Granite () is a coarse-grained (

phaneritic A phanerite is an igneous rock whose microstructure is made up of crystals large enough to be distinguished with the unaided human eye. In contrast, the crystals in an aphanitic rock are too fine-grained to be identifiable. Phaneritic texture fo ...

) intrusive

igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main The three types of rocks, rock types, the others being Sedimentary rock, sedimentary and metamorphic rock, metamorphic. Igneous rock ...

composed mostly of

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The atoms are linked in a continuous framework of SiO4 silicon-oxygen tetrahedra, with each oxygen being shared between two tetrahedra, giving an overall chemical form ...

alkali feldspar Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feldspa ...

, and

plagioclase Plagioclase is a series of tectosilicate (framework silicate) minerals within the feldspar group. Rather than referring to a particular mineral with a specific chemical composition, plagioclase is a continuous solid solution series, more prope ...

. It forms from

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natural sa ...

with a high content of

silica Silicon dioxide, also known as silica, is an oxide of silicon with the chemical formula , most commonly found in nature as quartz and in various living organisms. In many parts of the world, silica is the major constituent of sand. Silica is one ...

and

alkali metal oxide The alkali metals react with oxygen to form several different compounds: suboxides, oxides, peroxides, sesquioxides, superoxides, and ozonides. They all react violently with water. Alkali metal suboxides * Hexarubidium monoxide (Rb6O) h * Non ...

s that slowly cools and solidifies underground. It is common in the

continental crust Continental crust is the layer of igneous, sedimentary, and metamorphic rocks that forms the geological continents and the areas of shallow seabed close to their shores, known as continental shelves. This layer is sometimes called ''sial'' be ...

of Earth, where it is found in

igneous intrusion In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

s. These range in size from

dike Dyke (UK) or dike (US) may refer to: General uses * Dyke (slang), a slang word meaning "lesbian" * Dike (geology), a subvertical sheet-like intrusion of magma or sediment * Dike (mythology), ''Dikē'', the Greek goddess of moral justice * Dikes, ...

s only a few centimeters across to

batholith A batholith () is a large mass of intrusive igneous rock (also called plutonic rock), larger than in area, that forms from cooled magma deep in Earth's crust. Batholiths are almost always made mostly of felsic or intermediate rock types, such ...

s exposed over hundreds of square kilometers. Granite is typical of a larger family of ''granitic rocks'', or ''

granitoid A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quartz ...

s'', that are composed mostly of coarse-grained quartz and feldspars in varying proportions. These rocks are classified by the relative percentages of quartz, alkali feldspar, and plagioclase (the

QAPF classification A QAPF diagram is a double ternary diagram which is used to classify igneous rocks based on mineralogic composition. The acronym QAPF stands for "Quartz, Alkali feldspar, Plagioclase, Feldspathoid (Foid)". These are the mineral groups used for ...

), with true granite representing granitic rocks rich in quartz and alkali feldspar. Most granitic rocks also contain

mica Micas ( ) are a group of silicate minerals whose outstanding physical characteristic is that individual mica crystals can easily be split into extremely thin elastic plates. This characteristic is described as perfect basal cleavage. Mica is ...

amphibole Amphibole () is a group of inosilicate minerals, forming prism or needlelike crystals, composed of double chain tetrahedra, linked at the vertices and generally containing ions of iron and/or magnesium in their structures. Its IMA symbol is A ...

minerals, though a few (known as

leucogranite Leucogranite is a light-colored, granitic, igneous rock containing almost no dark minerals. Alaskite is a synonym. Granite is nearly always massive (lacking any internal structures), hard, and tough. These properties have made granite a widespread construction stone throughout human history.

Description

The word "granite" comes from the

Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...

''granum'', a grain, in reference to the coarse-grained structure of such a completely crystalline rock. Granitic rocks mainly consist of

feldspar Feldspars are a group of rock-forming aluminium tectosilicate minerals, also containing other cations such as sodium, calcium, potassium, or barium. The most common members of the feldspar group are the ''plagioclase'' (sodium-calcium) feldsp ...

, and

mineral In geology and mineralogy, a mineral or mineral species is, broadly speaking, a solid chemical compound with a fairly well-defined chemical composition and a specific crystal structure that occurs naturally in pure form.John P. Rafferty, ed. ( ...

s, which form an interlocking, somewhat

equigranular An equigranular material is composed chiefly of crystals of similar orders of magnitude to one another. Basalt and gabbro commonly exhibit an equigranular texture Texture may refer to: Science and technology * Surface texture, the texture mea ...

matrix Matrix most commonly refers to: * ''The Matrix'' (franchise), an American media franchise ** ''The Matrix'', a 1999 science-fiction action film ** "The Matrix", a fictional setting, a virtual reality environment, within ''The Matrix'' (franchis ...

of feldspar and quartz with scattered darker

biotite Biotite is a common group of phyllosilicate minerals within the mica group, with the approximate chemical formula . It is primarily a solid-solution series between the iron-endmember annite, and the magnesium-endmember phlogopite; more alumino ...

mica and amphibole (often

hornblende Hornblende is a complex inosilicate series of minerals. It is not a recognized mineral in its own right, but the name is used as a general or field term, to refer to a dark amphibole. Hornblende minerals are common in igneous and metamorphic rocks ...

) peppering the lighter color minerals. Occasionally some individual crystals (

phenocryst 300px, feldspathic phenocrysts. This granite, from the Switzerland">Swiss side of the Mont Blanc massif, has large white plagioclase phenocrysts, triclinic minerals that give trapezoid shapes when cut through). 1 euro coins, 1 euro coin (diameter ...

s) are larger than the

groundmass The matrix or groundmass of a rock is the finer-grained mass of material in which larger grains, crystals, or clasts are embedded. The matrix of an igneous rock consists of finer-grained, often microscopic, crystals in which larger crystals, ca ...

, in which case the texture is known as

porphyritic Porphyritic is an adjective used in geology to describe igneous rocks with a distinct difference in the size of mineral crystals, with the larger crystals known as phenocrysts. Both extrusive and intrusive rocks can be porphyritic, meaning all ...

. A granitic rock with a porphyritic texture is known as a granite porphyry.

Granitoid A granitoid is a generic term for a diverse category of coarse-grained igneous rocks that consist predominantly of quartz, plagioclase, and alkali feldspar. Granitoids range from plagioclase-rich tonalites to alkali-rich syenites and from quartz ...

is a general, descriptive

field Field may refer to: Expanses of open ground * Field (agriculture), an area of land used for agricultural purposes * Airfield, an aerodrome that lacks the infrastructure of an airport * Battlefield * Lawn, an area of mowed grass * Meadow, a grass ...

term for lighter-colored, coarse-grained igneous rocks.

Petrographic Petrography is a branch of petrology that focuses on detailed descriptions of rocks. Someone who studies petrography is called a petrographer. The mineral content and the textural relationships within the rock are described in detail. The class ...

examination is required for identification of specific types of granitoids. Granites can be predominantly white, pink, or gray in color, depending on their

mineralogy Mineralogy is a subject of geology specializing in the scientific study of the chemistry, crystal structure, and physical (including optical) properties of minerals and mineralized artifacts. Specific studies within mineralogy include the proces ...

. The

in granites is typically

orthoclase Orthoclase, or orthoclase feldspar (endmember formula K Al Si3 O8), is an important tectosilicate mineral which forms igneous rock. The name is from the Ancient Greek for "straight fracture," because its two cleavage planes are at right angles t ...

microcline Microcline (KAlSi3O8) is an important igneous rock-forming tectosilicate mineral. It is a potassium-rich alkali feldspar. Microcline typically contains minor amounts of sodium. It is common in granite and pegmatites. Microcline forms during slow ...

and is often

perthitic Perthite is used to describe an intergrowth of two feldspars: a host grain of potassium-rich alkali feldspar (near K-feldspar, KAlSi3O8, in composition) includes exsolved lamella (materials), lamellae or irregular intergrowths of sodic alkali feld ...

. The plagioclase is typically sodium-rich

oligoclase Oligoclase is a rock-forming mineral belonging to the plagioclase feldspars. In chemical composition and in its crystallographic and physical characters it is intermediate between albite ( Na Al Si3 O8) and anorthite ( CaAl2Si2O8). The albite:an ...

. Phenocrysts are usually alkali feldspar. Granitic rocks are classified according to the

QAPF diagram A QAPF diagram is a double ternary diagram which is used to classify igneous rocks based on mineralogic composition. The acronym QAPF stands for "Quartz, Alkali feldspar, Plagioclase, Feldspathoid (Foid)". These are the mineral groups used for ...

for coarse grained

plutonic rocks Intrusive rock is formed when magma penetrates existing rock, crystallizes, and solidifies underground to form '' intrusions'', such as batholiths, dikes, sills, laccoliths, and volcanic necks.Intrusive RocksIntrusive rocks accessdate: March ...

and are named according to the percentage of

, alkali feldspar (

sanidine Sanidine is the high temperature form of potassium feldspar with a general formula K(AlSi3O8). Sanidine is found most typically in felsic volcanic rocks such as obsidian, rhyolite and trachyte. Sanidine crystallizes in the monoclinic crystal system ...

, or

) and

feldspar on the A-Q-P half of the diagram. True granite (according to modern

petrologic Petrology () is the branch of geology that studies rocks and the conditions under which they form. Petrology has three subdivisions: igneous, metamorphic, and sedimentary petrology. Igneous and metamorphic petrology are commonly taught together ...

convention) contains between 20% and 60% quartz by volume, with 35% to 90% of the total feldspar consisting of

. Granitic rocks poorer in quartz are classified as

syenite Syenite is a coarse-grained intrusive igneous rock with a general composition similar to that of granite, but deficient in quartz, which, if present at all, occurs in relatively small concentrations (< 5%). Some syenites contain larger proport ...

s or

monzonite Monzonite is an igneous intrusive rock, formed by slow cooling of underground magma that has a moderate silica content and is enriched in alkali metal oxides. Monzonite is composed mostly of plagioclase and alkali feldspar. Syenodiorite is an o ...

s, while granitic rocks dominated by plagioclase are classified as

granodiorite Granodiorite () 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 gra ...

s or

tonalite Tonalite is an igneous, plutonic ( intrusive) rock, of felsic composition, with phaneritic (coarse-grained) texture. Feldspar is present as plagioclase (typically oligoclase or andesine) with alkali feldspar making up less than 10% of the total ...

s. Granitic rocks with over 90% alkali feldspar are classified as

alkali feldspar granite Alkali feldspar granite, some varieties of which are called 'red granite', is a felsic igneous rock and a type of granite rich in the mineral potassium feldspar (K-spar). It is a dense rock with a phaneritic texture. The abundance of K-spar gives ...

s. Granitic rock with more than 60% quartz, which is uncommon, is classified simply as quartz-rich granitoid or, if composed almost entirely of quartz, as quartzolite. True granites are further classified by the percentage of their total feldspar that is alkali feldspar. Granites whose feldspar is 65% to 90% alkali feldspar are

syenogranite Syenogranite is a fine to coarse grained intrusive igneous rock of the same general composition as granite. They are characteristically felsic. The feldspar component of syenogranite is predominantly alkaline in character (usually orthoclase ...

s, while the feldspar in

monzogranite Monzogranites are biotite granite rocks that are considered to be the final fractionation product of magma. Monzogranites are characteristically felsic (SiO2 > 73%, and FeO + MgO + TiO2 < 2.4), weakly

A granite containing both muscovite and biotite

s is called a binary or ''two-mica'' granite. Two-mica granites are typically high in

potassium Potassium is the chemical element with the symbol K (from Neo-Latin ''kalium'') and atomic number19. Potassium is a silvery-white metal that is soft enough to be cut with a knife with little force. Potassium metal reacts rapidly with atmosphe ...

and low in plagioclase, and are usually S-type granites or A-type granites, as described

below Below may refer to: *Earth *Ground (disambiguation) *Soil *Floor *Bottom (disambiguation) Bottom may refer to: Anatomy and sex * Bottom (BDSM), the partner in a BDSM who takes the passive, receiving, or obedient role, to that of the top or ...

. Another aspect of granite classification is the ratios of metals that potentially form feldspars. Most granites have a composition such that almost all their aluminum and alkali metals (sodium and potassium) are combined as feldspar. This is the case when K₂O + Na₂O +

CaO Cao or CAO may refer to: Mythology *Cao (bull), a legendary bull in Meitei mythology Companies or organizations * Air China Cargo, ICAO airline designator CAO *CA Oradea, Romanian football club *CA Osasuna, Spanish football club *Canadian Assoc ...

> Al₂O₃ > K₂O + Na₂O. Such granites are described as ''normal'' or ''metaluminous''. Granites in which there is not enough aluminum to combine with all the alkali oxides as feldspar (Al₂O₃ < K₂O + Na₂O) are described as ''peralkaline'', and they contain unusual sodium amphiboles such as

riebeckite Riebeckite is a sodium-rich member of the amphibole group of silicate minerals, chemical formula Na2(Fe2+3Fe3+2)Si8O22(OH)2. It forms a solid solution series with magnesioriebeckite. It crystallizes in the monoclinic system, usually as long prisma ...

. Granites in which there is an excess of aluminum beyond what can be taken up in feldspars (Al₂O₃ > CaO + K₂O + Na₂O) are described as ''peraluminous'', and they contain aluminum-rich minerals such as

muscovite Muscovite (also known as common mica, isinglass, or potash mica) is a hydrated phyllosilicate mineral of aluminium and potassium with formula K Al2(Al Si3 O10)( F,O H)2, or ( KF)2( Al2O3)3( SiO2)6( H2O). It has a highly perfect basal cleavage ...

Physical properties

The average

density Density (volumetric mass density or specific mass) is the substance's mass per unit of volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' can also be used. Mathematical ...

of granite is between , its

compressive strength In mechanics, compressive strength or compression strength is the capacity of a material or structure to withstand loads tending to reduce size (as opposed to tensile strength which withstands loads tending to elongate). In other words, compre ...

usually lies above 200 MPa, and its

viscosity The viscosity of a fluid is a measure of its resistance to deformation at a given rate. For liquids, it corresponds to the informal concept of "thickness": for example, syrup has a higher viscosity than water. Viscosity quantifies the inte ...

near

STP STP may refer to: Places * São Tomé and Príncipe (ISO 3166-1 alpha-3 code, IOC country code, and FIFA country code STP) * London St Pancras (Domestic) railway station (National Rail code STP) * St. Paul Downtown Airport (IATA airport code S ...

is 3–6·10²⁰ Pa·s. The melting temperature of dry granite at ambient pressure is ; it is strongly reduced in the presence of water, down to 650 °C at a few hundred megapascals of pressure. Granite has poor primary permeability overall, but strong secondary permeability through cracks and fractures if they are present.

Chemical composition

A worldwide average of the chemical composition of granite, by weight percent, based on 2485 analyses:Blatt and Tracy 1996, p.66 The medium-grained equivalent of granite is microgranite. The

extrusive Extrusive rock refers to the mode of igneous volcanic rock formation in which hot magma from inside the Earth flows out (extrudes) onto the surface as lava or explodes violently into the atmosphere to fall back as pyroclastics or tuff. In contras ...

igneous rock equivalent of granite is

rhyolite Rhyolite ( ) is the most silica-rich of volcanic rocks. It is generally glassy or fine-grained (aphanitic) in texture, but may be porphyritic, containing larger mineral crystals (phenocrysts) in an otherwise fine-grained groundmass. The mineral ...

Occurrence

Granitic rock is widely distributed throughout the

. Much of it was intruded during the

Precambrian The Precambrian (or Pre-Cambrian, sometimes abbreviated pꞒ, or Cryptozoic) is the earliest part of Earth's history, set before the current Phanerozoic Eon. The Precambrian is so named because it preceded the Cambrian, the first period of the ...

age; it is the most abundant

basement rock In geology, basement and crystalline basement are crystalline rocks lying above the mantle and beneath all other rocks and sediments. They are sometimes exposed at the surface, but often they are buried under miles of rock and sediment. The baseme ...

that underlies the relatively thin

sedimentary Sedimentary rocks are types of rock (geology), rock that are formed by the accumulation or deposition of mineral or organic matter, organic particles at Earth#Surface, Earth's surface, followed by cementation (geology), cementation. Sedimentati ...

veneer of the continents.

Outcrop An outcrop or rocky outcrop is a visible exposure of bedrock or ancient superficial deposits on the surface of the Earth. Features Outcrops do not cover the majority of the Earth's land surface because in most places the bedrock or superficial ...

s of granite tend to form

tors Tors may refer to: * Tor (rock formation), rock outcrops * Ivan Tors (1916–1983), playwright, screenwriter and film and television producer * TransOral Robotic Surgery, a surgical technique See also * Tor (disambiguation) * Ten Tors * Tors Cov ...

domes A dome () is an architectural element similar to the hollow upper half of a sphere. There is significant overlap with the term cupola, which may also refer to a dome or a structure on top of a dome. The precise definition of a dome has been a m ...

bornhardt A bornhardt () is a dome-shaped, steep-sided, bald rock outcropping at least in height and several hundred metres in width. They are named after Wilhelm Bornhardt (1864–1946), a German geologist and explorer of German East Africa, who first ...

s, and rounded

massif In geology, a massif ( or ) is a section of a planet's crust that is demarcated by faults or flexures. In the movement of the crust, a massif tends to retain its internal structure while being displaced as a whole. The term also refers to a ...

s. Granites sometimes occur in circular depressions surrounded by a range of hills, formed by the

metamorphic aureole Metamorphism is the transformation of existing rock (the protolith) to rock with a different mineral composition or texture. Metamorphism takes place at temperatures in excess of , and often also at elevated pressure or in the presence of chem ...

hornfels Hornfels is the group name for a set of contact metamorphic rocks that have been baked and hardened by the heat of intrusive igneous masses and have been rendered massive, hard, splintery, and in some cases exceedingly tough and durable. These pro ...

. Granite often occurs as relatively small, less than 100 km² stock masses (

stocks Stocks are feet restraining devices that were used as a form of corporal punishment and public humiliation. The use of stocks is seen as early as Ancient Greece, where they are described as being in use in Solon's law code. The law describing ...

) and in

s that are often associated with

orogenic Orogeny is a mountain building process. An orogeny is an event that takes place at a convergent boundary, convergent plate margin when plate motion compresses the margin. An ''orogenic belt'' or ''orogen'' develops as the compressed plate crumpl ...

mountain A mountain is an elevated portion of the Earth's crust, generally with steep sides that show significant exposed bedrock. Although definitions vary, a mountain may differ from a plateau in having a limited Summit (topography), summit area, and ...

ranges. Small

dikes Dyke (UK) or dike (US) may refer to: General uses * Dyke (slang), a slang word meaning "lesbian" * Dike (geology), a subvertical sheet-like intrusion of magma or sediment * Dike (mythology), ''Dikē'', the Greek goddess of moral justice * Dikes, ...

of granitic composition called

aplite Aplite () is an intrusive igneous rock in which the mineral composition is the same as granite, but in which the grains are much finer, under 1 mm across. Quartz and feldspar are the dominant minerals. The term ''aplite'' or ''aplitic'' ...

s are often associated with the margins of granitic

intrusion In geology, an igneous intrusion (or intrusive body or simply intrusion) is a body of intrusive igneous rock that forms by crystallization of magma slowly cooling below the surface of the Earth. Intrusions have a wide variety of forms and com ...

s. In some locations, very coarse-grained

pegmatite A pegmatite is an igneous rock showing a very coarse texture, with large interlocking crystals usually greater in size than and sometimes greater than . Most pegmatites are composed of quartz, feldspar, and mica, having a similar silicic com ...

masses occur with granite.

Origin

Granite forms from silica-rich (

felsic In geology, felsic is a modifier describing igneous rocks that are relatively rich in elements that form feldspar and quartz.Marshak, Stephen, 2009, ''Essentials of Geology,'' W. W. Norton & Company, 3rd ed. It is contrasted with mafic rocks, whi ...

) magmas. Felsic magmas are thought to form by addition of heat or water vapor to rock of the lower crust, rather than by decompression of mantle rock, as is the case with

basalt Basalt (; ) is an aphanite, aphanitic (fine-grained) extrusive igneous rock formed from the rapid cooling of low-viscosity lava rich in magnesium and iron (mafic lava) exposed at or very near the planetary surface, surface of a terrestrial ...

ic magmas. It has also been suggested that some granites found at

convergent boundaries A convergent boundary (also known as a destructive boundary) is an area on Earth where two or more lithospheric plates collide. One plate eventually slides beneath the other, a process known as subduction. The subduction zone can be defined by a ...

between

tectonic plate Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large te ...

s, where

oceanic crust Oceanic crust is the uppermost layer of the oceanic portion of the tectonic plates. It is composed of the upper oceanic crust, with pillow lavas and a dike complex, and the lower oceanic crust, composed of troctolite, gabbro and ultramafic cumu ...

subducts Subduction is a geological process in which the oceanic lithosphere is recycled into the Earth's mantle at convergent boundaries. Where the oceanic lithosphere of a tectonic plate converges with the less dense lithosphere of a second plate, the ...

below continental crust, were formed from

sediments Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand a ...

subducted with the oceanic plate. The melted sediments would have produced magma intermediate in its silica content, which became further enriched in silica as it rose through the overlying crust. Early fractional crystallisation serves to reduce a melt in magnesium and chromium, and enrich the melt in iron, sodium, potassium, aluminum, and silicon. Further fractionation reduces the content of iron, calcium, and titanium. This is reflected in the high content of alkali feldspar and quartz in granite. The presence of granitic rock in

island arc Island arcs are long chains of active volcanoes with intense seismic activity found along convergent tectonic plate boundaries. Most island arcs originate on oceanic crust and have resulted from the descent of the lithosphere into the mantle alon ...

s shows that

fractional crystallization Fractional crystallization may refer to: * Fractional crystallization (chemistry), a process to separate different solutes from a solution * Fractional crystallization (geology) Fractional crystallization, or crystal fractionation, is one of the ...

alone can convert a basaltic magma to a granitic magma, but the quantities produced are small. For example, granitic rock makes up just 4% of the exposures in the

South Sandwich Islands ) , anthem = "God Save the King" , song_type = , song = , image_map = South Georgia and the South Sandwich Islands in United Kingdom.svg , map_caption = Location of South Georgia and the South Sandwich Islands in the southern Atlantic Oce ...

. In continental arc settings, granitic rocks are the most common plutonic rocks, and batholiths composed of these rock types extend the entire length of the arc. There are no indication of magma chambers where basaltic magmas differentiate into granites, or of

cumulates Cumulate rocks are igneous rocks formed by the accumulation of crystals from a magma either by settling or floating. Cumulate rocks are named according to their texture; cumulate texture is diagnostic of the conditions of formation of this group o ...

produced by mafic crystals settling out of the magma. Other processes must produce these great volumes of felsic magma. One such process is injection of basaltic magma into the lower crust, followed by differentiation, which leaves any cumulates in the mantle. Another is heating of the lower crust by

underplating Magmatic underplating occurs when basaltic magmas are trapped during their rise to the surface at the Mohorovičić discontinuity or within the Crust (geology), crust. Entrapment (or 'stalling out') of magmas within the crust occurs due to the dif ...

basaltic magma, which produces felsic magma directly from crustal rock. The two processes produce different kinds of granites, which may be reflected in the division between S-type (produced by underplating) and I-type (produced by injection and differentiation) granites, discussed below.

Alphabet classification system

The composition and origin of any magma that differentiates into granite leave certain petrological evidence as to what the granite's parental rock was. The final texture and composition of a granite are generally distinctive as to its parental rock. For instance, a granite that is derived from partial melting of metasedimentary rocks may have more alkali feldspar, whereas a granite derived from partial melting of metaigneous rocks may be richer in plagioclase. It is on this basis that the modern "alphabet" classification schemes are based. The letter-based Chappell & White classification system was proposed initially to divide granites into I-type (igneous source) granite and S-type (sedimentary sources). Both types are produced by partial melting of crustal rocks, either metaigneous rocks or metasedimentary rocks. I-type granites are characterized by a high content of sodium and calcium, and by a

strontium isotope The alkaline earth metal strontium (38Sr) has four stable, naturally occurring isotopes: 84Sr (0.56%), 86Sr (9.86%), 87Sr (7.0%) and 88Sr (82.58%). Its standard atomic weight is 87.62(1). Only 87Sr is radiogenic; it is produced by decay from t ...

ratio, ⁸⁷Sr/⁸⁶Sr, of less than 0.708. ⁸⁷Sr is produced by radioactive decay of ⁸⁷Rb, and since rubidium is concentrated in the crust relative to the mantle, a low ratio suggests origin in the mantle. The elevated sodium and calcium favor crystallization of hornblende rather than biotite. I-type granites are known for their

porphyry copper Porphyry copper deposits are copper ore bodies that are formed from hydrothermal fluids that originate from a voluminous magma chamber several kilometers below the deposit itself. Predating or associated with those fluids are vertical dikes of ...

deposits. I-type granites are orogenic (associated with mountain building) and usually metaluminous. S-type granites are sodium-poor and aluminum-rich. As a result, they contain

s such as biotite and muscovite instead of hornblende. Their strontium isotope ratio is typically greater than 0.708, suggesting a crustal origin. They also commonly contain

xenolith A xenolith ("foreign rock") is a rock fragment (country rock) that becomes enveloped in a larger rock during the latter's development and solidification. In geology, the term ''xenolith'' is almost exclusively used to describe inclusions in igne ...

s of metamorphosed sedimentary rock, and host

tin Tin is a chemical element with the symbol Sn (from la, stannum) and atomic number 50. Tin is a silvery-coloured metal. Tin is soft enough to be cut with little force and a bar of tin can be bent by hand with little effort. When bent, t ...

ores. Their magmas are water-rich, and they readily solidify as the water outgasses from the magma at lower pressure, so they less commonly make it to the surface than magmas of I-type granites, which are thus more common as volcanic rock (rhyolite). They are also orogenic but range from metaluminous to strongly peraluminous. Although both I- and S-type granites are orogenic, I-type granites are more common close to the convergent boundary than S-type. This is attributed to thicker crust further from the boundary, which results in more crustal melting. A-type granites show a peculiar mineralogy and geochemistry, with particularly high silicon and potassium at the expense of calcium and magnesium and a high content of high field strength cations (cations with a small radius and high electrical charge, such as

zirconium Zirconium is a chemical element with the symbol Zr and atomic number 40. The name ''zirconium'' is taken from the name of the mineral zircon, the most important source of zirconium. The word is related to Persian '' zargun'' (zircon; ''zar-gun'', ...

niobium Niobium is a chemical element with chemical symbol Nb (formerly columbium, Cb) and atomic number 41. It is a light grey, crystalline, and ductile transition metal. Pure niobium has a Mohs hardness rating similar to pure titanium, and it has sim ...

tantalum Tantalum is a chemical element with the symbol Ta and atomic number 73. Previously known as ''tantalium'', it is named after Tantalus, a villain in Greek mythology. Tantalum is a very hard, ductile, lustrous, blue-gray transition metal that is ...

, and

rare earth element The rare-earth elements (REE), also called the rare-earth metals or (in context) rare-earth oxides or sometimes the lanthanides (yttrium and scandium are usually included as rare earths), are a set of 17 nearly-indistinguishable lustrous silv ...

s.) They are not orogenic, forming instead over hot spots and continental rifting, and are metaluminous to mildly peralkaline and iron-rich. These granites are produced by partial melting of refractory lithology such as granulites in the lower continental crust at high thermal gradients. This leads to significant extraction of hydrous felsic melts from granulite-facies resitites. A-type granites occur in the Koettlitz Glacier Alkaline Province in the Royal Society Range, Antarctica. The rhyolites of the Yellowstone Caldera are examples of volcanic equivalents of A-type granite. M-type granite was later proposed to cover those granites that were clearly sourced from crystallized mafic magmas, generally sourced from the mantle. Although the fractional crystallisation of basaltic melts can yield small amounts of granites, which are sometimes found in island arcs, such granites must occur together with large amounts of basaltic rocks. H-type granites were suggested for hybrid granites, which were hypothesized to form by mixing between mafic and felsic from different sources, such as M-type and S-type. However, the big difference in rheology between mafic and felsic magmas makes this process problematic in nature.

Granitization

Granitization is an old, and largely discounted, hypothesis that granite is formed in place through extreme

metasomatism Metasomatism (from the Greek μετά ''metá'' "change" and σῶμα ''sôma'' "body") is the chemical alteration of a rock by hydrothermal and other fluids. It is the replacement of one rock by another of different mineralogical and chemical com ...

. The idea behind granitization was that fluids would supposedly bring in elements such as potassium, and remove others, such as calcium, to transform a metamorphic rock into granite. This was supposed to occur across a migrating front. However, experimental work had established by the 1960s that granites were of igneous origin. The mineralogical and chemical features of granite can be explained only by crystal-liquid phase relations, showing that there must have been at least enough melting to mobilize the magma. However, at sufficiently deep crustal levels, the distinction between metamorphism and crustal melting itself becomes vague. Conditions for crystallization of liquid magma are close enough to those of high-grade metamorphism that the rocks often bear a close resemblance. Under these conditions, granitic melts can be produced in place through the partial melting of metamorphic rocks by extracting melt-mobile elements such as potassium and silicon into the melts but leaving others such as calcium and iron in granulite residues. This may be the origin of ''

migmatite Migmatite is a composite rock found in medium and high-grade metamorphic environments, commonly within Precambrian cratonic blocks. It consists of two or more constituents often layered repetitively: one layer is an older metamorphic rock tha ...

s''. A migmatite consists of dark, refractory rock (the ''melanosome'') that is permeated by sheets and channels of light granitic rock (the ''leucosome''). The leucosome is interpreted as partial melt of a parent rock that has begun to separate from the remaining solid residue (the melanosome). If enough partial melt is produced, it will separate from the source rock, become more highly evolved through fractional crystallization during its ascent toward the surface, and become the magmatic parent of granitic rock. The residue of the source rock becomes a

granulite Granulites are a class of high-grade metamorphic rocks of the granulite facies that have experienced high-temperature and moderate-pressure metamorphism. They are medium to coarse–grained and mainly composed of feldspars sometimes associated w ...

. The partial melting of solid rocks requires high temperatures and the addition of water or other volatiles which lower the

solidus temperature In chemistry, materials science, and physics, the solidus is the locus of temperatures (a curve on a phase diagram) below which a given substance is completely solid (crystallized). The solidus temperature, TS or Tsol, specifies the temperature ...

(temperature at which partial melting commences) of these rocks. It was long debated whether crustal thickening in orogens (mountain belts along

) was sufficient to produce granite melts by

radiogenic heating A radiogenic nuclide is a nuclide that is produced by a process of radioactive decay. It may itself be radioactive (a radionuclide) or stable (a stable nuclide). Radiogenic nuclides (more commonly referred to as radiogenic isotopes) form some of ...

, but recent work suggests that this is not a viable mechanism. In-situ granitization requires heating by the asthenospheric mantle or by underplating with mantle-derived magmas.

Ascent and emplacement

Granite magmas have a density of 2.4 Mg/m³, much less than the 2.8 Mg/m³ of high-grade metamorphic rock. This gives them tremendous buoyancy, so that ascent of the magma is inevitable once enough magma has accumulated. However, the question of precisely how such large quantities of magma are able to shove aside

country rock Country rock is a genre of music which fuses rock and country. It was developed by rock musicians who began to record country-flavored records in the late 1960s and early 1970s. These musicians recorded rock records using country themes, vocal s ...

to make room for themselves (the ''room problem'') is still a matter of research. Two main mechanisms are thought to be important: *Stokes

diapir A diapir (; , ) is a type of igneous intrusion in which a more mobile and ductily deformable material is forced into brittle overlying rocks. Depending on the tectonic environment, diapirs can range from idealized mushroom-shaped Rayleigh–T ...

* Fracture propagation Of these two mechanisms, Stokes diapirism has been favoured for many years in the absence of a reasonable alternative. The basic idea is that magma will rise through the crust as a single mass through

buoyancy Buoyancy (), or upthrust, is an upward force exerted by a fluid that opposes the weight of a partially or fully immersed object. In a column of fluid, pressure increases with depth as a result of the weight of the overlying fluid. Thus the p ...

. As it rises, it heats the

wall rocks A wall is a structure and a surface that defines an area; carries a load; provides security, shelter, or soundproofing; or, is decorative. There are many kinds of walls, including: * Walls in buildings that form a fundamental part of the super ...

, causing them to behave as a

power-law fluid __NOTOC__ In continuum mechanics, a power-law fluid, or the Ostwald–de Waele relationship, is a type of generalized Newtonian fluid (time-independent non-Newtonian fluid) for which the shear stress, , is given by :\tau = K \left( \frac \right) ...

and thus flow around the

allowing it to pass without major heat loss. This is entirely feasible in the warm,

ductile Ductility is a mechanical property commonly described as a material's amenability to drawing (e.g. into wire). In materials science, ductility is defined by the degree to which a material can sustain plastic deformation under tensile stres ...

lower crust where rocks are easily deformed, but runs into problems in the upper crust which is far colder and more brittle. Rocks there do not deform so easily: for magma to rise as a diapir it would expend far too much energy in heating wall rocks, thus cooling and solidifying before reaching higher levels within the crust.

Fracture Fracture is the separation of an object or material into two or more pieces under the action of stress. The fracture of a solid usually occurs due to the development of certain displacement discontinuity surfaces within the solid. If a displa ...

propagation is the mechanism preferred by many geologists as it largely eliminates the major problems of moving a huge mass of magma through cold brittle crust. Magma rises instead in small channels along self-propagating dykes which form along new or pre-existing fracture or fault systems and networks of active shear zones. As these narrow conduits open, the first magma to enter solidifies and provides a form of insulation for later magma. These mechanisms can operate in tandem. For example, diapirs may continue to rise through the brittle upper crust through

stoping Stoping is the process of extracting the desired ore or other mineral from an underground mine, leaving behind an open space known as a stope. Stoping is used when the country rock is sufficiently strong not to collapse into the stope, although i ...

, where the granite cracks the roof rocks, removing blocks of the overlying crust which then sink to the bottom of the diapir while the magma rises to take their place. This can occur as piecemeal stopping (stoping of small blocks of chamber roof), as cauldron subsidence (collapse of large blocks of chamber roof), or as roof foundering (complete collapse of the roof of a shallow magma chamber accompanied by a

caldera A caldera ( ) is a large cauldron-like hollow that forms shortly after the emptying of a magma chamber in a volcano eruption. When large volumes of magma are erupted over a short time, structural support for the rock above the magma chamber is ...

eruption.) There is evidence for cauldron subsidence at the Mt. Ascutney intrusion in eastern Vermont. Evidence for piecemeal stoping is found in intrusions that are rimmed with ''igneous breccia'' containing fragments of country rock. Assimilation is another mechanism of ascent, where the granite melts its way up into the crust and removes overlying material in this way. This is limited by the amount of thermal energy available, which must be replenished by crystallization of higher-melting minerals in the magma. Thus, the magma is melting crustal rock at its roof while simultaneously crystallizing at its base. This results in steady contamination with crustal material as the magma rises. This may not be evident in the major and minor element chemistry, since the minerals most likely to crystallize at the base of the chamber are the same ones that would crystallize anyway, but crustal assimilation is detectable in isotope ratios. Heat loss to the country rock means that ascent by assimilation is limited to distance similar to the height of the magma chamber.

Weathering

Physical weathering Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement), ...

occurs on a large scale in the form of

exfoliation joint Exfoliation joints or sheet joints are surface-parallel fracture systems in rock, and often leading to erosion of concentric slabs. ''(See Joint (geology)).'' General characteristics of exfoliation joints * Commonly follow topography. * Divid ...

s, which are the result of granite's expanding and fracturing as pressure is relieved when overlying material is removed by erosion or other processes.

Chemical weathering Weathering is the deterioration of rocks, soils and minerals as well as wood and artificial materials through contact with water, atmospheric gases, and biological organisms. Weathering occurs ''in situ'' (on site, with little or no movement), ...

of granite occurs when dilute carbonic acid, and other acids present in rain and soil waters,

alter Alter may refer to: * Alter (name), people named Alter * Alter (automobile) * Alter (crater), a lunar crater * Alter Channel, a Greek TV channel * Archbishop Alter High School, a Roman Catholic high school in Kettering, Ohio * ALTER, a comman ...

feldspar in a process called

hydrolysis Hydrolysis (; ) is any chemical reaction in which a molecule of water breaks one or more chemical bonds. The term is used broadly for substitution reaction, substitution, elimination reaction, elimination, and solvation reactions in which water ...

. As demonstrated in the following reaction, this causes potassium feldspar to form

kaolinite Kaolinite ( ) is a clay mineral, with the chemical composition Al2 Si2 O5( OH)4. It is an important industrial mineral. It is a layered silicate mineral, with one tetrahedral sheet of silica () linked through oxygen atoms to one octahedral ...

, with potassium ions, bicarbonate, and silica in solution as byproducts. An end product of granite weathering is grus, which is often made up of coarse-grained fragments of disintegrated granite. Climatic variations also influence the weathering rate of granites. For about two thousand years, the relief engravings on

Cleopatra's Needle Cleopatra's Needles are a separated pair of ancient Egyptian obelisks now in London and New York City. The obelisks were originally made in Heliopolis (modern Cairo) during the New Kingdom period, inscribed by the 18th dynasty pharaoh Thutmose I ...

obelisk had survived the arid conditions of its origin before its transfer to London. Within two hundred years, the red granite has drastically deteriorated in the damp and polluted air there. Soil development on granite reflects the rock's high quartz content and dearth of available bases, with the base-poor status predisposing the soil to

acidification Acidification may refer to: * Ocean acidification, decrease in the pH of the Earth's oceans * Freshwater acidification, atmospheric depositions and soil leaching of SOx and NOx * Soil acidification, buildup of hydrogen cations, which reduces the ...

and

podzol In soil science, podzols are the typical soils of coniferous or boreal forests and also the typical soils of eucalypt forests and heathlands in southern Australia. In Western Europe, podzols develop on heathland, which is often a construct of hum ...

ization in cool humid climates as the weather-resistant quartz yields much sand. Feldspars also weather slowly in cool climes, allowing sand to dominate the fine-earth fraction. In warm humid regions, the weathering of feldspar as described above is accelerated so as to allow a much higher proportion of clay with the

Cecil Cecil may refer to: People with the name * Cecil (given name), a given name (including a list of people and fictional characters with the name) * Cecil (surname), a surname (including a list of people with the name) Places Canada *Cecil, Alberta, ...

soil series a prime example of the consequent

Ultisol Ultisols, commonly known as red clay soils, are one of twelve soil orders in the United States Department of Agriculture soil taxonomy. The word "Ultisol" is derived from "ultimate", because Ultisols were seen as the ultimate product of continu ...

great soil group.

Natural radiation

Granite is a natural source of

radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...

, like most natural stones.

Potassium-40 Potassium-40 (40K) is a radioactive isotope of potassium which has a long half-life of 1.25 billion years. It makes up about 0.012% (120 ppm) of the total amount of potassium found in nature. Potassium-40 undergoes three types of radioactive de ...

is a

radioactive isotope A radionuclide (radioactive nuclide, radioisotope or radioactive isotope) is a nuclide that has excess nuclear energy, making it unstable. This excess energy can be used in one of three ways: emitted from the nucleus as gamma radiation; transferr ...

of weak emission, and a constituent of

, which in turn is a common component of granitic rocks, more abundant in

and

s. Some granites contain around 10 to 20

parts per million In science and engineering, the parts-per notation is a set of pseudo-units to describe small values of miscellaneous dimensionless quantities, e.g. mole fraction or mass fraction. Since these fractions are quantity-per-quantity measures, they ...

(ppm) of

uranium Uranium is a chemical element with the symbol U and atomic number 92. It is a silvery-grey metal in the actinide series of the periodic table. A uranium atom has 92 protons and 92 electrons, of which 6 are valence electrons. Uranium is weak ...

. By contrast, more mafic rocks, such as tonalite,

gabbro Gabbro () is a phaneritic (coarse-grained), mafic intrusive igneous rock formed from the slow cooling of magnesium-rich and iron-rich magma into a holocrystalline mass deep beneath the Earth's surface. Slow-cooling, coarse-grained gabbro is che ...

and

diorite Diorite ( ) is an intrusive igneous rock formed by the slow cooling underground of magma (molten rock) that has a moderate content of silica and a relatively low content of alkali metals. It is intermediate in composition between low-silic ...

, have 1 to 5 ppm uranium, and

limestone Limestone ( calcium carbonate ) is a type of carbonate sedimentary rock which is the main source of the material lime. It is composed mostly of the minerals calcite and aragonite, which are different crystal forms of . Limestone forms whe ...

s and

rocks usually have equally low amounts. Many large granite plutons are sources for

palaeochannel A palaeochannel, also spelt paleochannel and also known as palaeovalley or palaeoriver, is a geological term describing a remnant of an inactive river or stream channel that has been filled or buried by younger sediment. The sediments that the ...

-hosted or roll front

uranium ore deposits Uranium ore deposits are economically recoverable concentrations of uranium within the Earth's crust. Uranium is one of the more common elements in the Earth's crust, being 40 times more common than silver and 500 times more common than gold. It ...

, where the uranium washes into the

sediment Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand an ...

s from the granite uplands and associated, often highly radioactive pegmatites. Cellars and basements built into soils over granite can become a trap for

radon Radon is a chemical element with the symbol Rn and atomic number 86. It is a radioactive, colourless, odourless, tasteless noble gas. It occurs naturally in minute quantities as an intermediate step in the normal radioactive decay chains through ...

gas, which is formed by the decay of uranium. Radon gas poses significant health concerns and is the number two cause of

lung cancer Lung cancer, also known as lung carcinoma (since about 98–99% of all lung cancers are carcinomas), is a malignant lung tumor characterized by uncontrolled cell growth in tissue (biology), tissues of the lung. Lung carcinomas derive from tran ...

in the US behind smoking.

Thorium Thorium is a weakly radioactive metallic chemical element with the symbol Th and atomic number 90. Thorium is silvery and tarnishes black when it is exposed to air, forming thorium dioxide; it is moderately soft and malleable and has a high me ...

occurs in all granites.

Conway granite Conway granite is a typically pink (or mesoperthitic) biotite granite.

has been noted for its relatively high thorium concentration of 56±6 ppm. There is some concern that some granite sold as countertops or building material may be hazardous to health. Dan Steck of St. Johns University has stated that approximately 5% of all granite is of concern, with the caveat that only a tiny percentage of the tens of thousands of granite slab types have been tested. Resources from national geological survey organizations are accessible online to assist in assessing the risk factors in granite country and design rules relating, in particular, to preventing accumulation of radon gas in enclosed basements and dwellings. A study of granite countertops was done (initiated and paid for by the Marble Institute of America) in November 2008 by National Health and Engineering Inc. of USA. In this test, all of the 39 full-size granite slabs that were measured for the study showed radiation levels well below the European Union safety standards (section 4.1.1.1 of the National Health and Engineering study) and radon emission levels well below the average outdoor radon concentrations in the US.

Industry

Granite and related marble industries are considered one of the oldest industries in the world, existing as far back as Ancient Egypt. Major modern exporters of granite include China, India, Italy, Brazil, Canada, Germany, Sweden, Spain and the United States.

Uses

Antiquity

Cleopatra's Needle (London) inscriptions

The

Red Pyramid The Red Pyramid, also called the North Pyramid, is the largest of the pyramids located at the Dahshur necropolis in Cairo, Egypt. Named for the rusty reddish hue of its red limestone stones, it is also the third largest Egyptian pyramid, after th ...

Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a transcontinental country spanning the northeast corner of Africa and southwest corner of Asia via a land bridge formed by the Sinai Peninsula. It is bordered by the Mediter ...

(circa 2590 BC), named for the light crimson hue of its exposed limestone surfaces, is the third largest of

Egyptian pyramids The Egyptian pyramids are ancient masonry structures located in Egypt. Sources cite at least 118 identified "Egyptian" pyramids. Approximately 80 pyramids were built within the Kingdom of Kush, now located in the modern country of Sudan. Of ...

Pyramid of Menkaure The pyramid of Menkaure is the smallest of the three main pyramids of the Giza pyramid complex, located on the Giza Plateau in the southwestern outskirts of Cairo, Egypt. It is thought to have been built to serve as the tomb of the Fourth Dynasty ...

, likely dating 2510 BC, was constructed of

and granite blocks. The

Great Pyramid of Giza The Great Pyramid of Giza is the biggest Egyptian pyramid and the tomb of Fourth Dynasty pharaoh Khufu. Built in the early 26th century BC during a period of around 27 years, the pyramid is the oldest of the Seven Wonders of the Ancient World, ...

(c. 2580 BC) contains a huge granite

sarcophagus A sarcophagus (plural sarcophagi or sarcophaguses) is a box-like funeral receptacle for a corpse, most commonly carved in stone, and usually displayed above ground, though it may also be buried. The word ''sarcophagus'' comes from the Greek ...

fashioned of "Red

Aswan Aswan (, also ; ar, أسوان, ʾAswān ; cop, Ⲥⲟⲩⲁⲛ ) is a city in Southern Egypt, and is the capital of the Aswan Governorate. Aswan is a busy market and tourist centre located just north of the Aswan Dam on the east bank of the ...

Granite". The mostly ruined

Black Pyramid The Black Pyramid ( ar, الهرم الأسود, al-Haram al'Aswad) was built by King Amenemhat III (r. c. 1860 BC-c. 1814 BC) during the Middle Kingdom of Egypt (2055–1650 BC). It is one of the five remaining pyramids of the original eleven ...

dating from the reign of

Amenemhat III :''See Amenemhat, for other individuals with this name.'' Amenemhat III ( Ancient Egyptian: ''Ỉmn-m-hꜣt'' meaning 'Amun is at the forefront'), also known as Amenemhet III, was a pharaoh of ancient Egypt and the sixth king of the Twelfth Dy ...

once had a polished granite

pyramidion A pyramidion (plural: pyramidia) is the uppermost piece or capstone of an Egyptian pyramid or obelisk. Speakers of the Ancient Egyptian language referred to pyramidia as ''benbenet'' and associated the pyramid as a whole with the sacred b ...

or capstone, which is now on display in the main hall of the

Egyptian Museum The Museum of Egyptian Antiquities, known commonly as the Egyptian Museum or the Cairo Museum, in Cairo, Egypt, is home to an extensive collection of ancient Egyptian antiquities. It has 120,000 items, with a representative amount on display a ...

Cairo Cairo ( ; ar, القاهرة, al-Qāhirah, ) is the capital of Egypt and its largest city, home to 10 million people. It is also part of the largest urban agglomeration in Africa, the Arab world and the Middle East: The Greater Cairo metro ...

(see

Dahshur DahshurAlso transliterated ''Dahshour'' (in English often called ''Dashur'' ar, دهشور ' , ''Dahchur'') is a royal necropolis located in the desert on the west bank of the Nile approximately south of Cairo. It is known chiefly for several p ...

). Other uses in Ancient Egypt include

column A column or pillar in architecture and structural engineering is a structural element that transmits, through compression, the weight of the structure above to other structural elements below. In other words, a column is a compression member. ...

s, door

lintel A lintel or lintol is a type of beam (a horizontal structural element) that spans openings such as portals, doors, windows and fireplaces. It can be a decorative architectural element, or a combined ornamented structural item. In the case of w ...

s, sills,

jamb A jamb (from French ''jambe'', "leg"), in architecture, is the side-post or lining of a doorway or other aperture. The jambs of a window outside the frame are called “reveals.” Small shafts to doors and windows with caps and bases are know ...

s, and wall and floor veneer. How the

Egyptians Egyptians ( arz, المَصرِيُون, translit=al-Maṣriyyūn, ; arz, المَصرِيِين, translit=al-Maṣriyyīn, ; cop, ⲣⲉⲙⲛ̀ⲭⲏⲙⲓ, remenkhēmi) are an ethnic group native to the Nile, Nile Valley in Egypt. Egyptian ...

worked the solid granite is still a matter of debate. Patrick Hunt has postulated that the Egyptians used emery, which has greater

hardness In materials science, hardness (antonym: softness) is a measure of the resistance to localized plastic deformation induced by either mechanical indentation or abrasion. In general, different materials differ in their hardness; for example hard ...

on the

Mohs scale The Mohs scale of mineral hardness () is a qualitative ordinal scale, from 1 to 10, characterizing scratch resistance of various minerals through the ability of harder material to scratch softer material. The scale was introduced in 1812 by th ...

. The

Seokguram The Seokguram Grotto is a hermitage and part of the Bulguksa temple complex. It lies four kilometers east of the temple on Mt. Tohamsan, in Gyeongju, South Korea. It is classified as ''National Treasure No. 24'' by the South Korean government ...

Grotto in Korea is a

Buddhist Buddhism ( , ), also known as Buddha Dharma and Dharmavinaya (), is an Indian religion or philosophical tradition based on teachings attributed to the Buddha. It originated in northern India as a -movement in the 5th century BCE, and ...

shrine and part of the

Bulguksa Bulguksa is located on the slopes of Mount Toham (Jinheon-dong, Gyeongju city, North Gyeongsang province, South Korea). It is a head temple of the Jogye Order of Korean Buddhism and encompasses six National treasures of South Korea, including the ...

temple complex. Completed in 774 AD, it is an artificial grotto constructed entirely of granite. The main Buddha of the grotto is a highly regarded piece of

Buddhist art Buddhist art is visual art produced in the context of Buddhism. It includes depictions of Gautama Buddha and other Buddhas and bodhisattvas, notable Buddhist figures both historical and mythical, narrative scenes from their lives, mandalas, and ...

, and along with the temple complex to which it belongs, Seokguram was added to the

UNESCO World Heritage List A World Heritage Site is a landmark or area with legal protection by an international convention administered by the United Nations Educational, Scientific and Cultural Organization (UNESCO). World Heritage Sites are designated by UNESCO for h ...

in 1995.

Rajaraja Chola I Rajaraja I (947 CE – 1014 CE), born Arunmozhi Varman or Arulmozhi Varman and often described as Raja Raja the Great or Raja Raja Chozhan was a Chola emperor who reigned from 985 CE to 1014 CE. He was the most powerful Tamil king in South ...

of the Chola Dynasty in South India built the world's first temple entirely of granite in the 11th century AD in

Tanjore Thanjavur (), also Tanjore, Pletcher 2010, p. 195 is a city in the Indian state of Tamil Nadu. Thanjavur is the 11th biggest city in Tamil Nadu. Thanjavur is an important center of South Indian religion, art, and architecture. Most of the Gr ...

India India, officially the Republic of India (Hindi: ), is a country in South Asia. It is the seventh-largest country by area, the second-most populous country, and the most populous democracy in the world. Bounded by the Indian Ocean on the so ...

. The

Brihadeeswarar Temple Brihadishvara Temple, called Rajarajesvaram () by its builder, and known locally as ''Thanjai Periya Kovil'' ("Thanjavur Big Temple") and ''Peruvudaiyar Kovil'', is a Shaivite Hindu temple built in a Chola architectural style located on the ...

dedicated to Lord Shiva was built in 1010. The massive Gopuram (ornate, upper section of shrine) is believed to have a mass of around 81 tonnes. It was the tallest temple in south India. Imperial Roman granite was quarried mainly in Egypt, and also in Turkey, and on the islands of

Elba Elba ( it, isola d'Elba, ; la, Ilva) is a Mediterranean island in Tuscany, Italy, from the coastal town of Piombino on the Italian mainland, and the largest island of the Tuscan Archipelago. It is also part of the Arcipelago Toscano National ...

and Giglio. Granite became "an integral part of the Roman language of monumental architecture". The quarrying ceased around the third century AD. Beginning in Late Antiquity the granite was reused, which since at least the early 16th century became known as

spolia ''Spolia'' (Latin: 'spoils') is repurposed building stone for new construction or decorative sculpture reused in new monuments. It is the result of an ancient and widespread practice whereby stone that has been quarried, cut and used in a built ...

. Through the process of

case-hardening Case-hardening or surface hardening is the process of hardening the surface of a metal object while allowing the metal deeper underneath to remain soft, thus forming a thin layer of harder metal at the surface. For iron or steel with low carbon ...

, granite becomes harder with age. The technology required to make tempered metal chisels was largely forgotten during the Middle Ages. As a result, Medieval stoneworkers were forced to use saws or emery to shorten ancient columns or hack them into discs.

Giorgio Vasari Giorgio Vasari (, also , ; 30 July 1511 – 27 June 1574) was an Italian Renaissance Master, who worked as a painter, architect, engineer, writer, and historian, who is best known for his work ''The Lives of the Most Excellent Painters, Sculpt ...

noted in the 16th century that granite in quarries was "far softer and easier to work than after it has lain exposed" while ancient columns, because of their "hardness and solidity have nothing to fear from fire or sword, and time itself, that drives everything to ruin, not only has not destroyed them but has not even altered their colour."

Modern

Sculpture and memorials

In some areas, granite is used for gravestones and memorials. Granite is a hard stone and requires skill to carve by hand. Until the early 18th century, in the Western world, granite could be carved only by hand tools with generally poor results. A key breakthrough was the invention of steam-powered cutting and dressing tools by Alexander MacDonald of

Aberdeen Aberdeen (; sco, Aiberdeen ; gd, Obar Dheathain ; la, Aberdonia) is a city in North East Scotland, and is the third most populous city in the country. Aberdeen is one of Scotland's 32 local government council areas (as Aberdeen City), and ...

, inspired by seeing ancient Egyptian granite carvings. In 1832, the first polished tombstone of Aberdeen granite to be erected in an English cemetery was installed at

Kensal Green Cemetery Kensal Green Cemetery is a cemetery in the Kensal Green area of Queens Park in the Royal Borough of Kensington and Chelsea in London, England. Inspired by Père Lachaise Cemetery in Paris, it was founded by the barrister George Frederic ...

. It caused a sensation in the London monumental trade and for some years all polished granite ordered came from MacDonald's. As a result of the work of sculptor William Leslie, and later Sidney Field, granite memorials became a major status symbol in Victorian Britain. The royal sarcophagus at

Frogmore Frogmore is an estate within the Home Park, adjoining Windsor Castle, in Berkshire, England. It comprises , of primarily private gardens managed by the Crown Estate. It is the location of Frogmore House, a royal retreat, and Frogmore Cottage. Th ...

was probably the pinnacle of its work, and at 30 tons one of the largest. It was not until the 1880s that rival machinery and works could compete with the MacDonald works. Modern methods of carving include using computer-controlled rotary bits and

sandblasting Sandblasting, sometimes known as abrasive blasting, is the operation of forcibly propelling a stream of abrasive material against a surface under high pressure to smooth a rough surface, roughen a smooth surface, shape a surface or remove su ...

over a rubber stencil. Leaving the letters, numbers, and emblems exposed and the remainder of the stone covered with rubber, the blaster can create virtually any kind of artwork or epitaph. The stone known as "black granite" is usually

, which has a completely different chemical composition.

Buildings

Granite has been extensively used as a

dimension stone Dimension stone is natural stone or rock that has been selected and finished (e.g., trimmed, cut, drilled, ground, or other) to specific sizes or shapes. Color, texture and pattern, and surface finish of the stone are also normal requirements. A ...

and as flooring tiles in public and commercial buildings and monuments.

in Scotland, which is constructed principally from local granite, is known as "The Granite City". Because of its abundance in

New England New England is a region comprising six states in the Northeastern United States: Connecticut, Maine, Massachusetts, New Hampshire, Rhode Island, and Vermont. It is bordered by the state of New York to the west and by the Canadian provinces ...

, granite was commonly used to build foundations for homes there. The

Granite Railway The Granite Railway was one of the first railroads in the United States, built to carry granite from Quincy, Massachusetts, to a dock on the Neponset River in Milton. From there boats carried the heavy stone to Charlestown for construction of ...

, America's first railroad, was built to haul granite from the quarries in

Quincy, Massachusetts Quincy ( ) is a coastal U.S. city in Norfolk County, Massachusetts, United States. It is the largest city in the county and a part of Greater Boston, Metropolitan Boston as one of Boston's immediate southern suburbs. Its population in 2020 was 1 ...

, to the

Neponset River The Neponset River is a river in eastern Massachusetts in the United States. Its headwaters are at the Neponset Reservoir in Foxborough, near Gillette Stadium. From there, the Neponset meanders generally northeast for about to its mouth at ...

in the 1820s.

Engineering

Engineers Engineers, as practitioners of engineering, are professionals who invent, design, analyze, build and test machines, complex systems, structures, gadgets and materials to fulfill functional objectives and requirements while considering the limit ...

have traditionally used polished granite

surface plate A surface plate is a solid, flat plate used as the main horizontal reference plane for precision inspection, marking out (layout), and tooling setup. The surface plate is often used as the baseline for all measurements to a workpiece, therefore ...

s to establish a

plane Plane(s) most often refers to: * Aero- or airplane, a powered, fixed-wing aircraft * Plane (geometry), a flat, 2-dimensional surface Plane or planes may also refer to: Biology * Plane (tree) or ''Platanus'', wetland native plant * Planes (gen ...

of reference, since they are relatively impervious, inflexible, and maintain good dimensional stability. Sandblasted

concrete Concrete is a composite material composed of fine and coarse aggregate bonded together with a fluid cement (cement paste) that hardens (cures) over time. Concrete is the second-most-used substance in the world after water, and is the most wi ...

with a heavy

aggregate Aggregate or aggregates may refer to: Computing and mathematics * collection of objects that are bound together by a root entity, otherwise known as an aggregate root. The aggregate root guarantees the consistency of changes being made within the ...

content has an appearance similar to rough granite, and is often used as a substitute when use of real granite is impractical. Granite tables are used extensively as bases or even as the entire structural body of optical instruments,

CMMs A computerized maintenance management system (CMMS), also known as a computerized maintenance management information system (CMMIS), is any software package that maintains a computer database of information about an organization's maintenance o ...

, and very high precision CNC machines because of granite's rigidity, high dimensional stability, and excellent vibration characteristics. A most unusual use of granite was as the material of the tracks of the

Haytor Granite Tramway The Haytor Granite Tramway (also called Heytor) was a tramway built to convey granite from Haytor Down, Dartmoor, Devon to the Stover Canal. It was very unusual in that the track was formed of granite sections, shaped to guide the wheels of wagon ...

, Devon, England, in 1820. Granite block is usually processed into slabs, which can be cut and shaped by a

cutting center Cutting is the separation or opening of a physical object, into two or more portions, through the application of an acutely directed force. Implements commonly used for wikt:cut, cutting are the knife and saw, or in medicine and science the scal ...

. In military engineering, Finland planted granite boulders along its

Mannerheim Line The Mannerheim Line ( fi, Mannerheim-linja, sv, Mannerheimlinjen) was a defensive fortification line on the Karelian Isthmus built by Finland against the Soviet Union. While this was never an officially designated name, during the Winter War it ...

to block invasion by Russian tanks in the

Winter War The Winter War,, sv, Vinterkriget, rus, Зи́мняя война́, r=Zimnyaya voyna. The names Soviet–Finnish War 1939–1940 (russian: link=no, Сове́тско-финская война́ 1939–1940) and Soviet–Finland War 1 ...

of 1939–40.

Paving

Granite is used as a pavement material. This is because it is extremely durable, permeable and requires little maintenance. For example, in

Sydney Sydney ( ) is the capital city of the state of New South Wales, and the most populous city in both Australia and Oceania. Located on Australia's east coast, the metropolis surrounds Sydney Harbour and extends about towards the Blue Mountain ...

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

black granite stone is used for the paving and kerbs throughout the

Central Business District A central business district (CBD) is the commercial and business centre of a city. It contains commercial space and offices, and in larger cities will often be described as a financial district. Geographically, it often coincides with the "city ...

Curling stones

Curling Curling is a sport in which players slide stones on a sheet of ice toward a target area which is segmented into four concentric circles. It is related to bowls, boules, and shuffleboard. Two teams, each with four players, take turns sliding ...

stones are traditionally fashioned of Ailsa Craig granite. The first stones were made in the 1750s, the original source being

Ailsa Craig Ailsa Craig (; sco, Ailsae Craig; gd, Creag Ealasaid) is an island of in the outer Firth of Clyde, west of mainland Scotland, upon which microgranite has long been quarried to make curling stones. The now-uninhabited island comprises the r ...

Scotland Scotland (, ) is a country that is part of the United Kingdom. Covering the northern third of the island of Great Britain, mainland Scotland has a border with England to the southeast and is otherwise surrounded by the Atlantic Ocean to the ...

. Because of the rarity of this granite, the best stones can cost as much as US$1,500. Between 60 and 70 percent of the stones used today are made from Ailsa Craig granite, although the island is now a wildlife reserve and is still used for quarrying under license for Ailsa granite by

Kays of Scotland Kays of Scotland is the only remaining UK manufacturer and supplier of curling stones. Founded in 1851, it retains exclusive rights to harvest granite from Ailsa Craig, granted by the Marquess of Ailsa. Kays of Scotland produces the only stone ...

for curling stones.

Rock climbing

Granite is one of the rocks most prized by climbers, for its steepness, soundness, crack systems, and friction. Well-known venues for granite climbing include the

Yosemite Valley Yosemite Valley ( ; ''Yosemite'', Miwok for "killer") is a U-shaped valley, glacial valley in Yosemite National Park in the western Sierra Nevada (U.S.), Sierra Nevada mountains of Central California. The valley is about long and deep, surroun ...

, the

Bugaboos The Bugaboos are a mountain range in the Purcell Mountains of eastern British Columbia, Canada. The granite spires of the group are a popular mountaineering destination. The Bugaboos are protected within Bugaboo Provincial Park. Geography The B ...

, the

Mont Blanc Mont Blanc (french: Mont Blanc ; it, Monte Bianco , both meaning "white mountain") is the highest mountain in the Alps and Western Europe, rising above sea level. It is the second-most prominent mountain in Europe, after Mount Elbrus, and i ...

massif (and peaks such as the

Aiguille du Dru The Aiguille du Dru (also the Dru or the Drus; French, Les Drus) is a mountain in the Mont Blanc massif in the French Alps. It is situated to the east of the village of Les Praz in the Chamonix valley. "Aiguille" means "needle" in French. The m ...

, the

Mourne Mountains The Mourne Mountains ( ; ga, Beanna Boirche), also called the Mournes or Mountains of Mourne, are a granite mountain range in County Down in the south-east of Northern Ireland. They include the highest mountains in Northern Ireland, the high ...

, the

Adamello-Presanella Alps The Adamello-Presanella Alps Alpine group is a mountain range in the Southern Limestone Alps mountain group of the Eastern Alps. It is located in northern Italy, in the provinces of Trentino and Brescia. The name stems from its highest peaks: Ada ...

, the

Aiguille du Midi The Aiguille du Midi () is a mountain in the Mont Blanc massif within the French Alps. It is a popular tourist destination and can be directly accessed by cable car from Chamonix that takes visitors close to Mont Blanc. Cable car The idea fo ...

and the

Grandes Jorasses The Grandes Jorasses (4,208 m; 13,806 ft) is a mountain in the Mont Blanc massif, on the boundary between Haute-Savoie in France and Aosta Valley in Italy. The first ascent of the highest peak of the mountain (''Pointe Walker'') was by Hor ...

), the

Bregaglia Bregaglia (Italian and rm, ) is a municipality in the Maloja Region in the canton of Grisons in Switzerland. It was formed by the 2010 merger of the municipalities of Bondo, Castasegna, Soglio, Stampa and Vicosoprano, all located in the Val ...

Corsica Corsica ( , Upper , Southern ; it, Corsica; ; french: Corse ; lij, Còrsega; sc, Còssiga) is an island in the Mediterranean Sea and one of the 18 regions of France. It is the fourth-largest island in the Mediterranean and lies southeast of ...

, parts of the

Karakoram The Karakoram is a mountain range in Kashmir region spanning the borders of Pakistan, China, and India, with the northwest extremity of the range extending to Afghanistan and Tajikistan. Most of the Karakoram mountain range falls under the ...

(especially the

Trango Towers __NOTOC__ The Trango Towers ( ur, ) are a family of rock towers situated in Gilgit-Baltistan, in the north of Pakistan. The Towers offer some of the largest cliffs and most challenging rock climbing in the world, and every year a number of expedi ...

), the Fitzroy Massif,

Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and gl ...

Baffin Island Baffin Island (formerly Baffin Land), in the Canadian territory of Nunavut, is the largest island in Canada and the fifth-largest island in the world. Its area is , slightly larger than Spain; its population was 13,039 as of the 2021 Canadia ...

Ogawayama is a 2,418m tall mountain on the border of Nagano and Yamanashi prefectures in Japan. It is a famous rock climbing Rock climbing is a sport in which participants climb up, across, or down natural rock formations. The goal is to reach the ...

, the Cornish coast, the

Cairngorms The Cairngorms ( gd, Am Monadh Ruadh) are a mountain range in the eastern Highlands of Scotland closely associated with the mountain Cairn Gorm. The Cairngorms became part of Scotland's second national park (the Cairngorms National Park) on 1 S ...

Sugarloaf Mountain Sugarloaf Mountain ( pt, Pão de Açúcar, ) is a peak situated in Rio de Janeiro, Brazil, at the mouth of Guanabara Bay on a peninsula that juts out into the Atlantic Ocean. Rising above the harbor, the peak is named for its resemblance to ...

in Rio de Janeiro, Brazil, and the

Stawamus Chief The Stawamus Chief, officially Stawamus Chief Mountain (often referred to as simply The Chief, or less commonly Squamish Chief), is a granitic dome located adjacent to the town of Squamish, British Columbia, Canada. It towers over above the wat ...

, British Columbia, Canada.

Gallery

File:St. Louis wharf cobbles 20090121 1.jpg, Granite was used for

setts A sett, also known as a block or Belgian block, is a broadly rectangular quarried stone used in paving roads and walkways. Formerly in widespread use, particularly on steeper streets because setts provided horses' hooves with better grip tha ...

on the

St. Louis St. Louis () is the second-largest city in Missouri, United States. It sits near the confluence of the Mississippi and the Missouri Rivers. In 2020, the city proper had a population of 301,578, while the bi-state metropolitan area, which e ...

Mississippi River, riverfront and for the piers of the Eads Bridge (background) File:Torres del Paine, Patagonia (2004).jpg, The granite peaks of the Cordillera Paine in the Chilean

File:Yosemite 20 bg 090404.jpg, alt=Half Dome, Yosemeite National Park, Half Dome, Yosemite National Park, is actually a granite arête and is a popular rock climbing destination File:Rixö granitbrott 4.jpg, Rixö red granite quarry in Lysekil, Sweden File:Auyuittuq National Park, Baffin Island, Nunavut -c.jpg, Granite in Auyuittuq National Park on Baffin Island, Canada File:Paarl Mountain04.jpg, Granite in Paarl, South Africa

References

; Citations

External links

{{Authority control Granite, Felsic rocks National symbols of Finland Plutonic rocks Sculpture materials Symbols of Wisconsin Industrial minerals

Description

Physical properties

Chemical composition

Occurrence

Origin

Alphabet classification system

Granitization

Ascent and emplacement

Weathering

Natural radiation

Industry

Uses

Antiquity

Modern

Sculpture and memorials

Buildings

Engineering

Paving

Curling stones

Rock climbing

Gallery

See also

References

Further reading

External links