Chapter Notes

What is a Mineral?

A mineral is a homogenous, naturally occurring substance with a definable internal structure. This is the definition used by geologists. Minerals are found all around us in nature and can be as hard as a diamond or as soft as talc.

Our planet's crust is made of rocks, and rocks are simply combinations of minerals. Some rocks, like limestone, are made of just one mineral. However, most rocks are a mixture of several different minerals in various amounts. While over 2,000 minerals have been identified, only a few are common in most rocks.

The variety in minerals—their different colors, hardness, shine (lustre), and density—comes from the specific physical and chemical conditions under which they were formed. Geologists use these properties to tell minerals apart and classify them.

Study of Minerals by Geographers and Geologists

Geographers and geologists study minerals, but with different focuses:

• Geographers study minerals as a part of the Earth's crust to better understand landforms. They are interested in where mineral resources are located and the economic activities, like mining or industry, that are associated with them.
• Geologists are more focused on how minerals are formed, their age, and their physical and chemical makeup.

Mode of Occurrence of Minerals

Minerals are usually found in "ores". An ore is a natural rock or sediment that contains one or more valuable minerals, typically mixed with other, less valuable elements. For mining to be profitable, the mineral content in the ore must be high enough to make extraction commercially viable. The way minerals are found in the earth determines how easily and cheaply they can be mined.

Minerals generally occur in these five forms:

1. In Igneous and Metamorphic Rocks: Minerals can be found in the cracks, faults, and joints of these rocks.

   • Smaller occurrences are called veins.
   • Larger occurrences are called lodes.
   • They form when minerals in liquid, molten, or gaseous forms are forced upward through cavities, where they cool and solidify.
   • Examples: Tin, copper, zinc, and lead.

2. In Sedimentary Rocks: Many minerals in sedimentary rocks occur in layers or beds.

   • They are formed through deposition, accumulation, and concentration in horizontal layers (strata).
   • Examples: Coal and some types of iron ore were formed this way over long periods under great heat and pressure. Gypsum, potash salt, and sodium salt are formed by evaporation in dry regions.

3. Through Decomposition of Surface Rocks: This process involves the weathering of surface rocks and the washing away of soluble parts, leaving behind a residual mass of weathered material containing ores.

   • Example: Bauxite, the ore from which we get aluminium, is formed this way.

4. As Alluvial Deposits (Placer Deposits): These are deposits found in the sands of valley floors and at the base of hills.

   • Placer deposits contain minerals that are not corroded by water.
   • Examples: Gold, silver, tin, and platinum.

5. In Ocean Waters and Beds: The ocean contains vast quantities of minerals, but most are too spread out to be economically useful.

   • Examples from ocean water: Common salt, magnesium, and bromine.
   • Examples from ocean beds: The ocean floor is rich in manganese nodules.

Classification of Minerals

For general and commercial purposes, minerals are broadly classified as follows:

• Metallic Minerals: These contain metal.
  • Ferrous: Minerals that contain iron. (e.g., iron ore, manganese)
  • Non-Ferrous: Minerals that contain metals other than iron. (e.g., copper, bauxite, lead, zinc, gold)
  • Precious: High-value minerals. (e.g., gold, silver, platinum)
• Non-Metallic Minerals: These do not contain metals. (e.g., mica, salt, potash, limestone)
• Energy Minerals: These are used to produce energy. (e.g., coal, petroleum, natural gas)

Distribution of Minerals in India

India has rich and varied mineral resources, but they are not evenly distributed across the country. This is due to differences in geological structures and formation processes.

• Peninsular Rocks: This region contains most of India's reserves of coal, metallic minerals, mica, and many other non-metallic minerals.
• Gujarat and Assam: The sedimentary rocks in these states hold most of the petroleum deposits.
• Rajasthan: This region has reserves of many non-ferrous minerals.
• North Indian Plains: The vast alluvial plains of north India are almost completely devoid of economic minerals.

Ferrous Minerals

Ferrous minerals, which contain iron, are the foundation of metallurgical industries. They account for about three-fourths of the total value of metallic mineral production in India. After meeting its own needs, India exports substantial quantities of ferrous minerals.

Iron Ore

Iron ore is the most basic mineral and is considered the backbone of industrial development. India is fortunate to have abundant resources of good quality iron ores.

• Magnetite: This is the finest iron ore, with a very high iron content of up to 70%. It has excellent magnetic qualities, making it particularly valuable for the electrical industry.
• Hematite: This is the most important industrial iron ore in terms of the quantity used. Its iron content is slightly lower than magnetite, at 50-60%.

In 2018-19, about 97% of India's iron ore production came from Odisha, Chhattisgarh, Karnataka, and Jharkhand.

Major Iron Ore Belts in India

• Odisha-Jharkhand Belt: High-grade hematite ore is found in the Badampahar mines (Mayurbhanj and Kendujhar districts) in Odisha and the Gua and Noamundi mines (Singbhum district) in Jharkhand.
• Durg-Bastar-Chandrapur Belt: Located in Chhattisgarh and Maharashtra, this belt contains very high-grade hematite in the Bailadila range of hills. This ore has the best physical properties for steel-making and is exported to Japan and South Korea through the Vishakhapatnam port.
• Ballari-Chitradurga-Chikkamagaluru-Tumakuru Belt: This belt in Karnataka has large reserves of iron ore. The Kudremukh mines, a 100% export unit, are located here and are known to be one of the largest deposits in the world. The ore is transported as a slurry (a semi-liquid mixture) through a pipeline to a port near Mangaluru.
• Maharashtra-Goa Belt: This includes Goa and the Ratnagiri district of Maharashtra. Although the ores here are not of very high quality, they are still efficiently mined and exported through the Marmagao port.

Manganese

Manganese is a key raw material for manufacturing steel and ferro-manganese alloys.

• Nearly 10 kg of manganese is required to manufacture one tonne of steel.
• It is also used to make bleaching powder, insecticides, and paints.

Non-Ferrous Minerals

India's reserves and production of non-ferrous minerals are not very satisfactory. However, minerals like copper, bauxite, lead, zinc, and gold are vital for metallurgical, engineering, and electrical industries.

Copper

India is critically deficient in the reserve and production of copper.

• Properties: Copper is malleable (can be hammered into thin sheets), ductile (can be drawn into wires), and a good conductor of electricity.
• Uses: Because of these properties, it is mainly used in electrical cables, electronics, and chemical industries.
• Leading Producers: Balaghat mines in Madhya Pradesh, Khetri mines in Rajasthan, and the Singhbhum district of Jharkhand.

Bauxite

Bauxite is a clay-like substance from which alumina and, later, aluminium are obtained. Bauxite deposits are formed by the decomposition of rocks rich in aluminium silicates.

Aluminium is a very important metal because it combines the strength of metals like iron with extreme lightness. It is also a good conductor and is highly malleable.

• Major Deposits in India: Amarkantak plateau, Maikal hills, and the plateau region of Bilaspur-Katni.
• Largest Producer: Odisha was the largest bauxite-producing state in 2018-19. The Panchpatmali deposits in the Koraput district are the most important in the state.

Non-Metallic Minerals

Mica

Mica is a mineral made up of a series of plates or leaves that split easily into thin sheets. These sheets can be so thin that a thousand of them can be layered into a mica sheet just a few centimeters high.

• Properties: Mica has excellent di-electric strength, a low power loss factor, insulating properties, and resistance to high voltage.
• Uses: These properties make mica one of the most indispensable minerals for the electric and electronic industries.
• Major Deposits:
  • The northern edge of the Chota Nagpur plateau. The Koderma-Gaya-Hazaribagh belt of Jharkhand is the leading producer.
  • Around Ajmer in Rajasthan.
  • Nellore mica belt in Andhra Pradesh.

Rock Minerals

Limestone

Limestone is found in sedimentary rocks and is composed of calcium carbonates or calcium and magnesium carbonates.

• Uses: It is the basic raw material for the cement industry and is essential for smelting iron ore in a blast furnace.

Hazards of Mining

Mining is a hazardous industry that has significant impacts on the health of miners and the environment.

• Health Risks for Miners:
  • Inhaling dust and noxious fumes can lead to pulmonary diseases.
  • There is a constant threat of collapsing mine roofs, flooding (inundation), and fires in coal mines.
• Environmental Impacts:
  • Mining contaminates water sources in the region.
  • Dumping waste and slurry degrades land and soil.
  • It leads to increased pollution in streams and rivers.

Conservation of Mineral Resources

Minerals are non-renewable resources, and it is crucial to use them in a planned and sustainable manner.

• Improved Technology: We need to develop technologies that allow the use of low-grade ores at low costs.
• Recycling: Recycling metals and using scrap metals helps conserve resources.
• Substitutes: Using other materials as substitutes for minerals can reduce demand.

Energy Resources

Energy is essential for all activities, from cooking and lighting our homes to powering vehicles and machinery in industries. Energy resources can be classified into two main types:

• Conventional Sources: These are traditional sources of energy that have been in use for a long time. They are generally non-renewable (except for hydel power).
  • Examples: Firewood, cattle dung cake, coal, petroleum, natural gas, and electricity (both hydel and thermal).
• Non-Conventional Sources: These are newer sources of energy, often renewable and more environmentally friendly.
  • Examples: Solar, wind, tidal, geothermal, biogas, and atomic energy.

In rural India, over 70% of energy needs are met by firewood and cattle dung cake. However, this is becoming difficult due to deforestation, and using dung cake is discouraged because it consumes valuable manure needed for agriculture.

Conventional Sources of Energy

Coal

Coal is the most abundantly available fossil fuel in India and provides a substantial part of the nation's energy needs. It is formed from the compression of plant material over millions of years.

Types of Coal

The quality of coal depends on the degree of compression and the depth and time of burial.

• Peat: Low-grade, with low carbon and high moisture content. It has low heating capacity.
• Lignite: A low-grade brown coal. It is soft with high moisture content. The main reserves are in Neyveli, Tamil Nadu, used for electricity generation.
• Bituminous Coal: The most popular coal for commercial use. It is formed when coal is buried deep and subjected to increased temperatures. Metallurgical coal is a high-grade bituminous coal used for smelting iron.
• Anthracite: The highest quality hard coal.

Coalfields in India

Coal in India is found in rock series of two main geological ages:

1. Gondwana Coal: Over 200 million years old. This includes metallurgical coal and is located in the Damodar valley (West Bengal-Jharkhand), with Jharia, Raniganj, and Bokaro being important coalfields. It is also found in the Godavari, Mahanadi, Son, and Wardha valleys.
2. Tertiary Coal: About 55 million years old. These deposits are found in the northeastern states of Meghalaya, Assam, Arunachal Pradesh, and Nagaland.

Petroleum

Petroleum (or mineral oil) is the second major energy source in India after coal. It provides fuel for heat and lighting, lubricants for machinery, and raw materials for many industries like synthetic textiles, fertilisers, and chemicals.

• Occurrence: Most petroleum in India is found in anticlines and fault traps in the rock formations of the tertiary age. Oil is trapped in porous limestone or sandstone layers, held in place by non-porous layers above and below. Natural gas, being lighter, is usually found above the oil.
• Major Production Areas:
  • Mumbai High (offshore)
  • Gujarat (Ankeleshwar is the most important field)
  • Assam (the oldest oil-producing state in India, with fields like Digboi, Naharkatiya, and Moran-Hugrijan).

Natural Gas

Natural gas is an important clean energy resource often found with petroleum deposits.

• Uses: It is used as a domestic and industrial fuel, in power plants to generate electricity, as a raw material in chemical and fertilizer industries, and as a transport fuel (CNG - Compressed Natural Gas) and cooking fuel (PNG - Piped Natural Gas).
• Major Reserves: Mumbai High and allied fields on the west coast, Cambay basin, and the Krishna-Godavari basin on the east coast.
• Infrastructure: The 1,700 km long Hazira-Vijaipur-Jagdishpur (HVJ) pipeline was a landmark project that connected gas fields to markets in western and northern India. The gas pipeline network is now expanding across the country.

Electricity

Per capita consumption of electricity is often considered an index of development. Electricity is generated in two main ways:

1. Hydro Electricity: Generated by fast-flowing water that turns hydro turbines. It is a renewable resource. India has many multi-purpose projects like Bhakra Nangal and Damodar Valley Corporation that produce hydroelectric power.
2. Thermal Electricity: Generated by burning fossil fuels like coal, petroleum, and natural gas to drive turbines. This uses non-renewable resources.

Non-Conventional Sources of Energy

Growing energy consumption has made India dependent on fossil fuels, leading to concerns about energy security and environmental pollution. This has created a pressing need to use renewable, non-conventional energy sources.

Nuclear or Atomic Energy

This energy is obtained by altering the structure of atoms, which releases a huge amount of energy as heat. This heat is then used to generate electricity.

• Minerals Used: Uranium and Thorium.
• Availability: Uranium and Thorium are found in Jharkhand and the Aravalli ranges of Rajasthan. The Monazite sands of Kerala are also rich in Thorium.

Solar Energy

As a tropical country, India has enormous potential for tapping solar energy.

• Technology: Photovoltaic technology converts sunlight directly into electricity.
• Impact: Solar energy is becoming popular in rural and remote areas, reducing dependence on firewood and dung cakes, which helps conserve the environment and manure.

Wind Power

India has great potential for wind power.

• Major Wind Farms:
  • The largest wind farm cluster is in Tamil Nadu, from Nagarcoil to Madurai.
  • Other important states include Andhra Pradesh, Karnataka, Gujarat, Kerala, and Maharashtra.
  • Nagarcoil and Jaisalmer are well-known for the effective use of wind energy.

Biogas

Biogas is produced from shrubs, farm waste, and animal and human waste. It is mainly used for domestic consumption in rural areas.

• Gobar Gas Plants: Plants that use cattle dung are known as "Gobar gas plants."
• Twin Benefits: They provide farmers with both energy and improved quality of manure. This is a highly efficient use of cattle dung, preventing the loss of trees (as fuel wood) and manure.

Tidal Energy

This energy is generated from oceanic tides. Floodgate dams are built across inlets. During high tide, water flows in and is trapped. When the tide falls, the trapped water flows back to the sea through a pipe, turning a turbine to generate electricity.

• Ideal Locations in India: The Gulf of Khambhat, the Gulf of Kuchchh (Gujarat), and the Gangetic delta in the Sunderban regions (West Bengal).

Geothermal Energy

Geothermal energy refers to the heat and electricity produced using heat from the Earth's interior. As you go deeper into the earth, it gets hotter. In some areas, groundwater absorbs this heat, becomes extremely hot, and rises to the surface as steam. This steam is used to drive turbines.

• Experimental Projects in India:
  • Parvati valley near Manikaran in Himachal Pradesh.
  • Puga Valley in Ladakh.

Conservation of Energy Resources

Energy is a basic requirement for economic development. As India develops, its energy consumption is steadily rising. This makes it urgent to develop a sustainable path for energy.

India is currently one of the least energy-efficient countries in the world. As concerned citizens, we can all contribute to energy conservation:

• Use public transport instead of individual vehicles.
• Switch off electricity when not in use.
• Use power-saving devices.
• Use non-conventional sources of energy.

After all, "energy saved is energy produced."