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.