Vermiculite is a naturally forming mineral noted for its industrial uses. It resembles mica in appearance and vermiculite ores contain a number of other minerals formed with the rock and some formations can include asbestos.
When heated Vermiculite has the odd ability to exfoliate and expand into worm like pieces often increasing 8 to 15 times their original bulk volume. The mineral's name is actually derived from the Latin "vermiculare" - to breed worms.
Vermiculite is found across the globe including Australia, Brazil, China, Kenya, South Africa, The United States, and Zimbabwe. It is commonly used in construction, agriculture, and as domestic insulation.
A large portion of the world's supply of Vermiculite was mined in Libby, Montana during the 1960s up until 1990 by the W.R. Grace Company. The vermiculite ore was then processed at nearly 50 facilities across North America and sold under the name Zonolite as insulation.
It was later found that the Vermiculite mined from that area had been contaminated by an asbestos deposit. The contamination sickened and claimed the lives of many Libby residents which forced W.R. Grace into bankruptcy protection resulting from numerous lawsuits filed on behalf of victims.
In subsequent years a number of agencies have launched informational campaigns to educate homeowners on risks associated with contaminated vermiculite insulation.
Estimates on the number of affected homes is generally in the tens of millions. If you believe your home may be affected, the best thing to do is not to disturb the insulation as that may release asbestos fibers into the air.
Uses of Vermiculite
Agriculture and Gardening
List of Materials Often Used with Vermiculite