M439 -
The common name for salt rock is the mineral "halite". A sodium chloride. Not the same as table salt. Salt rock can have impurities of gypsum and sylvite, and occasionally polyhalite. There are many uses for rock salt including that for human consumption, spreading on roadways to melt snow and ice, making of ice cream, used in gourmet restaurants as a food additive, used in making candle holders, lamps, as bath salts, many other uses. The salt rock shown here is from the Himalayan salt mines in Pakistan. According to articles found on the internet about the Himalayan salt rock coming out of Pakistan this material is between 300 and 500 million years old.