Granodiorite ( ) 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 ( ), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rocks are formed through the cooling and solidification of magma or lava. The magma can be derived from partial ...

similar to

granite Granite ( ) is a coarse-grained (phanerite, phaneritic) intrusive rock, intrusive igneous rock composed mostly of quartz, alkali feldspar, and plagioclase. It forms from magma with a high content of silica and alkali metal oxides that slowly coo ...

, but containing more

plagioclase feldspar 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 pr ...

than

orthoclase feldspar 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 ...

. The term banatite is sometimes used informally for various rocks ranging from granite to

diorite Diorite ( ) is an intrusive rock, 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 composition, inter ...

, including granodiorite. The term ''granodiorite'' was first used by G. F. Becker (1893) to describe granitic rocks in the

Sierra Nevada The Sierra Nevada ( ) is a mountain range in the Western United States, between the Central Valley of California and the Great Basin. The vast majority of the range lies in the state of California, although the Carson Range spur lies primari ...

, United States.

Composition

According to the

QAPF diagram A QAPF diagram is a doubled-triangle plot diagram used to classify igneous rocks based on their mineralogy. The acronym QAPF stands for "quartz, alkali feldspar, plagioclase, feldspathoid (foid)", which are the four mineral groups used for clas ...

, granodiorite has a greater than 20%

quartz Quartz is a hard, crystalline mineral composed of silica (silicon dioxide). The Atom, atoms are linked in a continuous framework of SiO4 silicon–oxygen Tetrahedral molecular geometry, tetrahedra, with each oxygen being shared between two tet ...

by volume, and between 65% and 90% of the feldspar is plagioclase. A greater amount of plagioclase would designate the rock as

tonalite Tonalite is an igneous rock, igneous, plutonic (Intrusive rock, intrusive) rock (geology), rock, of felsic composition, with phaneritic (coarse-grained) texture. Feldspar is present as plagioclase (typically oligoclase or andesine) with alkali fe ...

. Granodiorite is

felsic In geology, felsic is a grammatical modifier, 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 ...

to intermediate in composition. It is the intrusive igneous equivalent of 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 contr ...

igneous

dacite Dacite () is a volcanic rock formed by rapid solidification of lava that is high in silica and low in alkali metal oxides. It has a fine-grained (aphanitic) to porphyritic texture and is intermediate in composition between andesite and rhyolite. ...

. It contains a large amount of

sodium Sodium is a chemical element; it has Symbol (chemistry), symbol Na (from Neo-Latin ) and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 element, group 1 of the peri ...

(Na) and

calcium Calcium is a chemical element; it has symbol Ca and atomic number 20. As an alkaline earth metal, calcium is a reactive metal that forms a dark oxide-nitride layer when exposed to air. Its physical and chemical properties are most similar to it ...

(Ca) rich plagioclase, potassium feldspar,

, and minor amounts of

muscovite Muscovite (also known as common mica, isinglass, or potash mica) is a hydrated phyllosilicate mineral of aluminium and potassium with formula KAl2(Al Si3 O10)( F,O H)2, or ( KF)2( Al2O3)3( SiO2)6( H2O). It has a highly perfect basal cleavage y ...

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

as the lighter colored mineral components.

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 al ...

and

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 ...

s often in the form of

hornblende Hornblende is a complex silicate minerals#Inosilicates, 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 ...

are more abundant in granodiorite than in granite, giving it a more distinct two-toned or overall darker appearance. Mica may be present in well-formed hexagonal crystals, and hornblende may appear as needle-like crystals. Minor amounts of

oxide minerals The oxide mineral class includes those minerals in which the oxide anion (O2−) is bonded to one or more metal alloys. The hydroxide-bearing minerals are typically included in the oxide class. Minerals with complex anion groups such as the Sili ...

such as

magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula . It is one of the iron oxide, oxides of iron, and is ferrimagnetism, ferrimagnetic; it is attracted to a magnet and can be magnetization, magnetized to become a ...

ilmenite Ilmenite is a titanium-iron oxide mineral with the idealized formula . It is a weakly magnetic black or steel-gray solid. Ilmenite is the most important ore of titanium and the main source of titanium dioxide, which is used in paints, printi ...

, and ulvöspinel, as well as some

sulfide minerals The sulfide minerals are a class of minerals containing sulfide (S2−) or disulfide () as the major anion. Some sulfide minerals are economically important as metal ores. The sulfide class also includes the selenides, the tellurides, the ar ...

may also be present.

Geology

On average, the upper

continental crust Continental crust is the layer of igneous, metamorphic, and sedimentary 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 '' si ...

has the same composition as granodiorite. Granodiorite is a plutonic igneous rock, formed by

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 ...

of silica-rich

magma Magma () is the molten or semi-molten natural material from which all igneous rocks are formed. Magma (sometimes colloquially but incorrectly referred to as ''lava'') is found beneath the surface of the Earth, and evidence of magmatism has also ...

, which cools in batholiths or

stocks Stocks are feet and hand 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 de ...

below the Earth's surface. It is usually only exposed at the surface after uplift and

erosion Erosion is the action of surface processes (such as Surface runoff, water flow or wind) that removes soil, Rock (geology), rock, or dissolved material from one location on the Earth's crust#Crust, Earth's crust and then sediment transport, tran ...

have occurred.

Etymology

The name comes from two related rocks to which granodiorite is an intermediate:

and

. The ''gran-'' root comes from the

Latin Latin ( or ) is a classical language belonging to the Italic languages, Italic branch of the Indo-European languages. Latin was originally spoken by the Latins (Italic tribe), Latins in Latium (now known as Lazio), the lower Tiber area aroun ...

'' grānum'' for "

grain A grain is a small, hard, dry fruit (caryopsis) – with or without an attached husk, hull layer – harvested for human or animal consumption. A grain crop is a grain-producing plant. The two main types of commercial grain crops are cereals and ...

", an

English language English is a West Germanic language that developed in early medieval England and has since become a English as a lingua franca, global lingua franca. The namesake of the language is the Angles (tribe), Angles, one of the Germanic peoples th ...

derivative. Diorite is named after the contrasting colors of the rock.

Banatite

Banatite is a term used informally for various rocks ranging from granite to

, but often granodiorite, that were intruded in the

Late Cretaceous The Late Cretaceous (100.5–66 Ma) is the more recent of two epochs into which the Cretaceous Period is divided in the geologic time scale. Rock strata from this epoch form the Upper Cretaceous Series. The Cretaceous is named after ''cre ...

in the

Banat Banat ( , ; ; ; ) is a geographical and Historical regions of Central Europe, historical region located in the Pannonian Basin that straddles Central Europe, Central and Eastern Europe. It is divided among three countries: the eastern part lie ...

and nearby regions of present-day

Hungary Hungary is a landlocked country in Central Europe. Spanning much of the Pannonian Basin, Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Croatia and ...

and

Serbia , image_flag = Flag of Serbia.svg , national_motto = , image_coat = Coat of arms of Serbia.svg , national_anthem = () , image_map = , map_caption = Location of Serbia (gree ...

. The term is also used in Australia in connection with Gulaga / Mount Dromedary in

New South Wales New South Wales (commonly abbreviated as NSW) is a States and territories of Australia, state on the Eastern states of Australia, east coast of :Australia. It borders Queensland to the north, Victoria (state), Victoria to the south, and South ...

, where it is described as "a rock of intermediate composition between

quartz diorite Quartz diorite is an igneous, plutonic ( intrusive) rock, of felsic composition, with phaneritic texture. Feldspar is present as plagioclase (typically oligoclase or andesine) with 10% or less potassium feldspar. Quartz is present at between 5 an ...

and quartz monzonite".

Occurrence

United States

Plymouth Rock Plymouth Rock is a boulder in Plymouth, Massachusetts, that symbolizes the historical disembarkation site of the '' Mayflower'' Pilgrims who founded Plymouth Colony in December 1620, and has been claimed to be the Pilgrims' actual landing site. ...

is a

glacial erratic A glacial erratic is a glacially deposited rock (geology), rock differing from the type of country rock (geology), rock native to the area in which it rests. Erratics, which take their name from the Latin word ' ("to wander"), are carried by gla ...

boulder In geology, a boulder (or rarely bowlder) is a rock fragment with size greater than in diameter. Smaller pieces are called cobbles and pebbles. While a boulder may be small enough to move or roll manually, others are extremely massive. In ...

of granodiorite. The

mountains 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 area, and is usually higher ...

contain large sections of granodiorite.

Egypt

Granodiorite was quarried at

Mons Claudianus Mons Claudianus was a Roman quarry in the eastern desert of Egypt. It consisted of a garrison, a quarrying site, and civilian and workers' quarters. Granodiorite was mined for the Roman Empire where it was used as a building material. Mons Clau ...

in the

Red Sea Governorate The Red Sea Governorate ( ) is one of the 27 governorates of Egypt. Located between the Nile and the Red Sea in the southeast of the country, its southern border forms part of Egypt's border with Sudan. Its capital and largest city is Hurgha ...

in eastern

Egypt Egypt ( , ), officially the Arab Republic of Egypt, is a country spanning the Northeast Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via the Sinai Peninsula. It is bordered by the Mediterranean Sea to northe ...

from the 1st century AD to the mid-3rd century AD. Much of the quarried stone was transported to

Rome Rome (Italian language, Italian and , ) is the capital city and most populated (municipality) of Italy. It is also the administrative centre of the Lazio Regions of Italy, region and of the Metropolitan City of Rome. A special named with 2, ...

for use in major projects such as

the Pantheon The Pantheon (, ; ,Although the spelling ''Pantheon'' is standard in English, only ''Pantheum'' is found in classical Latin; see, for example, Pliny, ''Natural History (Pliny), Natural History'36.38 "Agrippas Pantheum decoravit Diogenes Athen ...

and

Hadrian's Villa Hadrian's Villa (; ) is a UNESCO World Heritage Site comprising the ruins and archaeological remains of a large Roman villa, villa complex built around AD 120 by Roman emperor Hadrian near Tivoli, Italy, Tivoli outside Rome. It is the most impos ...

. Additionally, granodiorite was used for the

Rosetta Stone The Rosetta Stone is a stele of granodiorite inscribed with three versions of a Rosetta Stone decree, decree issued in 196 BC during the Ptolemaic dynasty of ancient Egypt, Egypt, on behalf of King Ptolemy V Epiphanes. The top and middle texts ...

. The extent of Egyptian granodiorite masonry is unclear. Egypt's 6000-year history makes determining the period of usage difficult as well. Perhaps like porphyry, it was ignored by the successive dynasties of Egypt and only heavily mined during Ptolemaic or Roman times. This is evidenced by the fact that most examples of granodiorite sculpture seem to have come from later dates. However, its presence in the Rosetta Stone implies that they had considerable experience with it and the fact that only newer artifacts are found may simply be because earlier pieces were lost.

Ireland

Granodiorite is quarried in the

Newry Newry (; ) is a City status in Ireland, city in Northern Ireland, standing on the Newry River, Clanrye river in counties County Down, Down and County Armagh, Armagh. It is near Republic of Ireland–United Kingdom border, the border with the ...

area of

County Armagh County Armagh ( ) is one of the six counties of Northern Ireland and one of the traditional thirty-two counties of Ireland. It is located in the Provinces of Ireland, province of Ulster and adjoins the southern shore of Lough Neagh. It borders t ...

with the common name of 'Newry granite'.

Uses

Granodiorite is most often used as

crushed stone Crushed stone or angular rock is a form of construction aggregate, typically produced by mining a suitable rock deposit and breaking the removed rock down to the desired size using crushers. It is distinct from naturally occurring gravel, whi ...

for road building. It is also used as construction material, building facade, and paving, and as an ornamental stone. The

is a

stele A stele ( ) or stela ( )The plural in English is sometimes stelai ( ) based on direct transliteration of the Greek, sometimes stelae or stelæ ( ) based on the inflection of Greek nouns in Latin, and sometimes anglicized to steles ( ) or stela ...

made from granodiorite.Image gallery: The Rosetta Stone
British Museum (2015-03-20). Retrieved on 2015-11-19. The portico columns of

in Rome are formed from single shafts of granodiorite, each 12 metres tall by 1.5 metres in diameter.

References

* .

External links

* {{Authority control Felsic rocks Granitic rocks Intermediate rocks Plutonic rocks