What are rocks made up of?
- Rocks are made of minerals.
- Rock may contain one or more minerals.
- Minerals are the building blocks of rocks; each rock is a mixture of one or more minerals.
- A single Rock may be made up of grains of different colors.
- The screens are of naturally occurring substances known as minerals.
Types of rocks
The type of a rock depends on the quality, the quantity and arrangement of minerals in it.
The earth’s crust is made of three main types of rocks. Each one of them is found in a different way.
- Igneous rocks are formed by the cooling and hardening of hot liquid Rock material, that lies in huge underground pockets of the earth which Is called magma.
- Magma gets pushed upward towards the surface of the earth because of the pressure inside. On the surface it cools to form solid rock which is called igneous rock.
- Some of the Magma cools and hardens below the surface of the earth while some flows out of the Earth surface and then hardens to form igneous rocks.
- The Magma that reaches the surface of the earth is called Lava.
- Igneous rocks are also called fiery rocks.
Types of igneous rocks
Igneous rocks are of different types depending on the kind of minerals Magma contains and the size of the mineral particles.
Different types of igneous rocks are as follows
- Granite is formed when Magma cools slowly under the surface of the Earth.
- It is very hard and has large grains.
- The color of the granite depends upon the content of its feldspar.
- Granites are white grey pink red or black depending on the mixture of mineral it contains.
The three main minerals in granite are
- Granite is very hard in easy used in making buildings and statues
- Polished granite is used for flooring.
- Small pieces of granite are used to make foundation for buildings and for paving roads.
- Pumice is a light color igneous rock that is formed when frothy Lava cools quickly on the Earth’s surface.
- As it cools, the gases in the froth remain trap inside. That is the reason why Pumice has many holes and pockets which are formed by the gases trap inside at the time of its formation.
- Pumice looks like a sponge with holes and pockets in it.
- Pumice is the light Lava rock which is light grey or cream-colored.
- Dentist use powder pumice for polishing our teeth.
- Pumice is also used as a body scrubber and also to polish furniture and floors.
- Obsidian is another Lava rock.
- It looks almost like Black glass.
- Obsidian because of its sharp edge is used to make cutting tools.
- Basalt is a fine grained and glassy igneous rock.
- Basalt is formed when volcanic Lava cools very fast and hardens quickly above the surface of the earth after coming in contact with air.
- Sedimentary rocks are formed from older rocks that have been broken into tiny fragments.
- Sedimentary rocks are formed from pebbles sand mud or clay that are deposited in in rivers lakes seas and oceans.
- At the bottom of this water bodies all this fragments sink to the bottom and form layers called sediments.
- As the layer of sediments builds up the layer below gets squeezed together. The layers are cemented together by minerals.
- Over millions of years the pressure turns this layer into Hard rocks such rocks are known as sedimentary rocks.
- Some kinds of sedimentary rocks are formed from the shells of tiny sea creatures. And the others are formed from dissolved minerals that settle by the side of oceans.
- Scientists can find out about life on earth by studying sedimentary rocks, because the traces of ancient plant and animal life for fossils are found in them.
- This may be shells, bones of animals, prints of leaves or footprints.
- Types of sedimentary rocks
- Sandstone is made from particles of send that get cemented together.
- Sandstone is a common sedimentary rock.
- Sandstone consists mostly of a mineral called quartz.
- Sandstone may be yellow, brown red or pink colored.
- Sandstone is commonly used in making buildings for example the Red fort is made out of red sandstone.
- Shale is made up of clay and mud particles that are piled up in layers.
- It is smooth.
- Shale is used to make tiles and bricks.
- Conglomerate is a rock of uneven texture.
- It looks like pebbles cemented together with minerals.
- It is formed from pebbles And gravel cemented together by minerals and sand and carried by water.
- Conglomerates are found mostly in shades of grey and orange.
- Conglomerate is used as an ornamental rock and also used for polishing ornaments.
- Limestone is made up of mineral calcite which was once a part of animal shells.
- This calcite comes from the shells and skeleton of tiny sea creatures.
- When this animal die their shells and skeletons settle on the seabed and form layers.
- It is mostly grey or white.
- Metamorphosis means change. Metamorphic rock is the result of the transformation of an existing rock.
- Metamorphic rock their original is sedimentary or igneous rock.
- Tons and tons of pressure which favours heat buildup change them to metamorphic rock.
- Deep inside the earth heat and pressure can bring about changes in their minerals .This changes their appearances and makes them tougher and harder.
- In some metamorphic rocks the minerals are broken into smaller ones while in others the minerals are stretched into flat particles.
Types of metamorphic rocks
- Marble is formed when limestone, a sedimentary rock undergoes changes.
- It is found in different colours, white being the most common.
- It can be carved and polished easily. Polished marble gleams.
- Marble is used to make statues and buildings.
- Taj Mahal is made of white marble.
- Slate is made by the metamorphosis of shale a sedimentary rock.
- Slater shiny and easily split into thin sheets.
- Slate is found in grey and other colours.
Slate is used to make slate, blackboards and roof of buildings.
- Gneiss is a metamorphic rock formed by the metamorphosis of of granite.
- It has light and dark bands.
- It is course green and has irregular bands of different colours.
- They often glitter because they contain shiny mineral mica.
- Quartzite is formed by the metamorphosis of sandstone.
- Quartzite is too hard to be used as a building stone but it is used for making statues.
- Minerals are underground natural resources.
- Some minerals found in rocks are metallic and some are non metallic.
- Some beautiful metals can be profitably obtained from metallic minerals called ores. For example hematite, bauxite, pyrite and calamine.
- We get iron aluminum copper and zinc respectively from these ores.
- Metals are commonly used for making utensils machines furnitures wires coins coaches of trains and airplanes.
- Precious metals like gold silver and platinum are used for making jewellery.
Non metallic minerals
- Coal and petroleum are valuable underground resources.
- The contribute greatly to our total energy supply.
Wealth from rocks
- Building materials
- Limestone marble and granite are used to make buildings.
- Cement is made from limestone.
- Slate is used to make the slanting roof of houses.
- Many many runs that make up rocks contain metals.
- The metals can be obtained from these rocks.
- Rocks containing metals that can be extracted are called ores. Example iron aluminium or copper are obtained from there respective ores.
- Many minerals are found in the form of crystals.
- They are hard and can be cut and polished into beautiful stones called gemstones.
- Rubies diamond sapphires and emeralds are gemstones used to make jewellery.
- Coal is a type of sedimentary rock.
- It is is formed from the remains of plants that grow in swampy forests millions of years ago.
- When they died they got buried in the swamps And begin to decay. Layers of mud sand and more dead plants deposited on them. As more And more layers deposited The heat and treasure in the latest below gradually change them.
- Due to extreme pressure the vegetable matter changed into Peat, lignite and Coal.
Uses of Coal
- For cooking
- For heating homes and buildings
- For producing electricity in power plants
- In steam engines
- In blast furnaces in the steel industry.
Crude oil or petroleum
- Petroleum or crude oil has several names like rock oil fossil fuel black gold and liquid sunlight.
- Petroleum is a fossil fuel and a 1/2 of the energy used in the world today comes from petroleum.
- It is as dark sticky liquid
- Petroleum is formed over millions of years from dead remains of plants and animals in the sea. When this plants and animals die they sang to the bottom of the sea. As the settlements build-up on the top the heat and pressure changed the remains into petroleum.
- In India petroleum is Obtain from many places like Ankleshwar in Gujarat, Digboi in Assam And Bombay high on the Mumbai coast.
Uses of petroleum
- The main use of petroleum is as fuel in different forms.
- Petrol and diesel obtained from petroleum are used to run cars busses and trucks.
- Petroleum also gives us plastic, push paints, fertilizers and cosmetics
- Petroleum is used for dry cleaning.
- Petroleum is also used for making lubricating oil printing ink and medicines.
- Parafin wax obtained from it is used to make candles waterproof cartons and Polish.
Conserve natural resources
- Due to large number of vehicles and industry the demand of the fuels has increased tremendously.
- The known reserves of petroleum may last only for 50-100 more years and those of coal for 250 years.
- We must conserve these fuels and look for alternative sources of energy such as solar energy.
- Burning off these fuels also causes Air pollution Which is one of the biggest healthy is out today.
- We must conserve our natural resources In following ways
- To save fuel at home we must keep our stoves and machines in good condition.
- We should use coal and oil very carefully. we should also use inexhaustible sources of energy like the sun wind and water.
- Mineral deposits in the Earth are limited they should not be used carelessly or wasted while mining.