are formed of aggregates of minerals which are composed of atoms with
orderly arrangements. The earth and planets are all built of rocks,
which are important in both their geological history and mineralogy.
There are mainly three groups of rocks according to their geology:
Igneous rocks: formed by the solidification of molten rock materials.
Sedimentary rocks: produced by the accumulation of rock waste
at the Earth's surface.
3- Metamorphic rocks: formed of the alteration
of igneous and sedimentary rocks by heat and pressure.