Fused silica or fused quartz, is a glass powder made of amorphous silica. It is commonly used in the fiber optics and glass industries. Sieving fused silica can be a challenging process because typically fused silica is extremely fine, which by nature makes it harder to screen. The shape of fused silica determines what the best method of sieving is. Fused silica can be either angular or round and this is typically the most important factor when determining how to sieve fused silica.