Distribution of minerals and the mineral belts

Detail

1. Why minerals are spread unevenly in India

• Distribution of minerals means the pattern of where mineral deposits occur. In India this pattern is very uneven.
• Three things cause it:
• Geological structure: the type of rock and how it is folded or faulted.
• Geological processes: heat, pressure, weathering and sediments laid down in water.

• Time: how long these processes have worked.

• Most valuable minerals are pre-Palaeozoic. Pre-Palaeozoic means older than about 540 million years.

• They lie in the metamorphic rocks (rocks changed by heat and pressure) and igneous rocks (rocks formed from cooled magma) of the Peninsular plateau.

• These old, hard rocks have been worn down for a very long time. That exposed the ores near the surface.

• What each rock region holds:

Rock region	Main minerals	Examples
Peninsular plateau (old crystalline rocks)	Metallic minerals and mica	Iron ore, manganese, bauxite, copper, mica
Gondwana basins in the Peninsula	Coal (over 97% of reserves)	Damodar, Sone, Mahanadi and Godavari valleys
Sedimentary flanks and offshore basins	Petroleum and natural gas	Gujarat (Ankleshwar, Cambay), Assam (Digboi), Mumbai High, Krishna–Godavari and Kaveri basins
Peninsular rocks of Rajasthan	Non-ferrous minerals	Copper, lead, zinc
Northern alluvial plains	Almost no economic minerals	Ganga plain

• Gondwana rocks: sedimentary rocks laid down about 250–300 million years ago in long, sunken river troughs. Plants buried in these troughs became coal. That is why coal lies along river valleys such as the Damodar.
• Why the northern plains lack minerals:
• They are made of thick, young layers of silt and sand laid down by Himalayan rivers.
• These layers cover any old ore-bearing rock deep below the surface.

2. The Mangaluru–Kanpur line

• Mangaluru–Kanpur line: an imaginary line drawn from Mangaluru (Karnataka coast) to Kanpur (Uttar Pradesh).
• Most major minerals lie east of this line. These include coal, iron ore, manganese, bauxite and mica.
• West of the line the main deposits are Rajasthan's non-ferrous minerals and building stones, Gujarat's petroleum and salt, and Goa–Karnataka iron ore near the line.
• Current data shows the same eastern pull:
• Odisha, Jharkhand, Chhattisgarh, West Bengal and northern Andhra Pradesh together hold about 80% of India's iron ore, about 100% of its coking coal, and a large share of its chromite, bauxite and dolomite reserves (Ministry of Steel, "Purvodaya", 2020) [2].
• Odisha alone has about 51% of India's bauxite, 25% of its coal, 34% of its iron ore, 96% of its chromite and 44% of its manganese resources (2020) [3].

3. Deposit vs mine

• A deposit is a place where a mineral occurs naturally. A mine is a deposit that is actually worked.
• A deposit becomes a mine only when three conditions are met:
• Grade: the ore must hold enough metal.
• Ease of extraction: depth, thickness and the rock around the ore must allow cheap mining.

• Nearness to market: transport cost must not eat up the profit.

• So India has many known deposits that are not mined.

4. The mineral belts of India

• Mineral belt: a large region where many mineral deposits occur together because they share the same old rocks.
• India has three main belts plus the Himalayan belt.

Belt	States	Rock base	Key minerals	Weakness
North-Eastern Plateau	Jharkhand (Chhotanagpur), Odisha, West Bengal, parts of Chhattisgarh	Archaean–Dharwar rocks and Gondwana coal basins	Iron ore, coal, manganese, bauxite, mica, copper, uranium	Most diverse; none
South-Western Plateau	Karnataka, Goa, Tamil Nadu uplands, Kerala	Dharwar and crystalline rocks	High-grade iron ore, manganese, bauxite, limestone; monazite in Kerala	No coal except Neyveli lignite; less diverse
North-Western	Rajasthan (Aravallis), part of Gujarat	Dharwar rocks	Copper, zinc, marble, granite, sandstone, gypsum, Fuller's earth, limestone, dolomite, salt; Gujarat petroleum	Few ferrous minerals
Himalayan	J&K, Himachal, Uttarakhand, North-East	Young folded rocks	Copper, lead, zinc, cobalt, tungsten; Assam oil; lithium (J&K)	Hard terrain, poor access

5. North-Eastern Plateau belt — the "storehouse of minerals"

• Extent: the Chhotanagpur plateau (Jharkhand), the Odisha plateau, West Bengal and parts of Chhattisgarh.
• Why it is called the "storehouse of minerals": it holds more kinds of minerals, in larger amounts, than any other region of India.
• Main deposits:
• Iron ore: Noamundi and Gua (West Singhbhum, Jharkhand); Gurumahisani, Badampahar and Kiriburu–Bonai (Odisha); Bailadila (Chhattisgarh).
• Coal: the Gondwana fields of Jharia, Bokaro and Karanpura (Damodar valley), Raniganj (West Bengal), Talcher (Mahanadi valley) and Korba (Chhattisgarh).
• Manganese: Keonjhar and Sundargarh (Odisha).
• Bauxite: Kalahandi and Koraput (Odisha), and the Chhattisgarh plateau.
• Mica: Koderma–Hazaribagh (Jharkhand).
• Copper: the Singhbhum copper belt (Jharkhand).

• Uranium: Jaduguda (Jharkhand).

• Coal resources in the core states:

• As of 1 April 2021 (GSI inventory), the leading states were Jharkhand at 86,216.82 million tonnes, Odisha at 84,878.05 million tonnes and Chhattisgarh at 73,423.54 million tonnes [5].

• India's total coal resource was 361,411.46 million tonnes as of 1 April 2022 (GSI) [6].

• Iron ore output (2018-19): Odisha produced 113,119 thousand tonnes, Chhattisgarh 34,893 thousand tonnes and Jharkhand 23,433 thousand tonnes. Odisha is the leading producer [7].

• Why steel plants grew here:
• Iron ore lies close to coking coal. Coking coal is coal that turns into hard coke when heated, and coke is the fuel and reducing agent in a blast furnace.
• Limestone, dolomite and manganese, which are also needed to make steel, are found nearby.
• Raw materials therefore travel short distances, so the cost of making steel is low.
• The result is a cluster of steel plants: Jamshedpur (Jharkhand), Bokaro (Jharkhand), Durgapur (West Bengal), Rourkela (Odisha) and Bhilai (Chhattisgarh).

6. South-Western Plateau belt

• Extent: Karnataka, Goa, the Tamil Nadu uplands and Kerala.
• Main minerals:
• High-grade iron ore: Kudremukh, Ballari and Chikkamagaluru (Karnataka), and Goa.

• Manganese, bauxite and limestone.

• Coal: the belt has no coal except Neyveli lignite (Tamil Nadu). Lignite is a low-grade brown coal with high moisture.

• Kerala: the beach sands hold monazite, a mineral rich in thorium (a nuclear fuel), and the state also has bauxite clay.
• Goa: iron ore, mostly exported through Mormugao port.
• Weakness: the belt has fewer kinds of minerals than the North-Eastern belt.

7. North-Western belt

• Extent: along the Aravalli range in Rajasthan and into part of Gujarat.
• Dharwar rocks: some of the oldest metamorphic rocks in India, about 2.5–1.8 billion years old. They are named after Dharwad in Karnataka and are rich in metallic ores.
• Main minerals:
• Copper: Khetri (Jhunjhunu, Rajasthan).
• Zinc and lead: Zawar (Udaipur, Rajasthan).
• Building stones: sandstone, granite and Makrana marble (Nagaur, Rajasthan).
• Gypsum and Fuller's earth (a fine clay used to clean and bleach oils).

• Limestone and dolomite, which feed cement plants.

• Gujarat: petroleum in the Cambay basin and at Ankleshwar.

• Salt: both states produce it. Gujarat makes it from sea water on the coast; Rajasthan from salt lakes such as Sambhar.
• Gujarat's coastal salt is the background to the Dandi March (1930), when Gandhi made salt from sea water at Dandi (Navsari).

8. Himalayan belt

• Known minerals: copper, lead, zinc, cobalt and tungsten, found in both the eastern and western Himalaya.
• Assam valley: oil at Digboi, Naharkatiya and Moran.
• Lithium (beyond NCERT):
• GSI has found an inferred resource (G3 stage) of 5.9 million tonnes of lithium ore in the Salal–Haimana area of Reasi district, Jammu & Kashmir. The work was done in the field seasons 2020-21 and 2021-22 (announced 2023) [4].
• G3 (inferred) stage: an early estimate based on limited drilling and sampling. It is not yet a proven reserve [4].

• Further exploration aims to move the estimate to a higher-confidence category. Bench-scale studies have produced very pure lithium carbonate from spodumene concentrate taken from the area [4].

• Limits: steep slopes, weak and broken rock, poor roads and landslide risk make mining here costly.

9. Map exercise: superimposition

• Lay the maps of iron ore, manganese, coal and steel plants on top of one another.
• What you see:
• Iron ore, manganese and coking coal cluster in the Jharkhand–Odisha–Chhattisgarh–West Bengal region.

• Integrated steel plants sit inside or next to this cluster.

• Reason: steel uses heavy raw materials that lose weight during processing. Plants are built near those raw materials to cut transport cost.

• Exceptions: coastal plants such as Visakhapatnam use imported coking coal or ore brought in by sea.
• Use GSI and IBM (Indian Bureau of Mines) mineral maps to plot the deposits.

Prelims Hooks

• Over 97% of India's coal reserves lie in the Gondwana basins of the Damodar, Sone, Mahanadi and Godavari valleys.
• Most major minerals lie east of the Mangaluru–Kanpur line.
• Lithium: Salal–Haimana, Reasi district, J&K, with 5.9 million tonnes at the G3 (inferred) stage. This is an early estimate, not a proven reserve [4].
• Odisha holds about 96% of India's chromite and about 51% of its bauxite resources (2020) [3].
• Coal resource ranking, 1 April 2021 (GSI): Jharkhand > Odisha > Chhattisgarh [5]. Odisha leads iron ore production (2018-19) [7].
• Pairs to remember: Khetri – copper (Rajasthan); Zawar – zinc and lead (Rajasthan); Makrana – marble (Rajasthan); Koderma – mica (Jharkhand); Jaduguda – uranium (Jharkhand); Neyveli – lignite (Tamil Nadu); Kudremukh – iron ore (Karnataka); Bailadila – iron ore (Chhattisgarh).
• Trap: the South-Western belt has no coal except Neyveli lignite. Its Kerala sands give monazite (thorium), not uranium.
• Trap: the North-Western belt lies in Dharwar rocks of the Aravallis, not in Gondwana rocks.
• Steel plants and states: Rourkela – Odisha; Bhilai – Chhattisgarh; Durgapur – West Bengal; Bokaro and Jamshedpur – Jharkhand.

Mains Points

• Geology controls the pattern. Old pre-Palaeozoic igneous and metamorphic rocks hold the metallic minerals. Gondwana troughs hold coal. Young sedimentary basins hold oil. The alluvial plains have almost none. This is why minerals are concentrated in the Peninsula, east of the Mangaluru–Kanpur line (GS-I).
• Mineral belts shape where industry grows. Iron ore, coking coal, manganese and limestone lie together in the North-Eastern Plateau, which created India's steel belt. The eastern states hold about 80% of iron ore and about 100% of coking coal [2]. That makes them central to plans such as "Purvodaya" (GS-I and GS-III).
• Mineral-rich regions face a "resource curse". Odisha, Jharkhand and Chhattisgarh hold most of the coal, iron ore and bauxite [3][5]. Yet they also face tribal displacement, forest loss and lower human development. Answers on this should mention benefit-sharing and sustainable mining (GS-III).
• New frontiers for critical minerals. The Reasi lithium find [4] shows the Himalaya and other unexplored terrains may hold critical minerals. But terrain, fragile ecology and the early G3 stage of exploration mean more survey work is needed before mining (GS-III).