• The earth is made up of rocks and soil.
• Rocks are made up of one or more minerals.

Igneous Rocks

• Igneous rocks are formed by the cooling of magma.
• The hot liquid rock that lies below the earth crust is known as magma.
• The magma that reaches out of earth crust is called as lava.

Basalt

• • It is a type of igneous rock formed by the cooling of lava.

Granite

• • It is the most common igneous rock.
  • It is formed by the cooling of magma under earth crust.
  • It is very hard and is used for making statues, buildings and for paving streets.

Pumice

• • It is a light coloured igneous rock.
  • It is thrown out during volcanic eruptions.
  • Dentists use it for polishing teeth and is also used as body scrubber.

Sedimentary Rocks

• This rock is formed by the accumulation of sediments.
• The weight of the top layers presses down the lower layers in due course of time are hardened to form rocks.

Sandstone

• • It is a very common sedimentary rock.
  • It is formed when sand grains get sedimented over one another.
  • It may be of different colours such as yellow, brown, red or pink.
  • It is often used for making buildings.
  • The Red Fort in Delhi is made up of red sandstone.

Conglomerate

• • The lower layers of sediments consisting of pebbles, sand and gravel harden to form conglomerate rock.

Limestone

• • It is formed from animal and plant remains.
  • Chalk is one of the forms of limestone.
  • It is formed from shells and skeletons of millions of tiny sea creatures.

Shale

• • It is made up of clay and mud particles.
  • It is a smooth sedimentary rock.
  • It is used to make tiles and bricks.

Fossils

• • Sedimentary rocks contain remains of plants and animals. These remains are called fossils.

Metamorphic Rocks

Due to the effect of high heat and pressure, the igneous and sedimentary rocks change into metamorphic rocks.

Slate

• • It is a metamorphic rock formed from shale.
  • It is grey and shiny.
  • It is used for making blackboards and slates.

Gneiss

• • It is formed by the metamorphosis of granite.
  • It has got light and dark bands.
  • It is used for making statues.

Marbles

• • It is formed by the metamorphosis of limestone.
  • It is used for making buildings and statues.
  • The Taj Mahal is made up of white marble.

Quartzite

• • It is formed from sandstone.
  • It is used for making statues.
• Minerals are mostly found in rocks and crystals.
• Granite is the most abundant rock.

Uses of the Rocks

• Rocks are used as a building material.
• Rocks are used as a decorative material.
• Precious stones(diamonds, rubies, emeralds and sapphires) obtained from rock are used for making ornaments.
• Diamond is one of the most valuable gemstones.
• Diamond is the hardest substance in the world.
• Minerals are added to the soil as fertilizers.
• Nitrate, phosphate, sulphate and potassium are good minerals for the growth of plants.

Coal

• • Under the earth when the dead trees and plant were subjected to great heat and pressure, after millions of years these plants finally changed into coal.

Uses of Coal

• • • It is used as fuel for cooking food.
    • It is used in thermal power plants as a fuel to produce electricity.
    • It is used in the steel industries and engines of the train.
    • It is used for the manufacture of coal gas, coal tar, pitch etc.

Petroleum

• • It is formed by the decomposition of matter, both animal and vegetable and after millions of years, they get converted into mineral matter, natural gas, petroleum and solids.

Uses of Petroleum

• • • The main use of petroleum oil is as a fuel for aeroplanes and automobiles.
    • It is used for dry cleaning woollen clothes and for making shoe polish and varnish.
    • It is used as a lubricant for machine parts.
    • Other petroleum products include cosmetics, medical ointment and paraffin wax etc.