diorite

noun

1. a granular igneous rock consisting essentially of plagioclase feldspar and hornblende.

noun

1. a dark coarse-grained igneous plutonic rock consisting of plagioclase feldspar and ferromagnesian minerals such as hornblende

1. A gray, coarse-grained plutonic rock. Diorite consists mainly of sodium-rich plagioclase and one or more mafic minerals such as biotite, hornblende, or pyroxene. It is the coarse-grained equivalent of andesite.