Colorless crystals or white amorphous powder. Silica is one of the most abundant natural materials in the earth's crust. In its purest form, silica, or silicon dioxide, occurs as crystalline Quartz. The more common, but less pure, forms are Quartzite, Sandstone, Flint, Agate, and Sand. The fossil form of silica is Diatomaceous earth. All forms of silica are inert, unaffected by heat, insoluble in strong acids (except hydrofluoric) and slowly attacked by strong alkalis. Silica is not commonly used as a pigment, however, it is found in grounds, primers and wood fillers. Silica is used in the manufacture of glass, water glass, abrasives, ceramics and enamelware.
|Silica||Pure silica is crystalline silicon dioxide found in nature as as quartz. Variations due to temperature and pressure produce amorphous, vitreous or glassy forms of silica.||quartz, sand, quartzite, sandstone, flint agate, diatomaceous earth||production of glass and ceramics; use as a filler in concrete; as an abrasive|
|Fumed silica||A white fluffy powder containg a colloidal form of silica produced by burning silicon tetrachloride. Untreated fumed silica is hydrophilic, but many commercial products are treated to make them hydrophobic||Aerosil; Cab-O-Sil; HDK; Zandosil; Reolosil; Orisil; XYSIL||thixotropic thickener, anti-caking agent, filtration; desiccant to kill insects|
|Silica gel||An amorphous, porous form of silica available as granules or beads. It has a strong affinity for water.||Grade 40; Grade 42; Arten Gel; Art-Sorb: Britesorb; MoisturePak; Prosorb; Rhapid Gel; Rhapid Pak; Sorb-It||desiccant, sorbent, humidity buffering|
Synonyms and Related Terms
silicon dioxide; silicic anhydride; quartz; silex; diatomaceous earth; flint; diatomite; sand; quartzite; sandstone; amethyst; jasper, chalcedony; agate; onyx; tridymite; opal; cristobalite; Pigment White 27; Siliziumdioxid (Deut.); Kieselgur (Deut.); Kieselerde (Deut.); silice (Fr., Esp., It.); chalazias (Gr.); kwarts (Ned.); sílica (Port.)
- Toxic by inhalation.
- Chronic exposure to dust may cause silicosis
Physical and Chemical Properties
- Soluble in hydrofluoric acid.
- Density (g/ml) = 2.2 (amorphous) and 2.65 (quartz).
|Melting Point||1710 C|
|Boiling Point||2230 C|
Resources and Citations
- Wikipedia: Silicon dioxide Accessed July 2023
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