Silicon dioxide, also known as silica (from the Latin silex), is an oxide of silicon with the chemical formula SiO2 ,
most commonly found in nature as quartz SiO2 and in various living organisms. In many parts of the world,
silica is the major constituent of sand. Silica is one of the most complex and most abundant families of materials,
existing as a compound of several minerals and as synthetic product. Notable examples include fused quartz,
fumed silica, silica gel, and aerogels. It is used in structural materials, microelectronics as component in the food
and pharmaceutical industry.
Fumed silica also known as pyrogenic silica is a very fine particulate or colloidal form of silicon dioxide. It is
prepared by burning SiCl4 in an oxygen-rich hydrogen flame to produce a "smoke" of SiO2.
The majority of optical fibers for telecommunication are also made from silica. It is a primary raw material for
many ceramics such as earthenware, stoneware, and porcelain.
Food and pharmaceutical applications
Silica is a common additive in food production, where it is used primarily as a flow agent in powdered foods, or to
adsorb water in hygroscopic applications. It is the primary component of diatomaceous earth. Colloidal silica is
also used as a wine, beer, and juice fining agent.
In pharmaceutical products, silica aids powder flow when tablets are formed.
Hydrated silica is used in toothpaste as a hard abrasive to remove tooth plaque.
Hydrophobic silica is used as a defoamer component.