Quartz
Properties of Quartz
Quartz is the crystalline form of SiO2. Fused SiO2 (the non-crystalline form of SiO2) , also called fused quartz, is used in a huge variety of technical and consumer products, mainly because of the high melting temperature and it’s resistance to thermal shock. Very pure fused SiO2 is also commonly used in the optics industry, because of it’s excellent UV transmission.
Crystalline quartz is a uniaxial positively birefringent optical material. Because of it’s birefringence, it is used for polarizing components such as waveplates and polarizers. Although it’s birefringence is lower than that of mica, it is unpractical for the production of true zero order retardation plates because – unlike mica – it cannot be cleaved, and other optical production methods are not available for the required thinness of retardation plates.
Pure Quartz (crystalline SiO2) Properties
Property
| Unit
| ‖ c
| typ. / bulk | ⊥ c |
General |
|
|
|
|
Colour |
|
| clear |
|
Crystal structure |
|
| trigonal |
|
Mechanical |
|
|
|
|
Density | g/cm3 |
| 2.65 |
|
Hardness - Mohs |
|
| 7 |
|
Shear modulus | GPa |
| 31 |
|
Compressive strength | GPa |
| 36 |
|
Modulus of elasticity | GPa | 97.2 |
| 76.5 |
Thermal |
|
|
|
|
Specific heat | J/(g•K) |
| 0.733 |
|
Thermal conductivity | W/(m•K) | 10.7 |
| 6.2 |
Coefficient of thermal expansion | 
|  |
| 
|
Melting point | °C |
| 1723 |
|
Boiling point | °C |
| 2230 |
|
Electrical |
|
|
|
|
Dielectric constant |
| 4.34 |
| 4.27 |
Optical |
|
|
|
|
Refractive index no (633 nm) |
|
| 1.543 |
|
Refractive index ne (633 nm) |
|
| 1.552 |
|
Birefringence (633 nm) |
|
| 0.0091 |
|
Specific optical rotation | °/mm |
| 21…28 |
|