crystalline silica encyclopedia

Mineral - Silicates, Crystalline, Structure: The silicates, owing to their abundance on Earth, constitute the most important mineral class. Approximately 25 percent of all known minerals and 40 percent of the …

The standard (29 CFR 1926.1153) requires employers to limit worker exposures to respirable crystalline silica and to take other steps to protect workers. Employers can either use a control method laid out in Table 1 of the construction standard, or they can measure workers' exposure to silica and independently decide which dust controls work ...

A silicate mineral (or silicate for short) is a mineral containing silicate structures; so silicate minerals can be classified according to their silicate structures as …

2. Occupational Exposure. Crystalline silica is the aetiological agent involved in the development of silicosis. It is a mineral found in the earth's crust, [] where it occurs in two distinctive forms: crystalline (quartz) and amorphous (diatom) [].Both crystalline and amorphous forms transform into tridymite at high temperatures …

Crystalline silica (silica) is found in sand, stone, concrete and mortar. It is also used to make a variety of products including engineered stone (used to fabricate kitchen and bathroom benchtops), bricks, tiles and some plastics. When workers cut, crush, drill, polish, saw or grind products that contain crystalline silica, dust particles are ...

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Reports. Crystalline Silica Primer. January 1, 1992. View Document. Crystalline silica is the scientific name for a group of minerals composed of silicon and …

The link between cumulative exposure to crystalline silica (including both quartz and cristobalite) and lung cancer was confirmed in 2001 in a pooled epidemiologic analysis of data from 10 studies, 2 including a cohort of workers in the diatomaceous earth industry. 27–29 Diatomaceous earth is the fossilized remains of certain algae whose cell ...

Silica. Also called silica sand or quartz sand, silica is silicon dioxide (SiO 2 ). Silicon compounds are the most significant component of the Earth's crust. Since sand is plentiful, easy to mine and relatively easy to …

Synonym: Silicon dioxide. •. Molecular Formula: SiO 2; crystalline silica, also called free silica, is defined as silicon dioxide (SiO 2 ). This molecular formula represents a very stable compound of silicon and oxygen, wherein Si is completely polymerized through Si O bonds in three dimensions. •.

A series of natural occurring crystalline silica modifications with well defined structures, such as quartz, tridymite, cristobalite, stishovite, and coesite is known. …

Amorphous silica, a three-dimensional, inorganic polymeric silicon dioxide, SiO2, does not have a crystalline structure as defined by the absence of definitive lines in X-ray diffraction ...

Table 4-4. Physical and Chemical Properties of Synthetic Amorphous Silica Compounds. Silica occurs naturally in crystalline and amorphous (or non-crystalline) forms, herein referred to as c-silica and a-silica, respectively. Silica has one general Chemical Abstract Service registry number (CASRN ) and more specific CASRNs for ...

Silica gel. Silica gel is a granular, porous form of silica, produced synthetically from sodium silicate. Despite the name, silica gel is a solid. It readily adsorbs water, making it extremely useful as a desiccant (drying …

Encyclopedia is a user-generated content hub aiming to provide a comprehensive record for scientific developments. All content free to post, read, share and reuse. ... Sarangi, M.; Nayak, P.; Tiwari, T. Effect of temperature on nano-crystalline silica and carbon composites obtained from rice-husk ash. Compos. Part B 2011, 42, 1994.

Background: Silicosis is a progressive and irreversible disease primarily caused by exposure to crystalline silica dust and, to a lesser extent, cigarette smoking. However, further research is needed to validate the potential combined effect of these risk factors on the increased incidence of the disease. Methods: A total of 1688 male workers …

Crystalline silica is the scientific name for a group of minerals composed of silicon and oxygen. The term crystalline refers to the fact that the oxygen and silicon atoms are arranged in a three- dimensional repeating pattern. This group of minerals has shaped human history since the beginning of civilization.

NIOSH Method 7602 – Silica, Crystalline, by IR. This method is recommended if there are minimal amounts of amorphous silica and silicates in the sample. There are potential interferences with this method that are difficult to identify without the help of an experienced geologist. NIOSH Method 7603 – Silica in Coal Mine Dust.

Define Crystalline silica. Crystalline silica synonyms, Crystalline silica pronunciation, Crystalline silica translation, English dictionary definition of Crystalline silica. n.

Overview. Crystalline silica is a common mineral found in the earth's crust. Materials like sand, stone, concrete, and mortar contain crystalline silica. It is also used to make products such as glass, pottery, ceramics, bricks, and artificial stone. Respirable crystalline silica – very small particles at least 100 times smaller than ordinary ...

In response, MDH developed a health-based guidance value for crystalline silica in the air and the Minnesota Pollution Control Agency (MPCA) received air quality monitoring data from silica sand facilities in Minnesota between 2012 and 2017. For more information, contact the MPCA at 651-296-6300 or 800-657-3864.

Anhydrous Crystalline Silicas Phosphoric acid does not react with anhydrous crystalline forms of Si02, AI2O3, Cr203, Z1O2 and Ti02 at room temperature. Some reaction occurs with the hydrated or colloidal forms of these oxides or with the anhydrous forms themselves if the temperature rises above about 200°C. Below this temperature silica glass is not …

When possible, choosing materials with a low quartz content is the most effective and cost-efficient way to prevent the respirable quartz exposure of workers and other end users of powdery products. Therefore, methods are needed to analyze low amounts of quartz from powdery products, such as sand, gravel, plaster, cement, and …

Silica minerals make up approximately 26 percent of Earth's crust by weight and are second only to the feldspars in mineral abundance. Free silica occurs in many crystalline forms with a composition very close to …

Silicon dioxide (SiO2), commonly known as silica, is a mineral that constitutes 59% of the Earth's crust by mass. It can be found in various natural sources such as soil, sand, granite, and concrete, and over 95% of known rock types on our planet. Silica exists in two primary forms: crystalline and non-crystalline, also known as amorphous.

The control measures that are the most effective for your workplace will depend on your industry, work processes and the risk of exposure. It is most likely you will need to use a range of control measures to protect your workers from exposure to respirable crystalline silica (RCS). You will also likely need air monitoring and health …

Occupational exposure to silica dust has been examined as a possible risk factor with respect to several systemic autoimmune diseases, including scleroderma, rheumatoid arthritis, systemic lupus erythematosus, and some of the small vessel vasculitidies with renal involvement (e.g., Wegener granulomatosis). Crystalline silica, …

silica silica or silicon dioxide, chemical compound, SiO2. It is insoluble in water, slightly soluble in alkalies, and soluble in dilute hydrofluoric acid. Pure silica is colorless to white. It occurs in several forms and is widely and abundantly distributed throughout the earth, both in the pure state and in silicates, e.g., in quartz (agate, amethyst ...

Silicon DioxideOVERVIEWSilicon dioxide (SILL-uh-kon dye-OK-side) is one of the most abundant chemical compounds on Earth. It makes up about 60 percent of the weight of the Earth's crust either as an independent compound (SiO2) or in combination with metallic oxides that form silicates. Silicates are inorganic compounds whose negative part is the …

Respirable crystalline silica, primarily quartz dusts occurring in industrial and occupational settings, is known to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in humans. Respirable crystalline silica was first listed in the Sixth Annual Report on Carcinogens in 1991 as reasonably anticipated to be a …

The name silicon derives from the Latin silex or silicis, meaning "flint" or "hard stone."Amorphous elemental silicon was first isolated and described as an element in 1824 by Jöns Jacob Berzelius, a Swedish chemist.Impure silicon had already been obtained in 1811. Crystalline elemental silicon was not prepared until 1854, when it was …

1. for a-quartz and coesite at high pressure are shown in Fig. l. The diffraction pattern from the quartz sample at -20 GPa (Fig. 1 a) consisted of sharp lines that could be readily indexed as ...

Crystalline silica is a common mineral found in many naturally occurring materials and used in many industrial products and at construction sites. Materials like sand, concrete, stone and mortar contain crystalline silica. Crystalline silica is also used to make products such as glass, pottery, ceramics, bricks, concrete and artificial stone. ...

Silica (SiO 2) is a commonly occurring compound in nature and serves as a basic raw material for silicate ceramics and silicate glasses. It can exist in various …

Resources for Silica in Industry. Construction. Dentistry. Mining. Oil and Gas Extraction. Manufacturing. Last Reviewed: July 11, 2023. Source: National Institute for Occupational Safety and Health. This NIOSH Topic Page presents information and links to other resources about Silica and Silicosis, and provides information to help workers ...