Quartz is extremely transparent over a wide spectral range, with a low coefficient of thermal expansion and quartz is resistant to scratching and thermal shock. Fused quartz is made form crushing and melting natural materials. The purity of quartz is paramount to the efficiency of the lamp and sleeve. Greater ultraviolet transmission, low coefficient of thermal expansion
Increased hardness and resistance to scratching. Higher resistance to solarisation or darkening from ultraviolet radiation.