Granodiorite

Granodiorite

Granodiorite is an intrusive igneous rock similar to granite, but contains more plagioclase than potassium feldspar. It usually contains abundant biotite mica and hornblende, giving it a darker appearance than true granite. Mica may be present in well-formed crystals, and hornblende may appear as acicular crystals. On average the upper continental crust has the same composition as granodiorite. Granodiorite is a plutonic igneous rock, formed by an intrusion of quartz-rich magma, which cools in the form of batholiths or stocks below the Earth's surface. It is usually only exposed at the surface after erosion and uplift have occurred.

FINLAND