What you use may be, pretending to be purple sand, which is generally true and will not crack due to sudden cooling and heating. This is a great advantage of purple sand. Due to the high cost of raw materials for purple sand, some people use ordinary clay to add chemical raw materials to make products that look like purple sand, which is not only useless, but also harmful to human body. Please note that knocking like porcelain is very likely to be fake (thinking that purple sand is breathable, its density is not as high as porcelain, and its sound is crisp and too low is mistaken for frying pan). !

My humble opinion is for reference only.