|Rock type||Igneous rock|
|Essential mineral(s)||plagioclase, alkali feldspar, quartz, biotite, hornblende|
|Accessory mineral(s)||Magnetite, ilmenite, ulvospinel, sulfide mineral|
|Similar rock(s)||Tonalite, between granite and diorite|
Granodiorite (// or //) is an intrusive igneous rock similar to granite, but containing more plagioclase than orthoclase-type feldspar. Officially, it is defined as a phaneritic igneous rock with greater than 20% quartz by volume where at least 65% of the feldspar is plagioclase. It usually contains abundant biotite mica and hornblende, giving it a darker appearance than true granite. Mica may be present in well-formed hexagonal crystals, and hornblende may appear as needle-like crystals.
On average the upper continental crust has the same composition as granodiorite.
Granodiorite is a plutonic igneous rock, formed by an intrusion of silica-rich magma, which cools in batholiths or stocks below the Earth's surface. It is usually only exposed at the surface after uplift and erosion have occurred. The volcanic equivalent of granodiorite is dacite.
The Rosetta Stone was carved out of granodiorite, and Plymouth Rock was a glacial erratic boulder of granodiorite.
Granodiorite is most often used as crushed stone for road building. However, it is also used as ornamental stone.