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Fused Silica VS Quartz

Nov. 23, 2022

What is Fused Silica?

Fused silica is a glass that contains almost pure amorphous silica. This type of glass differs from other available glasses on a commercial scale because fused silica is produced with different compositions than other glasses. These compositions result in changes in the optical and physical properties of the glass, including lower melting temperatures. As a result, fused quartz has a higher working temperature, higher melting temperature, etc.

Fused Silica Optical Dome

What is Quartz?

Quartz is a mineral compound containing silicon and oxygen atoms. It contains molecules of silicon dioxide (SiO2). In addition, it is the most abundant mineral in the earth's crust. Although it contains SiO2, the repeating unit of this mineral is SiO4. This is because the chemical structure of quartz contains one silicon atom bonded to four oxygen atoms surrounding it. Therefore, the geometry around the silicon atom is tetrahedral. However, the two tetrahedral structures share an oxygen atom between them. Therefore, the mineral has a hexagonal crystal system.

In addition, quartz crystals are chiral. This means that quartz exists in two forms, ordinary α-quartz and high-temperature β-quartz. α-type can be converted to β-type at about 573 °C. Visually, some quartz is colorless and transparent, while others are colored and translucent. The most common colors of this mineral are white, gray, purple and yellow.


Both fused quartz and quartz are extremely pure materials with very low thermal expansion and excellent optical properties. They both work well as high temperature viewing holes, optical windows and in areas where good chemical resistance is required.


The main difference between the two is that fused silica consists of non-crystalline quartz glass, while quartz is made of crystalline quartz. This difference gives fused silica a very high transmission in the UV spectrum compared to quartz. In addition, fused quartz is made by melting high purity silica sand containing quartz crystals, whereas quartz is naturally occurring and is industrially prepared by using quartz growth "seeds" (small pieces of carefully selected quartz).

CLZ Precision Optics is one of China's leading optical manufacturing companies. We manufacture a wide range of optical components for many different fields like Industrial Laser, Consumer products, Environmental Monitoring, Photography and Aerospace and R&D. If you want to know more information aboutfused silica, please contact us. We will provide professional answers.

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