View source for Granite

{{short description|Type of igneous rock}}
{{hatnote group|{{Other uses}}}}
{{use dmy dates|date=August 2025}}

{{Infobox rock
|name = Granite
|type = Igneous
|image = Bianco Sardo Granit mit polierter Oberfläche.jpg
|image_size = 300px
|caption = Granite containing [[plagioclase feldspar]], [[potassium feldspar]], [[quartz]], [[biotite]], and/or [[amphibole]]
|composition = [[potassium feldspar]], [[plagioclase feldspar]], and [[quartz]]
|composition_secondary = Differing amounts of [[muscovite]], [[biotite]], and [[hornblende]]-type [[amphibole]]s
|class=[[Felsic]]}}

'''Granite''' ({{IPAc-en|ˈ|ɡ|r|æ|.|n|ɪ|t}}, {{respell|GRAN|it}}) is a coarse-grained ([[phanerite|phaneritic]]) [[intrusive rock|intrusive]] [[igneous rock]] composed mostly of [[quartz]], [[alkali feldspar]], [[mica]] and [[plagioclase]]. It forms from [[magma]] with a high content of [[silica]] and [[alkali metal oxide]]s that slowly cools and solidifies underground. It is common in the [[continental crust]] of Earth, where it is found in [[igneous intrusion]]s. These range in size from [[dike (geology)|dike]]s only a few centimeters across to [[batholith]]s exposed over hundreds of square kilometers.

Granite is typical of a larger family of granitic rocks, or [[granitoid]]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 diagram|QAPF classification]]), with true granite representing granitic rocks rich in quartz and alkali feldspar. Most granitic rocks also contain [[mica]] or [[amphibole]] minerals, though a few (known as [[leucogranite]]s) contain almost no dark minerals.

Granite is nearly always massive (lacking any internal structures), hard (falling around 6.5 on the [[Mohs hardness scale]]),<ref name="JMWE">{{cite journal |last1=Anikoh |last2=Adiseda |last3=Afolabi |title=Investigation of Physical and Mechanical Properties of Selected Rock Types in Kogi State Using Hardness Tests |journal=Journal of Mining World Express |date=January 2015 |volume=4 |page=37 |doi=10.14355/mwe.2015.04.004 |doi-broken-date=13 January 2026 |url=https://www.researchgate.net/publication/285207561}}</ref> and tough. These properties have made granite a widespread construction stone throughout human history.

==Description==
{{multiple image
|align=right
|perrow=2
|total_width=400

|image1=Granite Rosa Porriño - es (rotated).jpg
|caption1=Granite with a moderate amount of plagioclase, alkali feldspar, and quartz

|image2=Granite BALMORAL.jpg
|caption2=Granite with a composition of alkali feldspar and quartz

}}
The word "granite" comes from the [[Latin]] ''granum'', a grain, in reference to the coarse-grained structure of such a [[holocrystalline|completely crystalline]] rock.<ref name="read-1943">{{cite journal |last1=Read |first1=H.H. |title=Meditations on granite: Part one |journal=Proceedings of the Geologists' Association |date=January 1943 |volume=54 |issue=2 |pages=64–85 |doi=10.1016/S0016-7878(43)80008-0|bibcode=1943PrGA...54...64R }}</ref> Granites can be predominantly white, pink, or gray in color, depending on their [[mineralogy]]. Granitic rocks mainly consist of [[feldspar]], [[quartz]], [[mica]], and [[amphibole]] [[mineral]]s, which form an interlocking, somewhat [[equigranular]] [[Matrix (geology)|matrix]] of feldspar and quartz with scattered darker [[biotite]] mica and amphibole (often [[hornblende]]) peppering the lighter color minerals. Occasionally some individual crystals ([[phenocryst]]s) are larger than the [[groundmass]], in which case the texture is known as [[porphyritic]]. A granitic rock with a porphyritic texture is known as a granite [[Porphyry (geology)|porphyry]]. [[Granitoid]] is a general, descriptive [[Field research|field]] term for lighter-colored, coarse-grained igneous rocks. [[Petrography|Petrographic]] examination is required for identification of specific types of granitoids.<ref>{{cite web |url=http://geology.about.com/od/more_igrocks/a/granitoids.htm |title=Granitoids – Granite and the Related Rocks Granodiorite, Diorite and Tonalite |publisher=Geology.about.com |date=2010-02-06 |access-date=2010-05-09 |archive-date=2009-08-10 |archive-url=https://web.archive.org/web/20090810214900/http://geology.about.com/od/more_igrocks/a/granitoids.htm |url-status=dead }}</ref> The [[alkali feldspar]] in granites is typically [[orthoclase]] or [[microcline]] and is often [[perthitic]]. The plagioclase is typically sodium-rich [[oligoclase]]. Phenocrysts are usually alkali feldspar.<ref name="blatt-tracy-1996-45">{{cite book |last1=Blatt |first1=Harvey |last2=Tracy |first2=Robert J. |title=Petrology : igneous, sedimentary, and metamorphic. |date=1996 |publisher=W.H. Freeman |location=New York |isbn=0-7167-2438-3 |page=45 |edition=2nd}}</ref>

Granitic rocks are classified according to the [[QAPF diagram]] for coarse grained [[pluton|plutonic rocks]] and are named according to the percentage of [[quartz]], alkali feldspar ([[orthoclase]], [[sanidine]], or [[microcline]]) and [[plagioclase]] feldspar on the A-Q-P half of the diagram. True granite (according to modern [[petrology|petrologic]] convention) contains between 20% and 60% quartz by volume, with 35% to 90% of the total feldspar consisting of [[alkali feldspar]]. Granitic rocks poorer in quartz are classified as [[syenite]]s or [[monzonite]]s, while granitic rocks dominated by plagioclase are classified as [[granodiorite]]s or [[tonalite]]s. Granitic rocks with alkali feldspar comprising over 90% of the total feldspar are classified as [[alkali feldspar granite]]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]].<ref name="iugs-1991">{{Cite journal|last1=Le Bas|first1=M. J.|last2=Streckeisen|first2=A. L.|title=The IUGS systematics of igneous rocks|journal=Journal of the Geological Society|volume=148|issue=5|pages=825–833|doi=10.1144/gsjgs.148.5.0825|bibcode=1991JGSoc.148..825L|year=1991|citeseerx=10.1.1.692.4446|s2cid=28548230}}</ref><ref name="BGS-1999">{{Cite journal|date=1999|title=Rock Classification Scheme - Vol 1 - Igneous|url=http://nora.nerc.ac.uk/id/eprint/3223/1/RR99006.pdf|journal=British Geological Survey: Rock Classification Scheme|volume=1|pages=1–52}}</ref><ref name="philpotts-ague-2009-139-143">{{cite book |last1=Philpotts |first1=Anthony R. |last2=Ague |first2=Jay J. |title=Principles of igneous and metamorphic petrology |date=2009 |publisher=Cambridge University Press |location=Cambridge, UK |isbn=9780521880060 |edition=2nd |pages=139–143}}</ref>
[[File:Гранит под микроскопом 2.jpg|thumb|Granite in [[thin section]], under cross-polarized light]]
True granites are further classified by the percentage of their total feldspar that is alkali feldspar. A granite containing 15% to 25% quartz and whose feldspar is 65% to 90% alkali feldspar is [[syenogranite]], while the feldspar in [[monzogranite]] is 35% to 65% alkali feldspar.<ref name="BGS-1999"/><ref name="philpotts-ague-2009-139-143"/> A granite containing both muscovite and biotite [[mica]]s is called a binary or ''two-mica'' granite. Two-mica granites are typically high in [[potassium]] and low in plagioclase, and are usually S-type granites or A-type granites, as described [[#Alphabet classification system|below]].<ref name="barbarin-1996">{{cite journal |last1=Barbarin |first1=Bernard |title=Genesis of the two main types of peraluminous granitoids |journal=Geology |date=1 April 1996 |volume=24 |issue=4 |pages=295–298 |doi=10.1130/0091-7613(1996)024<0295:GOTTMT>2.3.CO;2|bibcode=1996Geo....24..295B }}</ref><ref>{{cite journal |last1=Washington |first1=Henry S. |title=The Granites of Washington, D. C. |journal=Journal of the Washington Academy of Sciences |volume=11 |number=19 |year=1921 |pages=v459–470 |jstor=24532555}}</ref>

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 [[Potassium oxide|K<sub>2</sub>O]] + [[Sodium oxide|Na<sub>2</sub>O]] + [[Calcium oxide|CaO]] > [[Alumina|Al<sub>2</sub>O<sub>3</sub>]] > K<sub>2</sub>O + Na<sub>2</sub>O. 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 (Al<sub>2</sub>O<sub>3</sub> < K<sub>2</sub>O + Na<sub>2</sub>O) are described as ''peralkaline'', and they contain unusual sodium amphiboles such as [[riebeckite]]. Granites in which there is an excess of aluminum beyond what can be taken up in feldspars (Al<sub>2</sub>O<sub>3</sub> > CaO + K<sub>2</sub>O + Na<sub>2</sub>O) are described as ''peraluminous'', and they contain aluminum-rich minerals such as [[muscovite]].<ref>Harvey Blatt; Robert J. Tracy (1997). Petrology (2nd ed). New York: Freeman. p. 66. ISBN 0-7167-2438-3.</ref>

===Physical properties===
The average [[density]] of granite is between {{convert|2.65|and|2.75|g/cm3|lb/ft3|abbr=on}},<ref>{{cite web |url=http://www.edumine.com/xtoolkit/tables/sgtables.htm |title=Rock Types and Specific Gravities |website=EduMine |access-date=2017-08-27 |archive-url=https://web.archive.org/web/20170831000357/http://www.edumine.com/xtoolkit/tables/sgtables.htm |archive-date=2017-08-31 |url-status=dead }}</ref> its [[compressive strength]] usually lies above 200 MPa (29,000 psi), and its [[viscosity]] near [[Standard temperature and pressure|STP]] is 3–6·10<sup>20</sup> Pa·s.<ref>{{cite journal
  | last = Kumagai
  | first = Naoichi
  | author2 = Sadao Sasajima
  | author3 = Hidebumi Ito
  | title = Long-term Creep of Rocks: Results with Large Specimens Obtained in about 20 Years and Those with Small Specimens in about 3 Years
  | journal = Journal of the Society of Materials Science (Japan)
  | volume = 27
  | issue = 293
  | pages = 157–161
  |doi=10.2472/jsms.27.155
  | date = 1978| doi-access = free
  }}</ref>

The melting temperature of dry granite at ambient pressure is {{convert|1215–1260|°C|comma=off}};<ref>{{cite journal |url=http://www.minsocam.org/msa/collectors_corner/arc/tempmagmas.htm |journal=American Mineralogist |volume=14 |pages=81–94 |year=1929 |title=The temperatures of magmas |author=Larsen, Esper S.}}</ref> it is strongly reduced in the presence of water, down to 650&nbsp;°C at a few hundred megapascals of pressure.<ref>{{cite journal |author=Holland, Tim |author2=Powell, Roger |title=Calculation of phase relations involving haplogranitic melts using an internally consistent thermodynamic dataset |journal= Journal of Petrology |volume=42 |issue=4 |pages=673–683 |year=2001 |doi=10.1093/petrology/42.4.673 |bibcode=2001JPet...42..673H|doi-access=free }}</ref>

Granite has poor primary [[permeability (earth sciences)|permeability]] overall, but strong secondary permeability through cracks and fractures if they are present.

===Chemical composition===
[[File:Intrusive big.png|thumb|[[QAPF diagram]] with the granite field in pink]]
A worldwide average of the chemical composition of granite, by mass percent, based on 2485 analyses:<ref name="blatt-tracy-66">Blatt and Tracy 1996, p.66</ref>
{|
| [[Silicon dioxide|SiO<sub>2</sub>]]                 || {{bartable|72.04|% (silica)|5}}
|-
| [[Aluminium oxide|Al<sub>2</sub>O<sub>3</sub>]]     || {{bartable|14.42|% (alumina)|5}}
|-
| [[Potassium oxide|K<sub>2</sub>O]]                  || {{bartable|4.12|%|5}}
|-
| [[Sodium oxide|Na<sub>2</sub>O]]                    || {{bartable|3.69|%|5}}
|-
| [[Calcium oxide|CaO]]                               || {{bartable|1.82|%|5}}
|-
| [[Iron(II) oxide|FeO]]                              || {{bartable|1.68|%|5}}
|-
| [[Iron(III) oxide|Fe<sub>2</sub>O<sub>3</sub>]]     || {{bartable|1.22|%|5}}
|-
| [[Magnesium oxide|MgO]]                             || {{bartable|0.71|%|5}}
|-
| [[Titanium dioxide|TiO<sub>2</sub>]]                || {{bartable|0.30|%|5}}
|-
| [[Phosphorus pentoxide|P<sub>2</sub>O<sub>5</sub>]] || {{bartable|0.12|%|5}}
|-
| [[Manganese(II) oxide|MnO]]                         || {{bartable|0.05|%|5}}
|}

The medium-grained equivalent of granite is '''microgranite'''.<ref name="Microgran">{{cite web | url=https://www.open.edu/openlearn/science-maths-technology/science/geology/microgranite | title=Microgranite | publisher=[[The Open University]] | work=OpenLearn | accessdate=28 December 2021}}</ref> The [[extrusive]] igneous rock equivalent of granite is [[rhyolite]].<ref name="Haldar2014">{{cite book | title=Introduction to Mineralogy and Petrology | publisher=Elsevier |author1=Haldar, S.K.  |author2=Tišljar, J. | year=2014 | page=116 | isbn=978-0-12-408133-8}}</ref>

==Occurrence==
Granitic rock is widely distributed throughout the [[continental crust]].<ref>{{Cite book |url=https://books.google.com/books?id=iL8762HeViEC&q=granitic+rock+found+much+of+continental+crust&pg=PA27 |title=Earth Science Today |last=Singh |first=G. |date=2009 |publisher=Discovery Publishing House |isbn=9788183564380 |language=en}}</ref> Much of it was intruded during the [[Precambrian]] age; it is the most abundant [[basement rock]] that underlies the relatively thin [[sedimentary rock|sedimentary]] veneer of the continents. [[Outcrop]]s of granite tend to form [[tor (rock formation)|tors]], [[Granite dome|domes]] or [[bornhardt]]s, and rounded [[massif]]s. Granites sometimes occur in circular [[depression (geology)|depression]]s surrounded by a range of hills, formed by the [[metamorphic aureole]] or [[hornfels]]. Granite often occurs as relatively small, less than 100&nbsp;km<sup>2</sup> stock masses ([[stock (geology)|stocks]]) and in [[batholith]]s that are often associated with [[orogeny|orogenic]] [[mountain]] ranges. Small [[dike (geology)|dikes]] of granitic composition called [[aplite]]s are often associated with the margins of granitic [[intrusion (geology)|intrusion]]s. In some locations, very coarse-grained [[pegmatite]] masses occur with granite.<ref name="twidale-1982">{{cite book |last1=Twidale |first1=C. R. |title=Granite landforms |date=1982 |publisher=Elsevier Scientific Pub. Co |location=Amsterdam |isbn=0444421165 |url=https://books.google.com/books?id=Gac7AAAAQBAJ&q=occurrences+of+granite&pg=PP1 |access-date=10 October 2020}}</ref>

==Origin==
[[File:Xenolith, Yosemite National Park (19446829471).jpg|thumb|Mafic [[Enclave (geology)|enclave]] in granite rock, at [[Yosemite National Park]]]]
Granite forms from silica-rich ([[felsic]]) magmas. Felsic magmas are thought to form by addition of heat or water vapor to rock of the lower [[Earth's crust|crust]], rather than by decompression of mantle rock, as is the case with [[basalt]]ic magmas.{{sfn|Philpotts|Ague|2009|pp=15–16}} It has also been suggested that some granites found at [[convergent boundaries]] between [[tectonic plate]]s, where [[oceanic crust]] [[subducts]] below continental crust, were formed from [[Mélange|sediments]] subducted with the oceanic plate. The melted sediments would have produced magma [[intermediate magma|intermediate]] in its silica content, which became further enriched in silica as it rose through the overlying crust.<ref>{{cite journal |last1=Castro |first1=Antonio |title=The off-crust origin of granite batholiths |journal=Geoscience Frontiers |date=January 2014 |volume=5 |issue=1 |pages=63–75 |doi=10.1016/j.gsf.2013.06.006|doi-access=free |bibcode=2014GeoFr...5...63C }}</ref>

Early fractional crystallisation serves to reduce a melt in magnesium and chromium, and enrich the melt in iron, sodium, potassium, aluminum, and silicon.{{sfn|Blatt|Tracy|1996|p=128}} Further fractionation reduces the content of iron, calcium, and titanium.{{sfn|Blatt|Tracy|1996|p=172}} This is reflected in the high content of alkali feldspar and quartz in granite.

The presence of granitic rock in [[island arc]]s shows that [[fractional crystallization (geology)|fractional crystallization]] alone can convert a basaltic magma to a granitic magma, but the quantities produced are small.{{sfn|Philpotts|Ague|2009|p=378}} For example, granitic rock makes up just 4% of the exposures in the [[South Sandwich Islands]].<ref>{{cite journal |last1=Baker |first1=P. E. |title=Comparative volcanology and petrology of the atlantic island-arcs |journal=Bulletin Volcanologique |date=February 1968 |volume=32 |issue=1 |pages=189–206 |doi=10.1007/BF02596591|bibcode=1968BVol...32..189B |s2cid=128993656 }}</ref> 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 [[Igneous differentiation|differentiate]] into granites, or of [[cumulate rock|cumulates]] 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]] 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.{{sfn|Philpotts|Ague|2009|p=378}}

===Alphabet classification system===
[[File:Mineralogy igneous rocks EN.svg|thumb|upright=1.4|Mineral assemblage of igneous rocks]]
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 granite|I-type]] (igneous source) granite and [[S-type granite|S-type]] (sedimentary sources).<ref>{{cite journal |last1=Chappell |first1=B. W. |last2=White |first2=A. J. R. |title=Two contrasting granite types: 25 years later |journal=Australian Journal of Earth Sciences |date=2001 |volume=48 |issue=4 |pages=489–499 |doi=10.1046/j.1440-0952.2001.00882.x|bibcode=2001AuJES..48..489C |s2cid=33503865 |s2cid-access=free |url=https://faculty.uml.edu//nelson_eby/Research/A-type%20granites/Chappell%20and%20White%20S%20and%20I%20type%20granites.pdf |url-status=live |archive-url= https://web.archive.org/web/20221022054006/https://faculty.uml.edu/nelson_eby/research/a-type%20granites/chappell%20and%20white%20s%20and%20i%20type%20granites.pdf |archive-date= Oct 22, 2022 }}</ref> 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]] ratio,  <sup>87</sup>Sr/<sup>86</sup>Sr, of less than 0.708. <sup>87</sup>Sr is produced by radioactive decay of <sup>87</sup>Rb, 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]] deposits.{{sfn|Philpotts|Ague|2009|p=378}} I-type granites are orogenic (associated with mountain building) and usually metaluminous.{{sfn|Blatt|Tracy|1996|p=185}}

S-type granites are sodium-poor and aluminum-rich. As a result, they contain [[mica]]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]]s of metamorphosed sedimentary rock, and host [[tin]] 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).{{sfn|Philpotts|Ague|2009|p=378}} They are also orogenic but range from metaluminous to strongly peraluminous.{{sfn|Blatt|Tracy|1996|p=185}}

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.{{sfn|Philpotts|Ague|2009|p=378}}

A-type granites show a peculiar mineralogy and geochemistry, with particularly high silicon and potassium at the expense of calcium and magnesium<ref>{{cite book |last1=Winter |first1=John D. |title=Principles of igneous and metamorphic petrology |publisher=Pearson Education |year=2014 |location=Harlow |isbn=9781292021539 |page=381 |edition=Second ; Pearson new international}}</ref> and a high content of high field strength cations (cations with a small radius and high electrical charge, such as [[zirconium]], [[niobium]], [[tantalum]], and [[rare earth element]]s.){{sfn|Philpotts|Ague|2009|p=148}} They are not orogenic, forming instead over hot spots and continental rifting, and are metaluminous to mildly peralkaline and iron-rich.{{sfn|Blatt|Tracy|1996|p=185}} 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.{{sfn|Blatt|Tracy|1996|pp=203–206}}<ref>{{cite journal |last1=Whalen |first1=Joseph B. |last2=Currie |first2=Kenneth L. |last3=Chappell |first3=Bruce W. |title=A-type granites: geochemical characteristics, discrimination and petrogenesis |journal=Contributions to Mineralogy and Petrology |date=April 1987 |volume=95 |issue=4 |pages=407–419 |doi=10.1007/BF00402202|bibcode=1987CoMP...95..407W |s2cid=128541930 |url=http://www.gt-crust.ru/jour/article/view/579 |url-access=subscription }}</ref> A-type granites occur in the Koettlitz Glacier Alkaline Province in the Royal Society Range, Antarctica.<ref>{{cite journal |last1=Cottle |first1=John M. |last2=Cooper |first2=Alan F. |title=Geology, geochemistry, and geochronology of an A-type granite in the Mulock Glacier area, southern Victoria Land, Antarctica |journal=New Zealand Journal of Geology and Geophysics |date=June 2006 |volume=49 |issue=2 |pages=191–202 |doi=10.1080/00288306.2006.9515159|s2cid=128395509 |doi-access=free |bibcode=2006NZJGG..49..191C }}</ref> The rhyolites of the Yellowstone Caldera are examples of volcanic equivalents of A-type granite.<ref>{{cite journal |last1=Branney |first1=M. J. |last2=Bonnichsen |first2=B. |last3=Andrews |first3=G. D. M. |last4=Ellis |first4=B. |last5=Barry |first5=T. L. |last6=McCurry |first6=M. |title='Snake River (SR)-type' volcanism at the Yellowstone hotspot track: distinctive products from unusual, high-temperature silicic super-eruptions |journal=Bulletin of Volcanology |date=January 2008 |volume=70 |issue=3 |pages=293–314 |doi=10.1007/s00445-007-0140-7|s2cid=128878481 |hdl=2381/20233 |hdl-access=free }}</ref>

M-type granite was later proposed to cover those granites that were clearly sourced from crystallized mafic magmas, generally sourced from the mantle.<ref>{{cite journal |last1=Whalen |first1=J. B. |title=Geochemistry of an Island-Arc Plutonic Suite: the Uasilau-Yau Yau Intrusive Complex, New Britain, P.N.G |journal=Journal of Petrology |date=1 August 1985 |volume=26 |issue=3 |pages=603–632 |doi=10.1093/petrology/26.3.603|bibcode=1985JPet...26..603W }}</ref> Although the fractional crystallisation of basaltic melts can yield small amounts of granites, which are sometimes found in island arcs,<ref>{{cite journal |last1=Saito |first1=Satoshi |last2=Arima |first2=Makoto |last3=Nakajima |first3=Takashi |last4=Kimura |first4=Jun-Ichi |title=Petrogenesis of Ashigawa and Tonogi granitic intrusions, southern part of the Miocene Kofu Granitic Complex, central Japan: M-type granite in the Izu arc collision zone |journal=Journal of Mineralogical and Petrological Sciences |date=2004 |volume=99 |issue=3 |pages=104–117 |doi=10.2465/jmps.99.104|bibcode=2004JMPeS..99..104S |doi-access=free }}</ref> such granites must occur together with large amounts of basaltic rocks.{{sfn|Philpotts|Ague|2009|p=378}}

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.<ref>{{cite journal |last1=Castro |first1=A. |last2=Moreno-Ventas |first2=I. |last3=de la Rosa |first3=J.D. |title=H-type (hybrid) granitoids: a proposed revision of the granite-type classification and nomenclature |journal=Earth-Science Reviews |date=October 1991 |volume=31 |issue=3–4 |pages=237–253 |doi=10.1016/0012-8252(91)90020-G|bibcode=1991ESRv...31..237C }}</ref> However, the big difference in rheology between mafic and felsic magmas makes this process problematic in nature.{{sfn|Philpotts|Ague|2009|pp=104-105}}

===Granitization===
[[File:Migmatite (Morton Gneiss Complex, Archean, ~3.524 Ga; Cold Spring Granite Company quarry, Morton, Minnesota, USA) 3 (41897958622).jpg|thumb|Migmatite featuring felsic minerals, at [[Morton Gneiss|Morton Gneiss Complex]]]]
Granitization is an old, and largely discounted, hypothesis that granite is formed in place through extreme [[metasomatism]]. 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.{{sfn|Philpotts|Ague|2009|p=511}} 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.<ref>{{cite book |last1=McBirney |first1=Alexander R. |title=Igneous petrology |date=1984 |publisher=Freeman, Cooper |location=San Francisco, Calif. |isbn=0877353239 |pages=379–380}}</ref>

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.{{sfn|McBirney|1984|pp=379–380}} 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]]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).{{sfn|Philpotts|Ague|2009|p=44}} 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]].

The partial melting of solid rocks requires high temperatures and the addition of water or other volatiles which lower the [[solidus temperature]] (temperature at which partial melting commences) of these rocks. It was long debated whether crustal thickening in orogens (mountain belts along [[convergent boundaries]]) was sufficient to produce granite melts by [[radiogenic heating]], but recent work suggests that this is not a viable mechanism.<ref>{{cite journal |last1=Clark |first1=Chris |last2=Fitzsimons |first2=Ian C. W. |last3=Healy |first3=David |last4=Harley |first4=Simon L. |title=How Does the Continental Crust Get Really Hot? |journal=Elements |date=1 August 2011 |volume=7 |issue=4 |pages=235–240 |doi=10.2113/gselements.7.4.235|bibcode=2011Eleme...7..235C }}</ref> In-situ granitization requires heating by the asthenospheric mantle or by underplating with mantle-derived magmas.<ref>{{cite journal |last1=Zheng |first1=Y.-F. |last2=Chen |first2=R.-X. |title=Regional metamorphism at extreme conditions: Implications for orogeny at convergent plate margins |journal=Journal of Asian Earth Sciences |date=2017 |volume=145 |pages=46–73 |doi=10.1016/j.jseaes.2017.03.009|bibcode=2017JAESc.145...46Z |doi-access=free }}</ref>

==Ascent and emplacement==
Granite magmas have a density of 2.4 Mg/m<sup>3</sup>, much less than the 2.8 Mg/m<sup>3</sup> 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 (geology)|country rock]] to make room for themselves (the ''room problem'') is still a matter of research.{{sfn|Philpotts|Ague|2009|p=80}}

Two main mechanisms are thought to be important:
* Stokes [[diapir]]
* [[Fracture (geology)|Fracture propagation]]
[[File:Magma ascent mechanism.png|thumb|Schematic diagram illustrating the ascent and emplacement of magmas]]
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]]. As it rises, it heats the [[Country rock (geology)|wall rocks]], causing them to behave as a [[power-law fluid]] and thus flow around the [[intrusion]] allowing it to pass without major heat loss.<ref>{{Cite journal | doi = 10.1029/93JB03461| title = Diapiric ascent of magmas through power law crust and mantle| journal = Journal of Geophysical Research| volume = 99| issue = B5| page = 9543| year = 1994| last1 = Weinberg | first1 = R. F. | last2 = Podladchikov | first2 = Y. | s2cid = 19470906| bibcode=1994JGR....99.9543W}}</ref> This is entirely feasible in the warm, [[ductility|ductile]] 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 (geology)|Fracture]] 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 [[Dike (geology)|dykes]] which form along new or pre-existing fracture or [[fault (geology)|fault]] systems and networks of active shear zones.<ref>{{cite journal|title=Observations on the origins and ascent mechanisms of granitic magmas|journal=Journal of the Geological Society of London|year=1998|first=John|last=Clemens|volume=155|issue=Part 5|pages=843–51 | doi = 10.1144/gsjgs.155.5.0843 |url=http://eprints.kingston.ac.uk/2904/|bibcode=1998JGSoc.155..843C|s2cid=129958999|url-access=subscription}}</ref> 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 (geology)|stoping]], 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]] eruption.) There is evidence for cauldron subsidence at the Mt. Ascutney intrusion in eastern Vermont.{{sfn|Blatt|Tracy|1996|pp=21–22}} Evidence for piecemeal stoping is found in intrusions that are rimmed with ''igneous breccia'' containing fragments of country rock.{{sfn|Philpotts|Ague|2009|p=80}}

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.{{sfn|Philpotts|Ague|2009|pp=347–350}} Heat loss to the country rock means that ascent by assimilation is limited to distance similar to the height of the magma chamber.<ref>{{cite journal |title=Physical constraints on magma contamination in the continental crust: an example, the Adamello complex |journal=Philosophical Transactions of the Royal Society of London. Series A, Mathematical and Physical Sciences |date=27 April 1984 |volume=310 |issue=1514 |pages=457–472 |doi=10.1098/rsta.1984.0004|bibcode=1984RSPTA.310..457O |last1=Oxburgh |first1=E. R. |last2=McRae |first2=Tessa |s2cid=120776326 }}</ref>

==Weathering==
{{further|Weathering}}
[[File:GrusSand.JPG|thumb|[[Grus (geology)|Grus]] sand and granitoid from which it derived]]
[[Physical weathering]] occurs on a large scale in the form of [[exfoliation joint]]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]] of granite occurs when dilute [[carbonic acid]], and other acids present in rain and soil waters, [[mineral alteration|alter]] feldspar in a process called [[weathering|hydrolysis]].<ref>{{cite web |url=http://www.ucl.ac.uk/earth-sciences/impact/geology/london/citycemetery/weathering/granite |title=Granite [Weathering] |work=[[University College London]] |access-date=10 July 2014 |archive-url=https://web.archive.org/web/20141015040859/http://www.ucl.ac.uk/earth-sciences/impact/geology/london/citycemetery/weathering/granite |archive-date=15 October 2014 |url-status=dead }}</ref><ref>{{cite web |url=http://www.geolsoc.org.uk/ks3/gsl/education/resources/rockcycle/page3566.html |title= Hydrolysis |work=[[Geological Society of London]] |access-date=10 July 2014 }}</ref> As demonstrated in the following reaction, this causes potassium feldspar to form [[kaolinite]], with potassium ions, bicarbonate, and silica in solution as byproducts. An end product of granite weathering is [[grus (geology)|grus]], which is often made up of coarse-grained fragments of disintegrated granite.

{{block indent|2 KAlSi<sub>3</sub>O<sub>8</sub> + 2 H<sub>2</sub>CO<sub>3</sub> + 9 H<sub>2</sub>O → Al<sub>2</sub>Si<sub>2</sub>O<sub>5</sub>(OH)<sub>4</sub> + 4 H<sub>4</sub>SiO<sub>4</sub> + 2 K<sup>+</sup> + 2 HCO<sub>3</sub><sup>−</sup>}}

Climatic variations also influence the weathering rate of granites. For about two thousand years, the relief engravings on [[Cleopatra's Needle (London)|Cleopatra's Needle]] 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.<ref>{{cite book|last1=Marsh |first1=William M.|first2=Martin M. |last2=Kaufman|title=Physical Geography: Great Systems and Global Environments|year=2012|publisher=Cambridge University Press|isbn=9781107376649|page=510}}</ref>

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 [[soil acidification|acidification]] and [[podzol]]ization in cool humid climates as the weather-resistant quartz yields much sand.<ref>{{cite web |url=http://luitool.soilweb.ca/podzols/Land |title=Land Use Impacts |work=Land Use Impacts on Soil Quality |access-date=23 March 2022}}</ref> 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 (soil)|Cecil]] soil series a prime example of the consequent [[Ultisol]] great soil group.<ref>{{cite web |url=https://www.soils4teachers.org/files/s4t/k12outreach/nc-state-soil-booklet.pdf |title=Cecil – North Carolina State Soil |publisher=Soil Science Society of America |access-date=23 March 2022}}</ref>

Fires can also contribute to the weathering of granite. The high temperatures reached during a fire—often exceeding 1000&nbsp;°C—can cause significant physical and chemical processes that alter the rock. Among the physical processes, the differential thermal expansion of individual mineral grains, the anisotropic expansion of certain minerals, and polymorphic transformations, such as the alpha-beta quartz transition, induce substantial volume changes and generate internal stresses that damage the granite.<ref name=":0">{{Cite journal |last=Heuze |first=F. E. |date=1983-02-01 |title=High-temperature mechanical, physical and Thermal properties of granitic rocks— A review |url=https://linkinghub.elsevier.com/retrieve/pii/0148906283916091 |journal=International Journal of Rock Mechanics and Mining Sciences & Geomechanics Abstracts |volume=20 |issue=1 |pages=3–10 |doi=10.1016/0148-9062(83)91609-1 |bibcode=1983IJRMA..20....3H |issn=0148-9062|url-access=subscription }}</ref><ref name=":1">{{Cite journal |last1=Tomás |first1=R. |last2=Cano |first2=M. |last3=Pulgarín |first3=L. F. |last4=Brotóns |first4=V. |last5=Benavente |first5=D. |last6=Miranda |first6=T. |last7=Vasconcelos |first7=G. |date=2021-11-01 |title=Thermal effect of high temperatures on the physical and mechanical properties of a granite used in UNESCO World Heritage sites in north Portugal |url=https://linkinghub.elsevier.com/retrieve/pii/S2352710221006811 |journal=Journal of Building Engineering |volume=43 |article-number=102823 |doi=10.1016/j.jobe.2021.102823 |issn=2352-7102|hdl=10045/115630 |hdl-access=free }}</ref> Additionally, the decomposition of certain granite constituents, such as phyllosilicates, at specific temperatures further contributes to granite degradation. As a result, granite becomes micro-fractured, its total porosity increases, and its mechanical strength is significantly reduced.<ref name=":0" /><ref name=":1" /><ref>{{Cite journal |last1=Sha |first1=Song |last2=Rong |first2=Guan |last3=Peng |first3=Jun |last4=Li |first4=Bowen |last5=Wu |first5=Zhijun |date=2019-11-01 |title=Effect of Open-Fire-Induced Damage on Brazilian Tensile Strength and Microstructure of Granite |url=https://link.springer.com/article/10.1007/s00603-019-01871-z |journal=Rock Mechanics and Rock Engineering |language=en |volume=52 |issue=11 |pages=4189–4202 |doi=10.1007/s00603-019-01871-z |bibcode=2019RMRE...52.4189S |issn=1434-453X|url-access=subscription }}</ref>

==Natural radiation==
[[File:Fluorite-quarzo-ortoclasio.jpg|thumb|Pegmatitic granite composed of orthoclase and quartz]]
Granite is a natural source of [[Particle radiation|radiation]], like most natural stones. [[Potassium-40]] is a [[radioactive isotope]] of weak emission, and a constituent of [[alkali feldspar]], which in turn is a common component of granitic rocks, more abundant in [[alkali feldspar granite]] and [[syenite]]s. Some granites contain around 10 to 20 [[parts per million]] (ppm) of [[uranium]]. By contrast, more mafic rocks, such as tonalite, [[gabbro]] and [[diorite]], have 1 to 5 ppm uranium, and [[limestone]]s and [[sedimentary]] rocks usually have equally low amounts.

Many large granite plutons are sources for [[palaeochannel]]-hosted or roll front [[uranium ore deposits]], where the uranium washes into the [[sediment]]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]] gas,<ref>{{Cite web |last=US EPA |first=OAR |date=2015-05-04 |title=Granite Countertops and Radiation |url=https://www.epa.gov/radiation/granite-countertops-and-radiation |access-date=2024-09-12 |website=www.epa.gov |language=en}}</ref> which is formed by the decay of uranium.<ref>{{cite web|url=http://www.world-nuclear.org/images/info/decayseries.gif |title=Decay series of Uranium |access-date=2008-10-19 |url-status=dead |archive-url=https://web.archive.org/web/20120309161714/http://www.world-nuclear.org/images/info/decayseries.gif |archive-date=March 9, 2012 }}</ref> Radon gas poses significant health concerns and is the number two cause of [[lung cancer]] in the US behind smoking.<ref name="cancer1">{{cite web|url=http://www.cancer.gov/cancerTopics/factsheet/Risk/radon|title=Radon and Cancer: Questions and Answers|publisher=National Cancer Institute|access-date=2008-10-19}}</ref>

[[Thorium]] occurs in all granites.<ref name="Hubbert1956">{{cite web |url=http://www.hubbertpeak.com/hubbert/1956/1956.pdf |title=Nuclear Energy and the Fossil Fuels |author=Hubbert, M. King |author-link=M. King Hubbert |publisher=[[Shell Oil Company]]/[[American Petroleum Institute]] |date=June 1956 |access-date=2014-11-10 |url-status=dead |archive-url=https://web.archive.org/web/20080527233843/http://www.hubbertpeak.com/hubbert/1956/1956.pdf |archive-date=2008-05-27}}</ref> [[Conway granite]] has been noted for its relatively high thorium concentration of 56±6 ppm.<ref>{{Cite journal
 | pmid = 16591014
| pmc = 221093
| year = 1962
| last1 = Adams
| first1 = J. A.
| title = The Conway Granite of New Hampshire As a Major Low-Grade Thorium Resource
| journal = Proceedings of the National Academy of Sciences of the United States of America
| volume = 48
| issue = 11
| pages = 1898–905
| last2 = Kline
| first2 = M. C.
| last3 = Richardson
| first3 = K. A.
| last4 = Rogers
| first4 = J. J.
 | doi=10.1073/pnas.48.11.1898
| bibcode = 1962PNAS...48.1898A
| doi-access = free
}}</ref>

There is some concern that some granite sold as countertops or building material may be hazardous to health.<ref>{{cite web |title=Granite Countertops and Radiation |date=4 May 2015 |url=https://www.epa.gov/radiation/granite-countertops-and-radiation |publisher=United States Environmental Protection Agency |access-date=7 January 2020}}</ref> Dan Steck of [[St. John's University (New York City)|St. Johns University]] has stated<ref>{{cite book
 | chapter-url= http://www.aarst.org/proceedings/2009/PRE-AND_POST-MARKET_MEASUREMENTS_OF_GAMMA_RADIATION_AND_RADON_EMANATION_FROM_A_LARGE_SAMPLE_OF_DECORATIVE_GRANITES.pdf
 | title= Nineteenth International Radon Symposium|pages= 28–51|chapter=Pre- and Post-Market Measurements of Gamma Radiation and Radon Emanation from a Large Sample of Decorative Granites | first= Daniel J.
 | last= Steck | year=2009}}</ref> 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.<ref>{{Cite web
| archive-url = https://web.archive.org/web/20101103083546/http://www.marble-institute.com/industryresources/countertops_radon_wp.pdf
| archive-date= 3 November 2010
| url = http://www.marble-institute.com/industryresources/countertops_radon_wp.pdf
| url-status= usurped
|title= Natural Stone Countertops and Radon
| author = Environmental Health and Engineering
| year = 2008
|access-date=2023-02-20}}</ref>

==Industry and uses==
Granite and related [[marble industry|marble industries]] are considered one of the oldest industries in the world, existing as far back as [[Ancient Egypt]].<ref name="Nemerow2009">{{cite book |author=Nelson L. Nemerow |title=Environmental Engineering: Environmental Health and Safety for Municipal Infrastructure, Land Use and Planning, and Industry |url=https://books.google.com/books?id=VO-Unp1sFAMC&pg=PA40 |date=27 January 2009 |publisher=John Wiley & Sons |isbn=978-0-470-08305-5 |page=40}}</ref> Major modern exporters of granite include China, India, Italy, Brazil, Canada, Germany, Sweden, Spain and the United States.<ref name="Alexander2009">{{cite book |author=Parmodh Alexander |title=A Handbook of Minerals, Crystals, Rocks and Ores |url=https://books.google.com/books?id=4ubOP1s1nBIC&pg=PA585 |date=15 January 2009 |publisher=New India Publishing |isbn=978-81-907237-8-7 |page=585}}</ref><ref>{{Cite web |last= |date=2025-02-17 |title=Where Does the Hardest Granite Come From? |url=https://georgestones.com/where-does-the-hardest-granite-come-from/ |access-date=2025-05-14 |website=George Stone |language=en}}</ref> The term "granite" is a vague term in the construction industry as it usually includes other intrusive rocks such as gabbro and diorite besides true granite.

===Antiquity===
[[File:Cleopatra's Needle (London) inscriptions.jpg|thumb|upright|Cleopatra's Needle, London]]
The [[Red Pyramid]] of [[Ancient Egypt|Egypt]] ({{Circa|2590 BC}}), named for the light crimson hue of its exposed limestone surfaces, is the third largest of [[Egyptian pyramids]]. [[Pyramid of Menkaure]], likely dating 2510 BC, was constructed of [[limestone]] and granite blocks. The [[Great Pyramid of Giza]] (c. [[26th century BC|2580 BC]]) contains a granite [[sarcophagus]] fashioned of "Red [[Aswan]] Granite". The mostly ruined [[Black Pyramid]] dating from the reign of [[Amenemhat III]] once had a polished granite [[pyramidion]] or capstone, which is now on display in the main hall of the [[Egyptian Museum]] in [[Cairo]] (see [[Dahshur]]). Other uses in [[Ancient Egypt]] include [[column]]s, door [[lintel]]s, [[sill plate|sills]], [[jamb]]s, and wall and floor veneer.<ref>{{cite web| url=http://www.eeescience.utoledo.edu/Faculty/Harrell/Egypt/Mosques/CAIRO_Rocks_1.htm| title=Decorative Stones in the Pre-Ottoman Islamic Buildings of Cairo, Egypt| author=James A. Harrell| access-date=2008-01-06}}</ref> How the [[Egyptians]] worked the solid granite is still a matter of debate. Tool marks described by the Egyptologist Anna Serotta indicate the use of flint tools on finer work with harder stones, e.g. when producing the hieroglyphic inscriptions.<ref>{{Cite journal |last=Serotta |first=Anna |date=2023-12-19 |title=Reading Tool Marks on Egyptian Stone Sculpture |url=https://rivista.museoegizio.it/article/reading-tool-marks-on-egyptian-stone-sculpture/ |journal=Rivista del Museo Egizio |volume=7 |doi=10.29353/rime.2023.5098 |issn=2611-3295|doi-access=free }}</ref> [[Patrick Hunt (archaeologist)|Patrick Hunt]]<ref>{{cite web|url=http://hebsed.home.comcast.net/hunt.htm |title=Egyptian Genius: Stoneworking for Eternity |access-date=2008-01-06 |url-status=dead |archive-url=https://web.archive.org/web/20071014031747/http://hebsed.home.comcast.net/hunt.htm |archive-date=2007-10-14 }}</ref> has postulated that the Egyptians used [[emery (rock)|emery]], which has greater hardness.

The [[Seokguram]] Grotto in Korea is a [[Buddhist]] shrine and part of the [[Bulguksa]] 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]],<ref>{{Cite book|url=https://books.google.com/books?id=PiccCgAAQBAJ&q=seokguram+grotto&pg=PT91|title=Sculptures of Unified Silla: 통일신라의 조각|date=8 July 2015|publisher=국립중앙박물관 |isbn=9788981641306}}</ref> and along with the temple complex to which it belongs, Seokguram was added to the [[UNESCO World Heritage List]] in 1995.<ref>{{Cite web|url=http://english.visitkorea.or.kr/enu/ATR/SI_EN_3_1_1_1.jsp?cid=264260|title=Seokguram Grotto [UNESCO World Heritage] (경주 석굴암)}}</ref>

[[Rajaraja Chola I]] of the Chola Dynasty in South India built the world's first temple entirely of granite in the 11th century AD in [[Tanjore]], India. The [[Brihadeeswarar Temple]] 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.<ref>{{cite journal
| last  = Heitzman
| first = James
| title = Ritual Polity and Economy: The Transactional Network of an Imperial Temple in Medieval South India
| journal = Journal of the Economic and Social History of the Orient
| volume  = 34
| issue   = 1/2
| year    = 1991
| pages   = 23–54
| jstor=3632277
| publisher = BRILL
| doi=10.1163/156852091x00157
}}</ref>

Imperial Roman granite was quarried mainly in Egypt, and also in Turkey, and on the islands of [[Elba]] and [[Isola del Giglio|Giglio]]. Granite became "an integral part of the Roman language of monumental architecture".<ref name=a/> 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]]. Through the process of [[Case hardening of rocks|case-hardening]], granite becomes harder with age. The technology required to make [[tempered steel|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]] 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."<ref name=a>{{cite journal |last1= Waters|first1= Michael|date= 2016|title= Reviving Antiquity with Granite: Spolia and the Development of Roman Renaissance Architecture|journal=Architectural History |volume=59 |pages=149–179 |doi= 10.1017/arh.2016.5|doi-access= free}}</ref>

===Modern===

====Sculpture and memorials====
[[File:Olhares sobre o Museu do Ipiranga 2017 041.jpg|thumb|The grave of Emperor [[Pedro I of Brazil]] (who was also King of Portugal as Pedro IV) and those of his wives, [[Maria Leopoldina of Austria|Maria Leopoldina]] (not pictured, opposite his grave) and [[Amélie of Leuchtenberg|Amélie]] (left), are made of green granite. The walls as well as the floor are clad in the same material.<ref>{{cite web|author=De Matteo, Giovanna |title=Leopoldina e Teresa Cristina: descubra o que aconteceu com as "mães do Brasil"|url=https://aventurasnahistoria.uol.com.br/noticias/reportagem/leopoldina-e-tereza-cristina-descubra-o-que-aconteceu-com-as-maes-do-brasil.phtml|date=12 September 2020|language=pt|access-date=29 December 2022}}</ref> The crypt is located beneath the [[Monument to the Independence of Brazil]]]]

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]], 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]]. It caused a sensation in the London monumental trade and for some years all polished granite ordered came from MacDonald's.<ref>Friends of West Norwood Cemetery newsletter 71 [http://www.fownc.org/pdf/newsletter73.pdf Alexander MacDonald (1794–1860) – Stonemason],</ref> 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#Royal Mausoleum|Frogmore]] 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]] 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 [[gabbro]], which has a completely different chemical composition.<ref name="Geologydotcom">{{Cite web |title=Gabbro |url=https://geology.com/rocks/gabbro.shtml |access-date=2022-01-25 |website=Geology.com}}</ref>

====Buildings====
[[File:Graniittilinna.jpg|thumb|The [[Aulanko Castle|granite castle of Aulanko]] in [[Hämeenlinna]], Finland]]
Granite has been extensively used as a [[dimension stone]] and as flooring tiles in public and commercial buildings and monuments. [[Aberdeen]] in Scotland, which is constructed principally from local granite, is known as "The Granite City". Because of its abundance in [[New England]], granite was commonly used to build foundations for homes there. The [[Granite Railway]], America's first railroad, was built to haul granite from the quarries in [[Quincy, Massachusetts]], to the [[Neponset River]] in the 1820s.<ref>{{cite book |last1=Brayley |first1=A.W. |title=History of the Granite Industry of New England |date=1913 |publisher=Franklin Classics |edition=2018 |url=https://books.google.com/books?id=RasJAAAAIAAJ&q=granite+railway&pg=PP17 |access-date=3 December 2020}}</ref>

====Engineering====
[[Engineers]] have traditionally used polished granite [[surface plate]]s to establish a [[plane (mathematics)|plane]] of reference, since they are relatively impervious, inflexible, and maintain good dimensional stability. Sandblasted [[concrete]] with a heavy [[Aggregate (geology)|aggregate]] 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, [[Coordinate-measuring machine|CMMs]], 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]], Devon, England, in 1820.<ref name="Ewans">{{cite book| last=Ewans| first=M.C.| year=1966| title=The Haytor Granite Tramway and Stover Canal| publisher=David & Charles| location=Newton Abbot}}</ref> Granite block is usually processed into slabs, which can be cut and shaped by a [[cutting center]].<ref>{{cite journal |last1=Bai |first1=Shuo-wei |last2=Zhang |first2=Jin-sheng |last3=Wang |first3=Zhi |title=Selection of a sustainable technology for cutting granite block into slabs |journal=Journal of Cleaner Production |date=January 2016 |volume=112 |pages=2278–2291 |doi=10.1016/j.jclepro.2015.10.052|bibcode=2016JCPro.112.2278B }}</ref> In military engineering, Finland planted granite boulders along its [[Mannerheim Line]] to block invasion by Russian tanks in the [[Winter War]] of 1939–40.<ref>{{cite journal |last1=Chersicla |first1=Rick |title=What Free Men Can Do: The Winter War, the Use of Delay, and Lessons for the 21st Century |journal=Infantry |date=January–March 2017 |page=63 |url=https://www.benning.army.mil/infantry/magazine/issues/2017/JAN-MAR/pdf/Chersicla_WinterWar.pdf |access-date=3 December 2020 |archive-date=18 July 2020 |archive-url=https://web.archive.org/web/20200718000549/https://www.benning.army.mil/infantry/magazine/issues/2017/JAN-MAR/pdf/Chersicla_WinterWar.pdf |url-status=dead }}</ref>

====Paving====
Granite is used as a [[Pavers (flooring)|pavement]] material. This is because it is extremely durable, permeable and requires little maintenance.  For example, in [[Sydney]], Australia black granite stone is used for the paving and kerbs throughout the [[Central Business District]].<ref>{{cite web |title=Sydney Streets technical specifications |date=November 2020 |url=https://www.cityofsydney.nsw.gov.au/design-codes-technical-specifications/sydney-streets |access-date=25 January 2022}}</ref> Granite can be crushed using industrial equipment such as [[Crusher#Vertical shaft impactor (VSI)|VSI]] or [[Crusher#Cone crusher|cone crusher]].<ref>{{Cite journal |last1=Yang |first1=Jian-hong |last2=Chen |first2=Qi |last3=Zhou |first3=Jian-hua |last4=Fang |first4=Huai-ying |date=2018-11-01 |title=Experimental Study on Impact Crushing of Granite Particles |url=https://doi.org/10.1520/JTE20170180 |journal=Journal of Testing and Evaluation |volume=46 |issue=6 |pages=2376–2388 |doi=10.1520/JTE20170180 |url-access=subscription }}</ref>

====Curling stones====
[[File:Curling stones yellow.jpg|thumb|Curling stones]]
[[Curling]] stones are traditionally fashioned of Ailsa Craig granite. The first stones were made in the 1750s, the original source being [[Ailsa Craig]] in [[Scotland]]. 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, it is still quarried under license for Ailsa granite by [[Kays of Scotland]] for curling stones.<ref>{{cite web|url=http://news.nationalgeographic.com/news/2004/10/1027_041027_curling_stones.html |archive-url=https://web.archive.org/web/20041102011535/http://news.nationalgeographic.com/news/2004/10/1027_041027_curling_stones.html |url-status=dead |archive-date=November 2, 2004 |title=National Geographic News&nbsp;— Puffins Return to Scottish Island Famous for Curling Stones |publisher=National Geographic News|author=Roach, John |date=October 27, 2004}}</ref>

=== Countertops ===
In the United States, granite is a popular choice for countertops due to its affordability, aesthetic appeal, and convenience.

==Rock climbing==
Granite is one of the rocks most prized by climbers, for its steepness, soundness, crack systems, and friction.<ref>{{cite web |last1=Green |first1=Stewart |title=3 Types of Rock for Climbing: Granite, Sandstone & Limestone: The Geology of Rock Climbing |url=https://www.liveabout.com/types-of-rock-for-climbing-756145 |website=Liveabout.dotcom |publisher=Dotdash |access-date=3 December 2020}}</ref> Well-known venues for granite climbing include the [[Yosemite Valley]], the [[The Bugaboos|Bugaboos]], the [[Mont Blanc]] massif (and peaks such as the [[Aiguille du Dru]], the [[Mourne Mountains]], the [[Adamello-Presanella Alps]], the [[Aiguille du Midi]] and the [[Grandes Jorasses]]), the [[Bregaglia Range|Bregaglia]], [[Corsica]], parts of the [[Karakoram]] (especially the [[Trango Towers]]), the Fitzroy Massif and the [[Cordillera Paine|Paine Massif]] in [[Patagonia]], [[Baffin Island]], [[Ogawayama]], the [[Geography of Cornwall|Cornish coast]], the [[Cairngorms]], [[Sugarloaf Mountain]] in Rio de Janeiro, Brazil, and the [[Stawamus Chief]], British Columbia, Canada.

==Gallery==
<gallery widths="200" heights="160">
File:St. Louis wharf cobbles 20090121 1.jpg|Granite was used for [[setts]] on the [[St. Louis]] [[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 [[Chile]]an [[Patagonia]]
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
File:HuangShan.JPG|A granite peak at [[Huangshan]], China
File:The Cheesewring.jpg|The [[Cheesewring]], a granite [[Tor (rock formation)|tor]] in [[England]]
File:MawsonPlateau-03.jpg|Granite cliff overlooking Saucepan Creek, [[Mawson Plateau]], South Australia. 
</gallery>

==See also==
{{div col|colwidth=25em}}
* {{annotated link|Exfoliating granite}}
* {{annotated link|Greisen}}
* {{annotated link|Hypersolvus}}
* {{annotated link|List of rock types}}
* {{annotated link|Luxullianite}}
* {{annotated link|Orbicular granite}}
* {{annotated link|Quartz monzonite}}
* {{annotated link|Rapakivi granite}}
* {{annotated link|Subsolvus}}
{{div col end}}
{{Portal|Geology}}

== References ==
; Citations
{{Reflist}}

==Further reading==
* {{Cite book |editor1=Blasik, Miroslava |editor2=Hanika, Bogdashka |year=2012|title=Granite: Occurrence, Mineralogy and Origin|location=Hauppauge, New York|publisher=Nova Science |isbn=978-1-62081-566-3}}
* {{Cite book |author=Twidale, Charles Rowland|author-link=Charles Rowland Twidale|year=2005|title=Landforms and Geology of Granite Terrains|location=Leiden, Netherlands|publisher=A. A. Balkema |isbn=978-0-415-36435-5}}
* {{Cite book |author=Marmo, Vladimir|year=1971|title=Granite Petrology and the Granite Problem|location=Amsterdam, Netherlands|publisher=Elsevier Scientific |isbn=978-0-444-40852-5}}

==External links==
{{Commons}}

{{igneous rocks}}
{{Rock type}}
{{Stonemasonry}}

{{Authority control}}

[[Category:Granite| ]]
[[Category:Felsic rocks]]
[[Category:National symbols of Finland]]
[[Category:Plutonic rocks]]
[[Category:Sculpture materials]]
[[Category:Symbols of Wisconsin]]
[[Category:Industrial minerals]]