Rock and Minerals
Our earth is made of soils and rock. rocks are found everywhere in mountains , sea s and ground. All rocks on the earths are made up of minerals . some rocks contain only one minerals , while , other may contains many minerals .
Types of rocks
On the basis of their formation, rocks are of three types igneous, Sedimentary and metamorphic
Igneous rocks
The centre of the earth is made of hot molten rock called magma .When a volcano erupt , this magma flows out onto the surface of the earths . The magma that reaches the surface of the earths is called larva . Larva cool down and solidifies to form hard rocks igneous rocks .
Type of igneous rocks
1.Basalt : It is an igneous rock formed by the rapid cooling of the larva on the earths surface . it is dense and dark in color and has fine grains . The edge of this rock is called is very sharp. They are called scoria rocks.
2.Granite : It is formed when magma cools below the earths surface , it is the most common igneous rocks . It may be black, grey, white or pink in colour. it is very hard and therefore, used for flooring of houses , making statues and paving roads
3. Pumice : It is light , grey or cream- colored rock formed by quick cooling of frothy lava . It is the only rock that float . It has many holes because of the air trapped insides it can float . it has many holes because of the air trapped inside it at the time of its formation .
it is used as scrubbing stone to remove rough dead skin from the body. Dentist use powdered pumice for polishing our teeth
4. Obsidian : it is formed by quick cooling of larva . it looks like a glass and is black in co
lour . due to its sharp edges, it is use in making or cutting of jewellery.
Sedimentary rocks
Sedimentary rocks are formed from pebble , sand mud or clay that gets deposited in seas and oceans . Repeated heating and cooling of mountain by rain, wind and sunlight wear down the rock. These small pieces of rocks are carried down by rivers and strong wind s into the lakes and seas . They sink to the bottom and settle down from layers called sediments . As the time passes by , more sediments build up that press down the layers. continuous pressure upon the lower layers hardens them into rocks . Such rocks are called Sedimentary rocks . major portion of the earths surface is covered with sedimentary rocks .
Types of sedimentary rocks
1.Sandstone : It is formed when small particles of sand get compressed and cemented together . Sandstone mostly consist of a mineral called quartz. it is widely used for making building . Many of our old building in Delhi, Agra and Rajasthan are are made up of sandstone .
2. Conglomerate : it is solid mass of pebbles , sand and gravel cemented together with minerals like silks and calcium carbonates . It is mostly orange or grey in colour . it can be withstand weathering . it is used in construction and for polishing ornaments .
3.Shale : it is a smooth sedimentary rocks formed when layers of clay hardens . It is used to make tiles and bricks
4. Limestone: Lime stones are made of minerals called calcite this minerals comes from Shells of sea creatures. when shells and skeletons of millions of tiny sea creature s settle down in the sea bed , that from layers . These layers harden to form limestone . Chalk is a limestone rock. cement and lime are also made using lime stone . it is also used in making glass and for separating pure metals form their ores .
Metamorphic rocks
Metamorphic rocks are formed from igneous rock or sedimentary rocks . when igneous rocks or sedimentary rocks are subkjecteds to immerse heat or pressure inside the earth's , the minerals content of these rocks changes . these changed rocks are known as metamorphic rocks . These changes make them harder and tougher .
Types of metamorphic rocks
1. Marbles : When lime stone I A sedimentary rock ) undergoes several changes , it form marbles . It is found in various colour . It can be carve and polished easily . it is used for making writing slates blackboard and roof tiles .
2. Slate: When shale ( a sedimentary rocks ) undergoes several changes , it forms slate . It is dark grey in colour . It can easily be split into thin sheets . it is used for making writing sltes black board and roof tiles .
3.Gneiss : when granite ( an igneous rock ) undergoes many changes , it form gneiss. during its formation, the minerals within it get separated to form light and dark bands of different colours that can be seen separately. it often glitters because of the presence of shiny mica
4.Quartzite: When sandstone ( A sedimentary rock) undergoes several changes , it form Quartzite . It is a hard rock and can even scratch steel. it is used to make Statues . It is also used in making glass and in ceramic industries
Minerals :
Minerals are underground natural resources . Some are simple substances and some are complex ones . rocks are also formed from minerals . Coal and marble are examples of non metallic minerals Hematite and bauxite are some examples of metallic minerals
Uses of minerals and Rocks :
We use various rocks and mineral in our daily life in different ways :
1. We get useful metals from the rocks :
Different metals are extracted or mined from minerals . A minerals from which metals can be extracted is called an ore . We get iron, aluminum , copper , and zinc from hematite , bauxite , copper pyrites and calamine ores respectively. These metals are commonly used for making utensils , machine , furniture , wires, etc . precious metals like gold , silver and platinum are used for making jewellery.
2. we get fuels from rocks and minerals
Coal, petrol, diesel, kerosene , LPG, CNG, etc are fuels that we use in our daily life .
1. Coal: It is valuable natural resource . it is formed from the remains of plants and animals buried millions of years ago. Due to high temperature and pressure inside the earths these remains of plants turned into coals . It is widely used for cooking , producing electricity , making plastics ,nylon, fertilizers and in various industries as fuels .
2. Petroleum : It is dark colored , thick crude oil, It is also called black gold . Petroleum was formed when plants and animals got buried under the sea millions of years ago. Due to high pressure and temperature , their dead bodies got converted slowly into petroleum.
We get LPG, CNG, petrol, diesel and kerosene from petroleum, it is used in automobiles as fuels and in making chemicals paints , plastics , fertilizers , medicines cosmetics and produce electricity .
3.Uranium: It is not a minerals but found with mineral. It is used for producing tremendous amount of energy . This energy is called nuclear energy . Atomic power plants us uranium to produce nuclear energy.
3. We get Gemstones form the rocks
Many minerals are very hard and found in the form of crystals . They are cut and polished into beautiful stones called gemstones . Diamond , ruby, emerald and sapphire are some gemstones
used in making Jewellery.
4. We get Fertilizers from the minerals
Some of the minerals , like sulfates and nitrates are added as fertilizers to the soil fertilizers help to maintain the soil fertility and improve plants growth.
5. Minerals are Important Nutrients :
Our body needs minerals like sodium, potassium, calcium, zinc and iron in small quantities , for health growth Need to Conserve natural resources Coal and petroleum are very useful natural resources of energy. The consumption of these fuels is increasing day by day due to large numeber of vehicles and industries , however , these is a limited amount of these resources on the earth. Once these resource used up, they will not be available again. also burning of these fuels release harmful gases , in the atmosphere causing air pollution which is the biggest heals hazard
Judicious and economical use of these resources can help us to conserve them and prevent pollution. we should conserve these fuelsd by using alernate resources of energyt like solar enerfy, wind , energy. These are unlimited and do not cause pollution .
No comments:
Post a Comment