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The chemical compound silicon dioxide, also known as silica, is the oxide of silicon, chemical formula SiO2. Siliceous is an adjective meaning "referring to silica"
In nature Silica is found in nature in several forms, including quartz and opal. In fact, it has 17 crystalline forms (see Nomenclature of Silica). The most common constituent of sand in inland continental settings and non-tropical coastal settings is silica, usually in the form of quartz because the considerable hardness of this mineral resists erosion. However, the composition of sand varies according to local rock sources and conditions. Variants found in high-pressure impacts are coesite and stishovite. Many forms of life contain silica structures (biogenic silica), including microorganisms such as diatoms, plants such as horsetail, and animals such as hexactinellid sponges. It is present in the cell walls of various plants (including edible ones) to strengthen their structural integrity. Silica is used in plaster, this can have health implications for plasterers' children when work clothes and kids clothes are washed together. Microscopic particles of glass are held in the clothing and rubbed against the skin causing abrasion scars that go undiaognosed at the doctors. Applications Silica is manufactured in several forms including: It is used in the production of various products. Health effects Inhaling crystalline silica dust can lead to silicosis or cancer. Homeopathic use Silicon dioxide (silica) is widely used as a homeopathic remedy to treat impure blood, boils, brittle nails and lack-lustre hair. The homeopathic usage of silicon dioxide was introduced in the 19th century by * Dr. Wilhelm Heinrich Schüßler (1821-1898) through his biochemic method of healing. There is no experimental or clinical evidence that homeopathic silica is of actual medical value. Chemistry Silicon dioxide is formed when silicon is exposed to oxygen (or air). A very thin layer (approximately 1 nanometer or 10 angstroms) of so-called 'native oxide' is formed on the surface when silicon is exposed to air under ambient conditions. Higher temperatures and alternate environments are used to grow well-controlled layers of silicon dioxide on silicon. Silicon dioxide is attacked by hydrofluoric acid (HF). HF is used to remove or pattern silicon dioxide in the semiconductor industry. Beau is made of Silica. Reference See also | ||||||||
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