Granite is formed out of at least three different minerals:

---always QUARTZ

---always FELDSPAR

---always a dark mineral (usually MICA and/or HORNBLENDE,)


It can have more than one kind of feldspar in it, or have other minerals, too. Usually it is light colored. You can also see the mineral grains just by looking carefully.


It also has to have a certain amount of each of them. The recipe for GRANITE is:

27% or more Quartz

3-10% dark mineral

63-70% Feldspar and other minerals


For more information.