Kala namak or black salt is a kiln-fired rock salt with a sulphurous, pungent smell used in the Indian subcontinent. It is also known as “Himalayan black salt”, Sulemani namak, bit noon, bire noon, bit loona, bit lobon, kala loon, sanchal, kala meeth, guma loon, or pada loon, and is manufactured from the salts mined in the regions surrounding the Himalayas.
The condiment is composed largely of sodium chloride, with several other components lending the salt its colour and smell. The smell is mainly due to its sulfur content. Because of the presence of greigite (Fe3S4, Iron(II,III) sulfide) in the mineral, it forms brownish-pink to dark violet translucent crystals when whole. When ground into a powder, its colour ranges from purple to pink.
Kala namak has been praised in Ayurveda and used for its perceived medical qualities.