Maharashtra Board Class 7 Science Chapter 16 Natural Resources PDF Download

Natural Resources

1. What is meant by natural resources?

2. Give some examples of natural resources.

We get many substances from nature. They satisfy a variety of our daily needs. Soil, stones, minerals, air, water, plants and animals on the earth are all various kinds of natural resources.

What is meant by lithosphere?

Natural Resources In The Earth's Crust

The earth's lithosphere is made up of land and the hard crust beneath it. The lithosphere is not homogeneous but is made up of many types of rocks. Resources in the earth's crust include minerals, ores, mineral oil and other fuels, rocks, water, elements, etc.

Minerals And Ores

Mineral wealth has an important place among natural resources. Minerals are formed by various processes taking place in the environment.

The rocks on the earth are mainly made of minerals. These minerals can be obtained by mining.

Only a few metals like, for example, gold, silver, copper, platinum and bismuth occur in the free state in nature. A majority of the metals occur in the form of compounds. Minerals that contain a high proportion of metal are called ores. It is economical to obtain metals from ores. The properties of minerals become clear from their characteristic colour, lustre, hardness, shape (length), cleavage or fracture and streak.

Metals are obtained from their ore by extraction and purification. Impurities of sand and soil in an ore are called 'gangue'.

1. Why are all minerals not ores?

2. What is meant by 'metal mineral' and 'non-metal mineral'?

Teacher's Note

Natural resources like soil, water, and minerals come from the earth around us. In your village or town, you can see stones used for building houses and roads.

Exam Trick

Remember: Ore = mineral with lots of metal. Not all minerals are ores, but all ores are minerals. This is like how all apples are fruits, but not all fruits are apples.

Points to Remember

Natural resources come from nature and we use them every day.
Minerals are made by nature through different processes.
Ores are special minerals that have a lot of metal in them.
We get metals from ores by mining and purification.

How Are Minerals Formed?

Minerals are formed from the magma in the earth's crust and the lava from the eruption of volcanoes, when they cool and get transformed into crystals.

Minerals are formed when solid crystals remain behind after the process of evaporation.

Minerals get transformed from one form into another due to large changes in temperature and pressure.

Some living organisms produce inorganic minerals. For example, conches, shells, etc. formed for the protection of the body.

Teacher's Note

Minerals form over millions of years under the earth. When volcanoes erupt in your area, the hot lava slowly cools down and forms new minerals.

Exam Trick

Remember the four ways minerals form: from magma, from evaporation, from pressure and heat, and from living things. Think of the mnemonic: M.E.P.L (Magma, Evaporation, Pressure, Living things).

Points to Remember

Minerals form when hot magma from volcanoes cools down.
When water dries up, crystals are left behind and form minerals.
Heat and pressure can change one mineral into another.
Some animals like shells and conches make their own minerals.

Classification Of Minerals According To Their Properties

Gems and gemlike minerals: Some important minerals like diamond, ruby, sapphire, emerald, jade, zircon are used as gems. Gems are in great demand.

Deposits of common salt are also found in the earth. This salt is called rock salt. It is used in food and in some medicines.

Pictures of various minerals. www.rocksandminerals4u.com/mineral

Obtain videos related to mining from YouTube and present them in the class.

The Indian School of Mines, Dhanbad, was founded in 1926 to impart education in mining. This institute has now been converted into an Indian Institute of Technology.

Teacher's Note

Your classroom or school uses minerals every day. The chalk on the board is made from a mineral, and the metal benches are made from iron ore.

Exam Trick

Remember: Non-metal minerals do not have much metal. Metal minerals have lots of metal. Energy minerals give us fuel. This chart helps you remember the three types easily.

Points to Remember

There are three main types of minerals: non-metal, metal, and energy minerals.
Diamonds, rubies, and sapphires are very valuable gems.
Rock salt is found under the earth and we use it for food.
Different minerals have different colors and hardness.

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