... fabric to protect being damaged. Characteristic:Purple clay, which has high iron content, gives its ... to emerge from Yixing kilns. Red clay and yellow clay are also used, independently or mixed, ... is a rare earth, from scientific research, purple clay does not contain lead, arsenic, cadmium, chromium, ... human healthy, whereas the research proves that purple clay contains SiO2, Al2O3, Fe2O3, MGO, CaO, ...