Tea bricks (zhūan chá) or compressed tea (traditional: jǐnyā chá) 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 or eaten as food, and were also used in the past as a form of currency.

Production

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 trade prior to the 19th century in Asia since they were more compact than loose leaf tea and were also less susceptible to physical damage incurred through transportation over land by caravans on the Ancient tea route.
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 (standard size) is simply called tuóchá, 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 (the first word meaning "small") which usually weighs 3g–5g. A larger piece around 375g, which may be a disc with a dimple, is called bǐngchá (literally "biscuit tea" or "cake tea"). A large, flat, square brick is called fángchá (literally "square tea").

Food

Tea bricks are used as a form of food in parts of Central Asia and Tibet in the past as much as in modern times. In Tibet pieces of tea are broken from tea bricks, and boiled overnight in water, sometimes with salt. The resulting concentrated tea infusion is then mixed with butter, cream or milk and a little salt to make butter tea, a staple of Tibetan cuisine.

Individual portions of the mixture are kneaded in a small bowl, formed into balls and eaten. Some cities of the Fukui prefecture in Japan have food similar to tsampa, where concentrated tea is mixed with grain flour. However, the tea may or may not be made of tea bricks.
In parts of Mongolia and central Asia, a mixture of ground tea bricks, grain flours and boiling water is eaten directly. It has been suggested that tea eaten whole provides needed roughage normally lacking in the diet.

Health effects

Tea bricks are often made from old tea leaves and stems, which accumulate fluorine. This has led to floristic (a form of fluoride poisoning that affects the bones and teeth) in areas of high brick tea consumption, such as Tibet.