|Whether it's a rock in your backyard or in a canyon wall, almost every rock you've
ever seen is made of minerals.
Rocks are different because they have different types and amounts of minerals in them. One way scientists identify rocks is by looking closely at their minerals. For example, the rock sandstone is made of the mineral quartz. The rock granite contains quartz too, but it also has other minerals like mica and feldspar.
The kinds of minerals in a rock give clues to where the rocks formed. A rock with the mineral garnet probably formed deep in the Earth, like under a mountain. A rock with the mineral muscovite probably formed on land.