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25-409: The granodiorite has large crystals of biotite , hornblende , and both feldspars — orthoclase and plagioclase . The space between crystals tends to be filled with quartz . The hornblende tends to have large, over 0.5 in (1.27 cm) rectangular crystals . The biotite forms hexagonal "blocks," up to 0.25 in (6.35 mm) across. A knife blade can peel the edges. Sphene

50-430: A Mohs hardness of 2–2.25 parallel to the [001] face, 4 perpendicular to the [001] and a specific gravity of 2.76–3. It can be colorless or tinted through grays, violet or red, and can be transparent or translucent. It is anisotropic and has high birefringence . Its crystal system is monoclinic . The green, chromium -rich variety is called fuchsite ; mariposite is also a chromium-rich type of muscovite. Muscovite

75-465: A TOT-c structure. In other words, a crystal of muscovite consists of layers ( TOT ) bonded to each other by potassium cations ( c ). Each layer is composed of three sheets. The outer sheets ('T' or tetrahedral sheets) consist of silicon-oxygen tetrahedra and aluminium -oxygen tetrahedra, with three of the oxygen anions of each tetrahedron shared with neighboring tetrahedra to form a hexagonal sheet. The fourth oxygen anion in each tetrahedral sheet

100-506: A stub . You can help Misplaced Pages by expanding it . Granodiorite Granodiorite ( / ˌ ɡ r æ n oʊ ˈ d aɪ . ə r aɪ t , ˌ ɡ r æ n ə ˈ -/ GRAN -oh- DY -ə-ryte, GRAN -ə- ) is a coarse-grained ( phaneritic ) intrusive igneous rock similar to granite , but containing more plagioclase feldspar than orthoclase feldspar . The term banatite is sometimes used informally for various rocks ranging from granite to diorite , including granodiorite. According to

125-479: Is a hydrated phyllosilicate mineral of aluminium and potassium with formula KAl 2 (Al Si 3 O 10 )( F ,O H ) 2 , or ( KF ) 2 ( Al 2 O 3 ) 3 ( SiO 2 ) 6 ( H 2 O ). It has a highly perfect basal cleavage yielding remarkably thin laminae (sheets) which are often highly elastic . Sheets of muscovite 5 meters × 3 meters (16.5 feet × 10 feet) have been found in Nellore , India . Muscovite has

150-401: Is almost always much darker in color than muscovite. Paragonite can be difficult to distinguish from muscovite but is much less common, though it is likely mistaken for muscovite often enough that it may be more common that is generally appreciated. Muscovite mica from Brazil is red due to manganese(3+). Like all mica minerals, muscovite is a phyllosilicate (sheet silicate) mineral with

175-494: Is between 85 and 83.4 (+/-1 to 2%) Ma , with average age of 84.1 Ma. It is younger than Sentinel granodiorite (88.4 Ma), and older than Cathedral Peak granite (83.7 Ma). Half Dome Granodiorite is the Valley's youngest plutonic rock . Half Dome Granodiorite dominates Yosemite Valley area east of Royal Arches and Glacier Point . At Church Bowl and in the cliff west of Royal Arches, horizontal dikes of Half Dome Granodiorite cut

200-446: Is called an apical oxygen anion. There are three silicon cations for each aluminium cation but the arrangement of aluminium and silicon cations is largely disordered. The middle octahedral ( O ) sheet consists of aluminium cations that are each surrounded by six oxygen or hydroxide anions forming an octahedron, with the octahedrons sharing anions to form a hexagonal sheet similar to the tetrahedral sheets. The apical oxygen anions of

225-460: Is described as "a rock of intermediate composition between quartz diorite and quartz monzonite ". Plymouth Rock is a glacial erratic boulder of granodiorite. The Sierra Nevada mountains contain large sections of granodiorite. Granodiorite was quarried at Mons Claudianus in the Red Sea Governorate in eastern Egypt from the 1st century AD to the mid-3rd century AD. Much of

250-525: Is evidenced by the fact that most examples of granodiorite sculpture seem to have come from later dates. However, its presence in the Rosetta Stone implies that they had considerable experience with it and the fact that only newer artifacts are found may simply be because earlier pieces were lost. Granodiorite is quarried in the Newry area of County Armagh with the common name of 'Newry granite'. Granodiorite

275-516: Is found in Half Dome Granodiorite. The grains are honey-colored, and large at 0.25 in (6.35 mm) across. Uranium is also present. From petrographic observation, the average mineral proportion of non-layered rocks of Half Dome Granodiorite is 45% plagioclase feldspar, 25% quartz , 8% biotite , 15% K-feldspar , 5% hornblende , 1% titanite , and 1% magnetite . Half Dome Granodiorite traces to early Late Cretaceous . Its age

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300-562: Is in demand for the manufacture of fireproofing and insulating materials and to some extent as a lubricant . The name muscovite comes from Muscovy-glass , a name given to the mineral in Elizabethan England due to its use in medieval Russia ( Muscovy ) as a cheaper alternative to glass in windows. This usage became widely known in England during the sixteenth century with its first mention appearing in letters by George Turberville ,

325-838: Is most often used as crushed stone for road building. It is also used as construction material, building facade, and paving, and as an ornamental stone. The Rosetta Stone is a stele made from granodiorite. The portico columns of the Pantheon in Rome are formed from single shafts of granodiorite, each 12 metres tall by 1.5 metres in diameter. Volcanic rocks : Subvolcanic rocks : Plutonic rocks : Picrite basalt Peridotite Basalt Diabase (Dolerite) Gabbro Andesite Microdiorite Diorite Dacite Microgranodiorite Granodiorite Rhyolite Microgranite Granite Muscovite Muscovite (also known as common mica , isinglass , or potash mica )

350-414: Is the most common mica , found in granites , pegmatites , gneisses , and schists , and as a contact metamorphic rock or as a secondary mineral resulting from the alteration of topaz , feldspar , kyanite , etc. It is characteristic of peraluminous rock , in which the content of aluminum is relatively high. In pegmatites, it is often found in immense sheets that are commercially valuable. Muscovite

375-734: The Latin grānum for " grain ", an English language derivative. Diorite is named after the contrasting colors of the rock. Banatite is a term used informally for various rocks ranging from granite to diorite , but often granodiorite, that were intruded in the Late Cretaceous in the Banat and nearby regions of present-day Hungary and Serbia . The term is also used in Australia in connection with Gulaga / Mount Dromedary in New South Wales , where it

400-544: The QAPF diagram , granodiorite has a greater than 20% quartz by volume, and between 65% and 90% of the feldspar is plagioclase. A greater amount of plagioclase would designate the rock as tonalite . Granodiorite is felsic to intermediate in composition. It is the intrusive igneous equivalent of the extrusive igneous dacite . It contains a large amount of sodium (Na) and calcium (Ca) rich plagioclase, potassium feldspar , quartz , and minor amounts of muscovite mica as

425-414: The hydroxide. Muscovite in which the mole fraction of silicon is greater than aluminium, and magnesium or iron replaces some of the aluminium to maintain charge balance, is called phengite . Muscovite can be cleaved into very thin transparent sheets that can substitute for glass, particularly for high-temperature applications such as industrial furnace or oven windows. It is also used in the manufacture of

450-478: The lighter colored mineral components. Biotite and amphiboles often in the form of hornblende are more abundant in granodiorite than in granite, giving it a more distinct two-toned or overall darker appearance. Mica may be present in well-formed hexagonal crystals, and hornblende may appear as needle-like crystals. Minor amounts of oxide minerals such as magnetite , ilmenite , and ulvöspinel , as well as some sulfide minerals may also be present. On average,

475-438: The octahedral sheet; fluorine or chlorine can substitute for hydroxide; and the ratio of aluminium to silicon in the tetrahedral sheets can change to maintain charge balance where necessary (as when magnesium cations, with a charge of +2, substitute for aluminium ions, with a charge of +3). Up to 10% of the potassium may be replaced by sodium, and up to 20% of the hydroxide by fluorine. Chlorine rarely replaces more than 1% of

500-455: The older granodiorite of Kuna Crest . Half Dome Granodiorite forms the sheer cliffs to the north of the trail between the Ahwahnee Hotel and Mirror Lake . The trail to Vernal and Nevada Falls also crosses through Half Dome Granodiorite. This Mariposa County, California –related article is a stub . You can help Misplaced Pages by expanding it . This Yosemite -related article is

525-404: The outer T sheets face inwards and are shared by the octahedral sheet, binding the sheets firmly together. The relatively strong binding between oxygen anions and aluminium and silicon cations within a layer, compared with the weaker binding of potassium cations between layers, gives muscovite its perfect basal cleavage. In muscovite, alternate layers are slightly offset from each other, so that

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550-511: The quarried stone was transported to Rome for use in major projects such as the Pantheon and Hadrian's Villa . Additionally, granodiorite was used for the Rosetta Stone . The extent of Egyptian granodiorite masonry is unclear. Egypt's 6000-year history makes determining the period of usage difficult as well. Perhaps like porphyry , it was ignored by the successive dynasties of Egypt and only heavily mined during Ptolemaic or Roman times. This

575-569: The secretary of England's ambassador to the Russian tsar Ivan the Terrible , in 1568. Micas are distinguished from other minerals by their pseudohexagonal crystal shape and their perfect cleavage, which allows the crystals to be pulled apart into very thin elastic sheets. Pyrophyllite , and talc are softer than micas and have a greasy feel, while chlorite is green in color and its cleavage sheets are inelastic. The other common mica mineral, biotite ,

600-476: The structure repeats every two layers. This is called the 1 M polytype of the general mica structure. The formula for muscovite is typically given as KAl 2 (AlSi 3 O 10 )(OH) 2 , but it is common for small amounts of other elements to substitute for the main constituents. Alkali metals such as sodium , rubidium , and caesium substitute for potassium; magnesium , iron , lithium , chromium , titanium , or vanadium can substitute for aluminium in

625-500: The upper continental crust has the same composition as granodiorite. Granodiorite is a plutonic igneous rock, formed by intrusion of silica-rich magma , which cools in batholiths or stocks below the Earth's surface. It is usually only exposed at the surface after uplift and erosion have occurred. The name comes from two related rocks to which granodiorite is an intermediate: granite and diorite . The gran- root comes from

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