Mastic gum is made by scoring the bark of a specific tree variety found almost exclusively on the Greek island of Chios, then collecting the resin “tears” that weep out and harden over roughly two weeks. The entire process, from preparing the ground beneath the trees to washing and grading the final product, stretches from June through September and remains largely manual to this day.
The Only Tree That Produces It
Mastic gum comes from Pistacia lentiscus var. Chia, a drought-resistant evergreen shrub or small tree native to the Mediterranean. While the wild species grows across the region, only the Chia variety on the island of Chios produces resin in commercially meaningful quantities. These trees grow in the dry, warm southern part of the island in an area called Mastihohoria, and this geographic specificity is so important that Chios mastic has held Protected Designation of Origin (PDO) status from the European Union since 1997. No other region in the world produces mastic gum at commercial scale.
The trees are compact, with dense, dark-green leathery foliage, and they thrive in conditions that would stress most crops: poor soil, low rainfall, and salty air. A mature tree yields an average of 150 to 180 grams of mastic per year, though individual trees can produce anywhere from 10 grams to 2 kilograms depending on age, health, and weather.
Preparing the Trees and Ground
Production begins months before any resin flows. During winter, farmers (traditionally men) prune the trees and apply natural fertilizer to support healthy growth. Starting in mid-June, the ground around each tree trunk is swept, leveled, and cleaned so that any resin drops that fall can be easily spotted and recovered. This step is critical because the tears are small, often only about 3 millimeters across, and would be impossible to find on rough, debris-covered soil.
Scoring the Bark
The actual harvesting starts in July. Farmers use an iron tool to make small vertical incisions in the bark of the trunk and main branches. These cuts are shallow, penetrating only the outer bark layer rather than cutting deep into the wood. The goal is to puncture the resin canals just beneath the surface, giving the sap a path to seep out.
The resin begins exuding almost immediately after the cuts are made. It emerges as a sticky, translucent liquid that slowly drips down the bark or falls to the cleared ground below. Over the following days, exposure to air causes the resin to solidify into small, rounded or pear-shaped droplets called “tears.” The process from liquid sap to hardened tear takes about 15 days in the summer heat.
Collecting the Tears
Every two weeks or so between June and September, collectors gather the hardened tears. Traditionally, women handle this stage of the work. They pick the larger, cleaner tears first, separating them from smaller fragments and any pieces that have picked up dirt from the ground. Each tree is scored and collected from multiple times across the season, with the cycle of incision, exudation, and hardening repeating throughout the summer months.
The timing matters. Chios summers are hot and dry, which is exactly what the resin needs to solidify properly. Excessive humidity or rain during the collection window can slow hardening or cause the tears to cloud and degrade.
Washing, Sorting, and Grading
Once collected, the raw tears are washed with water to remove dirt, bark fragments, and other impurities. After washing, the mastic is sorted and graded based on two main criteria: color and size. The most prized tears are large, pale yellow or greenish-yellow, and translucent. Smaller, cloudier, or discolored pieces are separated into lower grades. After grading, the tears are placed in wooden boxes and stored in cool conditions to preserve their quality.
High-grade tears are sold whole for chewing or culinary use. Lower grades are typically directed toward industrial applications, including varnishes, cosmetics, or further processing into powder and oil.
Processing Into Powder and Oil
For supplement capsules and culinary powders, the raw resin tears are ground into a coarse or fine powder. This is straightforward mechanical processing with no chemical transformation involved. The powder retains the same chemical profile as the whole tears, which includes a complex mix of compounds: roughly 25% of the gum is a sticky polymer, with the remainder composed of various plant-derived compounds that give mastic its characteristic pine-like flavor and documented antioxidant properties.
Mastic essential oil is a different product. To extract it, the resin is coarsely powdered and then subjected to steam distillation or hydrodistillation, a process where the powdered gum is heated with water for several hours and the volatile aromatic compounds are captured as they evaporate. More advanced extraction methods, including supercritical fluid extraction, are also used in research and specialty production. The resulting essential oil is a concentrated source of the aromatic compounds naturally present in the resin.
Why Production Stays Small
Because each tree produces less than 200 grams per year on average, and production is limited to a single island, total mastic output is inherently constrained. The labor-intensive harvesting process, which still relies on hand-scoring and hand-picking, further limits scale. Climate change is an emerging concern: shifting rainfall patterns and rising temperatures on Chios could affect both tree health and the narrow summer window needed for proper resin hardening. The Chios Mastic Growers’ Association manages production and distribution, and the PDO designation ensures that only resin from this specific region can legally be sold as Chios mastic gum.