Q.1. What are minerals? How are they classified?
Ans. Minerals are natural resources which are obtained from rocks. Geologists define a mineral as a “homogeneous, naturally occurring substance with a definable internal structure.” They are normally found in solid, liquid and gaseous states. They have a definite chemical composition and crystalline structure. A particular mineral that will be formed from a single or certain combination of elements depends upon the physical and chemical conditions under which the material forms. Minerals are classified into metallic and non-metallic minerals and energy resources.
(a) Metals are obtained from metallic minerals. They are further subdivided into
(i) ferrous minerals containing iron, i.g. iron-ore manganese, nickel, cobalt, etc.
(ii) Non-ferrous minerals, e.g. copper, lead, tin, bauxite, etc. that do not contain iron.
(iii) Precious minerals, e.g. gold, silver, platinum.
(b) Non-metals, e.g. mica, salt, potash, sulphur, granite, limestone, dolamite, gypsum, marble, etc. lack the lustre and hardness of metals.
(c) Energy minerals are fossil fuels, e.g. coal, petroleum, natural gas used to generate energy.
Q.2. (i) What are ores? Give example.
(ii) What are ‘placer deposits’? Give examples of minerals found in such deposits. (2010)
(i) The term ore is used to describe an accumulation of any mineral mixed with other elements. Minerals are usually found in ores. Metals are extracted from the ores after removing the impurities. Iron ore, bauxite (ore of aluminium), copper ore are examples of ores, from which iron, aluminium and copper are derived respectively.
(ii) Certain minerals may occur as alluvial deposits in sands of valley floors and base of hills. These deposits are called ‘placer deposits’. They generally contain minerals which are not corroded by water. Gold, silver, tin and platinum are examples of some important minerals found in ‘placer deposits’.
Q.3. What is a mine ? Name the different types of mining prevalent in India. What is rat-hole mining and where in India is this type of mining done?
Ans. When the extraction of a mineral from its deposit or reserve becomes economically viable, that deposit is termed as a mine. The concentration of minerals in the ore, the ease of extraction and closeness to the market are important considerations to select a reserve to be a mine for extraction of the mineral.
The different types of mining prevalent in India are :
(a) Open-pit mining or open-cast mining.
(b) Underground mining or deep-shaft mining.
(c) Rat-hole mining.
(e) Drilling (for obtaining mineral oil or petroleum).
Rat-hole mining is a local form of coal mining prevalent in tribal areas of the north-east where some minerals like coal, iron ore, limestone and dolomite are owned by individuals and communities. In Jowai and Cherrapunji in Meghalaya, coal mining is done by family members of the tribal community in form of a long narrow tunnel. This is known as rat-hole mining.
Q.4. Mention any four uses of manganese ore. Name three areas where manganese is found.
Ans. Four uses of manganese ore are follows :
(i) It is an important raw material in the iron and steel industry, used in the manufacturing of steel. Nearly 10 kg of manganese is required to manufacture one tonne of steel.
(ii) It is used to prepare alloys or mixture of different metals to acquire special properties for the minerals, e.g. ferro-manganese alloys.
(iii) It is used to make bleaching powder and insecticides.
(iv) It is used in manufacturing of batteries and for making paints.
Orissa is the largest producer of manganese followed by Madhya Pradesh and Karnataka. Kendughar and Sundergarh of Orissa, Chhindwara and Balaghat in Madhya Pradesh and Shimoga of Karnataka are important areas of manganese mining.
Q.5. Which types of minerals have provided a strong base for development of metallurgical industries in India ? Which particular mineral is termed as the backbone of industrial development and why?
Ans. Ferrous minerals like iron ore, manganese etc., account for about three-fourth of the total value of the production of metallic minerals in India. As such, ferrous minerals provide a strong base for the development of metallurgical industries in India. These industries extract and purify the metals and produce them in usable forms for their application in various other industries. Iron ore, a ferrous mineral, is the basic mineral and the backbone of industrial development. It is the key to progress in the present mechanical civilisation. Iron and steel made from iron ore and its alloys is used to make machines. Machines determine the development of industries. As the basic tools, implements and machines required in the industries are made of iron, industrial development is determined by iron.
Q.6. Why is mica considered to be an indispensable mineral for the electronics industry? Mention the names of the main mica-producing areas of India.
Ans. Mica is a non-conductor of electricity. Due to its excellent di-electric strength, low power loss factor, insulating properties and resistance to high voltage, mica is an indispensable mineral for the electrical and electronics industries. Koderma-Gaya-Hazaribagh belt of Jharkhand is the leading mica-producing area of India. In Rajasthan, the major mica-producing area is around Ajmer. In Andhra Pradesh, the Nellore mica belt is an important mica-producing area.
Q.7. Why are petroleum refineries termed as ‘nodal industries’?
Ans. Petroleum refineries act as a ‘nodal industry’ for synthetic textile, fertiliser and numerous chemical industries. During fractional distillation of mineral oil, apart from petrol, diesel and kerosene which act as fuel, a number of byproducts like naptha, phyneyl, paraffin wax, asphalt or tar and a number of petrochemicals are obtained. Chemical fertilisers, insecticides and chemicals, artificial fibres and artificial rubber are products of petrochemicals. Thus, petrochemicals, provide raw materials for fertilisers, numerous chemicals, synthetic textiles, synthetic rubber and plastic industries.