29 August 2015


CBSE NCERT Class X (10th) | Social Studies | Geography


Types and Occurrence of Minerals
Minerals are defined as naturally occurring homogeneous substances that have a definite internal structure. Some minerals are essential for our body to carry out its chemical and biological processes. A rock may contain one or several types of minerals mixed with organic material.

A geographer studies about the distribution and economic importance of a mineral while, a geologist studies the formation, age and composition of minerals. The properties of a mineral depend on the elements it is made of, and the chemical and physical conditions in which it was formed.

Minerals are classified as metallic minerals, non-metallic minerals and energy or fuel minerals. The metallic minerals can be further classified as ferrous minerals, or the ones that contain iron, non-ferrous minerals and precious metals, like gold, silver and platinum.

Minerals occur in the earth’s crust as:
  • Veins and lodes in igneous and metamorphic rocks
  • Beds or layers in sedimentary rocks
  • Alluvial or placer deposits on valley floors
  • Residual mass after weathering of surrounding rocks

Some metallic minerals, like gold, silver, platinum and tin, are found as alluvial deposits in the sand and soil in valleys. Such alluvial deposits are also called placer deposits. Around 70% of the surface of the earth is covered by water. The water of the seas and oceans, and the ocean floors, also have rich mineral deposits.

India has rich mineral resources in some parts of its territory. To be an ore, a mineral should:
  • Be abundantly available
  • Offer sufficient concentration of an element
  • Have a commercially viable process of extraction

The places from where mineral ores are extracted are called mines. All the mineral reserves in India are owned by the government. In Meghalaya, families lay claim to coal deposits, and mine coal by digging long narrow tunnels in the ground. This practice is called rat hole mining.

Ferrous and Non-Ferrous Minerals

Ferrous minerals contain iron, non-ferrous minerals do not contain iron. Ferrous minerals constitute about 75% of the total production of minerals in India. India exports substantial amounts of ferrous minerals.

Iron ore and manganese are two important ferrous minerals mined in India. The two main ores of iron are magnetite and hematite. Magnetite has up to 70% iron, while hematite has 50-60% iron. Karnataka and Orissa are the main iron ore producing states in India, followed by Chhattisgarh, Goa and Jharkhand. Major iron ore producing belts of India, are: the Orissa-Jharkhand belt, the Durg-Bastar-Chandrapur belt, the Bellary-Chitradurga-Chikmaglur-Tumkur belt and the Maharashtra-Goa belt.

High-grade hematite is mined in the Badampahar mines in Mayurbhanj and Kendujhar districts of Orissa. The Durg-Bastar-Chandrapur belt is spread over parts of Chhattisgarh and Maharashtra. These hills contain 14 deposits of hematite.

The Bellary-Chitradurga-Chikmaglur-Tumkur belt lies in Karnataka. The Kudermukh mines in this region hold one of the largest deposits of iron ore in the world. Orissa is the main manganese-producing state in India, followed by Madhya Pradesh and Karnataka.

The Maharashtra-Goa belt is spread over parts of Goa and Ratnagiri district of Maharashtra. Steel is a mixture of several minerals besides iron ore, and one such important mineral is manganese. The reserves of non-ferrous minerals in India are not as abundant as those of ferrous minerals. Copper and bauxite are two important non-ferrous minerals mined in India. Copper is widely used in the electrical, electronic and chemical industries.

Madhya Pradesh, Rajasthan and Jharkhand are the main copper-producing states in India. Aluminium is a strong, yet light-weight metal derived from a non-ferrous mineral. Bauxite is the main ore of aluminium. Orissa is the main bauxite-producing state in India, followed by Gujarat, Jharkhand and Maharashtra.

Non-Metallic Minerals

Mica is a non-metallic mineral composed of thin leaves or sheets joined together. Mica is found in many colours, from transparent to black, green, yellow, brown and red. Mica provides excellent electrical insulation with low power-loss even at very high voltages. Mica is used extensively in the electrical and electronics industries.

The main mica-producing regions in India are the northern Chhota Nagpur Plateau in Jharkhand, Ajmer in Rajasthan and Nellore in Andhra Pradesh. The Koderma, Gaya and Hazaribagh belt in Jharkhand is the largest producer of mica in India. Limestone is a form of sedimentary rock almost entirely composed of calcium carbonate. Limestone is mainly used in smelting iron ore and in the manufacturing of cement.          
Andhra Pradesh is the main limestone-producing state in India, followed by Madhya Pradesh, Rajasthan, Gujarat, Tamil Nadu and others.

Mine workers face serious risks to their health and life. Indiscriminate mining leads to extensive deforestation. Dumping of mining waste results in soil and land degradation and pollution of air and fresh water bodies.

We need stricter laws and implementation of personal and environmental safety regulations to keep mining a safe activity. Usable minerals are only about 1% of the earth’s crust. Minerals are limited and non-renewable resources. Continuous mining starts yielding poor quality ores at much higher cost. We need to conserve our mineral resources. Recycling and reusing material finding suitable substitutes of minerals can help us conserve our mineral resources.
Energy Resources
We need energy in different forms for all our daily activities. The conventional sources of energy include firewood, cattle dung cakes, minerals like coal, petroleum and natural gas, and electricity generated by flowing water or burning fuel.

The non-conventional sources of energy include solar energy, wind energy, tidal energy, geothermal energy, atomic energy and biogas. Firewood and cattle dung cakes are the primary sources of energy, meeting around 70% of the total energy requirement in our villages.

The intense heat and pressure over millions of years has turned prehistoric plant material buried under the earth into coal. The variety of coal depends on how long the plant material has been buried, at what depth and under how much pressure. Peat is a low carbon variety that has high moisture and provides low heat output. Lignite is a soft, low-grade variety of coal that has high moisture content and appears brownish in colour.

Bituminous coal is formed from plant material buried deep in the earth and subjected to very high temperature. Bituminous coal is the most important commercial variety of coal used in metallurgical applications like smelting of iron. The best and the most expensive variety of coal is called anthracite.

In India, coal is found as Gondwana deposits that are over 200 million years old, and tertiary deposits that are just about 55 million years old. The Gondwana deposits in India are found in the Damodar valley in West Bengal and Jharkhand and the Mahanadi, Godavari, Son and Wardha valleys. Tertiary deposits of coal are found in the north-eastern states of Assam, Meghalaya, Arunachal Pradesh and Nagaland.

Coal is bulky and expensive to transport in large quantities so, most power plants and heavy industries relying on coal are located near coal fields. Petroleum provides fuels like petrol and diesel, industrial lubricants and raw material for a number of industries including textiles, fertilisers and cosmetics.

Petroleum deposits are found in anticlines and fault traps in rock formations. Off-shore oil fields in Mumbai High account for 63% of the total petroleum production in India. This is followed by 18% of the production coming from Gujarat and 16% from Assam. Ankaleshwar in Gujarat, and Digboi, Naharkatiya and Moran-Hugrijan in Assam are other major oil fields in India. Assam is the oldest oil-producing state in India.

Natural gas is a mixture of gases, primarily methane, which is found trapped in rocks. Natural gas is used as auto fuel (CNG), to generate electricity and in the fertiliser industry. Large deposits of natural gas have been found in the Krishna-Godavari basin, Mumbai High, the Gulf of Cambay and the Andaman and Nicobar Islands.

The natural gas fields in Mumbai High and Bassein are linked to the power and fertiliser plants in western and northern India by the 1700-kilometre long Hazira-Vijaipur-Jagdishpur or HVJ Natural Gas Pipeline.  

Electricity and Non-Conventional Sources of Energy

The electricity generated by the energy of flowing water is called hydroelectricity which is a renewable resource of energy. Large hydropower plants like Bhakra Nangal, Damodar Valley Corporation and Kopili are called multi-purpose river projects.

Electricity generated from the heat of burning fuel minerals like coal, petroleum and natural gas is called thermal electricity and hence is produced using non-renewable fossil fuels. India has over 310 thermal power plants. Nuclear or atomic energy is also used to generate electricity.

India currently has 6 operational nuclear power plants in Uttar Pradesh, Maharashtra, Karnataka, Rajasthan, Tamil Nadu and Gujarat. The increasing prices, shortage in supply and environmental concerns against using fossil fuels can severely affect our energy security.

The answer to the problem of energy security lies in using non-conventional sources of energy like solar energy, wind energy, biogas, tidal energy and geothermal energy. The secret of using solar power lies in photovoltaic technology. This technology uses panels made of photovoltaic cells that trap solar energy and convert it into electricity.

The use of solar energy in rural India can reduce dependence on firewood and cattle dung cakes. Wind turbines convert the energy of the blowing wind into electricity. The largest wind farm in India is in Tamil Nadu, spread from Nagercoil to Madurai. Animal, human and farm waste produce biogas on decomposition, which is a better fuel than kerosene, cattle dung cakes, firewood and coal. Biogas plants that operate on animal waste are called gobar gas plants in India.

Oceanic tides are used to generate electricity called tidal energy. The National Hydropower Corporation has set up a 900 megawatt tidal energy plant in the Gulf of Kutch that provides excellent conditions for harnessing tidal energy. The heat trapped in the depths of the earth is called geothermal energy. Experimental projects to utilise geothermal energy have been set up at the Parvati Valley near Manikaran in Himachal Pradesh, and the Puga Valley in Ladakh.

Conservation of Energy

Energy requirements are rising in all parts of India. We are largely dependent on fuel minerals like coal, petroleum and natural gas to fulfil our energy requirements.

Minerals are non-renewable resources. Thus, the supply of coal, petroleum and natural gas is limited. Heavy dependence on fuel minerals for energy is not a sustainable plan to meet our future energy requirements.

A sustainable path of energy development involves:
  • Finding renewable, non-conventional sources of energy
  • Conservation of the energy available today

A lot of energy is wasted in our country through inefficient means of usage. We can conserve fuel minerals like petroleum and natural gas by forming car pools and using public transport instead of private vehicles. And also, by using better, renewable fuels like biogas in place of coal for cooking. We can conserve energy by switching off all lights, fans and electrical devices when not required and using power saving devices

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