SiO2 is a covalent three dimensional network solid.
Silica (commonly known as quartz) is SiO2 which is usually used to manufacture glass, ceramics, piezoclectric materials. Most common use of silica is in water filtration. because of its uniform shape and size, it is an effective filtration bed that removes contaminants from water. SiO2 is less reactive due to high Si−O bond enthalpy.