Chios Mastic Mastiha is a resin obtained from the mastic tree (Pistacia lentiscus). In pharmacies and nature shops, it is called "Arabic gum" (not to be confused with gum arabic) and "Yemen gum". In Greece, it is known as the "tears of Chios," being traditionally produced on that Greek island, and, like other natural resins, is produced in "tears" or droplets.