Minerals and Energy Resources

1. What is a mineral?

Rocks are combinations of homogeneous substances called minerals. Some rocks, like limestone, are made of a single mineral, but most rocks contain several minerals in varying proportions. Over 2000 minerals have been identified, yet only a few occur abundantly in most rocks.

A particular mineral forms from a certain combination of elements, depending on the physical and chemical conditions under which the material forms. This gives each mineral its own range of colour, hardness, crystal form, lustre and density — the properties geologists use to classify them.

• Geographers study minerals as part of the earth’s crust to understand landforms and the distribution of resources and economic activities.
• Geologists are interested in the formation of minerals, their age, and their physical and chemical composition.

2. Mode of occurrence of minerals

Minerals are usually found in ores — an accumulation of any mineral mixed with other elements. The mineral content of an ore must be in sufficient concentration to make extraction commercially viable. The type of formation decides how easily ores can be mined and how much extraction costs. The main modes are:

Three factors decide whether a deposit becomes a working mine: the concentration of mineral in the ore, the ease of extraction, and closeness to market.

3. Distribution — an uneven picture

India has fairly rich and varied mineral resources, but they are unevenly distributed.

• Peninsular rocks hold most reserves of coal, metallic minerals, mica and many non-metallic minerals.
• Sedimentary rocks on the western and eastern flanks of the peninsula (Gujarat, Assam) hold most petroleum.
• Rajasthan, with peninsular rock systems, has reserves of many non-ferrous minerals.
• The vast alluvial plains of north India are almost devoid of economic minerals.

These variations arise from differences in geological structure, processes and the time involved in mineral formation.

4. Ferrous minerals — Iron ore

Ferrous minerals contain iron and account for about three-fourths of the total value of metallic mineral production; they form a strong base for metallurgical industries. India even exports them after meeting internal demand.

Iron ore is the basic mineral and the backbone of industrial development. The main types:

In 2018–19 about 97% of iron ore production came from Odisha, Chhattisgarh, Karnataka and Jharkhand. The four major belts are:

• Odisha–Jharkhand belt: high-grade hematite at Badampahar (Mayurbhanj, Kendujhar); Gua and Noamundi in Singhbhum.
• Durg–Bastar–Chandrapur belt (Chhattisgarh & Maharashtra): very high grade hematite in the famous Bailadila range; exported to Japan and South Korea via Vishakhapatnam port.
• Ballari–Chitradurga–Chikkamagaluru–Tumakuru belt (Karnataka): Kudremukh mines (Western Ghats) are a 100% export unit; ore moved as slurry via pipeline to a port near Mangaluru.
• Maharashtra–Goa belt: Goa and Ratnagiri (Maharashtra); ore not very high quality but efficiently exploited, exported through Marmagao port.

5. Manganese

Manganese is mainly used in manufacturing steel and ferro-manganese alloy — nearly 10 kg is needed per tonne of steel. It is also used in bleaching powder, insecticides and paints.

6. Non-ferrous minerals — Copper & Bauxite

India’s reserves and production of non-ferrous minerals (copper, bauxite, lead, zinc, gold) are not very satisfactory, yet they are vital for metallurgical, engineering and electrical industries.

Copper: India is critically deficient. Being malleable, ductile and a good conductor, copper is used in electrical cables, electronics and the chemical industry. Leading producers: Balaghat (Madhya Pradesh), Khetri (Rajasthan) and the Singhbhum district of Jharkhand. (Malanjkhand is a famous copper mine.)

Bauxite: from this clay-like substance, alumina and then aluminium are obtained. Bauxite forms by the decomposition of rocks rich in aluminium silicates. Aluminium combines the strength of iron with extreme lightness, good conductivity and malleability. India’s deposits are mainly in the Amarkantak plateau, Maikal hills and the Bilaspur–Katni plateau. Odisha was the largest producer (65%, 2018–19), with the important Panchpatmali deposits in Koraput district.

7. Non-metallic minerals — Mica & rock minerals

Mica is made of a series of plates or leaves and splits easily into very thin sheets. It can be clear, black, green, red, yellow or brown. Because of its excellent di-electric strength, low power-loss factor, insulating properties and resistance to high voltage, mica is one of the most indispensable minerals in the electric and electronic industries.

• Mica deposits lie on the northern edge of the Chota Nagpur plateau; the Koderma–Gaya–Hazaribagh belt of Jharkhand is the leading producer.
• In Rajasthan, mica is produced around Ajmer; the Nellore mica belt of Andhra Pradesh is also important.

Limestone (a rock mineral): found in rocks of calcium carbonate or calcium-magnesium carbonate, in sedimentary rocks of most geological formations. It is the basic raw material for the cement industry and is essential for smelting iron ore in the blast furnace.

8. Hazards of mining & conservation of minerals

Hazards of mining: dust and noxious fumes make miners vulnerable to pulmonary diseases; collapsing roofs, inundation and fires in coal mines are constant threats. Mining contaminates water sources, and dumping of waste & slurry degrades land and pollutes streams and rivers. Stricter safety and environmental laws are needed so mining does not become a “killer industry”.

Why conserve? Workable mineral deposits are only about one per cent of the earth’s crust, took millions of years to form, and replenish far slower than we consume them. They are therefore finite and non-renewable — valuable but short-lived possessions. Continued extraction means greater depths, higher costs and falling quality.

9. Conventional sources of energy

Energy is needed to cook, light, heat, drive vehicles and run machines. Conventional sources include firewood, cattle dung cake, coal, petroleum, natural gas and electricity (hydel and thermal). Firewood and dung cake meet over 70% of rural household energy, but their use is falling as forests shrink and dung is needed as manure.

Coal — India’s most abundant fossil fuel, used for power generation, industry and domestic needs. It forms by compression of plant material over millions of years, so its form depends on the degree of compression and depth/time of burial:

Coal occurs in two geological ages: Gondwana coal (~200 million years; metallurgical) in the Damodar valley (West Bengal–Jharkhand) — Jharia, Raniganj, Bokaro — and in the Godavari, Mahanadi, Son and Wardha valleys; Tertiary coal (~55 million years) in Meghalaya, Assam, Arunachal Pradesh and Nagaland. Because coal is bulky and loses weight on use, heavy industries and thermal plants sit on or near coalfields.

Petroleum (mineral oil) — the next major source after coal. It provides fuel, lubricants and raw material; refineries are a “nodal industry” for synthetic textiles, fertilisers and chemicals. Most occurrences are in anticlines and fault traps of tertiary rocks, where oil is trapped in a porous limestone/sandstone layer between non-porous layers; gas, being lighter, sits above the oil. Major areas: Mumbai High, Gujarat (Ankleshwar) and Assam (Digboi, Naharkatiya, Moran–Hugrijan) — Assam is the oldest oil-producing state.

Natural gas — found with petroleum and released when crude oil surfaces. Used to generate electricity, for heating, as raw material in chemicals/fertilisers, as transport fuel (CNG) and cooking fuel (PNG). Major reserves: Mumbai High and west-coast fields, the Cambay basin, and the Krishna–Godavari basin on the east coast. The Hazira–Vijaipur–Jagdishpur (HVJ) pipeline by GAIL was the first major cross-country gas pipeline.

Electricity — per-capita consumption is an index of development. Generated two ways: hydro electricity (running water drives turbines; renewable; projects like Bhakra Nangal, Damodar Valley Corporation, Kopili Hydel) and thermal electricity (burning coal, petroleum, natural gas; non-renewable). Once generated, the electricity is identical.

10. Non-conventional sources of energy

Growing dependence on fossil fuels, rising prices, possible shortages and environmental damage have created a pressing need for renewable, non-conventional sources. India is blessed with abundant sunlight, water, wind and biomass.

• Nuclear / atomic energy: obtained by altering the structure of atoms, releasing heat to generate power. Uranium and thorium (Jharkhand and the Aravalli ranges of Rajasthan) are used; Monazite sands of Kerala are rich in thorium.
• Solar energy: India is tropical with huge potential. Photovoltaic technology converts sunlight directly into electricity; popular in rural and remote areas, reducing dependence on firewood and dung.
• Wind power: India has great potential. The largest wind-farm cluster is in Tamil Nadu (Nagarcoil to Madurai); Nagarcoil and Jaisalmer are well known for effective use of wind.
• Biogas: decomposition of shrubs, farm waste, animal & human waste yields gas with higher thermal efficiency than kerosene, dung cake or charcoal. Cattle-dung plants are called ‘Gobar gas plants’; biogas is the most efficient use of cattle dung, giving energy plus better manure.
• Tidal energy: floodgate dams across inlets trap high-tide water; on the falling tide the water flows back through a power-generating turbine. Ideal: Gulf of Khambhat, Gulf of Kuchchh (Gujarat) and the Gangetic delta (Sunderban, West Bengal).
• Geothermal energy: heat and electricity from the Earth’s interior; groundwater heated by hot rocks becomes steam to drive turbines. Experimental projects: Parvati valley near Manikaran (Himachal Pradesh) and the Puga Valley (Ladakh).

11. NCERT Exercises — fully answered

Q1. Multiple choice questions.

• (i) Mineral formed by decomposition of rocks, leaving a residual weathered mass → (b) bauxite.
• (ii) Koderma, Jharkhand is the leading producer of → (b) mica.
• (iii) Minerals deposited and accumulated in the strata of → (a) sedimentary rocks.
• (iv) Mineral contained in Monazite sand → (c) thorium.

Q2. Answer in about 30 words.

(i)(a) Ferrous vs non-ferrous minerals: Ferrous minerals contain iron (iron ore, manganese) and form the base of metallurgical industries; non-ferrous minerals do not contain iron (copper, bauxite, lead, zinc, gold).

(i)(b) Conventional vs non-conventional energy: Conventional sources (coal, petroleum, natural gas, firewood, electricity) are widely used and mostly non-renewable; non-conventional sources (solar, wind, tidal, geothermal, biogas, nuclear) are renewable and eco-friendly.

(ii) What is a mineral? A mineral is a naturally occurring, homogeneous substance with a definite internal structure and a specific chemical and physical composition; rocks are made of one or more minerals.

(iii) How are minerals formed in igneous and metamorphic rocks? In these rocks minerals form in cracks, faults and joints when molten/gaseous minerals are forced upward, then cool and solidify. Smaller occurrences are called veins and larger ones lodes.

(iv) Why conserve mineral resources? Minerals are finite, non-renewable and take millions of years to form, while consumption is rapid. Conservation through recycling, substitutes and planned use keeps them available for future generations.

Q3. Answer in about 120 words.

(i) Distribution of coal in India: Coal occurs in rocks of two geological ages. Gondwana coal (over 200 million years old), which includes metallurgical coal, is found in the Damodar valley on the West Bengal–Jharkhand border — with major fields at Jharia, Raniganj and Bokaro — and in the Godavari, Mahanadi, Son and Wardha valleys. Tertiary coal (about 55 million years old) is found in the north-eastern states of Meghalaya, Assam, Arunachal Pradesh and Nagaland. Because coal is bulky and loses weight when used, heavy industries and thermal power stations are located on or near the coalfields.

(ii) Why does solar energy have a bright future in India? India is a tropical country receiving abundant sunlight almost all year, giving enormous potential to tap solar energy. Photovoltaic technology converts sunlight directly into electricity, and solar is becoming popular in rural and remote areas. Big solar plants reduce rural dependence on firewood and dung cakes, which helps the environment and leaves dung free as manure for agriculture. Being clean, renewable and pollution-free, solar energy reduces dependence on costly, polluting fossil fuels and strengthens energy security — so it has a bright future.

Activity (crossword answers): ACROSS — 1 Manganese, 2 Limestone, 3 Magnetite, 4 Anthracite, 5 Bauxite, 6 Copper, 7 Potash. DOWN — 1 Gold, 2 Hematite, 3 Mica, 4 Tertiary, 5 Tin.

12. Common confusions

• Mineral vs ore vs rock: a rock is made of minerals; a mineral is the substance; an ore is a mineral concentrated enough to be mined profitably.
• Magnetite vs Hematite: magnetite has the highest iron content (up to 70%) and is magnetic; hematite is the most-used industrial ore (50–60%).
• Veins vs lodes: both are in igneous/metamorphic rocks — veins are the smaller occurrences, lodes the larger.
• Bauxite vs aluminium: bauxite is the ore; alumina, then aluminium, is extracted from it.
• Conventional vs non-conventional: conventional are traditional & mostly non-renewable; non-conventional are renewable & eco-friendly. Note hydel electricity is conventional but renewable.
• Gobar gas: a biogas plant using cattle dung — a non-conventional source, not conventional dung-cake burning.

13. Quick revision checklist

• Mineral = homogeneous natural substance; mined from ore; concentration + ease of extraction + market → mine.
• Modes: veins/lodes, beds/layers, residual (bauxite), placer (gold), ocean.
• Ferrous: iron ore (magnetite, hematite), manganese. Non-ferrous: copper, bauxite. Non-metallic: mica, limestone.
• Iron-ore belts: Odisha–Jharkhand, Durg–Bastar–Chandrapur (Bailadila), Karnataka (Kudremukh), Maharashtra–Goa.
• Coal forms: peat → lignite → bituminous → anthracite (best). Gondwana & Tertiary ages.
• Non-conventional: solar, wind (Nagarcoil–Madurai), tidal (Gulf of Khambhat), geothermal (Manikaran, Puga), biogas, nuclear (uranium/thorium).
• Minerals are finite & non-renewable — recycle, substitute, plan. “Energy saved is energy produced.”