Diorite

Diorite is a dark grey intrusive igneous rock composed principally of plagioclase (with an anorthite content of less than 50%) and hornblende. Varieties deficient in hornblende and other pigmental minerals are called leucodiorite. It is used as a building and facing stone.

Diorite is a relatively rare rock; source localities include Sondrio, Italy; Thuringia and Sassonia in Germany; Finland; Romania; central Sweden; Scotland and Minnesota, USA.

An orbicular variety found in Corsica is called corsite.

See also: Granodiorite, tonalite, list of rocks