July, 2003
Inspection News and Views from the American Society of Home Inspectors

Asbestos Contamination in Vermiculite


Following is information from the EPA. Consumer information on vermiculite attic information.

Asbestos contamination in vermiculite and vermiculite products has become a national concern to federal agencies and to many private citizens throughout the country. A tremendous amount of information has been made available to the public via print, television/radio and the Internet. EPA’s vermiculite pages provides users with basic information about Vermiculite and its uses, fact sheets, Q&A documents, reports and links to EPA Regional vermiculite pages.   

Vermiculite and Its Uses

What is vermiculite?
Vermiculite is the mineralogical name given to hydrated laminar magnesium-aluminum-ironsilicate which resembles mica in appearance. All vermiculite ores contain a range of other minerals that were formed along with the vermiculite in the rock. Vermiculite ores from some sources have been found to contain asbestos minerals but asbestos is not intrinsic to vermiculite and only a few ore bodies have been found to contain more than tiny trace amounts.

Vermiculite mines are surface operations where ore is separated from other minerals, and then screened or classified into several basic particle sizes. Vermiculite is found in various parts of the world. Locations of the predominant commercial mines are in Australia, Brazil, China, Kenya, South Africa, USA and Zimbabwe.

When subjected to heat, vermiculite has the unusual property of exfoliating or expanding into worm-like pieces (the name vermiculite is derived from the Latin ‘vermiculare’ - to breed worms). This characteristic of exfoliation, the basis for commercial use of the mineral, is the result of the mechanical separation of the layers by the rapid conversion of contained water to steam. The increase in bulk volume of commercial grades is 8 to 12 times, but individual flakes may exfoliate as many as 30 times. There is a color change during expansion that is dependent upon the composition of the vermiculite and furnace temperature.

How is vermiculite used?
Vermiculite has been used in various industries for over 80 years. It is used in the construction, agricultural, horticultural and industrial markets.

Acoustic finishes, Loft insulation, Gypsum plaster, Fire protection, Air setting binder board, Sound deadening compounds, Floor and roof screed (lightweight insulating concrete)
Animal feed, Pesticides, Anti-caking material, Bulking agent, Seed encapsulant,    Fertilizer, Soil conditioner

Blocking mixes, Seed germination, Hydroponics, Micro-propagation, Sowing composts, Root cuttings, Potting mixes, Twin scaling bulbs, Seedling wedge mix

Absorbent packing, Castables, Dispersions, Furnaces, Molded products, Drilling muds, Insulation, Filtration, Paints, Fireproof safes, Perfume absorbent, Sealants, Nuclear waste disposal, Molten metal insulation, Fixation of hazardous materials, Insulation blocks and shapes, Brake pads and brake shoes