Diorite
- intermediate composition between felsic and mafic
- classically a salt and pepper rock
- white to light gray plagioclase and black hornblende
- some diorites contain biotite as well as hornblende, and some contain up to 10% quartz
- If you have more than 10% quartz, you probably have a granite on your hands. If you clearly have abundant K-feldspar, you probably have a granite on your hands.
- Diorite occurs in small bodies such as sills, dikes, stocks, or as more irregular masses associated with gabbro and batholiths of granodiorite and granite.