Diorite

Diorite (IPA: ) is a grey to dark grey intermediate intrusive igneous rock composed principally of plagioclase feldspar (typically andesine), hornblende, and/or pyroxene. It can also be black or bluish-grey, and frequently has a greenish cast. Varieties deficient in hornblende and other dark minerals are called leucodiorite. It is often described as "salt and pepper" when composed largely of light-colored minerals randomly interspersed with dark minerals. When olivine and more iron-rich augite are present, the rock grades into ferrodiorite, which is transitional to gabbro. The presence of quartz makes the rock type quartz-diorite or tonalite, and if orthoclase (potassium feldspar) is present the rock type grades into granodiorite.