Technical Glass Products, Inc. (TGP)

World Leaders in the
Fabrication & Distribution of Fused Quartz

Opaque Quartz Labware

The opaque quality comes from quartz sands of high purity when reduced to a molten state at a temperature of
approximately 2000° C. The high temperature produces a vitreous material characterized by the presence of a multitude of
gaseous micro-bubbles. These bubbles diffract light, giving the material its opacity. The term opaque silica is mainly
used for molded or centrifuged parts, while the product obtained by drawing is normally referred to as translucent.

Opaque silica glass offers a number of exceptional properties, such as:

  • Extreme Hardness
  • Low Expansion
  • Excellent High Temperature Resistance
  • Maximum Continuous Temperature 1100° C
  • Extreme Chemical Purity
  • Excellent Corrosion Resistance
  • Excellent Electrical Insulation Properties
  • Remarkable Stability Under Atomic Bombardment


Specific Density (according to fusion process)
1.98 to 2.12


Hardness (Mohs scale)
Rupture stress: traction N.m-2 2.107
  compression N.m-2 5.108


Dielectric constants        3.5
Dielectric rigidity V.m-1 5.106
Loss coefficients at 1 MHz   20.10-4


Linear expansion coefficient  K-1 5.4.10-7
Specific heat at 20° C K-1 7.5.102
Heat conductivity at 20° C W.m-1. K-1 1.05
Annealing point ° C 1120
Softening point ° C 1460


SiO2 content       % 99.8
Element content (typical analysis) Fe ppm 14
  Ti ppm 100
  Al ppm 550
  Ca ppm 40
  Mg ppm 11
  Na ppm 25
  K ppm 20
  Li ppm 5