Petrology and Genesis of Igneous Rocks comprises of two parts - the first part deals with constituent minerals, texture, thermodynamic principles, phase relations in natural rock systems and causes of diversity in a single petrographic province. Petrology of the crust, mantle and core, the convective cycle patterns in the mantle and their relation to magma genesis and physicochemical properties of magma are also discussed in this part. Use of Isotope geology in determination of age and degree of magma mixing is included towards the end of the first part. The second part describes individual rock types, from various countries including their geochemistry, petrology and genesis.