What's the Composition of Fused Silica Glass?
Fused silica is composed exclusively of high-purity silica (SiO2) in amorphous (non-crystalline) form. In contrast, other common glasses (Borosilicate, soda-lime, pyrex...etc.) are mixed composition glasses – in addition to SiO2, they include such ingredients as Na2O, CaO, and B2O3.

Properties of Fused Silica

Mechanical Properties
Density		2.20±0.02 g/cm3	Bulk modulus	36 GPa
Young's modulus		72 GPa	Poisson’s ratio	0.17
Shear modulus		32 GPa	Knoop Hardness	550 kg/mm2
Compressive strength		1.2 GPa	Mohs	5-6
Bending strength		85 N/mm2	Stress optical coefficient	3.4× 10–121/Pa
Ultrasonic Transversal		3.75×103m/sec	Ultrasonic Longitudinal	5.95×103m/sec

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