Minerals and Energy Resources — Notes

A mineral is a naturally formed substance with a uniform make-up and a definite internal structure. Rocks are combinations of minerals; a few, such as limestone, consist of one. An ore is a mineral mixed with other elements and concentrated enough for mining to be worthwhile.

Modes of occurrence

1. Veins and lodes in cracks, faults and joints of igneous and metamorphic rocks, where hot fluids and gases rising through the rock harden as they cool (small = veins, large = lodes). Tin, copper, zinc, lead.
2. Beds or layers in sedimentary rocks, formed by deposition and concentration over long periods under heat and pressure (coal, some iron ore); evaporation in dry regions leaves gypsum, potash salt and sodium salt.
3. Residual deposits: weathering removes soluble parts and leaves the ore, e.g. bauxite.
4. Placer deposits: alluvial sands of valley floors and hill bases hold minerals that water does not dissolve or wear away — gold, silver, tin, platinum.
5. Ocean waters and beds: common salt, magnesium, bromine; manganese nodules on the sea floor.

Distribution: the old rocks of the peninsula hold most coal, metallic minerals and mica; sedimentary rocks in Gujarat and Assam hold most petroleum; Rajasthan has many non-ferrous minerals; the northern plains have almost none. Rat-hole mining of coal by families in Meghalaya (e.g. Jowai, Cherrapunjee) has been declared illegal by the National Green Tribunal.

Classification: metallic — ferrous (iron ore, manganese, nickel, cobalt), non-ferrous (copper, lead, tin, bauxite), precious (gold, silver, platinum); non-metallic (mica, salt, potash, sulphur, granite, limestone, marble, sandstone); energy minerals (coal, petroleum, natural gas). Ferrous minerals make up about three-quarters of the value of metallic minerals produced.

Iron ore — the basic mineral of industry. Magnetite: the finest ore, up to about 70 per cent iron, strongly magnetic, valued in the electrical industry. Hematite: 50–60 per cent iron, the ore used in the largest quantity.

• Odisha–Jharkhand belt: high-grade hematite at Badampahar (Mayurbhanj and Kendujhar, Odisha); Gua and Noamundi (Singhbhum, Jharkhand).
• Durg–Bastar–Chandrapur belt (Chhattisgarh, Maharashtra): very high-grade hematite of the Bailadila hills (14 deposits), well suited to steel making; exported to Japan and South Korea via Visakhapatnam.
• Ballari–Chitradurga–Chikkamagaluru–Tumakuru belt (Karnataka): large reserves; Kudremukh in the Western Ghats was developed as a 100 per cent export unit, its ore sent as slurry by pipeline to a port near Mangaluru.
• Maharashtra–Goa belt: Goa and Ratnagiri; ore of lower quality but mined efficiently and exported via Marmagao.

Manganese: about 10 kg per tonne of steel (ferro-manganese alloy); also bleaching powder, insecticides, paints.

Copper: India has too little of its own. Malleable, ductile, a good conductor: cables, electronics, chemicals. Balaghat (Madhya Pradesh), Khetri (Rajasthan), Singhbhum (Jharkhand).

Bauxite: an earthy ore formed by the decomposition of rocks rich in aluminium silicates; gives aluminium, which is strong yet very light, conducts well and is easily shaped. Amarkantak plateau, Maikal hills, Bilaspur–Katni plateau; Odisha leads, with Panchpatmali (Koraput) its key deposit.

Mica: thin layers that peel apart into sheets; a very good insulator with high dielectric strength that withstands high voltage — vital in electrical and electronic industries. Koderma–Gaya–Hazaribagh (Jharkhand), around Ajmer (Rajasthan), Nellore belt (Andhra Pradesh).

Limestone: rocks of calcium or calcium–magnesium carbonates in sedimentary formations; basic raw material of cement; used to smelt iron ore.

Mines on the map list (locate): iron ore — Mayurbhanj, Durg, Bailadila, Ballari, Kudremukh.

• Industry and agriculture depend heavily on minerals, yet workable deposits are a tiny fraction of the Earth's crust.
• Minerals form over millions of years but are consumed rapidly; replenishment is negligible on a human timescale, so they are finite and non-renewable.
• Continued extraction means ore must come from greater depths and is of lower quality, so costs rise.
• Measures: plan use sustainably; improve technology to use low-grade ores at low cost; recycle metals; use scrap and substitutes.
• Hazards of mining: dust and harmful fumes cause pulmonary (lung) diseases; risk of roof collapse, inundation and fires in coal mines; water sources contaminated; dumping of waste and slurry degrades land and soil and pollutes streams and rivers. Stricter safety regulations and environmental laws are essential.

Conventional: firewood, cattle dung cake, coal, petroleum, natural gas, electricity (hydel and thermal). Firewood and dung cake are common in rural homes, but forests are shrinking and burning dung wastes manure.

Coal — India's most abundant fossil fuel; used for power, industry and homes. Formed from plant material compressed over millions of years: peat (low carbon, high moisture) → lignite (low-grade brown coal, soft, moist; main reserves at Neyveli, Tamil Nadu, used for power) → bituminous (most common commercial coal; high-grade metallurgical coal for blast furnaces) → anthracite (highest quality). Gondwana coal (a little over 200 million years): Damodar valley — Jharia, Raniganj, Bokaro; also the Godavari, Mahanadi (Talcher), Son and Wardha valleys. Tertiary coal (about 55 million years): Meghalaya, Assam, Arunachal Pradesh, Nagaland. Coal is heavy, and much of its weight is left as ash, so heavy industries and thermal plants are built on or near coalfields.

Petroleum — fuel, lubricants and raw materials; refineries are a nodal industry that feeds makers of synthetic fibres, fertilisers and many chemicals. Found in anticlines and fault traps in tertiary rocks: oil in porous limestone or sandstone, sealed by non-porous layers; gas above oil. Areas: Mumbai High (offshore), Gujarat (Ankleshwar most important; Kalol), Assam — the oldest producer (Digboi, Naharkatiya, Moran-Hugrijan).

Natural gas — a cleaner fuel (less carbon dioxide); energy source and petrochemical raw material. Reserves: Krishna–Godavari basin, Mumbai High and allied fields, Gulf of Khambhat, Andaman and Nicobar Islands. The Hazira–Vijaipur–Jagdishpur (HVJ) pipeline links Mumbai High and Bassein with fertiliser, power and industrial complexes; CNG is replacing liquid fuels in vehicles.

Electricity — hydel (fast-flowing water, renewable; Bhakra Nangal, Damodar Valley Corporation, Kopili) and thermal (coal, petroleum, natural gas; non-renewable).

Board map list (locate and label): thermal — Namrup (Assam), Singrauli (Uttar Pradesh–Madhya Pradesh), Ramagundam (Telangana); nuclear — Narora (Uttar Pradesh), Kakrapar (Gujarat), Tarapur (Maharashtra), Kalpakkam (Tamil Nadu). Coal mines (Raniganj, Bokaro, Talcher, Neyveli) and oil fields (Digboi, Naharkatiya, Mumbai High, Bassein, Kalol, Ankleshwar) are also on the syllabus map list.

Growing energy use has increased dependence on fossil fuels; rising oil and gas prices and possible shortages raise doubts about energy security, and fossil fuels cause serious pollution. Hence the need for renewable sources.

• Nuclear (atomic) energy: heat released by altering the structure of atoms generates electricity. Uranium and thorium occur in Jharkhand and the Aravallis of Rajasthan; monazite sands of Kerala are rich in thorium.
• Solar energy: photovoltaic technology turns sunlight directly into electricity; spreading in rural and remote areas; large plants reduce dependence on firewood and dung cake, saving forests and manure.
• Wind power: the largest cluster runs from Nagercoil to Madurai (Tamil Nadu); also Andhra Pradesh, Karnataka, Gujarat, Kerala, Maharashtra, Lakshadweep; Nagercoil and Jaisalmer are known for effective use.
• Biogas: shrubs, farm waste and animal and human waste decompose to give gas with higher thermal efficiency than kerosene, dung cake and charcoal. Gobar gas plants give twin benefits — fuel and better manure — and save trees.
• Tidal energy: floodgate dams across inlets trap water at high tide and release it through turbines; Gulf of Khambhat, Gulf of Kachchh and the Sundarbans delta are ideal.
• Geothermal energy: where the Earth is hot at shallow depth, groundwater turns to steam that drives turbines; hundreds of hot springs; experimental projects in the Parvati valley near Manikaran (Himachal Pradesh) and the Puga valley (Ladakh).

Conservation of energy: energy is needed by every sector; energy conservation and more renewable energy are the twin planks of sustainable energy. Use public transport, switch off unused electricity, use power-saving devices, use non-conventional sources. Energy saved is energy produced.