The first documented reference to Shilajit in the form of "Shilajatu" dates back to the sixth century BCE. Sushruta Samhita , an ancient Sanskrit medicine treatise states: "A gelatinous substance that is secreted from the side of the mountains when they have become heated by the rays of the sun in the months of Jyaishta and Ashadha. This substance is what is known as Šilájatu and it cures all distempers of the body.  " Shilajit is found predominantly in Himalaya , Tibet mountains , Altai and Caucasus mountains . The color range varies from a yellowish brown to pitch-black, depending on composition. For use in Ayurvedic medicine the black variant is considered the most potent. Shilajit has been described as 'mineral oil', 'stone oil', 'Mountain Blood' or 'rock sweat', as it seeps from cracks in mountains due mostly to the warmth of the sun. There are many local legends and stories about its origin, use and properties, often wildly exaggerated. It should not be confused with ozokerite , also a humic substance, similar in appearance, but apparently without medicinal qualities.