Black salt powder is created by heating regular salt, often pink Himalayan salt or sea salt, along with specific herbs and spices in a furnace for several hours. The process involves exposing the salt to intense heat, which, combined with the unique blend of ingredients, transforms the salt into its distinctive dark color. This method also imparts a strong sulfuric aroma, characteristic of black salt.
https://natures-spice.com/product/natures-spices-black-salt-powder/