Chapter 5: Minerals and Energy Resources
What is a Mineral?
Geologists define a mineral as a "homogeneous, naturally occurring substance with a definable internal structure". Minerals are found in varied forms in nature — from the hardest diamond to the softest talc. Rocks are combinations of homogeneous substances called minerals; some rocks (like limestone) consist of a single mineral, but most rocks are combinations of several minerals. Over 2000 minerals have been identified, though only a few are abundantly found.
Mode of Occurrence of Minerals
- Veins and lodes: minerals occur in cracks, crevices, faults and joints of igneous and metamorphic rocks; smaller occurrences are veins, larger are lodes (e.g. tin, copper, zinc, lead).
- Beds or layers: in sedimentary rocks, formed by deposition, accumulation and concentration in horizontal strata (coal, some iron ore, gypsum, potash salt, sodium salt — the latter formed by evaporation in arid regions).
- Residual mass of weathered material: decomposition of surface rocks and removal of soluble constituents leaves ores (bauxite).
- Alluvial deposits (placer deposits): in sands of valley floors and hill bases — minerals not corroded by water, e.g. gold, silver, tin, platinum.
- Ocean waters: common salt, magnesium and bromine largely derived from ocean waters; manganese nodules on ocean beds.
Classification of Minerals
| Category | Sub-type | Examples |
|---|---|---|
| Metallic | Ferrous (contain iron) | Iron ore, manganese, nickel, cobalt |
| Non-ferrous (no iron) | Copper, bauxite (aluminium ore), lead, zinc, gold | |
| Non-metallic | — | Mica, salt, potash, sulphur, granite, limestone, marble, sandstone |
| Energy minerals | — | Coal, petroleum, natural gas |
Ferrous Minerals
Iron Ore
Iron ore is the basic mineral and the backbone of industrial development. India is rich in good-quality iron ores.
| Type | Iron content | Features |
|---|---|---|
| Magnetite | Up to 70% | Finest iron ore; excellent magnetic qualities, valuable in the electrical industry |
| Hematite | 50–60% | Most important industrial iron ore in terms of quantity used |
Major iron-ore belts:
- Odisha–Jharkhand belt: high-grade hematite in Badampahar mines (Mayurbhanj and Kendujhar districts, Odisha); Gua and Noamundi (Singbhum, Jharkhand).
- Durg–Bastar–Chandrapur belt (Chhattisgarh–Maharashtra): very high-grade hematite in the Bailadila range of hills (Bastar, Chhattisgarh); ore exported to Japan and South Korea via Vishakhapatnam port.
- Ballari–Chitradurga–Chikkamagaluru–Tumakuru belt (Karnataka): large reserves; Kudremukh mines in the Western Ghats — a 100% export unit; ore transported as slurry through a pipeline to a port near Mangaluru.
- Maharashtra–Goa belt: Goa and Ratnagiri district; ores not of very high quality but exploited efficiently, exported through Marmagao port.
Manganese
Used mainly in manufacturing steel and ferro-manganese alloy (nearly 10 kg of manganese is required to make 1 tonne of steel); also used to make bleaching powder, insecticides and paints. Producing regions: Odisha (largest producer), Karnataka, Madhya Pradesh, Maharashtra.
Non-Ferrous Minerals
- Copper: malleable, ductile and a good conductor — used in electrical cables, electronics and chemical industries. India is critically deficient. Major producers: Balaghat mines (Madhya Pradesh), Khetri mines (Rajasthan), Singbhum (Jharkhand).
- Bauxite: the ore from which aluminium is obtained; formed by decomposition of rocks rich in aluminium silicates. Aluminium combines the strength of metals like iron with extreme lightness, good conductivity and malleability. Deposits: Amarkantak plateau, Maikal hills, plateau region of Bilaspur-Katni; Odisha is the largest producer — Panchpatmali deposits in Koraput district are the most important.
Non-Metallic Minerals
Mica splits easily into thin sheets (plates/leaves); it can be clear, black, green, red, yellow or brown. Due to its excellent di-electric strength, low power loss factor, insulating properties and resistance to high voltage, mica is indispensable in electric and electronic industries. Regions: northern edge of the Chota Nagpur plateau — the Koderma–Gaya–Hazaribagh belt (Jharkhand) is the leading producer; Ajmer region (Rajasthan); Nellore mica belt (Andhra Pradesh).
Limestone (rock mineral) is the basic raw material for the cement industry and essential for smelting iron ore in blast furnaces.
Hazards of Mining and Conservation of Minerals
Miners breathe dust and noxious fumes, risking pulmonary diseases; mines can collapse or flood; slums develop around mining areas; dumping of waste and slurry degrades land and pollutes streams. Minerals form over millions of years and are finite and non-renewable — hence conserve them by: using minerals in a planned and sustainable manner, improving technology to use low-grade ores at low cost, recycling metals using scrap metals, and using substitutes.
Energy Resources: Conventional vs Non-Conventional
| Basis | Conventional sources | Non-conventional sources |
|---|---|---|
| Examples | Firewood, cattle dung cake, coal, petroleum, natural gas, electricity (thermal and hydel) | Solar, wind, tidal, geothermal, biogas, atomic/nuclear energy |
| Nature | Mostly exhaustible (except hydel); in use for a long time | Mostly renewable and inexhaustible; recently developed |
| Environment | Cause pollution (smoke, ash, greenhouse gases) | Largely pollution-free and eco-friendly |
| Cost | Cheaper to use but reserves are limited | High initial cost, low running cost |
Coal
Coal is the most abundantly available fossil fuel in India, providing a substantial part of the nation's energy needs. Formed from plant material compressed over millions of years, coal varies by degree of compression, depth and time of burial:
| Type | Carbon / quality | Occurrence |
|---|---|---|
| Peat | Low carbon, low heat, high moisture | First stage of decayed plant matter |
| Lignite | Low-grade brown coal, soft, high moisture | Neyveli (Tamil Nadu) — used for electricity generation |
| Bituminous | Most popular coal in commercial use; high grade used in blast furnaces (metallurgical coal) | Coal buried deep, subjected to increased temperature |
| Anthracite | Highest quality hard coal | Very limited occurrence in India |
Coal in India occurs in Gondwana rock series (over 200 million years old — Damodar valley: Jharia, Raniganj, Bokaro; also Godavari, Mahanadi, Son and Wardha valleys — major resources of metallurgical coal) and Tertiary deposits (about 55 million years old — Meghalaya, Assam, Arunachal Pradesh, Nagaland).
Petroleum and Natural Gas
Petroleum is the next major energy source after coal — fuel for heat and lighting, lubricants for machinery, and raw material for a number of manufacturing industries (petrochemicals: synthetic textiles, fertilisers, chemicals). It occurs in anticlines and fault traps of tertiary-age rock formations. Mumbai High contributes about 63% of India's production, Gujarat about 18% and Assam about 13%. Fields: Ankleshwar (Gujarat); Digboi, Naharkatiya, Moran-Hugrijan (Assam — the oldest oil-producing state). Natural gas is a clean, environment-friendly fuel; large reserves in the Krishna–Godavari basin; the Hazira–Vijaipur–Jagdishpur (HVJ) pipeline links Mumbai High and Bassein with fertiliser, power and industrial complexes; CNG is increasingly used for vehicles.
Electricity and Non-Conventional Sources
- Thermal power (coal, petroleum, natural gas) and hydro electricity (running water driving turbines — Bhakra Nangal, Damodar Valley Corporation, Kopili Hydel Project) are the two main ways of generating electricity.
- Nuclear energy: obtained by altering the structure of atoms; uranium and thorium (Jharkhand and the Aravalli ranges of Rajasthan) are used; the monazite sands of Kerala are rich in thorium.
- Solar energy: India is a tropical country with enormous potential; photovoltaic technology converts sunlight directly into electricity; expected to minimise dependence of rural households on firewood and dung cakes.
- Wind power: largest wind farm cluster from Nagarcoil to Madurai (Tamil Nadu); also Andhra Pradesh, Karnataka, Gujarat, Kerala, Maharashtra, Lakshadweep.
- Biogas: shrubs, farm waste, animal and human waste produce biogas — higher thermal efficiency than kerosene, dung cake and charcoal; gobar gas plants give twin benefit of energy and improved manure, and prevent loss of trees and manure due to burning of dung cakes.
- Tidal energy: floodgate dams across inlets; ideal conditions in the Gulf of Khambhat, Gulf of Kachchh and the Gangetic delta (Sunderban).
- Geothermal energy: heat from the interior of the earth; two experimental projects — Parvati valley near Manikarn (Himachal Pradesh) and Puga valley (Ladakh).
Map Work (CBSE Prescribed)
- Iron ore mines: Mayurbhanj (Odisha), Durg (Chhattisgarh), Bailadila (Chhattisgarh), Bellary (Karnataka), Kudremukh (Karnataka)
- Coal mines: Raniganj (West Bengal), Bokaro (Jharkhand), Talcher (Odisha), Neyveli (Tamil Nadu — lignite)
- Oil fields: Digboi and Naharkatia (Assam), Mumbai High and Bassein (offshore, Arabian Sea), Kalol and Ankleshwar (Gujarat)
- Thermal power plants: Namrup (Assam), Singrauli (Madhya Pradesh), Ramagundam (Telangana)
- Nuclear power plants: Narora (Uttar Pradesh), Kakrapara (Gujarat), Tarapur (Maharashtra), Kalpakkam (Tamil Nadu)