Silicon dioxide, or silica, is a chemical compound that is the main component of sand, glass and quartz. By processing sand at high temperatures, glass is formed. Sand, and therefore glass, may also contain other minerals.
Quartz is formed from larger crystallized lumps of silica and has a milky transparency. When a voltage is applied to quartz, the quartz vibrates at a regular oscillation meaning it can be used as a timer. Alternatively, applying pressure to quartz produces electricity.
The chemical formula of silicon dioxide is SiO2, which is two oxygen atoms per silicon atom. Silica is a simple compound but one that has many uses in its different forms.