Fuse quartz and fused silica are types of glass containing primarily silica in amorphous (non-crystalline) form. They are manufactured using several different processes. Note that glasses formed by the traditional 'melt-quench' methods (heating the material to melting temperatures, then rapidly cooling to the solid glass phase), are often referred to as 'vitreous', as in 'vitreous silica'. The term 'vitreous' is synomynous with 'glass', when used in the melt-quench context.