The raw material for producing kala namak was originally obtained from natural halite from mines in Bangladesh, India, Nepal and Pakistan in certain locations of the Himalayas salt ranges, or from salt harvested from the North Indian salt lakes of Sambhar Salt Lake or Didwana and the Mustang District of Nepal.
Traditionally, the salt was transformed from its raw natural forms into commercially sold kala namak through a reductive chemical process that transforms some of the naturally occurring sodium sulfate of the raw salt into pungent hydrogen sulfide and sodium sulfide.
This involves firing the raw salts in a furnace for 24 hours while sealed in a ceramic jar with charcoal along with small quantities of harad seeds, amla, bahera, babul bark, or natron. The fired salt is then cooled, stored, and aged prior to sale.
Kala namak is prepared in this manner in northern India with production concentrated in Hisar district, Haryana. The salt crystals appear black as a whole are actually pink when grounded into a fine powder.
Uses
Kala Namak is commonly used in South Asian cuisines of Bangladesh, India and Pakistan as a condiment or added to chaats, chutneys, salads, all kinds of fruits, raitas and many other savory Indian snacks. Chaat masala, an Indian spice blend, is dependent upon black salt for its characteristic sulfurous hard-boiled-egg aroma. Those who are not accustomed to black salt often describe the smell as similar to rotten eggs.
Kala Namak is often used by vegans to mimic the taste of eggs. It is used, for example, to season tofu to mimic an egg salad.
