Processing involves full oxidation (or fermentation) of the leaves. After the leaves are plucked, they are laid out to wither for about 18 hours, evaporating the excess moisture. The  withered leaves are rolled to catalyzed fermentation. The oxidized hair like curled leaves, on attaining a bright emerald or copper hue, subject to the season, is dried by a heater in an oven, to maintain its aroma and fragrance for years

"Soils constitute the foundation of vegetation and agriculture. Forests need it to grow. We need it for food, feed, fiber, fuel and much more."

José Graziano da Silva, FAO Director-General - International Year of Soils 2015: Healthy soils for a healthy life