PETROLEUM OR CRUDE OIL

PETROLEUM OR CRUDE OIL The word 'petroleum' has been derived from the word 'petra', which means rock, and 'oleum' which means oil. Thus 'petroleum' means 'rock-oil'. It is one of the important mineral fuels and is a complex mixture of hydrocarbtm compounds with minor amounts of ir.\1purities like nitrogen, sulphur and oxygen. The liquid pet.roleum is called crude oil, petroleum gas is called natural gas and the semi-solid to solid forms of petroleum are known as asphalt, tar, pitch, bitumen, etc.

For petroleum to accumulate in commercial quantities in an area, the"oil mttSt originate in a source bed. A marine shale, once a black mud rich in organic compound, is thought to be a common source rock. The oil then migrates to permeable reservoir rocks after travelling for long distances both vertically and horizontally. The source beds tend to lack the permeability necessary for profitable extraction of the oil. A non-permeable layer must occur above the reservoir bed. A favourable structure must exist.

Three principal grades of crude oil are considered important. Paraffin-Base Oil with a high percentage of the lighter hydrocarbons such as methane gives products, such as petrol, paraffin and high r;rade lubricating oils which are commercially more valued. Asphalt-Base Oil consists mainly of the heavier hydrocarbons with a viscous, asphaltic base. Mixed-Based Oil is an intermediate group with mixed properties of the lighter and heavier oils. It has use in lubricants and fuel oils.

Economic Uses The chief use of petroleum is as fuel, particularly in transport operations. The petrochemical derivations of petroleum have a wide range of uses in agricultural, industrial and medicinal industries. It is also used for the purpose of generation of heat and power.

FUEL/POWER MINERALS: COAL

FUEL/POWER MINERALS

1. COAL A principal mineral fuel, coal is a combustible, solid stratified rock of organic and mineral matter. The organic matter constitutes carbon (60 to 90 per cent), hydrogen (one to 12 per cent), oxygen (two to 20 per cent), nitrogen (one to three per cent) and also small amounts of phosphorus and sulphur. Coal occurs as a sedimentary rock in association with carbonaceous shale, sandstone and even fireclay in a regular succession and in repetitions. Gondwana coal is found as drifted deposits and tertiary coal occurs as in situ deposits.

Coal originates from the accumulation of vegetable matter in swampy areas on broad delta, coastal plains and basin lowlands. The vegetable matter is subjected to geo­logical processes that effect physical and chemical changes. The changes can be seen in the darkening of colour, increase in compactness, hardness and carbon content, and decrease in volatility and moisture. The growth in situ and drift theories explain the origin of coal. The complex process of coal formation involves physical and bacteriological agencies. Favourable climatic conditions for coal formation are mild temperature to sub-tropical climate with well­-distributed moderate to heavy rainfall.

Stages of Coal Formation Peat is the first stage of coal formation and varies considerably in extent and thickness. It has a high percentage of moisture and volatile matter. Carbon makes up only about one-third of its bulk.

Anthracite, the hardest variety, ranks highest amongst the coals. It has a carbon content of almost 95 per cent with practically no volatile matter. Only about 5 per cent of the world's coal is anthracite.

Economic Uses Coal, a primary source of heat and power (thermal power), is used in the production of water­gas; in metallurgical operations for the purpose of extrac­tion of metals like iron, zinc, etc.; in the production of coal gas, tar, coke, etc.; and to produce different types of varnish and germicides.

Distribution of Coal in the World Fenno-Scandinavia is one of the main deposits of peat in the world. Take (A) on P 196 of GS. The world's 50 per cent of anthracite comes from the Pennsylvanian fields of the USA. Russia, Ukraine, Kyrgyzstan and Kazakhstan account for another 25 per cent.

In overall coal production, China and the USA together contribute about 60% of the total coal production in the world. China has been the main coal producing country
in the world since 1986. Here, coal is mined mainly in the north in Inner Mongolia, Shansi, Anhui, Jiangsu, Henan and Hegei regions. In USA, coal mining showed a decline after the Second World War due to subsidised oil and gas prices, development of nuclear energy and environmental restric­tions, but it picked up after the oil crisis of the 1970s. Mining in USA is done mainly in the Appalachian region and in the interior stales.

In erstwhile USSR, major coal producing regions are Kuznetsk in Karganda, Kuzbas basin, Pechora basin, Donbass region and Tungus basin. In Europe, coal is mined in'Franco-Belgian coalfields, in Ruhr, Saar, Silesia, Pilsen, Saxony in Germany and in Poland, UK, Spain and the Central French Plateau.

Distribution of Coal in India In India, coal belongs to two principal geological periods, i.e., the lower Gondwana coals of Permian age, and Tertiary coals of Eocene to Miocene age. The greatest period of coal formation in India is the Permian. The important coal bearing formations are collectively known as Damudas and belong to the lower Gondwana system. The series of coal formations are Peat­lignite-bituminous-Anthracite. The lower Gondwana coals account for more then 90 per cent of the annual production of coal which is generally of bituminous rank. In Tertiary coalfields, lignite predominates.

The Gondwana coals are largely confined to the river valleys like those of the Damodar, Mahanadi, Godavari, etc. Tertiary coals principally occur in Assam, in the Himalayan foothills of Kashmir and in Rajasthan (Palna in Bikaner) in Eocene strata. Besides these, lignite deposits are found to occur in the South Arcot district of Tamil Nadu, in Kutch of Gujarat and also in the state of Kerala. The Neyveli lignite field of Tamil Nadu (which is of the Miocene Age) is the largest lignite deposit in South India.

Major Coal Fields The statewise list of major coal fields is given below.
West Bengal Raniganj.

Jharkhand Jharia, Bokaro, Giridih, Karanpura, Ramgarh. Madhya Pradesh Singniuli, Pench Valley. Chhattisgarh Korba.

Orissa Talcher, Himgir.

Andhra Pradesh Kantapalli, Singareni.

Tamil Nadu Neyveli (lignite).

Assam Namchik~Namphuk, Makum, Najira, Janji.

Meghalaya Umralong, Darrangiri

Production India at present is the fifth largest producer
of coal in the world. Coal is also India's largest mineral resource. Given our large coal reserves and the high cost of importing alternative fuels, it is important to develop advanced utilisation techniques and minimise environmen­tal dCKr'adation.

NON-METALLIC MINERAL: MICA

NON-METALLIC MINERALS
1. Mica The term 'mica' covers a large group of rock­forming minerals. Natural mica forms hexagonal crystals of varying size. Owing to its excellent dielectric strength, low loss power factor and insulating properties, mica is one of the indispensable minerals used in electrical and electron­ics industry. The main mica minerals are:

(a) muscovite also known as white-mica or potash mica.
(b) biotite known as black mica or magnesium iron mica.
(c) phlogopite, i.e., amber mica or magnesium mica.
(d) zinnwaldite, also termed as lithium iron mica.
(e) roscoelite or vanadium mica.
(f) fuschsite, Le., chrome mica.

Economic Uses

(i) Mica is used as an insulating material in electrical industry.

(ii) Muscovite, phlogopite splittings are used in making of build-up mica or micanite and other insulation products, for heat insulation and also electrical insulation.

(iii) In powder form, it is used in lubricating oils and
decorative wall papers.

Distribution in the World India is the most important mica producing country in the world and it supplies- 80 per cent of the world requirements of block mica.
Distribution in India The principal members of the mica group found in India are muscovite, phlogopite and biotite-all being hydrosilicates. The micas which are usu­ally associated with acid igneous rocks are formed towards the end of the process of crystallisation. They are mostly formed as pegmatite deposits consisting of very coarse grained igneous rocks occurring as dykes or veins.

Mica minerals occur in igneous, sedimentary and metamorphic rocks formed under different geological conditions. While muscovite occurs in pegmatites of acidic natur~, phlogopite mica is restricted to basic pegmatite. Commercial biotite is found to occur mostly in biotiteschists.

Mica is produced mainly in the three states of Jharkhand, Rajasthan and Andhra Pradesh. Major producing regions include the following.

Jharkhand Here, mica is extracted from the Hazaribagh belt, with Koderma contributing a large part of the country's total production.

Rajasthan Here, mica is mined in the Beawar, Ajmer belt, Banswara-Dungarpur belt, Bhilwara, Tonk and Kaunthal in Udaipur.

Andhra Pradesh Here, mica is extracted from Nellore
in Gudur district.

Reserves and Production in India India is world's leading producer of sheet mica and accounts for about 60 per cent of global mica trade.

Matalic Mineral: BAUXITE

BAUXITE The only ore from which aluminium is extracted is called 'bauxite', which is not a IJJineral but an aggregate chiefly, of gibbsite, boehmite and a little of kaolinite. Bauxite is a secondary product in between monohydrate diaspore and trihydrate gibbsite, i.e., be­tween AlP3Hp and A12033H2O. Thus it is a generic term for rock rich in hydrous aluminium oxide (AlP32HP). The bauxite ore has a typical oolitic or pisolitic structure and it is found in an amorphous form. Presence of about 50 per cent Al203 is considered to be the lower limit for good commercial bauxite.

Economic Uses Bauxite is used in the manufacture of alum, aluminous sulphates and other chemicals; the construction of airplanes, automobiles, electrical appliances, etc; and the manufacture of containers, utensils and ma­chineries.

Distribution in the World Major bauxite producing countries in the world are Australia, Guin~a, Jamaica, Brazil, Surinam Yugoslavia, and the state of Arkansas in USA China, Malaysia, Indonesia, Turkey and India also contrib­ute small amounts.

Distribution in India Bauxite is associated with laterite rocks occurring extensively as blankets or cappings either on the plateau or hill ranges of peninsular India or in certain low level laterites in the inland area or in coastal tracts of the country. It is a result of the residual weathering process which leads to leaching of the silica.

The bauxite deposits are mainly spread over the Eastern Ghats. A statewise survey of bauxite reserves is given below.

Madhya Pradesh Nearly 30% of the country's prodlIC­tion of bauxite comes from Madhya Pradesh. Bauxite deposits here are found in Amarkantak plateau in Shahdot district, Maikala hills and the plateau region of Sarguja­Bilaspur- Raigarh-Katni.

Bihar In Bihar, bauxite deposits occur in Ranchi and Palamau.

Gujarat Here, bauxite is found in Jamnagar, Kaira, Sabarkantha, Surat and Kachchh.

Kamataka In Karnataka, bauxite reserves are found in Belgaum.

Maharashtra Kolaba, Kolhapur and Ratnagiri in Mahar.ashtra have copper reserves.

Tamil Nadu Here, bauxite is found in Salem, Nilgiri, Coimbatore and Madurai.

Uttar Pradesh Bauxite is extracted in Uttar Pradesh in Banda.

Jammu and Kashmir Here, high grade bauxite deposits are found in Poonch and Udhampur.

Metalic Minerals: TIN, LEAD and ZINC

TIN The main ore of tin 'is cassiterite or tinstone with about 75 per cent of tin. It occurs in igneous and metamorphic rocks. Nearly 80 per cent of the world's supplies come from alluvial deposits.
Distribution in the World Malaysia is the world's leading producer and exporter of tin. Other producers are Chma, Indonesia, Thailand, Nigeria, Zaire, Bolivia and Australia.

Distribution in India In India, Bihar, Jharkhand and Rajasthan are main l?roducers of tin.

5. LEAD AND ZINC The two metals, lead and zinc, rarely occur in native state. They generally occur in combination with other elements. Galena is the chief ore of lead while sphalerite or zinc blende is the chief ore of zinc. These sulphide ore minerals of lead and zinc are formed due to contact metasomatism, replacement by hydrothermal solutions. Galena is found in veins in lime­stones, calcareous slates and sandstones and occasionally in metamorphic rocks or in association with volcanic rocks, while zinc blende or sphalerite is found in veins in asso­ciation with galena, chalcopyrites, iron pyrites and other sulphide ores. The chief rock types associated with the sulphide ores of lead and zinc are pyrite, slate, dolomite and quartz.
Economic Uses (i) Lead is used in the construction of accumulators, for lead piping and sheeting cable covers, as pigments in glass making and in medicine.
(ii) Zinc is used for coating, galvanising iron and steel products, in the manufacture of pigments and alloys with other metals (like brass, bronze, german silver) and in the manufacture of batteries and electric appliances. Besides, it is widely used in textile industry, timber preservation, etc.
Distribution in the World Major producers of lead are the USA, Russia, Australia, Canada, Peru and Bulgaria. Leading producers of zinc are Canada, Russia, Peru, Aus­tralia and the USA.

Distribution in India Given below is a statewise survey of lead and zinc resources in the country.

Rajasthan Here, lead and zinc are extracted from the Zawar mines in Udaipur district and from Anguncha­Rampura in Bhilwara district. In these mines, silver ore is also extracted.

Andhra Pradesh Cuddapah district has the reserves. Gujarat Here, lead and zinc are extracted from Banaskantha, Vadodara, Panchmahal and Surat.

Lead and zinc reserves also occur in Meghalaya and Sikkim.

METALIC MINERALS: SILVER, COPPER Coper

SILVER

The ore minerals are stephanite, agentite, proustite and pyrargyrite. Silver is found in the galena ores that may have up to one per cent of this metallic mineral.
Distribution in the World Mexico is the chid producer of silver; other producers are Russia, Canada, Peru and Australia.

Distribution in India In India, the lead-zinc ores of Zawar in Rajasthan yield silver. Silver is derived as a by­product in the Kamataka gold fields. The lead ores in Andhra Pradesh (Guntur, Cuddapah, Kumool districts), Jharkhand (Santhal Parganas, Singhbhum), Bihar (Bhagalpur), Gujarat (Vadodara district), Karnataka (the district of Bellary), Uttaranchal (Almora district) and Jammu and Kashmir (Baramula district) are also expected to yield some silver.

3. COPPER ORE Copper is the most important non­ferrous metal and was the earliest metal used bv man. In nature copper occurs in the native form and- in three principal combinations, viz., sulphides (chalcopyrite, bornite, chalcocite, tetrahedrite, covellite and enargite), oxides (cu­prite, tenorite) and carbonates (malachite and azurite). To be economically exploitable, copper ores should contain at least 2.5 per ceni of copper.

Economic Uses The metal is of great industrial impor­tance due to its high electric conductivity, high ductility and malleability. Thus it is mostly used in electrical manufac­turing. Besides, the copper alloys are used in buildings, automobiles, airplanes, naval ships, household utensils as weU as in metallurgy and paints. However, in recent years, the increasing use of glass fibres has reduced the pressure on copper.

Distribution in the World The world's largest pro­ducers of copper ores are the U5A, Russia, Chile, Zambia, Canada and Zaire. Chile is the largest producer.

Distribution in India India is deficient in copper ores and thus depends to a large ~xtent on imports. In India, copper ores occur as sulphides. They occur both in ancient crystalline and younger rock formations including the Cuddapahs, Bijawars and Aravallis.

It is mostly believed that copper deposits are formed through hydrothermal solutions either as cavity filling or replacement deposits. But replacement has been a more dominant process than cavity filling. The ores found in India are sparsely disseminated or locally concentrated in the form of bunches in the enclosing rocks.

Important copper deposits in India are:
Rajasthan Khetri complex which includes the Khi­Dariba area in Alwar district and the Khetri-Singhana area in Jhujhunu district. (Khetri copper deposit is one of the important copper deposits in the country.)

Jharkhand Singhbhum district

Andhra Pradesh Bondalamottu, Nalankonda and
Dhukonda in the Agnigundala belt of Guntur district; Ganikalava, Gumankonda and Somalapilli in Kamool dis­trict; and Garimanipenta in Nellore district.

Other important copper deposits of the country are in Himachal Pradesh-Kangra-Kulu valley: Mysore­Chit tal drug, Hassan, Bellary districts; West Bengal­Darjeeling, Jalpaiguri districts; Sikkim-Rangpo and Oickchu deposits which are found to occur in association with metamoJPhic rocks.

METALLIC MINERAL: GOLD

GOLD

Economic Uses (i) Gold is a precious metal and till very
recently constituted the international standard of exchange. (ii) In alloy state with other metals, it is mostly used in ornamentation. (iii) The industrial uses of gold alloys are in dentistry, and in chemical plants, thermo-couples, watches, X-ray equipment, photography and some medicines.

Distribution in the World The greatest producer is South Africa, with major mines in the Witwatersrand, Odendaalrus and Lydenburg. Canada, Japan, the USA, Zimbabwe and Ghana also produce gold.

Distribution in India In India, the vein gold deposits are found in Kamataka, Andhra Pradesh, Assam, Bihar, Madhya Pradesh and Tamil Nadu while alluvial gold is mainly found in Bihar, Assam, Uttar Pradesh, Madhya Pradesh, Kerala, Punjab and Meghalaya.
The Kolar gold field in Karnataka has been the principal source of gold production in India since 1871 when mining first started. It has four productive mines­Nandydroog, Champion Reef, Mysore and Ooregaum. The Champion Reef mine is the deepest mine in the world. Th~ Oharwar schists on which the Kolar gold fields are situated run in a north-south direction for 80 km. 'However, the quartz veins bearing gold are confined to only a 6-7 km section near Marikuppan. The mineralising solutions re­sponsible for the development of the auriferous veins of South India were probably derived from the magma which gave rise to champion gneisses. The Kolar field mined by the Bharat Gold Mines Limited has always had the highest output in India, but it now faces closure.
In the Raichur district, the auriferous veins occur within the schistose rocks of Dharwarian age. There are six auriferous quartz reefs of which the Oakley reef is the main producer. It is worked by Hutti Gold Mines Company of Karnataka state. According to the Geological Survey of India, the reserves in both these fields are estimated at about 4.5 million tonnes with a total gold content of about
45,000 kg. In addition ore reserves of about 60,000 tonnes with 8.5 gm per tonne have been indicated in Budini area.

New fields have been found at Kempinkote (Hassan district), HOimali (Shimoga district), Siddarahalli (Chikmaglur district), Bellara (Chitradurg district) and Munglur (Gulbarga district).

In Andhra Pradesh, the Ramgiri field of Anantapur district is the main source of gold.