Hei Cha (Dark)

Hei Cha is tea that is fermented. The leaves may be intentionally fermented through a piling and turning process or the leaves may ferment naturally over time. Aged Hei Chas are prized for their depth of flavor and medicinal qualities, and they are often pressed into cakes. 

Sources: 

• https://westchinatea.com/tea/hei-cha/