Mica is a mineral name given to a group of physically and chemically similar minerals. Common ores of mica are Muscovite and Biotite. Due to its exceptional insulation property, it is one of the indispensable minerals used in the electrical and electronics industry.
It is also used as a lubricant in its powder form. China is the world’s top producer of mica. Other countries that produce mica are Russia, Finland, the United States, Turkey and the Republic of Korea. Andhra Pradesh, Rajasthan and Jharkhand accounts for about 95 per cent of India’s mica.
Limestone is exclusively a sedimentary rock composed mostly of the mineral calcite. Limestone comprises about 10% of the Earth's sedimentary crust. Primarily it is made of skeletal fragments of marine organisms such as coral, foraminifera and molluscs. Most of the limestone is made into crushed stone and used as a construction material. It is used for stair treads, facing stone, floor tiles, windows sills and many other purposes.
Crushed limestone is used in smelting and other metal refining process. Portland cement is made from limestone. China produces more than \(50%\) of limestone production in the world. Besides this, United States, Russia, India, Brazil and Japan also produce more Limestone. Rajasthan, Madhya Pradesh, Andhra Pradesh, Chhattisgarh, Gujarat, and Tamil Nadu Produce over \(75% \)of the total limestone of India. In Tamil Nadu, large scale limestone reserve found in Ariyalur, Ramanathapuram, Tirunelveli, Salem, Coimbatore and Madurai districts.