Naftalan oil

Naftalan is a unique grade of black oil, found in Naftalan, Azerbaijan, known for its naphthalene content and use in alternative medicine.
The first mention of Naftalan oil is found in the works of Azerbaijani poet and thinker Nizami Ganjavi (1141-1201). Traveler Marco Polo also mentions Naftalan in his treatise "On the Great Tartary" (13th century).
While Naftalan crude oil is too heavy for normal export uses (unlike Azerbaijan's plentiful Caspian Sea oil), it contains about 50 percent naphthenic hydrocarbons, which are used to treat psoriasis. As such, it is only used for medicinal purposes. According to scientists, it is naphthenic hydrocarbons that precondition its therapeutic properties. Such hydrocarbons form the basis of many biologically active substances (sterols, bile acids, vitamin D, progesterone). They also participate in biosynthesis reactions of steroid hormones. Naftalan also contains a large number of physiologically active microelements, such as zinc, boron, manganese, iodine, copper, lithium, rubidium, cobalt, molybdenum, etc., which certainly plays a role in medicinal effects. Also biologically active is the nitrogenous basis of Naftalan, as well as naphthenic acids http://irs-az.com/new/pdf/201109/1316508008796389694.pdf.
People using the oil generally sit in a bath and are covered in oil up to their necks. There are numerous petroleum spas in the city of Naftalan itself.
References.
4. Naftalan-a magical gift of Nature.Nazim Badalov http://irs-az.com/new/pdf/201109/1316508008796389694.pdf