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.

Photographed by Michael P. Klimetz

FINLAND