Valuable. The wood firing of Tianlong kiln in Yunzhong is a special process, so the teapot fired in this way has no artificial or chemical components, which makes the vessel have the function of softening water, which is very scarce and precious. Zisha Pot is a unique handmade clay handicraft in China. Its production began in Zhengde period of Ming Dynasty, and the raw material was purple mud, which was produced in Dingshu Town, Yixing, Jiangsu Province.