DIORITE

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.