Rock salt associated with bedded sedimentary rocks is currently mined in the Mandi area of Himachal Pradesh. Here outcrops of rock salt are found in the Gobhar-ki-Dhar Mountains between Joginder nagar and Mandi. Guma and Darang are two main centers of production.
The Mandi salt is hard and massive and has to be blasted. It is purplish in colour. The total reserves are estimated at 7.55 million tons; the total production being 1,621 tons in 2002-03 (cf. 4,326 tones in 1981). 1
A thick bed of rock salt spreads over a large area. It has been found in a few hundred meters below the surface of the Thar Desert Large deposits of potash are also associated with this salt bed.
Process of Salt Making
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Marine salt works produce about 75 percent t of the total salt production of the country. The process uses large reservoir or brine pond wherein sea water is collected during high tides. Saturated brine is pumped into smaller evaporation pans known as crystallisers where the salt crystallises. Here the density increases and about 80% of the sodium chloride (salt) present in sea water solidifies.
The harvested salt is washed to reduce impurities (magnesium and potassium salt). Factors favorable for salt production are fair weather (8-9 months), high temperature, low relative humidity, cloudless sky, low rainfall, and high wind velocity and low soil permeability. The coastal areas of Saurashtra, south Tamil Nadu and the Sambhar Lake have ideal conditions for salt manufacturing.
The Government of India, in collaboration with the WHO and UNICEF, has started manufacturing iodized salt to control goitre for which plants have been set up in Kolkata, Khargoda and Sambhar lake area.
Trade
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India exports small quantity of salt to neighbouring countries like Bangladesh, Bhutan, Nepal and Maldives. South Korea, Indonesia, Taiwan, Hongkong, Japan and Singapore are other important buyers.