Brick tea

Compressed tea, called tea bricks, tea cakes or tea lumps, and tea nuggets according to the shape and size, are blocks of whole or finely ground black tea, green tea, or post-fermented tea leaves that have been packed in molds and pressed into block form. This was the most commonly produced and used form of tea in ancient China prior to the Ming Dynasty. Although tea bricks are less commonly produced in modern times, many post-fermented teas, such as pu-erh, are still commonly found in bricks, discs, and other pressed forms. Tea bricks can be made into beverages like tea or eaten as food, and were also used in the past as a form of currency. In ancient China, compressed teas were usually made with thoroughly dried and ground tea leaves that were pressed into various bricks or other shapes, although partially dried and whole leaves were also used. Some tea bricks were also mixed with binding agents such as flour, blood, or manure to better preserve their form so they could withstand physical use as currency. Newly formed tea bricks were then left to cure, dry, and age prior to being sold or traded. Tea bricks were preferred in Asian trade prior to the 19th century, since they were more compact and less susceptible to physical damage than loose leaf tea. This was important during transportation over land by caravans on the Tea Horse Road. Tea bricks are still currently manufactured for drinking, as in pu-erh teas, as well as for souvenirs and novelty items, though most compressed teas produced in modern times are usually made from whole leaves. The compressed tea can take various traditional forms, many of them still being produced. A dome-shaped nugget of 100g is simply called tuóchá (沱茶), which is translated several ways, sometimes as "bird's nest tea" or "bowl tea". A small dome-shaped nugget with a dimple underneath just enough to make one pot or cup of tea is called a xiǎo tuóchá (小沱茶; the first word meaning "small") which usually weighs 3g–5g. A larger piece around 357g, which may be a disc with a dimple, is called bǐngchá (饼茶, literally "biscuit tea" or "cake tea"). A large, flat, square brick is called fāngchá (方茶, literally "square tea").

Source: Wikipedia