Sometimes alternatively known as black granite, diorite is a plutonic rock with a granular texture that is composed primarily of plagioclase feldspar and small amounts of hornblende, biotite, and other dark-colored minerals. The composition of the rock results in its characteristic “salt and pepper” appearance.

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Diorite may be dark gray to black, sometimes with a greenish hue, depending on the percentage of dark minerals it contains. The rock is formed in the continental crust above subduction zones and is found worldwide, but primarily in the roots of mountains. Diorite may occur independently, but is often associated with granite and gabbro intrusions, with which the rock sometimes merges. Diorite is utilized as a building material and as an ornamental rock, though it is not particularly high in demand, perhaps because of its dark coloration. Ancient artists, however, often used the material, which takes a good polish, to create beautiful sculptures, many of which have withstood the test of time and can be viewed in modern museums.