Mastic

Mastic ( "Mastika") is a resin that comes from the mastic tree, "Pistacia lentiscus". The tree grows in the Mediterranean region. In pharmacies and nature shops, it is called "Arabic gum" (not to be confused with gum arabic).
The resin is harvested in various places, especially the Greek island of Chios. 
It is a liquid when the tree first produces it. Then it dries in the sun into drops of hard resin. When chewed, the resin softens and becomes a white, opaque gum. The flavour is bitter at first. After some chewing, it has a refreshing, slightly pine or cedar-like flavour.
Mastic is used in food, medicine, and industry.