Mastiha is a natural resin from the Southern part of the island of
Chios in Greece.  It has been harvested for centuries using the same
technique: the Pistacia Lentiscus (schinos) trees are incised, the sap
is "wept" out, and then the resin solidifies into "tear" shaped pieces
after 15-20 days.  It is then harvested and cleaned by the women of the
21 Mastiha villages (Mastihohoria). The cultivation of the resin is
exclusive to the sourthern area of Chios due to its unique microclimate
and the fact that the trees there have had centuries of cultivation and
controlled propagation, making them highly productive in the best
quality resin. 
Mastiha has been used since ancient times for both its flavor as a
spice, as well as for its therapeutic properties.  It is an
antibacterial, antioxidant, and anti-inflammatory, and has long been
lauded for its beneficial use in skin care, oral hygiene, and for
curing digestive disorders.  To use as a spice, all you have to do is
crush the tears using a mortar and pestle with a pinch of salt (for
savory) or sugar (for sweet).  The tears will turn into a fine powder
with a refreshingly alpine, and slightly camphoric aroma.  Mastiha is
often associated with ice creams and other sweetened milk preparations
in the Middle East, but it can also flavor savory dishes with anything
from cheese to meat to vegetables. 

Ever since 1997, the European Union has protected the product under the
Protected Designation of Origin.  The Mastiha growers are also
protected by the Greek government, and the resin and its products are
all sold at a fair trade price in order to preserve this ancient
tradition. You can purchase Mastiha from Mastiha Shop NY.