UPSC Geography Interior of the Earth / पृथ्वी का आंतरिक भाग Short Notes - Rocks and Minerals

Rocks and Minerals

• Rocks are naturally occuring hard substances made up of either single or multiple minerals compactly held together by cement like mineral matrix.
• As many as 87% of the minerals in the Earth's crust are silicates.

Types of Rocks

• On the basis of modes of formation there are three types of rocks.
• Igneous Rocks: Igneous rock is formed through the cooling and solidification of magma or lava such as granite and diorite.
• Sedimentary Rocks: Sedimentary rocks are derived from the process of deposition and  solidification of sediments after the process of
• denudation. For instance; Sandstone, limestone and chalk rock salts, gypsum or calcium sulphate, etc.
• Metamorphic Rocks: Metamorphic rocks arise from the transformation of existing rock types, in a process called metamorphism, which means
• "change in form". Gneiss phyllite, slate, schist, marble, quartzite, etc belongs to the category ofmetamorphic rocks.

Basic rocks Metamorphosed

1. Limestone to Marbles
2. Sand stones to Quartzites
3. Shales/ Clays to Slates / Schist
4. Granite to Gneisses
5. Gabro to Serpentine
6. Coal to Graphite

Whole Earth's Composition

Earth's Crust