Yixing pottery (pottery made of zisha clay) has been part of Chinese tea culture for centuries. We mention it here shortly for those collectors interested in tea wares in general.
During the Tang and Song dynasties preparation of tea (tea brewing) was quite different, and a coarse type of tea was used. The preparation for drinking consisted mainly in grinding it with a pestle in a rubbing movement inside a wide bowl with grooves down its inside. This is not unlike the preparation of Lei Cha (Lei Tea) of the Hakka people today.
In those days mostly pewter tea pots were used for the tea. During the Song dynasty, as the quality of the tea itself improved over time the use of pottery became also more and more frequent, and teapots made of zisha clay all but replaced pewter in China's tea culture.
Today, many Chinese fond of drinking or brewing tea in the traditional manner are avid collectors of "zisha" tea pots. Zisha (literally meaning "purple sand") is the name for the clay used for Yixing pottery in the Chinese language. "Yixing" itself is the name of the place where the zisha pottery has been made for centuries.
Yixing pottery is now mostly used for tea wares, both pots and cups, and some other tea paraphernalia. The clay ranges from a reddish brown to a very dark brown and a blackish gray. Basically, these pots and cups are all left unglazed.
However, tea wares were not the only products of the Yixing kilns in the distant past. In the Ming and Qing dynasties Yixing did also make life-like figurines, ceramic replica of walnuts, lotus kernels, lychees, pomegranates, water caltrop and other produce, as well as crabs, coiled sea shells, etc..Later, during the Qianlong reign Jingdezhen followed suite and started also making such porcelain items.
A little about modern Chinese tea culture
Modern tea culture enthusiasts call tea pots made of zisha clay "living" pots, and they are "keeping the pot" (as one "keeps" a pet)... Other types of tea pots are called "dead" pots. After drinking the tea is finished the tea leaves are removed from the pot, but the pot is not cleaned. Instead, it is flushed with water or left to dry. The outside of the pot is rubbed off with a cloth. They call this "keeping the pot".
After doing this for a long time a thin layer of tea residue forms on the inside of the pot and some of the tea is able to penetrate the pores of the clay. Accordingly, merely adding hot water without any tea leaves can flush out these tea residues. Such pots are said to produce drinkable tea without tea leaves, hence they are called "living" pots. Tea pots made of porcelain or other non-porous materials on the other hand are called "dead" pots.