The Salt Works near Urubamba, Peru is an ancient site in "the Sacred Valley", perhaps going back thousands of years.  It may have been more valuable to the Inca than gold.  The salt comes from a spring which is heavily laden in salt dissolved from a long vanished deposit of a land lock sea.  Salt would have been traded widely and may have been the root of the Inca wealth.  The salt water is evaporated in small plots that are presently worked by families groups who sell the scraped and sacked salt.