How Are The Three Groups Of Rocks Classified?

There are three groups of rocks in nature. These groups are classified according to different attributes. The classification is as under:
- Igneous rocks: This kind of rocks are solidified directly from molten silicates. These include magma, basalt, Pumice etc.

- Sedimentary Rocks: These rocks are formed after the erosion of igneous rocks as a sediment under the sea. These include limestone, chalk etc.

- Metamorphic Rocks: These rocks are a mixture of Sedimentary rocks and Igneous rocks. However, these rocks have been subjected to intense pressure. Examples are slate, marble etc.

All the rocks are thus made up of Igneous rocks one way or the other. Their classification is based on the external factor that has affected those rocks over time.