is made by melting a variety of pure natural quartz (such as crystal, quartz sand, etc.). The coefficient of linear expansion is extremely small, which is 1/10-1/20 of ordinary glass, and has good thermal shock resistance. It has high heat resistance, often used at temperatures between 1100 and 1200 degrees Celsius, and short-term temperatures of up to 1400 degrees Celsius. Quartz glass is mainly used in laboratory equipment and refining equipment for special high-purity products. Because of its high spectral transmission, it is not damaged by radiation (other glass will be dark after being irradiated by radiation), so it is also an ideal glass for spacecraft, wind tunnels and spectrophotometer optical systems.