Chapter 9 — ଖଣିଜ ସମ୍ବଳ

Everything we use in daily life, from the steel spoon and the aluminium vessel to the mobile phone and the cement of the house wall, is made from material that came out of the earth. The earth's crust is made of rocks, and rocks are made of minerals. A mineral is a naturally occurring, homogeneous, inorganic substance that has a definite chemical composition and a definite internal (crystalline) structure. Each part of this definition matters. 'Naturally occurring' means the substance is formed by geological processes, not manufactured by man; steel and glass are therefore not minerals though they are made from minerals. 'Inorganic' means it is not formed from living things; coal and petroleum are formed from the remains of plants and animals, so geologists do not treat them as true minerals, although for convenience textbooks group them with minerals as 'energy minerals' or 'mineral fuels'. 'Definite chemical composition' means that a given mineral always has the same formula: haematite is always Fe₂O₃, quartz is always SiO₂ and rock salt is always NaCl.

Geologists have identified more than 2,000 minerals, but only a few dozen are abundant and useful. Minerals are recognised by their physical properties: colour, lustre (the way the surface reflects light), hardness (measured on the Mohs scale from talc at 1 to diamond at 10), streak (the colour of the powder), cleavage (the way it breaks along flat planes), specific gravity and crystal form. Gold and copper have a metallic lustre; quartz and mica have a glassy lustre; graphite is soft enough to write with, while corundum can scratch glass.

A rock from which a mineral can be extracted profitably is called an ore. The word 'ore' is an economic term: a rock becomes an ore only when the mineral in it is present in sufficient concentration and can be mined and refined at a cost lower than the price the metal fetches. Iron ore, bauxite (the ore of aluminium) and chalcopyrite (an ore of copper) are common examples. Minerals are an important part of the natural resources of any country because industry, agriculture, transport and defence all rest on them. In India, the study of minerals is done by the Geological Survey of India (GSI), founded in 1851, and the Indian Bureau of Mines keeps the records of mining. Minerals are non-renewable: they took millions of years to form and once they are dug out and used they cannot be replaced within human time, which is why their careful use is the last theme of this chapter.

Because minerals differ so widely in composition and use, they are classified in several ways. The classification used in this chapter, which is the one followed by the Indian mining industry, divides them into three broad groups on the basis of their chemical and physical properties and use.

1. Metallic minerals are those from which metals are obtained. They are usually hard, have a shine, are good conductors of heat and electricity and are malleable and ductile. They are further divided into two: (a) Ferrous minerals, which contain iron or are used along with iron in making steel: iron ore itself, manganese, chromite, nickel, cobalt and tungsten. The word 'ferrous' comes from the Latin ferrum, iron. About three-fourths of the value of all metallic mineral production in India comes from ferrous minerals. (b) Non-ferrous minerals, which contain no iron: copper, bauxite (aluminium), lead, zinc, tin, gold and silver. Gold, silver and platinum are sometimes listed separately as precious metals.

2. Non-metallic minerals do not yield metals. They may be used directly, as building material or as raw material for chemical and other industries. Mica, limestone, dolomite, gypsum, graphite, asbestos, kaolin (china clay), quartz, salt, potash and the precious stones such as diamond belong here. Limestone and dolomite are needed for cement and as flux in iron smelting; mica is used as an insulator in electrical goods; gypsum goes into plaster and fertiliser.

3. Energy minerals or mineral fuels are the sources of power: coal, petroleum, natural gas and the atomic minerals uranium and thorium. They are organic (coal, oil, gas) or radioactive (uranium, thorium) and are studied in detail in the next chapter on energy resources.

A second way of classifying minerals is by the rock in which they occur. Igneous and metamorphic rocks hold most of the metallic minerals, because molten magma cooling in cracks concentrates metals such as copper, zinc, tin and gold. Sedimentary rocks hold the non-metallic minerals and the fuels, because these form by the deposition of layers over long periods: coal, limestone, gypsum, potash and petroleum. This connection is useful: the old, hard peninsular plateau of India (Chhotanagpur, Odisha, Chhattisgarh, Karnataka) built of ancient crystalline rocks holds the metallic minerals, while the younger sedimentary basins of the Gondwana river valleys hold coal and the sedimentary rocks of Assam, Gujarat and Mumbai High hold petroleum.

Minerals are found in ores in a number of ways, and knowing the mode of occurrence tells the miner where to look and how to dig. Five modes are important.

1. In veins and lodes of igneous and metamorphic rocks. When molten magma rises through cracks, joints and faults in the crust, it cools and the metallic minerals dissolved in it crystallise in these cracks. A small crack filled with mineral is called a vein; a large one is a lode. Copper, zinc, lead, tin, gold and silver are mostly obtained from veins and lodes. The copper of Khetri in Rajasthan and Malanjkhand in Madhya Pradesh, and the gold of the Kolar fields in Karnataka, occur in this way.

2. In beds or layers of sedimentary rocks. Sedimentary rocks are formed layer upon layer by the deposition of sediments, and several minerals are laid down in the same way, either by deposition and concentration in horizontal strata (as coal, some iron ore) or by evaporation of water in dry regions (gypsum, potash salt, sodium salt). Coal in the Talcher and Ib valley fields of Odisha occurs in seams, which are simply beds.

3. By decomposition of surface rocks (residual deposits). When rocks weather in a hot, wet climate the soluble constituents are washed away and the insoluble residue is left behind, enriched in a particular mineral. Bauxite is formed like this from the weathering of aluminium-rich rocks such as laterite, which is why the great bauxite deposits of Odisha sit as caps on the flat tops of the Eastern Ghats plateaus of Koraput and Kalahandi.

4. As alluvial or placer deposits. Rivers carry weathered rock and drop the heavier particles first in the sands and gravels of valley floors and the base of hills. Minerals that are heavy and do not corrode, such as gold, silver, tin and platinum, are found as placer deposits and are recovered by washing the sand. The gold of the Subarnarekha (literally 'streak of gold') river and the monazite sands of the Kerala and Odisha (Chhatrapur, Ganjam) coasts are placer deposits.

5. In ocean water. Sea water contains large quantities of dissolved minerals, but most are so diluted that recovery is not economic. Common salt, magnesium and bromine are, however, obtained from ocean water, and manganese nodules lie on the deep ocean floor as a resource for the future.

Thus the mode of occurrence decides the method of mining: veins deep in hard rock need underground shafts, beds near the surface need open-cast quarrying, placers need washing and bauxite caps need surface stripping.

Iron ore is the backbone of industrial development, because iron and steel go into machines, vehicles, railways, bridges, buildings and tools. India is fortunate to have very large reserves of good quality iron ore, among the largest in the world, and is one of the leading producers and exporters. Four types of iron ore are distinguished by their iron content.

Magnetite (Fe₃O₄) is the finest ore, with about 70 per cent iron. It is black, and as the name says it has magnetic properties, which are valuable in the electrical industry. Haematite (Fe₂O₃) is reddish, contains 60 to 70 per cent iron and is the most important industrial ore in terms of the quantity used; nearly all the ore mined in Odisha and Jharkhand is haematite. Limonite is a yellowish hydrated oxide with 40 to 60 per cent iron, and siderite is a carbonate with only 40 to 50 per cent iron; both are of poor quality and are little used in India.

The major iron ore belts of India are four. (1) The Odisha–Jharkhand belt is the most important. In Odisha, high-grade haematite is mined in the Badampahar mines of Mayurbhanj and Kendujhar (Keonjhar) districts, in the Gorumahisani, Sulaipat and Badampahar ranges, in Barbil, Joda, Bolani and Thakurani of Keonjhar and in the Koira valley of Sundargarh; across the border in Jharkhand, in Gua and Noamundi of Singhbhum. (2) The Durg–Bastar–Chandrapur belt of Chhattisgarh and Maharashtra has the very high grade haematite of the Bailadila range in Dantewada (Bastar), whose 14 deposits are exported through the port of Visakhapatnam to Japan and South Korea, and the mines of Dalli-Rajhara in Durg feed the Bhilai steel plant. (3) The Bellary–Chitradurga–Chikkamagaluru–Tumakuru belt of Karnataka has large reserves; the Kudremukh mines in the Western Ghats were once among the largest in the world and the ore was carried as slurry through a pipeline to the port at Mangaluru. (4) The Maharashtra–Goa belt covers Goa and Ratnagiri district; the ores are not of very high quality but are cheaply exported through Marmagao port.

Odisha alone accounts for roughly half of India's iron ore output, followed by Chhattisgarh, Karnataka and Jharkhand. Much of the ore is consumed in the integrated steel plants at Rourkela, Bhilai, Bokaro, Jamshedpur, Durgapur and Burnpur, which stand close to the ore fields, and the rest is exported from Paradip, Visakhapatnam, Marmagao and Mangaluru.

Manganese is a hard, brittle, greyish metal that is never used alone but is indispensable to the iron and steel industry. Its chief use is in making steel and ferro-manganese alloys: manganese removes oxygen and sulphur from molten iron, and about 10 kg of manganese is required to manufacture one tonne of steel. Steel containing 12 to 14 per cent manganese is extremely hard and is used for railway crossings, crusher jaws and the tracks of bulldozers. Manganese is also used in making bleaching powder, insecticides, paints and dry-cell batteries (manganese dioxide is the depolariser in the ordinary torch cell). Because of these uses manganese is grouped with the ferrous minerals.

Manganese ore occurs mainly in the ancient metamorphic rocks of the Dharwar and Gondite series of the peninsula, in association with the same rock groups that hold iron ore. The chief ore minerals are pyrolusite, psilomelane and braunite. India has one of the largest reserves of manganese in the world and is among the top producers. The leading producing states are Madhya Pradesh, Maharashtra, Odisha, Karnataka and Andhra Pradesh, whose relative ranks change from year to year.

In Madhya Pradesh the Balaghat and Chhindwara districts hold the biggest deposits; the Balaghat mines are the deepest manganese mines in the country. In Maharashtra the ore comes from Nagpur and Bhandara districts, forming one belt with the Madhya Pradesh deposits. In Odisha manganese is mined in the Bonai–Keonjhar–Sundargarh belt alongside iron ore (Joda, Barbil, Koira), in the Koraput and Rayagada districts of the Eastern Ghats and in Bolangir and Kalahandi. Odisha is now often the largest producer in the country. In Karnataka the mines lie in Shivamogga, Bellary, Chitradurga and Tumakuru districts, and in Andhra Pradesh in Srikakulam and Vizianagaram districts. Smaller amounts come from Jharkhand (Singhbhum), Gujarat (Panchmahals) and Goa.

The ferro-manganese and silico-manganese industry has grown at Joda, Rayagada and Therubali in Odisha, at Tumsar in Maharashtra and near the steel plants. A part of Indian manganese is exported through Visakhapatnam, Paradip and Marmagao, chiefly to Japan. Because high-grade ore is being exhausted, the beneficiation of low-grade ore and the recovery of manganese from ocean-floor nodules are being studied for the future.

Copper was the first metal used by man, and the age between the Stone Age and the Iron Age is named the Chalcolithic or Copper Age after it. Copper is malleable, ductile and an excellent conductor of electricity and heat, so it is the metal of the electrical industry: electric wires, cables, motors, transformers and generators. It is also used in electronics, in the chemical industry and in making the alloys brass (copper and zinc), bronze (copper and tin) and German silver. Because it contains no iron it is a non-ferrous mineral.

Copper ore is found in veins and lodes of igneous and metamorphic rocks. The chief ore minerals are chalcopyrite, chalcocite and malachite. India is critically deficient in copper: reserves are small and of low grade (the ore usually contains less than 1 per cent metal), production is far below demand and a large part of the copper we use is imported. The three main producing regions are:

(1) Madhya Pradesh: The Balaghat mines at Malanjkhand are the largest copper mines of India and produce more than half the country's ore. The deposit is worked as a huge open-cast pit. (2) Rajasthan: The Khetri copper belt in Jhunjhunu district, together with Alwar and Bhilwara, has been mined since ancient times; Khetri is the seat of the Khetri Copper Complex which smelts and refines the ore. (3) Jharkhand: The Singhbhum district has the old Mosabani, Rakha and Surda mines along the Singhbhum copper belt, and the smelter at Ghatsila; this was the first modern copper field in India but is now much depleted. Smaller deposits occur in Karnataka (Chitradurga, Hassan), Andhra Pradesh (Agnigundala in Guntur), Sikkim and Tamil Nadu.

Odisha has no copper mine of importance, though traces occur in the Sundargarh and Keonjhar hills. The state, however, has a copper smelting and refining connection: copper concentrate is imported and processed at the coast, and Odisha's aluminium partly substitutes copper in power transmission lines, which is one of the ways the copper shortage is met. The other ways are the recycling of scrap copper, which is very efficient since copper does not lose its properties on remelting, and the use of optical fibre in place of copper cable in telecommunication.

Bauxite is the ore from which aluminium is obtained. It is not a single mineral but a clay-like rock made of hydrated aluminium oxides (gibbsite, boehmite and diaspore) with impurities of iron and silica; its reddish or creamy colour depends on the iron content. Aluminium is a remarkable metal: it is light (one-third the weight of iron), strong when alloyed, resistant to corrosion, a good conductor of electricity and easily rolled into foil or drawn into wire. It is therefore used in aircraft, railway coaches, motor vehicles, electrical transmission lines, cooking utensils, packaging foil and building frames. Its importance has grown so much that aluminium is called 'the metal of the future'.

Bauxite is a residual deposit: it is formed by the deep weathering of aluminium-rich rocks (laterite, granite, basalt) in a hot, wet climate with alternating dry seasons, which dissolves and removes the silica and leaves the aluminium oxides behind. This is why the deposits of India lie as flat caps on plateau tops that have been exposed to weathering for a very long time.

India has large reserves and is one of the largest producers of bauxite in the world. Odisha is by far the largest producer, giving about half the national output. Its deposits lie in the Eastern Ghats plateaus of Koraput, Rayagada and Kalahandi districts: the Panchpatmali plateau near Damanjodi in Koraput is the single largest bauxite deposit in the country, and other plateaus are Gandhamardan (Bolangir–Bargarh), Baphlimali (Rayagada), Karlapat and Niyamgiri (Kalahandi) and Kodingamali. Gujarat (Jamnagar, Kachchh, Bhavnagar), Jharkhand (Lohardaga and Gumla on the Ranchi plateau), Maharashtra (Kolhapur, Ratnagiri, Thane), Chhattisgarh (Amarkantak plateau, Surguja, Bilaspur), Madhya Pradesh (Katni, Jabalpur, Shahdol, the Maikala range) and Tamil Nadu (the Shevaroy and Nilgiri hills) are the other producers.

Aluminium is produced in two steps: bauxite is first refined to alumina (Al₂O₃) in an alumina refinery, and alumina is then reduced to metal in an aluminium smelter by electrolysis, which consumes a great deal of electricity (about 14,000 to 16,000 units per tonne). Hence smelters are placed near cheap power. Odisha has the country's largest alumina refinery at Damanjodi (NALCO) beside the Panchpatmali mine, and the NALCO smelter at Angul near the Talcher coalfields with its own captive power plant; the Hirakud smelter uses power from the Hirakud dam, and Vedanta's refinery at Lanjigarh and smelter at Jharsuguda have made Odisha the aluminium capital of India. Other plants are at Renukoot (Uttar Pradesh), Korba (Chhattisgarh), Belagavi (Karnataka), Mettur (Tamil Nadu) and Alupuram (Kerala).

Chromite (FeCr₂O₄) is the only ore of chromium. Chromium gives steel its resistance to rust and heat: stainless steel contains 12 to 18 per cent chromium, and chromium plating on taps, bicycle parts and vehicle fittings keeps them bright. Chromite is also used to make refractory bricks for furnaces and chemicals for tanning leather, dyes and pigments. It is a ferrous mineral because it is used chiefly in steel-making as ferro-chrome.

Chromite occurs in ultrabasic igneous rocks such as peridotite and serpentine. India's chromite is highly concentrated: Odisha holds about 95 to 98 per cent of the country's reserves and production, almost all of it in the Sukinda valley of Jajpur district (Kaliapani, Sukrangi, Saruabil, Kathpal, Ostapal) along the boundary with Dhenkanal and Keonjhar; smaller deposits lie in the Boula–Nuasahi area of Keonjhar and near Baula. Outside Odisha only small quantities are found in Karnataka (Hassan), Jharkhand (Singhbhum), Andhra Pradesh, Manipur and Nagaland. Ferro-chrome plants at Jajpur Road, Choudwar, Bhadrak and Therubali in Odisha convert the ore into alloy, much of which is exported to China, Japan and Korea. The open pits of Sukinda are among the largest chromite mines in the world, but hexavalent chromium leaching from their overburden pollutes the Damsala nala and the Brahmani river, which is a well-known environmental problem of the state.

Nickel is another ferrous mineral used in stainless steel, coins and batteries. India has no working nickel mine, but the largest known deposit lies in the same Sukinda belt of Jajpur, where nickel occurs in the lateritic overburden of the chromite mines; its extraction is still under study. Cobalt also occurs with it in small amounts.

Tungsten (from wolframite) is used for filaments of electric bulbs and for hardening steel; it is mined at Degana in Nagaur district of Rajasthan. Pyrite (iron sulphide) at Amjhore in Bihar was worked for sulphuric acid. Vanadium and titanium, both steel-hardeners, occur in the vanadiferous magnetite of Mayurbhanj and Keonjhar and in the ilmenite sands of the Odisha and Kerala coasts. Thus even the minor ferrous minerals of India lean heavily on Odisha, which is why the steel industry, from Rourkela to Jamshedpur, clusters around the state's northern hills.

Mica is a non-metallic mineral composed of a series of plates or leaves, so thin that they can be split into sheets less than a thousandth of a centimetre thick. It is found in three varieties: muscovite (white or ruby mica, the most useful), biotite (black mica) and phlogopite (amber mica). Sheet mica is transparent, colourless or slightly tinted, and possesses three properties that no substitute has fully matched: an excellent dielectric strength (it does not allow electricity to pass), a low power loss factor, and a very high resistance to heat and sudden changes of voltage. Because of these it is one of the most indispensable minerals of the electrical and electronic industries: it is used as an insulator in condensers, in the commutators of motors, in electric irons and heaters, in aircraft spark plugs and in radio and television sets. Ground mica goes into paints, wallpaper, lubricants, cosmetics and the glitter on decorations.

Mica occurs in pegmatite veins of granite and gneiss, which are coarse-grained igneous rocks. India for a long time produced the bulk of the world's sheet mica, and still has among the largest reserves. The three important belts are: (1) the Chhotanagpur belt of Jharkhand, running for about 150 km along the northern edge of the plateau through Koderma, Giridih and Hazaribagh districts; the Koderma–Gaya–Hazaribagh belt is the leading producer and Koderma is called the mica capital of India; (2) the Rajasthan belt, about 320 km long, around Ajmer, Beawar, Bhilwara, Jaipur, Tonk and Udaipur; and (3) the Andhra Pradesh belt in Nellore district, which produces the best quality green mica. Smaller quantities come from Karnataka (Mysuru, Hassan), Tamil Nadu, Kerala, Odisha (Koraput and Ganjam) and West Bengal.

The mica trade has declined since the 1960s because synthetic substitutes and plastics have replaced sheet mica in many uses, and the mines of Koderma and Giridih, which once employed tens of thousands, are now small and partly illegal. Mica is still exported, mostly as scrap and ground mica, to Japan, the United States and Europe. The sorting and splitting of mica is a cottage industry done by hand, and the health hazard from mica dust to workers, including children, in Jharkhand is a serious concern.

Limestone is a sedimentary rock composed chiefly of calcium carbonate (CaCO₃), formed from the shells of sea creatures deposited on ancient sea floors, or from the chemical precipitation of lime. It is found in association with rocks of many ages. Limestone is the basic raw material of the cement industry, which uses about three-fourths of the output; it is essential as a flux in the smelting of iron ore in blast furnaces (it combines with the impurities to form slag); and it is used in the chemical industry (lime, bleaching powder, calcium carbide), in sugar refining, glass making, paper and as building stone. India has enormous reserves in almost every state. The chief producers are Rajasthan (Jodhpur, Nagaur, Chittaurgarh, Kota), Madhya Pradesh (Satna, Katni, Jabalpur, Rewa), Andhra Pradesh and Telangana (Guntur, Krishna, Cuddapah, Nalgonda), Chhattisgarh (Raipur, Bilaspur, Durg), Gujarat (Junagadh, Kachchh), Karnataka (Gulbarga, Bijapur) and Tamil Nadu (Tiruchirappalli, Ariyalur). In Odisha limestone is quarried in Sundargarh (Purnapani, Biramitrapur, Lanjiberna), which supplies the Rourkela steel plant and the cement factories at Rajgangpur, in Bargarh (Dungri, feeding the Bargarh cement plant), in Koraput and in Bolangir.

Dolomite (calcium magnesium carbonate) is a related rock used as a flux and refractory in steel plants and in the glass and fertiliser industries. Odisha is a major producer, with quarries at Biramitrapur in Sundargarh, one of the largest dolomite deposits in India, and in Koraput; Chhattisgarh, Jharkhand and Karnataka are the other producers.

Gypsum (hydrated calcium sulphate) is used in cement (to control setting), plaster of Paris, fertiliser and chalk; Rajasthan (Bikaner, Jodhpur, Nagaur) produces most of it, followed by Jammu and Kashmir, Tamil Nadu and Gujarat. Graphite, a soft form of carbon used in pencils, crucibles, lubricants and electrodes, is mined in Odisha (Bolangir, Bargarh, Nuapada, Rayagada and Koraput are the principal graphite districts of India), Jharkhand and Tamil Nadu. Kaolin or china clay for pottery, paper and ceramics comes from Kerala, West Bengal, Rajasthan and Odisha (Mayurbhanj, Sundargarh). Quartz and silica sand for glass are widespread. Salt is obtained from sea water in Gujarat, Tamil Nadu and Odisha (Ganjam, Balasore), from Sambhar lake in Rajasthan and from rock salt in Himachal Pradesh. Diamonds are mined at Panna in Madhya Pradesh, and precious and semi-precious stones such as garnet and beryl occur in Rajasthan and Odisha (Kalahandi, Bolangir).

Odisha is the richest mineral state in India, and understanding why explains much of its economy. The northern and western parts of the state, the districts of Keonjhar, Sundargarh, Mayurbhanj, Jajpur, Dhenkanal, Angul, Jharsuguda and Sambalpur, and the Eastern Ghats districts of Koraput, Rayagada, Kalahandi and Bolangir, are made of some of the oldest crystalline rocks of the earth's crust, the Iron Ore Series and the Eastern Ghats granulites, interrupted by the Gondwana sedimentary basins of the Mahanadi and Brahmani valleys. The ancient rocks hold the metallic minerals; the Gondwana basins hold coal; the weathered plateau tops hold bauxite; and the coastal sands hold heavy minerals. Few regions of the world combine all four.

The state's share of India's reserves, in round figures, is: chromite about 95 per cent, nickel about 92 per cent, bauxite about 50 per cent, iron ore about 33 to 50 per cent, coal about 25 per cent, manganese about 30 per cent, graphite about 40 per cent, and it also has large reserves of dolomite, limestone, china clay, quartz, fire clay, pyrophyllite, vanadium, titanium-bearing sands, gemstones and traces of gold. Odisha is the largest producer in India of chromite, bauxite, iron ore and manganese and among the top producers of coal. Mining and quarrying contribute a large share of the state's income and of the royalty received by the government.

District-wise: Keonjhar (Joda, Barbil, Bolani, Thakurani, Gandhamardan) and Sundargarh (Koira, Kalta, Bonai) are the iron ore districts; Mayurbhanj (Gorumahisani, Badampahar, Sulaipat) has iron ore and vanadium; Jajpur (Sukinda) has chromite and nickel; Koraput, Rayagada and Kalahandi have bauxite, manganese and graphite; Sundargarh has limestone and dolomite; Angul and Jharsuguda have coal; Ganjam (Chhatrapur) has ilmenite, monazite and zircon sands; Bolangir and Nuapada have graphite and gemstones; Bargarh has limestone.

On this mineral base stand the state's industries: the integrated steel plant at Rourkela, steel plants at Kalinganagar (Jajpur), Angul, Jharsuguda and Paradip, the aluminium complexes of NALCO (Damanjodi–Angul) and Vedanta (Lanjigarh–Jharsuguda), ferro-alloy plants at Jajpur Road, Choudwar, Bhadrak and Therubali, cement plants at Rajgangpur and Bargarh, the thermal power stations at Talcher, Ib valley and Kaniha, and the ports of Paradip, Dhamra and Gopalpur which export ore. The Odisha Mining Corporation (OMC) and the Mineral Exploration Corporation carry out mining and prospecting on behalf of the state. The other side of the picture is that the mining districts of Keonjhar and Sundargarh are also among the poorest in the state and suffer severe environmental damage, which the last topics of this chapter address.

Minerals are extracted from the earth by mining, of which there are three methods. Open-cast or surface mining is used when the ore lies close to the surface: the soil and rock above it, called the overburden, are removed and the ore is dug out in huge stepped pits with excavators and dumpers. It is the cheapest and safest method and is used for most of the iron ore, bauxite, chromite and limestone of Odisha. Underground or shaft mining is needed when the deposit lies deep: a vertical shaft is sunk and horizontal tunnels or galleries are driven along the ore body; this is the method for deep coal seams, copper lodes, gold and some chromite. Drilling is the method for liquid and gaseous minerals: petroleum and natural gas are reached by deep wells. Placer minerals are recovered by dredging and washing river or beach sand.

Mining is a hazardous occupation. For the miner, underground work carries the dangers of roof collapse, flooding, explosion and fire from methane and coal dust, poisonous gases and inadequate ventilation; the constant breathing of dust causes silicosis, pneumoconiosis and other lung diseases, and mica and asbestos dust are especially harmful. Accidents in Indian coal mines have killed thousands of workers over the years, and the Mines Act and the Directorate General of Mines Safety exist to regulate conditions.

For the environment, mining damages land, water, air and forest. Open-cast mining strips away the vegetation and top soil, leaves enormous pits and heaps of overburden and tailings, and turns green hills into barren wasteland; the iron ore belt of Keonjhar and Sundargarh and the coal belt of Talcher show this vividly. Dust from blasting, crushing and the movement of trucks pollutes the air for kilometres around, coating fields and houses red. Mine water and the run-off from dumps pollute rivers and streams: hexavalent chromium from the Sukinda mines in the Damsala nala, acid mine drainage from coal mines, and the silting of the Baitarani and Brahmani rivers with ore fines are examples. Underground mining causes subsidence of the land above and, in the coalfields of Jharia and Talcher, underground fires that burn for decades. Mining also displaces tribal communities who lose their land and forest, as in the bauxite hills of Koraput and Kalahandi, and the mineral wealth of a district does not automatically become the wealth of its people. Illegal mining, exposed in Odisha's iron ore belt by an inquiry commission, adds to the damage because it follows no rules at all.

The remedies are strict enforcement of safety and pollution laws, dust suppression, the treatment of mine water, the compulsory reclamation of mined-out land by refilling and afforestation, and the sharing of mining revenue with the affected districts through District Mineral Foundations.

The industry and agriculture on which our lives depend rest heavily on minerals, and the demand for them grows every year with population and industrialisation. But minerals are finite and non-renewable. The geological processes of mineral formation are so slow that their rate of replenishment is infinitely small in comparison with the present rate of consumption; deposits that took millions of years to form can be exhausted in a few decades. Moreover, the richest and most accessible deposits are always worked first, so that as time passes the miner must dig deeper for ore of lower grade, and the cost of extraction rises in money, energy and environmental damage. Only about one per cent of the earth's crust consists of workable mineral deposits. For all these reasons a planned and sustainable use of minerals, in other words their conservation, is necessary.

Conservation does not mean stopping the use of minerals; it means using them so that they last longer and serve more people. The important measures are:

1. Reduce wastage in mining and processing. Modern mining should extract the whole ore body, not only the rich part, and the beneficiation of low-grade ore (concentrating it by crushing, washing and magnetic or flotation methods) should be encouraged so that ore once thrown on the dumps can be used. Fines and slimes of iron ore, once wasted, are now sintered and pelletised.

2. Recycling and reuse. Metals do not lose their properties on remelting. Scrap iron, copper, aluminium, lead and zinc should be collected and reused; recycled aluminium needs only about 5 per cent of the energy of primary aluminium. India's scrap collection, though informal, is one of the most efficient in the world.

3. Substitution. A scarce mineral should be replaced by a plentiful or renewable one wherever possible: aluminium for copper in cables, plastic and optical fibre for metal, and ceramics or synthetic mica for natural mica.

4. Improved technology. Research should develop methods that use less mineral per unit of product, that recover metal from low-grade ore and tailings, and that find substitutes.

5. Export of finished goods, not raw ore. Exporting raw ore drains the resource for a small price; value should be added within the country.

6. Regulation and protection. Illegal mining must be stopped, mining leases must follow the Mines and Minerals (Development and Regulation) Act and environmental clearance, and mined land must be reclaimed. Exploration of new reserves, including the ocean floor and deep deposits, and the mapping of resources by the GSI, are part of the same effort.

Every citizen contributes by not wasting metal goods, returning scrap for recycling and using products for their full life.

Minerals matter to a country not only for what they are but for what they make possible. The mining and quarrying sector contributes a modest share of India's national income, around two to three per cent, but the industries that depend on minerals, iron and steel, aluminium, cement, chemicals, electricity, engineering, automobiles and construction, contribute a far larger share, and almost every manufactured export contains minerals. The location of industry in India follows the minerals closely: the great industrial region of the Chhotanagpur plateau and northern Odisha grew because iron ore, coal, manganese, limestone and dolomite occur together within a short distance, which is why Jamshedpur, Rourkela, Bokaro, Durgapur and Burnpur all lie in this region. Cement plants stand on limestone, aluminium smelters near bauxite and cheap power, ferro-alloy plants beside chromite and manganese.

India is well endowed in some minerals and poor in others. It has large reserves of iron ore, coal, manganese, bauxite, chromite, mica, limestone, dolomite and thorium, adequate quantities of copper, lead, zinc, gold and gypsum for some needs, and is deficient in petroleum, natural gas, copper, tin, nickel, sulphur, potash, platinum and uranium, which it imports. The pattern of trade reflects this: iron ore, chromite, manganese, ferro-alloys, alumina, granite and processed minerals are exported, while crude petroleum, copper concentrate, gold, fertiliser minerals and coking coal are imported. Petroleum alone is the single largest item of India's import bill.

Ownership matters too. Under the Constitution, minerals belong to the state governments, which grant leases and collect royalty; the central government makes the law and controls atomic minerals and offshore areas. Public sector companies such as Coal India, NMDC (iron ore), NALCO (aluminium), Hindustan Copper, Hindustan Zinc (now private) and the Odisha Mining Corporation were set up to develop minerals in the national interest, and since 1991 private and foreign companies have entered mining on a large scale. Odisha's government earns a large part of its own revenue from mineral royalty and the auction of mining leases.

For a mineral-rich state, the lesson of the chapter is that mineral wealth is an opportunity, not a guarantee. It becomes prosperity only when the ore is processed within the region into steel, aluminium and finished goods, when the earnings are invested in schools, roads and health in the mining districts, when the land and water are protected, and when the finite resource is stretched by conservation for the generations to come.