Indian black salt, or kala namak, is an Indian volcanic rock salt. It is known by many names including Himalayan black salt, sulemani namak, and kala loon. It is commonly used in Pakistan, India and other Asian countries. It starts out as Himalayan Pink Salt or sodium chloride and is then heated to extremely high temperatures and mixed with Indian spices and herbs including the seeds of the harad fruit which contains sulfur. It also contains trace impurities of sulfates, sulfides, iron and magnesium which all contribute to the salt’s color, smell and taste.

Some varieties of black salt, such as black lava salt, are actually black in color, but many aren’t. In its rock form, it ranges from brownish-pink to deep purple. When the salt is ground up, it becomes a pinkish-gray or light purple color. When mixed with food, it becomes a deep red with purple and brown tints. The color is due to the iron sulfides.

Kala namak has a very distinctive smell. The sulfur compounds cause the salt to smell like hard-boiled or rotten eggs. In my experience, the salt has very little odor in the jar. It is only when it is added to food that the smell becomes apparent. The smell is very strong at first but then disappears and the finished dish does not smell like rotten eggs at all.