Silicon dioxide (SiO2) or silica, is the main component of glass and concrete, and is a natural mineral that occupies most of the earth's crust.
It is a safe material that withstands high temperatures, and has a very small expansion rate, and is resistant to rapid thermal changes. Thus, the temperature rises quickly, and does not rise above a certain temperature and melt or deform, and is free from the risk of various accidents such as an electric shock.