The chemical compound silicon dioxide, commonly referred to as silica, is found in nature in the form of sand and quartz, both plentiful on this planet. It is processed into several forms: pyrogenic silica, colloidal silica, silica gel and aerogel. Pyrogenic silica is produced in a flame in which amorphous silica is fused into secondary particles which then agglomerate into tertiary particles; it is used as a thickening and anticaking agent, primarily for viscosity in paints, inks, artificial adhesives and in unsaturated polyester resins. Colloidal silica comes from a multi-stage process where an alkali-silica mixture is neutralized, producing a colloidal suspension which is then concentrated by evaporation; the resultant powder can be used as an abrasive, a chemical catalyst, an absorbent, and a surfactant. Perhaps the most important use of colloidal silica by colonists lays in the manufacture of “quantum dots,” very small semi-conductors. Silica gel is a granular, vitreous form used in food processing (primarily as a desiccant) and in chromatography. Aerogel, occasionally referred to as “frozen smoke,” is a synthetic, ultralight, porous solid produced from gel; the material has extremely low density and low thermal conductivity. Aerogel has a wide range of applications: in spacecraft and satellites, in particle physics as Cherenkov effect radiators, as nanocomposites, as drug-delivery systems, as chalcogels in absorbing heavy metal pollutants, and in production of superfluid helium-3, to name a few.