Diorite
is a plutonic igneous rock composed primarily of
plagioclase feldspars, biotite,
hornblende and/or
pyroxene. It is gray to dark gray (even nearly black), and may
have a blue or green tint. It can have a salt and pepper appearance.
Diorite
is very hard, and has been used as structural stones and pavement cobblestones.
It has also been used for statuary, and can take a high polish.
