In general we divide the glass materials that we use into two groups: quartz and optical glass. Quartz consists exclusively of silicon dioxide (SiO2) and shows some remarkable properties:
- Quartz displays a high UV transmission, in highly purified synthetic quartz down to well below 200 nm.
- The thermal expansion of quartz is extremely low, its coefficient of thermal expansion being 6 x 10-7K-1 between 20 °C and 300 °C.
- Quartz is chemically very resistant and maintains its shape, even at high temperatures up to approximately 1000 °C.