Cryptocrystalline form of silica. Composed of extremely fine (submicroscopic) crystals of
Amorphous: Solid material that is composed of randomly orientated atoms, ions,
or molecules that do not form defined patterns or lattice structures (non-crystalline).
Chalcedony: Cryptocrystalline silica. Composed of extremely fine
(submicroscopic) silica crystals.
Citation: Under Section 17 of the Occupational Safety and Health Act, OSHA is
authorized to give citations to employees. Citations describe the item or items within the
workplace that do not comply with OSHA regulations, date when the items must be corrected,
and any associated fine or penalty. Employer and employee rights and responsibilities are
also included in the citation.
Chert: Cryptocrystalline silica. Composed of extremely fine (submicroscopic)
Colloidal Silica: Extremely fine amorphous silica particles dispersed in water.
Colloids do not settle out of suspension over time. Colloidal silica is used commercially
as binders and stiffeners and as polishing agents.
Cristobalite: The form of crystalline silica that is stable at the highest
temperature. It occurs naturally in volcanic rock.
Crystalline: Solid material composed of regularly repeating atoms, ions, or
molecules that form defined patterns or lattice structures.
Diatomaceous Earth: See Diatomite.
Diatomite: A rock, high in amorphous silica content, formed from the structures
of tiny fresh- and salt-water organisms called diatoms. Diatomite has several commercial
Fumed Silica: An amorphous form of silica formed by the combustion of silicom
tetrachloride in hydrogen-oxygen furnaces.
Fused Quartz: The material formed by the rapid melting of quartz crystals. A
meteor strike or a lightning bolt striking sand can form fused quartz. The term quartz
glass is often erroneously used to mean fused quartz, but quartz glass is a misnomer
because quartz is crystalline and glass is noncrystalline.
Fused Silica: The material formed by heating cristobalite to the melting point
(1710° C) and cooling it rapidly.
Jasper: Cryptocrystalline silica. Composed of extremely fine (submicroscopic)
Label: 29 CFR 1910.1200 (Manufacturer's Responsibility)
(f) "Labels and other forms of warning." (1) The chemical manufacturer,
importer, or distributor shall ensure that each container of hazardous chemicals leaving
the workplace is labeled, tagged or marked with the following information: (i) Identity of
the hazardous chemical(s); (ii) Appropriate hazard warnings; and (iii) Name and address of
the chemical manufacturer, importer, or other responsible party.
29 CFR 1910.1200 (Employer's Responsibility)
(I) Employers shall ensure that labels on incoming containers of hazardous chemicals
are not removed or defaced;
Material Safety Data Sheet: 29 CFR 1910.1200
Manufacturer's Responsibility: (1) Chemical manufacturers and importers shall obtain or
develop a material safety data sheet for each hazardous chemical they produce or import.
Employers shall have a material safety data sheet in the workplace for each hazardous
chemical they use. (2) Each material safety data sheet shall be in English (although the
employer may maintain copies in other languages as well), and shall contain at least the
(I) The identity used on the label, and, except as provided for in paragraph (I) of
this section on trade secrets:
29 CFR 1910.1200(g)(2)(I)(A)
(2) The chemical and common name(s) of all ingredients which have been determined to be
health hazards, and which comprise less than 1% (0.1% for carcinogens) of the mixture, if
there is evidence that the ingredient(s) could be released from the mixture in
concentrations which would exceed an established OSHA permissible exposure limit or ACGIH
Threshold Limit Value, or could present a health risk to employees; and,
(3) The chemical and common name(s) of all ingredients which have been determined to
present a physical hazard when present in the mixture;
(ii) Physical and chemical characteristics of the hazardous chemical (such as vapor
pressure, flash point);
(iii) The physical hazards of the hazardous chemical, including the potential for fire,
explosion, and reactivity;
(iv) The health hazards of the hazardous chemical, including signs and symptoms of
exposure, and any medical conditions which are generally recognized as being aggravated by
exposure to the chemical;
(v) The primary route(s) of entry;
(vi) The OSHA permissible exposure limit, ACGIH Threshold Limit Value, and any other
exposure limit used or recommended by the chemical manufacturer, importer, or employer
preparing the material safety data sheet, where available;
(vii) Whether the hazardous chemical is listed in the National Toxicology Program (NTP)
Annual Report on Carcinogens (latest edition) or has been found to be a potential
carcinogen in the International Agency for Research on Cancer (IARC) Monographs (latest
editions), or by OSHA;
(viii) Any generally applicable precautions for safe handling and use which are known
to the chemical manufacturer, importer or employer preparing the material safety data
sheet, including appropriate hygienic practices, protective measures during repair and
maintenance of contaminated equipment, and procedures for clean-up of spills and leaks;
(ix) Any generally applicable control measures which are known to the chemical
manufacturer, importer or employer preparing the material safety data sheet, such as
appropriate engineering controls, work practices, or personal protective equipment;
(x) Emergency and first aid procedures;
(xi) The date of preparation of the material safety data sheet or the last change to
(xii) The name, address and telephone number of the chemical manufacturer, importer,
employer or other responsible party preparing or distributing the material safety data
sheet, who can provide additional information on the hazardous chemical and appropriate
emergency procedures, if necessary.
(ii) Employers shall maintain copies of any material safety data sheets that are received
with incoming shipments of the sealed containers of hazardous chemicals, shall obtain a
material safety data sheet as soon as possible for sealed containers of hazardous
chemicals received without a material safety data sheet if an employee requests the
material safety data sheet, and shall ensure that the material safety data sheets are
readily accessible during each work shift to employees when they are in their work area(s)
Opal: An amorphous form of silica.
PPE: Personal protective equipment used to prevent worker exposure to silica.
This includes respirators, hoods, gloves, goggles, etc.
29 CFR 1910.1200: Occupational Safety and Health Administration's Hazard
Permissible Exposure Limit (PEL): This is the airborne concentration of silica
above which employees can not be exposed.
Precipitated Silica: Amorphous silica that is precipitated from either a vapor
Quartz: The most common type of crystalline silica. Some publications will use
quartz and crystalline silica interchangeably, but the term crystalline silica actually
encompasses several forms: quartz, cristobalite, tridymite, and several rarer forms. Also
the term sand is used interchangeably.
Radiolarian Earth: Soil, high in amorphous silica content, composed
predominantly from the remains of radiolaria. Radiolarian earth that has been consolidated
(hardened) into rock is called radiolarite.
Radiolarite: A rock, high in amorphous silica content, formed from the shells of
tiny fresh- and salt-water organisms called radiolaria.
Silica: The common name for silicon dioxide. A compound formed from silicon and
oxygen. Silica is a polymorph, that is, it exists in more than one state. The states of
silica are crystalline and noncrystalline (also called amorphous). Crystalline silica can
take several forms: quartz (most common), cristobalite, tridymite, and four rare forms.
Silica Brick: Brick composed of silica that is used as a lining in furnaces.
Silica Gel: Amorphous silica, prepared in formation with water. Removal of the
liquid creates xerogels and further treatment with alcohol creates aerogels. Silica gels
are used as drying agents and to alter viscosity of liquids.
Silica Flour: Finely ground quartz, typically 98% of the particles are below 55
microns in diameter.
Silica Sand: A common term in industry. It generally is used to mean a sand that
has a very high percentage of silica, usually in the form of quartz. Silica sand is used
as a source of pure silicon and as a raw material for glass and other products. Also
called quartz sand.
Silicate: A common name for compounds that are composed of atoms of slicon,
oxygen, one or more metals and possibly hydrogen. Many natural minerals are silicates.
Tridymite: A form of crystalline silica. It is found in nature in volcanic rocks
and stony meteorites. It is also found in fired silica bricks.
Tripoli: (rottenstone) Soft decomposed rock that may contain crystalline
(quartz) or amorphous forms of silica.