rocks and minerals / class-5 / chapter - 8 / science / New St. Mery English School

 

Chapter -8

Rock and Minerals

          What are rocks?                                                                                                                          

Rocks are natural mass of mineral matter that makes up the earth's crust. all rocks on the earth are made up of minerals. rocks have different colours because of different colours of minerals.

How many types of rock based on their formation?                                                                                                                          

There are three types of rocks based on their formation.

1- Igneous rock

2- Sedimentary rocks

3- Metamorphic rock

What is igneous rock?                                                                                                                          

Igneous rocks are formed by the cooling and hardening of the hot and molten rocks present in the earth's core which are called magma.

Basalt, Granite, Pumic and Obsidian are some example of igneous rocks.

 

 

What is lava?

The magma that reaches the surface of the earth is called lava.

 

What is Basalt?

Basalt is an igneous rock formed by lava cooling on the earth's surface. It is dense and dark and has fine grains.

What is Granite?

Granite is formed when magma cools below the surface of the earth. It has large grains than basalt. It contains three main minerals, feldspar, quartz and mica. Pink coloured granite contains feldspar. Grey coloured granite contains quartz. and shiny black coloured granite contains mica.

What is use of Granite?

Granite is very hard, therefor it is used in making buildings and statues. It is also used in paving roads.

What is Pumic?

Pumic is a light coloured stone formed when lava cools on the earth's surface. It has several holes because it is made from frothy lava that containing a lot of dissolved gas.

What is use of pumic?

Pumic is used as a scrubber to remove rough skin from the body.

What is Obsidian?

Obsidian is produced when lava containing a high amount of silica cools rapidly and solidifies without time for crystal growth. It is also found in dark green and brownish black colour because of presence of iron and magnesium. it is known as natural glass because of its glassy appearance.

What is use of Obsidian?

Obsidian is used in making surgical and scalpel blades.

in ancient time it was used to make tools

What are sediments?

Sediments are fragments of rock that have been broken down due to weathering like wind, ice, running water etc.

What are sedimentary rocks?

Sedimentary rocks are types of rock that are formed by the  deposition of small particles and subsequent cementation of mineral  on the floor of oceans or other bodies of water at the Earth's surface.

Ex- sandstone, conglomerate, shale, limestone.

What is sandstone?

Sandstone is a type of sedimentary rock that is formed when grains of sand become cemented together by other minerals. The cementing minerals are silica and calcite. Sand also contains a minerals quartz that helps in cementation.

What is the use of sandstone?

Sandstone is used to make buildings. The red fort and Qutab minar

are formed by red sand stone

What is conglomerate?

Conglomerate is a type of sedimentary rock that is made of pebbles cemented together by minerals.

What is shale?

Shale is a type of sedimentary rock that is mainly made up of clay.

It is used to make tiles and bricks.

What is Limestone?

Limestone is a type of sedimentary rock that are formed from animals and plants remains.It is used in making bricks. 

What is metamorphic rock?

Metamorphic rocks are the rocks that are formed under the great heat and pressure. When igneous or sedimentary rocks go under a great heat and pressure then they convert into metamorphic rock.Ex:- Slate, Marble, Quartzite etc.

What is slate?

Slate is a dark grey shiny metamorphic rock made by the metamorphism of shale. It is used in making slates, blackboards and slanting roof. 

What is marble?

Marble is a metamorphic rock that is formed from the metamorphism of limestone. It is found in various colours. It can be carved and polished easily. It is used to make statue and building.

What is gneiss?

Gneiss is a metamorphic rock that is formed from the metamorphism of granite.  

What is Quartzite?

Quartzite is a metamorphic rock that is formed from the metamorphism of sandstone.

What are minerals?

Minerals are solid substances that contain several important substances. Minerals are the building blocks of rocks. Rocks are made by minerals.

How many types of minerals?

There are two types of minerals.

1- Metallic minerals

2- Non-metallic minerals

What are metallic minerals?

Minerals that contain metals like gold, iron, aluminium, copper etc. are called metallic minerals.

What are ores?

Those minerals from which metals are extracted conveniently and profitably are called ores

Ex:- 

Hematite (Fe₂O₃) - It is an ore of Iron.

Copper pyrite (CuFeS₂ ) - It is an ore of copper. 

Pyrolusite ( MnO₂ ) - It is an ore of manganese.

Galena ( PbS ) - It is an ore of lead.

Bauxite ( Al₂O₃ . 2H₂O ) - It is an ore of Aluminum.

Zinc blend(ZnS ) - It is an ore of zinc.

Horn silver(AgCl ) - It is an ore of silver.

Cinnabar (HgS ) - It is an ore of mercury. 

What is the use of gold and silver?

Gold and silver are used for making jewellery.  

What is the use of mercury?

Mercury is used for making thermometers. 

What are Non-metallic minerals?

Minerals that are associated with sedimentary rocks are called Non-metallic minerals.  

Ex:- Graphite, mica, asbestos, potassium, magnesium, feldspar

Write some Non-metallic minerals that are used in making buildings?

basalt, granite, marble, gypsum  

What are fossil fuels? Write example.

Ans:- The fuels that are formed in nature from dead remains of plants and animals are called fossil fuels.

What is coal?

Coal is a hard, black, combustible minerals that consist mainly of carbon. It is a sedimentary rock formed from the remains of plants.

How many types of coal?

There are three types of coal.

1:- Anthracite

2:- Bituminous 

3:- Lignite 

What is petroleum?

Petroleum is naturally occurring dark- coloured viscous liquid formed trapped under the ground. It is the complex mixture of various hydrocarbons . It is insoluble in water and lighter than water.

Why is petroleum called petroleum?

 petroleum is called petroleum  because it is found under the crust of earth trapped in rocks.

How is petroleum formed?

 Petroleum was formed from organisms living in the sea. As these organisms died, their bodies settled at the bottom of the sea and got covered with layers of sand and clay. Over millions of years, absence of air, high temperature and high pressure transformed the dead organisms into petroleum and natural gas.

How can we conserve petroleum?

We can conserve fossil fuels by following ways

1- Use an alternative source of energy like solar energy and wind energy.

2- Avoid wastage of coal and petroleum.

3- Avoid using private vehicles.