What is Silicon Dioxide?

Silicon Dioxide aka Silica

Silicon dioxide, also known as silica, is a chemical compound of two of the most abundant chemical elements in Earth's crust, silicon (Si) and oxygen (O₂).

Made up of one atom of silicon and two of oxygen, the chemical formula for silicon dioxide is SiO₂. 

Silicon dioxide is most commonly found in nature as the mineral quartz. It's present in water, sand, animals, plants, and soil.

Silicon dioxide exists in many crystalline, and cryptocrystalline forms.  It can also be non-crystalline (amorphous).

In its purest form, the crystalline form of silicon dioxide, which is quartz, is colourless and transparent.  However, impurities can introduce many different colours.
Fibrous varieties of crystalline silicon dioxide are generally known as chalcedony.  Examples include agate, onyx, bloodstone and carnelian. 

Silicon dioxide is widely used in industry because its melting point is higher than copper, iron and aluminium.

It's used in the production of glass, optical fibres and as a raw material in whiteware ceramics, stoneware, porcelain, and industrial cement. Silicon dioxide is also used in toothpaste because its hardness helps remove plaque.

As a food additive, silicon dioxide protects dried foods from moisture and powdered foods from clumping or sticking together. 

The small white packets called silica gel, often found with new merchandise, contain grains of silicon dioxide.  These absorb moisture so protect whatever they're packed with.