Final answer:
Rocks are made of minerals and there are three basic types of rocks: igneous, sedimentary, and metamorphic. Only seven minerals make up the majority of the Earth's crust.
Step-by-step explanation:
Rocks are made of minerals. There are three basic rock types: igneous, sedimentary, and metamorphic. Minerals are the basic building blocks of rocks, and most rocks are composed of just a few common minerals. In fact, only seven minerals make up 84% of Earth's crust. Therefore, the answer to your question is 4) three quarters of them.