Geology of Minerals and Rocks

Marble

• Widely used metamorphic rock
• Found in various colours, white being the most common
• Polished marble gleams, used for statues and buildings

Quartzite

• Formed from sandstone
• Too hard to be used as a building stone
• Used for making statues

Minerals

• Natural underground resources
• Metallic Minerals:
  • Ores like haematite, bauxite, pyrite, and calamine
  • Used to obtain iron, aluminium, copper, and zinc
  • Used for utensils, machines, furniture, wires, coins, trains, and airplanes
  • Precious metals like gold, silver, and platinum used for jewellery
• Non-metallic Minerals:
  • Includes coal and petroleum
  • Valuable underground resources, contributing to energy supply

Coal

• Valuable mineral stored in Earth
• Used as fuel for hundreds of years
• Asia holds over one-third of the world's coal reserves
• Formed from ancient swampy forests over millions of years
  • Plants died and decayed in swamps
  • New vegetation pressed dead plants down
  • Extreme pressure transformed vegetable matter into peat, lignite, and coal
• Coal mines found in India:
  • Sohagpur (Madhya Pradesh), Dhanbad (Jharkhand), Raniganj (West Bengal), Neyveli (Tamil Nadu), and Singareni (Telangana)
• Used as fuel:
  • Cooking
  • Heating homes and buildings
  • Electricity production in power plants
  • Steam engines
  • Blast furnaces in the steel industry

Petroleum

• Also known as crude oil, rock oil, fossil fuel, and liquid sunlight
• Formed from dead remains of ancient land and sea creatures over millions of years
• Found in India:
  • Ankleshwar in Gujarat, Digboi in Assam, and Bombay High on the Mumbai coast
• Used as fuel in various forms
• Also used:
  • Dry-cleaning
  • Making lubricating oil, printing ink, and medicines
  • Paraffin wax used for making candles, waterproof cartons, and polish

Conserve Natural Resources

• “The earth has enough for everybody’s need but not enough for everybody’s greed,” Mahatma Gandhi
• Saving fuel at home by keeping stoves and machines in good condition
• Using coal and oil carefully
• Using inexhaustible sources of energy like the sun, wind, and water
• Avoiding careless use and wastage of mineral deposits
• Maintaining balance between animals and plants for their survival

Let us answer

A

• 1. The base of plains, mountains, and ocean beds is igneous rocks
• 2. This is not a main mineral of granite: calcite
• 3. The traces of ancient plants and animals found in rocks are called fossils
• 4. This is formed from trees and other plants which died millions of years ago: coal
• 5. Which of the following is obtained from petroleum and is used for making candles and waterproof cartons: paraffin wax

B

• 1. Precious metals like gold and silver are used for making utensils (False)
• 2. Asia has more than one-third of the world's coal (True)
• 3. Fossil fuel and black gold are some other names of coal (False)

Rocks and Minerals

• Rocks are made of minerals
• Minerals are natural non-living substances. A rock may contain one or more minerals
• Rocks are divided into three types: igneous, sedimentary, and metamorphic

Kinds of Rocks

Igneous Rocks

• Form the base of plains, mountains, and ocean beds
• Formed by the cooling and hardening of magma, hot liquid rock material found in underground pockets
• Magma pushed upward by pressure of other rocks
• Cools and hardens below or on the surface of the Earth, forming igneous rocks
• Magma that reaches the surface is called lava
• Type of igneous rock depends on mineral content and size of mineral particles

Granite

• Most common igneous rock on Earth's surface
• Main minerals: quartz, feldspar, and mica
• Colour (grey or pink) depends on feldspar content
• Used for buildings, statues, and streets

Pumice

• Light-coloured igneous rock
• Contains many holes and pockets formed by trapped gases during formation
• Light grey or cream-coloured
• Used as powdered pumice by dentists for polishing teeth

Obsidian

• Lava rock, resembling black glass
• Sharp edges used to make cutting tools

Sedimentary Rocks

• Cover a major portion of Earth's land surface
• Formed by the accumulation and cementation of sediments, small particles of rocks, minerals, or organic matter
• Sediments transported by water, wind, or ice, deposited in layers
• Over time, layers are compressed and cemented together under pressure, forming sedimentary rocks

Sandstone

• Formed from sand grains cemented together
• Common sedimentary rock
• Used for building stone and construction

Limestone

• Formed from calcium carbonate, shells, and skeletons of marine creatures
• Used for building stone, cement, and making lime

Shale

• Formed from fine-grained clay particles
• Easily broken and layered
• Used in making bricks and tiles

Metamorphic Rocks

• Formed when existing rocks (igneous, sedimentary, or other metamorphic rocks) are transformed by heat, pressure, or chemical reactions
• During transformation, texture, structure, and mineral composition of the rock change

Marble

• Formed from limestone under heat and pressure
• Widely used metamorphic rock
• Found in various colours, white being the most common
• Polished marble gleams, used for statues and buildings

Slate

• Formed from shale under heat and pressure
• Easily split into thin sheets
• Used for roofing, flooring, and blackboards

Quartzite

• Formed from sandstone under heat and pressure
• Very hard and durable
• Used for making statues, paving stones, and building stone