Explanation:

There are 3 major types of Rocks:

1. Igneous rocls:

Igneous rocks are formed by the cooling of highly heated molten fluid material called as Magma. Major examples:Granite, dolerite,  Gabbro, Basalt.

2. Sedimentary rocks:

These rocks are formed by successive deposition of sediments.These sediments may be the debris eroded from any previous existing rock which may be igneous, metamorphic or old sedimentary rocks.Eg: Conglomerate, Breccia, Sandstone, Shale,Coal, limestone, chalk,Gypsum, rock salt, limestone.
3. Metamorphic Rocks:

The word metamorphic means ‘change of form’.Hence, these rocks form under the action of temperature, pressure and volume changes on original rocks.Metamorphic rocks are formed under the influence of heat or pressure on original rocks which cause to change their colour, hardness, structure and composition.
Eg:Slate, Schist, Gneiss, Quartzite, Marble etc