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Fused Silica (Fused Quartz)

Fused silica is a glass-type material. It has a fairly low density among the glass and glass-ceramics in the database.

The properties of fused silica include two common variations. This page shows summary ranges across both of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare fused silica to other glass and glass-ceramics (top) and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Compressive (Crushing) Strength

1100 MPa 160 x 103 psi

Elastic (Young's, Tensile) Modulus

73 GPa 11 x 106 psi

Flexural Strength

67 MPa 9.7 x 103 psi

Knoop Hardness


Poisson's Ratio


Shear Modulus

31 GPa 4.5 x 106 psi

Tensile Strength: Ultimate (UTS)

50 MPa 7.2 x 103 psi

Thermal Properties

Maximum Temperature: Decomposition

1100 °C 2010 °F

Maximum Temperature: Mechanical

1080 °C 1980 °F

Melting Onset (Solidus)

1900 °C 3450 °F

Specific Heat Capacity

720 J/kg-K 0.17 BTU/lb-°F

Thermal Conductivity

1.4 W/m-K 0.79 BTU/h-ft-°F

Thermal Expansion

0.5 µm/m-K

Electrical Properties

Dielectric Constant (Relative Permittivity) At 1 MHz


Dielectric Strength (Breakdown Potential)

30 kV/mm 1.2 V/mil

Electrical Dissipation At 1 MHz


Electrical Resistivity Order of Magnitude

14 10x Ω-m

Otherwise Unclassified Properties


2.2 g/cm3 140 lb/ft3

Light Transmission Range

0.16 to 3.5 µm

Refractive Index


Common Calculations

Stiffness to Weight: Axial

18 points

Stiffness to Weight: Bending

63 points

Strength to Weight: Axial

6.3 points

Strength to Weight: Bending

14 points

Thermal Diffusivity

0.85 m2/s

Thermal Shock Resistance

97 points

Followup Questions

Further Reading

Ceramic and Glass Materials: Structure, Properties and Processing, James F. Shackelford and Robert H. Doremus (editors), 2008

Glass: Mechanics and Technology, Eric Le Bourhis, 2007

Handbook of Optical Materials, Marvin J. Weber, 2003

Handbook of Optical Constants of Solids, Edward D. Palik (editor), 1998

Ceramics and Composites: Processing Methods, Narottam P. Bansal and Aldo R. Boccaccini (editors), 2012