Rocks and Minerals Chapter Notes | Eureka Plus Class 5: Book Solutions, Notes & Worksheets PDF Download

Introduction

• Everywhere on Earth: Rocks are present all around our planet.
• Three Types of Rocks: There are three main types of rocks—igneous, sedimentary, and metamorphic.

Igneous Rocks

Igneous Rocks on the Earth's Surface

• Hot Magma Below: Deep below the Earth, there is extremely hot magma.
• Volcanic Eruptions: Sometimes, magma rises to the surface, causing volcanic eruptions.
• Lava Formation: When magma reaches the surface, it becomes lava.
• Igneous Rocks Form: As lava cools, it turns into igneous rocks.
• Examples: Pumice and basalt are igneous rocks formed during volcanic eruptions.

Igneous Rocks Below the Earth's Surface

• Magma Settles Below: Some magma settles deep below the Earth's surface.
• Granite Formation: This magma takes a long time to cool and forms granite—an igneous rock.
• Granite Characteristics: Granite is hard, strong, and comes in many colors.
• Uses: Granite is used in building construction and monuments.

Sedimentary Rocks

• Rock Breakdown: Rocks break into tiny pieces due to wind, water, and weather.
• Transportation to Seas: Rain washes rock fragments into lakes and rivers, which then flow into the sea.
• Sediment Layers: Rock fragments settle at the sea bottom, forming layers of sediments.
• Hardening Process: The upper layers' weight compresses lower layers, gradually hardening and fusing to form sedimentary rocks.
• Examples: Sandstone, conglomerate, limestone, and shale are sedimentary rocks.

Uses of Sedimentary Rocks

• Limestone: Used for making cement and chalk (for blackboards).
• Sandstone: Used in constructing buildings.
• Shale: Used for making tiles and roofs.

Metamorphic Rocks

• Transformation Process: Existing rocks are pushed deep into the Earth.
• Heat and Pressure: Weight and heat change these rocks into metamorphic rocks over millions of years.
• Examples: Quartz and marble are metamorphic rocks.

Minerals

• Natural Substances: Minerals are found in nature, either on or below the Earth's surface.
• Solid Form: They exist in a solid form.
• Crystal Structure: Minerals are made up of crystals, which have a definite structure.
• Examples: Sea salt (on the surface) and diamond (below the surface) are minerals.

Metal Ores

• Metal Occurrence: Metals occur naturally in certain rocks called metal ores.
• Mining Process: Ores are extracted from the Earth through mining.
• Metal Separation: Extracted ores are sent to factories to separate metals.

Gemstones

• Precious Minerals: Some minerals in their pure form are called gemstones.
• Examples: Diamond, ruby, topaz, and opal are gemstones.
• Use: Gemstones are used for making expensive ornaments.

Additional Concepts

Mohs' Scale of Hardness

• Developed by Friedrich Mohs: Mohs' scale measures the hardness of minerals.
• Scale Range: The scale ranges from 1 to 10.
• Diamond Hardest: Diamond is the hardest mineral, and talc is the softest.

Protection of the Taj Mahal

• Yellowing Issue: The Taj Mahal is turning yellow over the years.
• Government Action: Motor vehicles banned within two kilometers to reduce air pollution.
• Purpose: To protect the Taj Mahal from further discoloration caused by air pollution.