Granodiorite () is a coarse-grained ( phaneritic) intrusive

igneous rock Igneous rock (derived from the Latin word ''ignis'' meaning fire), or magmatic rock, is one of the three main rock types, the others being sedimentary and metamorphic. Igneous rock is formed through the cooling and solidification of magma o ...

similar to

granite Granite () is a coarse-grained ( phaneritic) 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 cools and solidifies un ...

, but containing more plagioclase feldspar 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 ...

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

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-sil ...

, including granodiorite.

Composition

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 us ...

, granodiorite has a greater than 20%

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 f ...

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

felsic 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, wh ...

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

. It contains a large amount of

sodium Sodium is a chemical element with the symbol Na (from Latin ''natrium'') and atomic number 11. It is a soft, silvery-white, highly reactive metal. Sodium is an alkali metal, being in group 1 of the periodic table. Its only stable ...

(Na) and

calcium Calcium is a chemical element with the 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 ...

(Ca) rich plagioclase, potassium feldspar,

, and minor amounts of muscovite

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 ...

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 ...

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

magnetite Magnetite is a mineral and one of the main iron ores, with the chemical formula Fe2+Fe3+2O4. It is one of the oxides of iron, and is ferrimagnetic; it is attracted to a magnet and can be magnetized to become a permanent magnet itself. With ...

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, printing ...

, and ulvöspinel, as well as some

sulfide minerals The sulfide minerals are a class of minerals containing sulfide (S2−) or disulfide (S22−) as the major anion. Some sulfide minerals are economically important as metal ores. The sulfide class also includes the selenides, the tellurides, ...

may also be present.

Geology

On average, the upper continental crust 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 is found beneath the surface of the Earth, and evidence of magmatism has also been discovered on other terrestrial planets and some natura ...

, which cools in batholiths or

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 ...

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

uplift Uplift may refer to: Science * Geologic uplift, a geological process ** Tectonic uplift, a geological process * Stellar uplift, the theoretical prospect of moving a stellar mass * Uplift mountains * Llano Uplift * Nemaha Uplift Business * Upli ...

and

erosion Erosion is the action of surface processes (such as water flow or wind) that removes soil, rock, or dissolved material from one location on the Earth's crust, and then transports it to another location where it is deposited. Erosion is d ...

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 a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through ...

'' grānum'' for "

grain A grain is a small, hard, dry fruit ( caryopsis) – with or without an attached 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 legum ...

", an

English language English is a West Germanic language of the Indo-European language family, with its earliest forms spoken by the inhabitants of early medieval England. It is named after the Angles, one of the ancient Germanic peoples that migrated to the ...

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 younger 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 ''creta'', ...

in the

Banat Banat (, ; hu, Bánság; sr, Банат, Banat) is a geographical and historical region that straddles Central and Eastern Europe and which is currently divided among three countries: the eastern part lies in western Romania (the counties of ...

and nearby regions of present-day

Hungary Hungary ( hu, Magyarország ) is a landlocked country in Central Europe. Spanning of the Carpathian Basin, it is bordered by Slovakia to the north, Ukraine to the northeast, Romania to the east and southeast, Serbia to the south, Cr ...

and

Serbia Serbia (, ; Serbian: , , ), officially the Republic of Serbia ( Serbian: , , ), is a landlocked country in Southeastern and Central Europe, situated at the crossroads of the Pannonian Basin and the Balkans. It shares land borders with Hu ...

. The term is also used in Australia in connection with

Gulaga / Mount Dromedary Gulaga, dual-named as Mount Dromedary and also referred to as Mount Gulaga, is mountain located in the south coast region of New South Wales, Australia. It rises above the village of Central Tilba and is within the Gulaga National Park. At its ...

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

, 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 Quartz monzonite is an intrusive, felsic, igneous rock that has an approximately equal proportion of orthoclase and plagioclase feldspars. It is typically a light colored phaneritic (coarse-grained) to porphyritic granitic rock. The plagio ...

Occurrence

United States

Plymouth Rock is a

glacial erratic A glacial erratic is glacially deposited rock differing from the type of rock native to the area in which it rests. Erratics, which take their name from the Latin word ' ("to wander"), are carried by glacial ice, often over distances of hundred ...

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

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 primar ...

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 th ...

contain large sections of granodiorite.

Egypt

Granodiorite was quarried at Mons Claudianus in the Red Sea Governorate in eastern

Egypt Egypt ( ar, مصر , ), officially the Arab Republic of Egypt, is a List of transcontinental countries, transcontinental country spanning the North Africa, northeast corner of Africa and Western Asia, southwest corner of Asia via a land bridg ...

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

Rome , established_title = Founded , established_date = 753 BC , founder = King Romulus ( legendary) , image_map = Map of comune of Rome (metropolitan city of Capital Rome, region Lazio, Italy).svg , map_caption ...

for use in major projects such as

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

and Hadrian's Villa. Additionally, granodiorite was used for the

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

. 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 area of

County Armagh County Armagh (, named after its county town, Armagh) is one of the six counties of Northern Ireland and one of the traditional thirty-two counties of Ireland. Adjoined to the southern shore of Lough Neagh, the county covers an area of an ...

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, which ...

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 ( ),Anglicized plural steles ( ); Greek plural stelai ( ), from Greek language, Greek , ''stēlē''. The Greek plural is written , ''stēlai'', but this is only rarely encountered in English. or occasionally stela (plural ''stelas'' or ...

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