To Identify Megascopically the Igneous Rocks which are characterized by vesicular structure, amygdaloidal structure and Aphanitic structure if they are volcanic. If they are Hypabyssal or plutonic, they are dense, compact and exhibit interlocking texture.

A central goal of studies in igneous petrology is to understand the factors that lead to the compositional diversity of magmatic rocks and the related issue of the origin of the Earth's crust and mantle.