Geological rocks of India and minerals found in them

• Geological rocks refer to the rocks found under the earth’s surface.
• In the beginning the earth was like a ball of fire.  Over time, in the course of the cooling of the hot earth, the formation of rocks started.
• Different types of rocks were formed in India at different times. A total of 6 types of rocks are found in India. On the basis of the time of formation of rocks, their order is as follows:

 (i) Rocks of Archean ordered

 (ii) Dharwad rocks

 (iii) Cuddapah rocks

 (iv) Rocks of Vindhyan order

 (v) Gondwana rocks

 (vi) Deccan Trap

Archean rocks

The first Archean order rocks were formed on Earth.  In other words, it can be said that the oldest rocks on earth are the rocks of Archean order.

Rocks of Dharwad order

The rocks of Dharwad order are named after Dharwad district of Karnataka, because these rocks were first discovered in Dharwad district itself.

The rocks of Dharwad order are found mainly in two areas in India –

 (i) Karnataka region

 (ii) in the Aravalli region

Dharwad rocks are found in three districts of Karnataka –

 (i) Dharwad District

 (ii) Bellary District

 (iii) Shimogal District

• The rocks of Dharwad order are very rich in economic terms.  The major metals of India, which include gold, manganese, copper, zinc, chromium, tungsten and iron, etc., are found under the Dharwad rocks.
• In India, under the rocks of the Sona-Dharwad order, it is found in the mines of Kolar and Hatti.

The rocks of Cuddapakram-

• After the Dharwad rocks, the Cuddapah rocks were formed.
• The rocks of Cuddapah order are named after Cuddapah district of Andhra Pradesh, because these rocks were first found in Cuddapah district of Andhra Pradesh.

Rocks of Vindhya sequence-

• Rocks of Vindhya order are found in and around the Vindhya Mountains.  Expansion of rocks of Vindhyan order is also found in some quantity in Andhra Pradesh.
• The main feature of the rocks of Vindhya order is that these rocks are famous for building materials.  For example – Limestone, sandstone, marble, etc. are found in the rocks of Vindhya order.
• Diamonds come out from the emerald mines in Madhya Pradesh and Golcondal mines in Andhra Pradesh, these mines are located under the rocks of Vindhya order.

Rocks of Gondwana order-

• Rocks of Gondwana order are mainly found in river valleys in India.
• The extension of the Godwana order of rocks is found mainly in three river basins in India.  For example – Damodar river valley, Mahanadi valley and Godavari river valley.
• About 98% of India’s coal is found only in the rocks of Gondwana order. This means that coal in India is found in Damodar river valley, Mahanadi valley and Godavari river valleys.
• Situated in the Singaraini coal field Godavari river valley in Andhra Pradesh.
• The Talcher coal field is located in the Mahanadi valley in Orissa.
• Located in Orissa, Jharia coal area is in Damodar river valley.
• Bituminous type of coal is found in India, which is considered to be the second class coal.  The first grade coal is called anthracite.