Igneous Rocks

They are formed due to cooling, solidification and crystallization of molten Earth material(lava). Found in the volcano prone regions. 

Characteristics:

1.hard( except basalt)

2.impermeable(water cannot pass through)

3.are of crystalline structure ( the crystal size vary depending on the place and rate of solidification)

4.they do not have layers unless repeated volcanic eruption have created them eg at khandala, valleys of koyna river. 

5.they do not contain fossils within them due to there origin lying in the immense heated and pressurized region.

6.are not affected by the chemical weathering except basalt etc.