What Are Rocks?
Rocks are combinations of one or more minerals that we find in nature.
- Limestone is composed of only one mineral – calcite
- Basalt is commonly composed of three minerals – feldspar, pyroxene, and olivine
- Granite is commonly composed of five minerals – two kinds of feldspar, mica, amphibole, and quartz
Just like minerals, there are many different kinds of rocks. Geologists group rocks into three different categories; igneous, sedimentary, and metamorphic.
- Igneous rocks form from magma or lava
- Sedimentary rocks form from pieces of other rocks or are formed by minerals being precipitated from water
- Metamorphic rocks form by recrystallizing the minerals in a rock under high pressures or temperatures