Transmute is one of the generic and broadly named Recipes in Conan Exiles. This recipe teaches the ability to change several different types of materials into other types of materials. Depending on how devote a follower is to the God of Derketo, and how upgraded the temple of Derketo is, changes what this recipe gives back or is required.
See Pleasure Place of Derketo, Pleasure Dome of Derketo for more information.