Minerals – Homogeneous, naturally occurring substance with a definable internal structure. Minerals are usually found in “ores”
Rocks are combinations of homogeneous substances called minerals.
The type of formation or structure in which they are found determines the relative ease with which mineral ores may be mined. This also determines the cost of extraction.
Minerals generally occur in these forms:
(i) In igneous and metamorphic rocks minerals may occur in the cracks, crevices, faults or joints. The smaller occurrences are called veins and the larger are called lodes. In most cases, they are formed when minerals in liquid/ molten and gaseous forms are forced upward through cavities towards the earth’s surface. They cool and solidify as they rise. Major metallic minerals like tin, copper, zinc and lead etc. are obtained from veins and lodes.
(ii) In sedimentary rocks a number of minerals occur in beds or layers. They have been formed as a result of deposition, accumulation and concentration in horizontal strata. Minerals include coal, gypsum, potash salt and sodium salt. These are formed as a result of evaporation especially in arid regions.
(iii) Another mode of formation involves the decomposition of surface rocks, and the removal of soluble constituents, leaving a residual mass of weathered material containing ores. Bauxite is formed this way.
(iv) Certain minerals may occur as alluvial deposits in sands of valley floors and the base of hills. These deposits are called ‘placer deposits’ and generally contain minerals, which are not corroded by water. Gold, silver, tin and platinum are most important among such minerals.
(v) The ocean waters contain vast quantities of minerals, but most of these are too widely diffused to be of economic significance. Common salt, magnesium and bromine are largely derived from ocean waters.
Minerals can be categorized into 3 types:
1) Metallic minerals
- a) Ferrous
- b) Non-ferrous
- c) Precious
2) Non-metallic minerals
3) Energy minerals – coal, petroleum, gas
- a) Ferrous Minerals – account for about three fourths of the total value of the production of metallic minerals. They provide a strong base for the development of metallurgical industries.
- Iron ore is the basic mineral and the backbone of industrial development.
- India is rich in good quality iron ores.
- Magnetite is the finest iron ore with a very high content of iron up to 70 per cent. It has excellent magnetic qualities, especially valuable in the electrical industry.
- Hematite ore is the most important industrial iron ore in terms of the quantity used, but has a slightly lower iron content than magnetite. (50-60 per cent).
- The major iron ore belts in India are:
- Odisha-Jharkhand belt: In Odisha high grade hematite ore is found in Badampahar mines in the Mayurbhanj and Kendujhar districts. In the adjoining Singbhum district of Jharkhand haematite iron ore is mined in Gua and Noamundi.
- Durg-Bastar-Chandrapur belt lies in Chhattisgarh and Maharashtra. Very high grade hematites are found in the famous Bailadila range of hills in the Bastar district of Chhattisgarh.
- Ballari-Chitradurga-ChikkamagaluruTumakuru belt in Karnataka has large reserves of iron ore. The Kudremukh mines located in the Western Ghats of Karnataka are a 100 per cent export unit. Kudremukh deposits are known to be one of the largest in the world. The ore is transported as slurry through a pipeline to a port near Mangaluru.
- Maharashtra-Goa belt includes the state of Goa and Ratnagiri district of Maharashtra. Iron ore is exported through Marmagao port.
- Manganese is mainly used in the manufacturing of steel and ferro-manganese alloy.
- It is also used in manufacturing bleaching powder, insecticides and paints.
- Odisha is the largest producer of manganese ores in India
- b) Non-ferrous Minerals – include copper, bauxite, lead, zinc and gold and play a vital role in a number of metallurgical, engineering and electrical industries.
Being malleable, ductile and a good conductor copper is mainly used in electrical cables, electronics and chemical industries. The Balaghat mines in Madhya Pradesh, Khetri mines in Rajasthan and Singhbhum district of Jharkhand are leading producers of copper.
- Bauxite deposits are formed by the decomposition of a wide variety of rocks rich in aluminium silicates.
- Aluminium is an important metal because it combines the strength of metals such as iron, with extreme lightness and also with good conductivity and great malleability.
- India’s bauxite deposits are mainly found in the Amarkantak plateau, Maikal hills and the plateau region of Bilaspur-Katni.
- Mica is a mineral made up of a series of plates or leaves. It splits easily into thin sheets.
- Mica can be clear, black, green, red yellow or brown.
- Due to its excellent di-electric strength, low power loss factor, insulating properties and resistance to high voltage, mica is one of the most indispensable minerals used in electric and electronic industries.
- Mica deposits are found in the northern edge of the Chota Nagpur plateau. Koderma Gaya – Hazaribagh belt of Jharkhand is the leading producer.
Limestone is found in association with rocks composed of calcium carbonates or calcium and magnesium carbonates. It is found in sedimentary rocks of most geological formations. Limestone is the basic raw material for the cement industry and essential for smelting iron ore in the blast furnace.
Conventional Sources of Energy
- It is used for power generation, to supply energy to industry as well as for domestic needs.
- Coal is formed due to the compression of plant material over millions of years. Coal, therefore, is found in a variety of forms depending on the degrees of compression and the depth and time of burial.
- Decaying plants in swamps produce peat which has a low carbon and high moisture contents and low heating capacity.
- Lignite is a low grade brown coal, which is soft with high moisture content. The principal lignite reserves are in Neyveli in Tamil Nadu and are used for generation of electricity.
- Coal that has been buried deep and subjected to increased temperatures is bituminous coal. It is the most popular coal in commercial use. Metallurgical coal is high grade bituminous coal which has a special value for smelting iron in blast furnaces.
- Anthracite is the highest quality hard coal.
- Jharia, Raniganj, Bokaro are important coalfields.
- Coal is a bulky material, which loses weight on use as it is reduced to ash. Hence, heavy industries and thermal power stations are located on or near the coalfields
- It provides fuel for heat and lighting, lubricants for machinery and raw materials for a number of manufacturing industries.
- Petroleum refineries act as a “nodal industry” for synthetic textile, fertiliser and numerous chemical industries.
- Most of the petroleum occurrences in India are associated with anticlines and fault traps in the rock formations of the tertiary age. In regions of folding, anticlines or domes, it occurs where oil is trapped in the crest of the upfold. The oil bearing layer is a porous limestone or sandstone through which oil may flow. The oil is prevented from rising or sinking by intervening non-porous layers. Petroleum is also found in fault traps between porous and non-porous rocks.
- Gas, being lighter usually occurs above the oil. About 63 per cent of India’s petroleum production is from Mumbai High, 18 per cent from Gujarat and 16 per cent from Assam.
- Natural gas is an important clean energy resource found in association with or without petroleum.
- It is used as a source of energy as well as an industrial raw material in the petrochemical industry.
- Natural gas is considered an environment friendly fuel because of low carbon dioxide emissions.
- Large reserves of natural gas have been discovered in the Krishna- Godavari basin. Along the west coast the reserves of the Mumbai High and allied fields are supplemented by finds in the Gulf of Cambay.
- Electricity is generated mainly in two ways: by running water which drives hydro turbines to generate hydroelectricity; and by burning other fuels such as coal, petroleum and natural gas to drive turbines to produce thermal power.
- There are over 310 thermal power plants in India. India has a number of multi-purpose projects like the Bhakra Nangal, Damodar Valley corporation, the Kopili Hydel Project etc.
Non-Conventional Sources of Energy
1) Nuclear or Atomic Energy
It is obtained by altering the structure of atoms. When such an alteration is made, much energy is released in the form of heat and this is used to generate electric power. Uranium and Thorium, which are available in Jharkhand & the Aravalli ranges of Rajasthan are used for generating atomic or nuclear power.
2) Solar Energy
India is a tropical country. It has enormous possibilities of tapping solar energy. Photovoltaic technology converts sunlight directly into electricity. It will minimise the dependence of rural households on firewood and dung cakes, which in turn will contribute to environmental conservation and adequate supply of manure in agriculture.
3) Wind power
India has great potential of wind power. The largest wind farm cluster is located in Tamil Nadu from Nagarcoil to Madurai. Apart from these, Andhra Pradesh, Karnataka, Gujarat, Kerala, Maharashtra and Lakshadweep have important wind farms.
Shrubs, farm waste, animal and human waste are used to produce biogas for domestic consumption in rural areas. Decomposition of organic matter yields gas, which has higher thermal efficiency in comparison to kerosene, dung cake and charcoal. Biogas plants are set up at municipal, cooperative and individual levels. The plants using cattle dung are known as ‘Gobar gas plants’ in rural India.
5) Tidal Energy
Oceanic tides can be used to generate electricity. Floodgate dams are built across inlets. During high tide water flows into the inlet and gets trapped when the gate is closed. After the tide falls outside the flood gate, the water retained by the floodgate flows back to the sea via a pipe that carries it through a power-generating turbine. In India the Gulf of Khambhat, the Gulf of Kuchchh in Gujarat on the western coast and Gangetic delta in Sunderban regions of West Bengal provide ideal conditions for utilising tidal energy.
6) Geo Thermal Energy
Geo thermal energy refers to the heat and electricity produced by using the heat from the interior of the Earth. Geothermal energy exists because the Earth grows progressively hotter with increasing depth. Where the geothermal gradient is high, high temperatures are found at shallow depths. Groundwater in such areas absorbs heat from the rocks and becomes hot. It is so hot that when it rises to the earth’s surface, it turns into steam.