Fused Silica and Fused Quartz are two terms often used interchangeably, but they actually possess distinct definitions and properties. Fused Silica is synthesized by the oxidation of high purity silicon. This process results in a material made up almost entirely of Silicon Dioxide (SiO2), also known as pure silica. On the other hand, Fused Quartz is produced by melting naturally occurring crystalline quartz. Both materials are types of silica glass, known for their exceptional resistance to thermal shock and their high working and melting temperatures.