Purple clay teapots (zishahu) are produced in Yixing, China from "purple" clay. ... Purple clay (zisha) has the reputation of being a high quality clay because of its fine texture and porous nature, as well as being easy to mould. They became popular during the Ming Dynasty gradually replacing porcelain china.
Yixing Teapot is fired under the condition of high oxygen and high temperature, generally using flat firework contact, and the firing temperature is between 1100-1300℃. The water absorption rate of the finished product is greater than 2%. The roasting temperature range of purple sand mud is also wide, from 1190℃ to 1270℃, which is another reason why purple sand products do not leak and do not age, and the more they are used, the more shiny and smooth.