Specialists in the field of technical glass working img
Basic parameters of quartz glass:

Density 2.203 g/cm3
Hardness 5.3–6.5 (Moh's scale)
Tensile strength 48,3 MPa
Compression strength > 1.1 GPa
Thermal expansion coefficient 5.5×10-7 cm/(cm·K)
Heat conduction coefficient 1.3 W/(m·K)
Heat capacity 45,3 J/mol
Softening point 1665 °C
Annealing point 1140 °C
Strain point 1070 °C
Maximum working temperature 1100 °C