Wednesday, November 4, 2009

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.

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