Hazard
Avoid inhalation of fine particles.
Potential Exposure
Cristobalite is used in the manufacture of water glass, refractories, abrasives, ceramics and enamels. Quartz is used as a mineral, natural or synthetic fiber. Tridymite is used as a filtering and insulating media and as a refractory material for furnace linings. Workers are potentially exposed to crystalline silica in such industries as granite quarrying and cutting, foundry operations; metal, coal, dentistry, painting, and nonmetallic mining; and manufacture of clay and glass products.
First aid
If this chemical gets into the eyes, remove any contact lenses at once and irrigate immediately for at least 15 minutes, occasionally lifting upper and lower lids. Seek medical attention immediately. If this chemical contacts the skin, remove contaminated clothing and wash immediately with soap and water. Seek medical attention immediately. If this chemical has been inhaled, remove from exposure, begin rescue breathing (using universal precautions, including resuscitation mask) if breathing has stopped and CPR if heart action has stopped. Transfer promptly to a medical facility. When this chemical has been swallowed, get medical attention. Give large quantities of water and induce vomiting. Do not make an unconscious person vomit.
Incompatibilities
Violent reactions with powerful oxidizers: fluorine, chlorine trifluoride; manganese trioxide; oxygen difluoride, hydrogen peroxide, etc.; acetylene; ammonia.
Chemical Properties
granular abrasive solid of varied colour, depending upon other
Chemical Properties
Silicon dioxide/crystalline silica is a component of many mineral dusts and materials which melts to a glass at very high temperature.
Waste Disposal
Sanitary landfill
Occurrence
QUARTZ is the mineral quartz, oxide of the nonmetallic element silicon, is the commonest of minerals, and appears in a greater number of forms than any other. Its formula is SiO2. Quartz commonly occurs in prismatic hexagonal crystals terminated by a pyramid. This pyramid is due to the equal development of two rhombohedrons, and may be observed in cases where one rhombohedron predominates. Cleavage is not observed; the fracture is typically conchoidal; hardness is 7; specific gravity, 2.65; luster, vitreous to greasy or dull; colorless to white, pink, purple, yellow, blue, green, smoky brown to nearly black; transparent to opaque.
Characteristics
Silica can exist in either a crystalline or noncrystalline form. In quartz, SiO2 exists in the natural crystalline state and possesses long-range order, with the silicon atom covalently bonded to oxygen atoms in a tetrahedral arrangement in a regular repeating pattern. Glass is an example of noncrystalline silica. Although natural glasses exist, silica glasses are produced when silica is heated to an elevated temperature and then rapidly cooled. The rapid cooling does not allow the SiO2 to form a regular crystalline structure with long-range order. The result is a solid that behaves like a viscous liquid when heated. Glass is sometimes called a solid solution and fl ows at a very slow rate. This can sometimes be seen in old window glass where the bottom is slightly thicker than the top. The actual structures form a three-dimensional tetrahedral pattern. Silica is sold as sand and its main uses are for glass; ceramics; foundry sand, a source of silicon in the chemical industry; as a filtration media; a filler/extender; an abrasive; and as an adsorbent.
Reactions
SiO2 shows strong absorption at 8.5 mm, 9.2 mm, and 12.5 mm (refer to the Silica) and SiO at 10.4 m. Thin films of SiO2 are fabricated by oxidizing the SiO in air after deposition of SiO by vacuum evaporation.
General Description
This Standard Reference Material (SRM) is intended for use in evaluating methods used to determine trace constituents in starting materials for the manufacture of glasses and similar products. This SRM is offered in 75 g units. For more information, please refer to the SDS and COA.
SRM 165A_cert SRM 165A _SDS
Health Hazard
Exposure to silica can result in the disease called silicosis. Silicosis is a disabling, nonreversible,
and sometimes fatal lung disease caused by overexposure to respirable crystalline
silica. In silicosis, silica particles enter the lung where they become trapped, producing areas
of swelling. The swelling results in nodules that become progressively larger as the condition
worsens. Silicosis is defi ned at several levels of severity: chronic silicosis, accelerated silicosis,
and acute silicosis. Chronic silicosis results from long-term (20 years) exposure to low
concentrations of silica, whereas acute silicosis is the result of a short-term exposure (a year
or less) to high concentrations. Symptoms may not be obvious in cases of chronic silicosis
and x-ray screening is recommended for at-risk groups. Th ese include sand-blasters, miners,
laborers who regularly saw, drill, and jack-hammer concrete, and general construction such as
tunnel drilling. In advanced stages of silicosis, individuals have difficulty breathing, especially
when active.
Industrial uses
Crushed and graded quartz is used as the abrasive in flint sandpapers. Almost any deposit of massive white quartz is suitable. Being the cheapest of all the abrasive-coated paper, this product is still sold in fair amounts, mainly in hardware stores and by small jobbers. It is made only in the form of paper, not as cloth. True chalk flint from England and France is used extensively for this purpose in Europe; it has better cutting qualities and longer life than ordinary quartz. Crushed and ground sand, sandstone, powdered quartz, and silt are sometimes used in hand soaps, scouring compounds, and harsher metal polishes.
Carcinogenicity
Silica was not mutagenic in bacterial
assays; both positive and negative results have
been reported in a wide variety of in vivo and
in vitro genotoxic assays.
Toxics Screening Level
The Initial Threshold Screening Level for crystalline silica is 3 μg/m3, with an annual
averaging time.
