2020Minerals & Rocks - First Day Cover

The study of rock formation and classification is called petrology, and the study of minerals that the rocks are composed of is called mineralogy. Rocks form the solid outer shell of the Earth, known as the lithosphere, which consists of the crust and the solid outermost layer, and reaches up to 100 km in depth. The mantle extends to the depth of 2900 km underneath the lithosphere, and the core continues to the centre of the Earth, to the depth of 6370 km.