A rocks is a naturally formed aggregate composed of one or more mineral. Rocks are classified on the basis of how they form. There are 3 major classes of rocks:
1. Igneous rocks
This rocks form by cryztallization of molten rock material. Molten rock material below earth’s surface is called magma. Molten rock material erupted above earth’s surface is called lava. Example granit and basalt.
2. Sedimentary rocks
This rocks formed from material derived from preexisting rocks by surfacial processes followed by diagenesis. Example conglomerate and breccia
3. Metamorphic rocks
This rocks formed by temperature and pressure influence. Example marmer and gneiss.