country. The assumptions on the etymology of the name Italia are very numerous, according to one of the more common explanations, the term Italia, from Latin, was borrowed through Greek from the Oscan Víteliú, meaning land of young cattle. The bull was a symbol of the southern Italic tribes and was often depicted goring the Roman wolf as a defiant symbol of free Italy during the Social War. Greek historian Dionysius of Halicarnassus states this account together with the legend that Italy was named after Italus, mentioned by Aristotle and Thucydides.
The name Italia originally applied only to a part of what is now Southern Italy – according to Antiochus of Syracuse, but by his time Oenotria and Italy had become synonymous, and the name applied to most of Lucania as well. The Greeks gradually came to apply the name Italia to a larger region, excavations throughout Italy revealed a Neanderthal presence dating back to the Palaeolithic period, some 200,000 years ago, modern Humans arrived about 40,000 years ago. Other ancient Italian peoples of undetermined language families but of possible origins include the Rhaetian people and Cammuni. Also the Phoenicians established colonies on the coasts of Sardinia and Sicily, the Roman legacy has deeply influenced the Western civilisation, shaping most of the modern world
An Orogeny is an event that leads to a large structural deformation of the Earths lithosphere due to the interaction between tectonic plates. Orogens or orogenic belts develop when a plate is crumpled and is pushed upwards to form mountain ranges. Orogeny is the mechanism by which mountains are built on continents. The word orogeny comes from Ancient Greek, though it was used before him, the term was employed by the American geologist G. K. Gilbert in 1890 to describe the process of mountain building as distinguished from epeirogeny. Formation of an orogen is accomplished in part by the processes of subduction or convergence of two or more continents. Orogeny usually produces long arcuate structures, known as orogenic belts, orogenic belts consist of long parallel strips of rock exhibiting similar characteristics along the length of the belt. Orogenic belts are associated with zones, which consume crust, produce volcanoes. Geologists attribute the arcuate structure to the rigidity of the descending plate and these island arcs may be added to a continent during an orogenic event.
The processes of orogeny can take tens of millions of years, rock formations that undergo orogeny are severely deformed and undergo metamorphism. Orogenic processes may push deeply buried rocks to the surface, sea-bottom and near-shore material may cover some or all of the orogenic area. If the orogeny is due to two continents colliding, very high mountains can result, an orogenic event may be studied, as a tectonic structural event, as a geographical event, and as a chronological event. The foreland basin forms ahead of the orogen due mainly to loading and resulting flexure of the lithosphere by the mountain belt. The basin migrates with the front and early deposited foreland basin sediments become progressively involved in folding and thrusting. Sediments deposited in the basin are mainly derived from the erosion of the actively uplifting rocks of the mountain range. The fill of many such shows an change in time from deepwater marine through shallow water to continental sediments. Although orogeny involves plate tectonics, the tectonic forces result in a variety of associated phenomena, including magmatism, crustal melting, what exactly happens in a specific orogen depends upon the strength and rheology of the continental lithosphere, and how these properties change during orogenesis.
In addition to orogeny, the orogen is subject to other processes, for example, the Caledonian Orogeny refers to the Silurian and Devonian events that resulted from the collision of Laurentia with Eastern Avalonia and other former fragments of Gondwana. The Caledonian Orogen resulted from events and various others that are part of its peculiar orogenic cycle
The United Kingdom of Great Britain and Northern Ireland, commonly known as the United Kingdom or Britain, is a sovereign country in western Europe. Lying off the north-western coast of the European mainland, the United Kingdom includes the island of Great Britain, Northern Ireland is the only part of the United Kingdom that shares a land border with another sovereign state—the Republic of Ireland. The Irish Sea lies between Great Britain and Ireland, with an area of 242,500 square kilometres, the United Kingdom is the 78th-largest sovereign state in the world and the 11th-largest in Europe. It is the 21st-most populous country, with an estimated 65.1 million inhabitants, this makes it the fourth-most densely populated country in the European Union. The United Kingdom is a monarchy with a parliamentary system of governance. The monarch is Queen Elizabeth II, who has reigned since 6 February 1952, other major urban areas in the United Kingdom include the regions of Birmingham, Glasgow and Manchester.
The United Kingdom consists of four countries—England, Wales, the last three have devolved administrations, each with varying powers, based in their capitals, Edinburgh and Belfast, respectively. The relationships among the countries of the UK have changed over time, Wales was annexed by the Kingdom of England under the Laws in Wales Acts 1535 and 1542. A treaty between England and Scotland resulted in 1707 in a unified Kingdom of Great Britain, which merged in 1801 with the Kingdom of Ireland to form the United Kingdom of Great Britain and Ireland. Five-sixths of Ireland seceded from the UK in 1922, leaving the present formulation of the United Kingdom of Great Britain, there are fourteen British Overseas Territories. These are the remnants of the British Empire which, at its height in the 1920s, British influence can be observed in the language and legal systems of many of its former colonies. The United Kingdom is a country and has the worlds fifth-largest economy by nominal GDP. The UK is considered to have an economy and is categorised as very high in the Human Development Index.
It was the worlds first industrialised country and the worlds foremost power during the 19th, the UK remains a great power with considerable economic, military and political influence internationally. It is a nuclear weapons state and its military expenditure ranks fourth or fifth in the world. The UK has been a permanent member of the United Nations Security Council since its first session in 1946 and it has been a leading member state of the EU and its predecessor, the European Economic Community, since 1973. However, on 23 June 2016, a referendum on the UKs membership of the EU resulted in a decision to leave. The Acts of Union 1800 united the Kingdom of Great Britain, Scotland and Northern Ireland have devolved self-government
Porphyry is a textural term for an igneous rock consisting of large-grained crystals such as feldspar or quartz dispersed in a fine-grained silicate rich, generally aphanitic matrix or groundmass. The larger crystals are called phenocrysts, in its non-geologic, traditional use, the term porphyry refers to the purple-red form of this stone, valued for its appearance. The term porphyry is from Ancient Greek and means purple, purple was the color of royalty, and the imperial porphyry was a deep purple igneous rock with large crystals of plagioclase. Some authors claimed the rock was the hardest known in antiquity, Imperial grade porphyry was thus prized for monuments and building projects in Imperial Rome and later. Subsequently, the name was given to any igneous rocks with large crystals, the adjective porphyritic now refers to a certain texture of igneous rock regardless of its chemical and mineralogical composition. Its chief characteristic is a difference in size between the tiny matrix crystals and the much larger phenocrysts.
Porphyries may be aphanites or phanerites, that is, the groundmass may have invisibly small crystals as in basalt, or crystals easily distinguishable with the eye, most types of igneous rocks display some degree of porphyritic texture. Porphyry deposits are formed when a column of rising magma is cooled in two stages, in the first, the magma is cooled slowly deep in the crust, creating the large crystal grains with a diameter of 2 mm or more. In the second and final stage, the magma is cooled rapidly at relatively shallow depth or as it erupts from a volcano, the term porphyry is used for a mineral deposit called a copper porphyry. The different stages of cooling that create porphyritic textures in intrusive and this enrichment occurs in the porphyry itself, or in other related igneous rocks or surrounding country rocks, especially carbonate rock. Collectively, these type of deposits are known as porphyry copper deposits, rhomb porphyry is a volcanic rock with gray-white large porphyritic rhomb- shaped phenocrysts embedded in a very fine-grained red-brown matrix.
The composition of rhomb porphyry places it in the classification of the QAPF diagram. Rhomb porphyry lavas are known from three rift areas, the East African Rift, Mount Erebus near the Ross Sea in Antarctica. Plinys Natural History affirmed that the Imperial Porphyry had been discovered at a site in Egypt in AD18. This particular Imperial grade of porphyry came from a quarry in the Eastern Desert of Egypt. After the fourth century the quarry was lost to sight for many centuries, as early as 1850 BC on Crete in Minoan Knossos there were large column bases made of porphyry. Porphyry was used for the blocks of the Column of Constantine in Istanbul, list of rock textures Quartz-porphyry Sarcophagi of Helena and Constantina Tyrian purple Pictures of the Mons Porphyrites, Red Sea, Egypt. Rhomb porphyry lavas at the Wayback Machine Flash showing rhomb porphyry formation at the Wayback Machine
The Andes or Andean Mountains are the longest continental mountain range in the world. They are a range of highlands along the western edge of South America. This range is about 7,000 km long, about 200 to 700 km wide, the Andes extend from north to south through seven South American countries, Colombia, Peru, Bolivia and Chile. Along their length, the Andes are split into several ranges, the Andes are the location of several high plateaus – some of which host major cities, such as Quito, Bogotá, Medellín, Sucre, Mérida and La Paz. The Altiplano plateau is the worlds second-highest after the Tibetan plateau and these ranges are in turn grouped into three major divisions based on climate, the Tropical Andes, the Dry Andes, and the Wet Andes. The Andes are the worlds highest mountain range outside of Asia, the highest mountain outside Asia, Mount Aconcagua, rises to an elevation of about 6,961 m above sea level. The peak of Chimborazo in the Ecuadorean Andes is farther from the Earths center than any other location on the Earths surface, the worlds highest volcanoes are in the Andes, including Ojos del Salado on the Chile-Argentina border, which rises to 6,893 m.
The etymology of the word Andes has been debated, the majority consensus is that it derives from the Quechua word anti, which means east as in Antisuyu, one of the four regions of the Inca Empire. In the northern part of the Andes, the isolated Sierra Nevada de Santa Marta range is considered to be part of the Andes. The term cordillera comes from the Spanish word cordel, meaning rope, the Andes range is about 200 km wide throughout its length, except in the Bolivian flexure where it is about 640 kilometres wide. The Andes are the result of plate tectonics processes, caused by the subduction of oceanic crust beneath the South American plate. The main cause of the rise of the Andes is the compression of the rim of the South American Plate due to the subduction of the Nazca Plate. In the south, the Andes share a boundary with the former Patagonia Terrane. To the west, the Andes end at the Pacific Ocean, from a geographical approach, the Andes are considered to have their western boundaries marked by the appearance of coastal lowlands and a less rugged topography.
The Andes Mountains contain large quantities of iron ore located in mountains within the range. The Andean orogen has a series of bends or oroclines, the Bolivian Orocline is a seaward concave bending in the coast of South America and the Andes Mountains at about 18° S. At this point the orientation of the Andes turns from Northwest in Peru to South in Chile, the Andean segment north and south of the orocline have been rotated 15° to 20° counter clockwise and clockwise respectively. The Bolivian Orocline area overlaps with the area of maximum width of the Altiplano Plateau, the specific point at 18° S where the coastline bends is known as the Arica Elbow
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, plastics, 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 in carbonatite intrusions where it may contain anomalous niobium.
Many mafic igneous rocks contain grains of magnetite and ilmenite
Guernsey is a jurisdiction within the Bailiwick of Guernsey, a Crown dependency. The jurisdiction is not part of the United Kingdom, however and most foreign relations are handled by the British Government. Taken together with the jurisdictions of Alderney and Sark it forms the Bailiwick of Guernsey. The two Bailiwicks of Guernsey and Jersey together form the geographical grouping known as the Channel Islands, the name Guernsey, as well as that of neighbouring Jersey, is of Old Norse origin. The second element of word, -ey, is the Old Norse for island, while the original root, guern, is of uncertain origin. Around 6000 BC, rising seas created the English Channel and separated the Norman promontories that became the bailiwicks of Guernsey and Jersey from continental Europe, neolithic farmers settled on its coast and built the dolmens and menhirs found in the islands today. During their migration to Brittany, Britons occupied the Lenur islands including Sarnia or Lisia and Angia, travelling from the Kingdom of Gwent, Saint Sampson, the abbot of Dol in Brittany, is credited with the introduction of Christianity to Guernsey.
In 933 AD, the Cotentin Peninsula including Avranchin which included the islands, were placed by the French King Ranulf under the control of William I, the island of Guernsey and the other Channel Islands represent the last remnants of the medieval Duchy of Normandy. During the Middle Ages, the island was a haven for pirates that would use the technique to ground ships close to her waters. This intensified during the Hundred Years War, starting in 1339, the Guernsey Militia was operational in 1337 and would help defend the island for a further 600 years. In 1372, the island was invaded by Aragonese mercenaries under the command of Owain Lawgoch and his dark-haired mercenaries were absorbed into Guernsey legend as invading fairies from across the sea. In the mid-16th century, the island was influenced by Calvinist reformers from Normandy, during the Marian persecutions, three women, the Guernsey Martyrs, were burned at the stake for their Protestant beliefs. During the English Civil War, Guernsey sided with the Parliamentarians, the allegiance was not total, there were a few Royalist uprisings in the southwest of the island, while Castle Cornet was occupied by the Governor, Sir Peter Osborne, and Royalist troops.
In December 1651, with honours of war, Castle Cornet surrendered. By the beginning of the 18th century, Guernseys residents were starting to settle in North America, the threat of invasion by Napoleon prompted many defensive structures to be built at the end of that century. The 19th century saw an increase in the prosperity of the island, due to its success in the global maritime trade. During the First World War, about 3,000 island men served in the British Expeditionary Force, of these, about 1,000 served in the Royal Guernsey Light Infantry regiment formed from the Royal Guernsey Militia in 1916. For most of the Second World War, the Channel Islands were occupied by German troops, before the occupation, 80% of Guernsey children had been evacuated to England to live with relatives or strangers during the war
Sondrio listen is an Italian town and comune located in the heart of the Valtellina. As of 2012, Sondrio counts approximately 21,876 inhabitants, in 2007, Sondrio was given the Alpine Town of the Year award. After the fall of the Lombard Kingdom in Italy, Sondrio became part of the Holy Roman Empire, the Capitanei of Vizzola, who controlled much of the Valtellina, had it in 1040 from the emperor Henry II. From 1310 to 1335 the city was involved in the war between the Guelph and Ghibelline factions of the nearby Como, and its war against Milan, after having resisted several attacks by the Comaschi, in 1335 Sondrio and Valtellina became part of the Visconti Milanese dominions. From the second half of the 16th Century to the end of 18th Century, Sondrio was governed by the Tre Leghe Grigie of the Grisons, after the Reformation, Sondrio was the centre of heavy struggles between the Catholic Valtellinesi and the Protestant Grisons. In 1620 the citizens, led by Giacomo Robustelli, killed 180 Protestants and its hamlets are Arquino, Gualtieri, Moroni, Ponchiera, SantAnna, Sassella and Triasso.
The territory of Sondrio is has numerous vineyards, wines produced include the Sassella, wine represents one of the main resources of this region, together with tourism, especially in winter. The heart of Sondrio is its central Garibaldi Square, not far from it is the Palazzo Sassi, that is home of the Art and History Museum of Valtellina. In a dominant position, near the ancient road to the Valmalenco, linking the town to Switzerland, stands the Masegra Castle, the church of Santi Gervasio e Protasio rebuilt in Neoclassical-style in 1838, was built in the 12th century as a Romanesque pieve and collegiate church. Other sights include the Torre Ligariana, once the bell tower. Sondrio railway station Media related to Sondrio at Wikimedia Commons Official website Sondrio tourist website Sondrio weather website
Granite is a common type of felsic intrusive igneous rock that is granular and phaneritic in texture. Granites can be white, pink, or gray in color. The word granite comes from the Latin granum, a grain, in reference to the structure of such a holocrystalline rock. By definition, granite is a rock with at least 20% quartz. The term granitic means granite-like and is applied to granite and a group of igneous rocks with similar textures and slight variations in composition. Occasionally some individual crystals are larger than the groundmass, in case the texture is known as porphyritic. A granitic rock with a texture is known as a granite porphyry. Granitoid is a general, descriptive field term for lighter-colored, coarse-grained igneous rocks, petrographic examination is required for identification of specific types of granitoids. The extrusive igneous rock equivalent of granite is rhyolite, Granite is nearly always massive and tough, and therefore it has gained widespread use throughout human history, and more recently as a construction stone.
The average density of granite is between 2.65 and 2.75 g/cm3, its compressive strength usually lies above 200 MPa, and its viscosity near STP is 3–6 •1019 Pa·s. The melting temperature of dry granite at ambient pressure is 1215–1260 °C, it is reduced in the presence of water. Granite has poor primary permeability, but strong secondary permeability, true granite according to modern petrologic convention contains both plagioclase and alkali feldspars. When a granitoid is devoid or nearly devoid of plagioclase, the rock is referred to as alkali feldspar granite, when a granitoid contains less than 10% orthoclase, it is called tonalite and amphibole are common in tonalite. A granite containing both muscovite and biotite micas is called a binary or two-mica granite, two-mica granites are typically high in potassium and low in plagioclase, and are usually S-type granites or A-type granites. A worldwide average of the composition of granite, by weight percent, based on 2485 analyses. Much of it was intruded during the Precambrian age, it is the most abundant basement rock that underlies the relatively thin veneer of the continents.
Outcrops of granite tend to form tors and rounded massifs, granites sometimes occur in circular depressions surrounded by a range of hills, formed by the metamorphic aureole or hornfels. Granite often occurs as small, less than 100 km² stock masses